Early Universe and AliCPT Forum

“早期宇宙与阿里原初引力波探测实验”线上论坛

This online forum aims to bring together researchers worldwide from all aspects of cosmology study including theories and observations to share their breakthroughs and to promote academic communications. With this forum, we also wish to conduct popular science lectures on the frontiers to the public. The topics of the forum include, but are not limited to, the latest developments on CMB theory and observations, cosmological parameters, the Hubble crisis, primordial gravitational waves, dark matter and dark energy, early universe models, cosmological phase transitions, and their underlying connections. The forum format will be held through online meeting apps, and under the premise of the speakers’ authorization, the live broadcast will be considered to allow more young students to enjoy the study.

本论坛旨在全球领域吸引宇宙学理论和观测的一线研究人员共同分享创新并促进国内外学术交流,以及面向社会大众进行宇宙学前沿的科普宣讲。论坛的主题包括但不限于CMB理论与观测、宇宙学参数、哈勃危机、原初引力波、暗物质暗能量、早期宇宙模型、宇宙学相变等专题的最新动态以及之间的科学关联。论坛形式将通过线上会议进行,并在报告人授权的前提下考虑结合线上直播的渠道让更多年轻学者获得学习的通道。

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2023-02-15 (Wednesday) 9:00 PM CST [Webinar]

Title: Tensions in cosmology and implications for the standard model
Speaker: Dr. Eleonora Di Valentino
Institutions: University of Sheffield (UK)

Short-bio:
Regarding my bio, I am a Royal Society Dorothy Hodgkin Research Fellow at the University of Sheffield (UK). Previous to this I've been an Addison-Wheeler fellow at Durham University (UK), a postdoc at the University of Manchester (UK), and a Lagrange fellow at the IAP in Paris (France). I had my PhD in Rome at "La Sapienza" University.

Abstract:
The scenario that has been selected as the standard cosmological model is Lambda Cold Dark Matter (ΛCDM), which provides a remarkable fit to the bulk of available cosmological data. However, discrepancies among key cosmological parameters of the model have emerged with different statistical significance. While some portion of these discrepancies may be due to systematic errors, their persistence across probes can indicate a failure of the canonical ΛCDM model. I will review these tensions, showing some interesting extended cosmological scenarios that can alleviate them.

Zoom Meeting: 833 9022 1307 Password: 782677
https://dooyle.zoom.us/j/83390221307?pwd=MGpnQWgzS3IzWmFjbGd4d2RXWWZzQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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Webinar 020 20230215

Speaker: Dr. Eleonora Di Valentino
Institutions: University of Sheffield (UK)
Title: Tensions in cosmology and implications for the standard model

Webinar 019 20230125

Speaker: Dr. Valerio De Luca
Institutions: University of Pennsylvania
Title: Tidal Love Numbers of Black Holes

Webinar 018 20230111

Speaker: Dr. Ricardo Z. Ferreira
Institutions: Institute for High Energy Physics,Autonomous University of Barcelona
Title: Primordial black holes and axions: a tale of (galactic and extragalactic) light

Webinar 017 20221221

Speaker: Dr. Albert Escrivà
Institutions: Nagoya University, Japan
Title: Simulation of Primordial Black Hole formation

Webinar 016 20221207

Speaker: Prof. Andrea Valerio Macciò
Institutions: New York University, Abu Dhabi
Title: Do we need to move beyond Cold Dark Matter?

Webinar 015 20221130

Speaker: Prof. Alexandre Refregier
Institutions: ETH Zürich, Switzerland
Title: Cosmological Weak Lensing

Webinar 014 20221116

Speaker: Prof. Roy Maartens
Institutions: University of Western Cape, South Africa
Title: Testing a key foundation of the concordance model

Webinar 013 20221026

Speaker: Prof. Aurel Schneider
Institutions: University of Zurich, Switzerland
Title: Precision Cosmology at Nonlinear Scales

Webinar 012 20221013

Speaker: Dr. Atsuhisa Ota
Institutions: The HKUST Jockey Club Institute for Advanced Study
Title: Scale-invariant enhancement of gravitational waves during inflation

Webinar 011 20220921

Speaker: Dr. Fangxia An
Institutions: Purple Mountain Observatory
Title: LOFAR+GMRT+ MeerKAT+VLA: Radio spectral properties at 150—5000MHz of star-forming galaxies

Webinar 010 20220914

Speaker: Dr. Yuber Perez-Gonzalez
Institutions: Fermi National Accelerator Laboratory
Title: Primordial Black Holes and Leptogenesis: An unexpected interplay

Webinar 010 20220817

Speaker: Dr. Tomohiro Fujita
Institutions: Waseda Institute for Advanced Study, Waseda University
Title: What can we learn from primordial gravitational waves?

Webinar 009 20220808

Speaker: Dr. Tao Liu
Institutions: Hong Kong University of Science and Technology
Title: Pulsar Polarization Arrays

Webinar 008 20220727

Speaker: Prof. Antonio De Felice
Institutions: Kyoto University
Title: Minimal theories and modified gravity models

Webinar 007 20220713

Speaker: Prof. Robert Brandenberger
Institutions: McGill University
Title: Emergent Cosmology from Matrix Theory

Webinar 006 20220629

Speaker: Prof. Nicolas Bernal
Institutions: Universidad Antonio Nariño in Bogotá, Colombia
Title: Dark Matter in the Time of Primordial Black Holes

Webinar 005 20220622

Speaker: Dr. Taishi Katsuragawa
Institutions: Institute of Astrophysics of Central China Normal University
Title: Compact Star in F(R) Gravity: Degeneracy Problem and Non-Integer Power Correction

Webinar 004 20220615

Speaker: Prof. Teruaki Suyama
Institutions: Tokyo Institute of Technology, Tokyo (Japan)
Title: Universal relation in the gravitational lensing of gravitational waves

Webinar 003 20220608

Speaker: Dr. Dong-Gang Wang
Institutions: University of Cambridge, UK
Title: Bootstrapping inflation: A new perspective towards cosmological correlators

Webinar 002 20220601

Speaker: Dr Reinoud Jan Slagter
Institutions: Asfyon, Astronomisch Fysisch Onderzoek Nederland and University of Amsterdam, The Netherland
Title: Alternative for Black Hole Paradoxes

Webinar 001 20220504

Speaker: Prof. Antonino Marciano (马安东 教授)
Institutions: Fudan University 复旦大学
Title: Emergent inflation from a Nambu–Jona-Lasinio mechanism in gravity with non-dynamical torsion

Open Lecture 001 20220521

Speaker: 袁业飞教授、薛涌泉教授、蔡一夫教授
Institutions: 中国科学技术大学
Title: 银河系中心的脉动——人马座A*黑洞照片的全面解读

Colloquium 003 20220525

Speaker: Prof. Chunshan Lin (林春山 教授)
Institutions: Jagiellonian University 雅盖隆大学
Title: Beyond Einstein: a journey in the swamp

Colloquium 002 20220518

Speaker: Prof. Mark Devlin (Mark Devlin 教授)
Institutions: University of Pennsylvania 宾夕法尼亚大学
Title: Current and Future Millimeter Wave Surveys of the Sky – From the Cosmic Microwave Background to the Local Universe

Colloquium 001 20220511

Speaker: Prof. Misao Sasaki (佐佐木节 教授)
Institutions: IPMU 数物连携宇宙物理学研究所
Title: Primordial Black Holes from Inflation

2023-01-25 (Wednesday) 9:00 PM CST [Webinar]

Title: Tidal Love Numbers of Black Holes
Speaker: Dr. Valerio De Luca
Institutions: University of Pennsylvania

Short-bio:
Bachelor and Master degree at the University of Pisa (Italy);

PhD at the University of Geneva (Switzerland) under the supervision of Prof. Antonio Riotto;

Postdoc researcher at the University of Pennsylvania (United States).

Abstract:
Tidal Love numbers describe the deformability of compact objects under the presence of external tidal perturbations, and are found to be exactly zero for black holes. We discuss about their connection to the weak gravity conjecture and investigate the scenario of black holes dressed with an ultralight scalar field, addressing their detectability at future gravitational wave experiments.

Zoom Meeting: 833 9022 1307 Password: 782677
https://dooyle.zoom.us/j/83390221307?pwd=MGpnQWgzS3IzWmFjbGd4d2RXWWZzQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2023-01-11 (Wednesday) 9:00 PM CST [Webinar]

Title: Primordial black holes and axions: a tale of (galactic and extragalactic) light
Speaker: Dr. Ricardo Z. Ferreira
Institutions: Institute for High Energy Physics, Autonomous University of Barcelona

Short-bio:
Ricardo is a Beatriu de Pinós fellow at IFAE, the Institute for High Energy Physics at the U. Autónoma of Barcelona in Spain. He obtained his PhD in 2016 at the CP3-Origins Institute, University of Southern Denmark, and has held postdoctoral positions at the U. Barcelona, Nordita (Stockholm) and IFAE (Barcelona). His research has been devoted to topics in the interface between cosmology, axion physics and gravity including inflation, gravitational waves and the cosmic microwave background.

Abstract:
Primordial black holes with asteroid-like masses (10^{14-18} kg) can still account for all the dark matter. In this talk, I will discuss a new indirect probe of PBH dark matter. I will show that axions with masses in the 0.1eV-MeV range can form in clouds around such PBHs, via superradiance, and ultimately decay, if coupled to photons. The decay products will contribute to the galactic or extragalactic background flux at frequencies between the UV and the gamma-rays, depending on the axion mass. I will show that current data already constraints a large range of parameters and that searches for narrow lines with future experiments such as the Athena X-ray telescope will further test this co-existence of PBH dark matter and axions. If time allows I will also discuss recent work on another probe of axion physics: gravitational waves.

Zoom Meeting: 833 9022 1307 Password: 782677
https://dooyle.zoom.us/j/83390221307?pwd=MGpnQWgzS3IzWmFjbGd4d2RXWWZzQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-12-21 (Wednesday) 3:00 PM CST [Webinar]

Title: Simulation of Primordial Black Hole formation
Speaker: Dr. Albert Escrivà
Institutions: Nagoya University, Japan

Short-bio:
Albert Escrivà is a JSPS postdoctoral fellow in the QG-lab at Nagoya University (Japan) since November 2022. Previously, he was a postdoctoral researcher at Brussels University (Belgium) for one year and finished his PhD in 2021 at the University of Barcelona (Spain). His current main research interest is devoted to the numerical simulation of primordial black holes.

Abstract:
Primordial Black Holes (PBHs) are black holes that could have been formed in the very early universe due to the collapse of large curvature fluctuations after inflation. PBHs are nowadays one of the most attractive and fascinating research areas in cosmology for their possible theoretical and observational implications. In this talk, I will review the physical process of PBH formation and its numerical simulation, focusing on the definition of "threshold for PBH formation" and its analytical estimation, which is essential to estimate the abundance of PBHs correctly. Moreover, I will present recent results about the formation of PBHs when a time-dependent equation of state is considered, which has a significant phenomenological impact compared with the standard case of a radiation-dominated era.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-12-07 (Wednesday) 9:00 AM CST [Webinar]

Title: Do we need to move beyond Cold Dark Matter?
Speaker: Prof. Andrea Valerio Macciò
Institutions: New York University, Abu Dhabi

Short-bio:
Andrea V. Macciò is a Professor of Physics at New York University, Abu Dhabi and the Director of the Center for Astro, Particle and Planetary Physics.

Professor  Macciò is interested in understanding the nature and origin of the mysterious dark components of our cosmos: dark energy and dark matter, which account for 95 percent of the total energy/matter budget of the universe. In order to achieve this goal, he studies the formation and evolution of galaxies in such a dark universe via large computer numerical simulations

Abstract:
Our current understanding of galaxy formation is based on the presence of an elusive matter component: the Cold Dark Matter (CDM) This simple model has ben challenged many times in the past decade, mainly by galaxy observations on small scales: from the abundance of satellites, to the distribution of dark matter within galaxies, and more recently by the discovery of galaxies "without" dark matter. In my talk I will first revise all these claims with the help of cosmological numerical simulations of galaxy formation from the NIHAO project. I will then discuss whether there is indeed an observationally motivated need to abandon Cold Dark Matter and move beyond such a simple model.

Zoom Meeting: 865 7871 0701 Password: Ustc1234
https://dooyle.zoom.us/j/86578710701?pwd=Q2p5UEsxWjJ4ZWs4RmlPbnRpczNsdz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-11-30 (Wednesday) 3:00 PM CST [Webinar]

Title: Cosmological Weak Lensing
Speaker: Prof. Alexandre Refregier
Institutions: ETH Zürich, Switzerland

Short-bio:
Prof. Alexandre Refregier obtained his PhD in Physics from Columbia University, New York, NY, USA in 1997. Following this, he was a postdoc at Princeton University, Princeton, NJ, USA (1997 – 1999) and the University of Cambridge, Cambridge, UK (1999 - 2002). He was then Astrophysicist at CEA Saclay, France (2002 – 2011) and is currently Professor at ETH Zürich, Switzerland since 2011. His research interest are cosmology, structure formation, gravitation lensing and statistical methods.

Abstract:
Weak gravitational lensing is a unique technique to map the distribution of dark matter in the universe. It is also a sensitive probe of dark energy, large scale structures in the universe, and cosmological parameters. We will first briefly describe the principles of weak lensing. We will then review the current observational status of this field, highlighting several new measurements and the resulting sigma8 tension between different cosmological probes. We will then present recent measurements of non-gaussian statistics based on human-made summaries and machine  learning at map-level.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-11-16 (Wednesday) 3:00 PM CST [Webinar]

Title: Testing a key foundation of the concordance model
Speaker: Prof. Roy Maartens
Institutions: University of Western Cape, South Africa

Short-bio:
Prof. Roy has held a Research Chair at the University of the Western Cape since 2011, which supports a team of students and postdocs working on cosmology with the SKA and other surveys. He got his PhD from the University of Cape Town in 1980 (advisor George Ellis). He was at the University of Portsmouth in the UK during 1994-2010, where he was the founding Director of the Institute of Cosmology & Gravitation, one of the top cosmology research groups in the UK. His main interests are in the nature and applications of general relativistic effects in cosmology.

Abstract:
Tensions in the observed values of some key parameters of the concordance model of cosmology may indicate problems in the model itself. This motivates further independent tests of the model. I will describe a test of a key foundation of the concordance model - the Cosmological Principle. According to the Cosmological Principle, the Universe should be statistically isotropic. In particular, isotropy in the CMB must be consistent with isotropy in the galaxy distribution. This means that the dipole in the CMB should agree in direction and amplitude with the dipole in the galaxies. Current results suggest that there is a significant tension between the amplitudes of these dipoles. I will discuss some theoretical and observational issues that remain to be clarified before this can be declared as a new tension.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-10-26 (Wednesday) 3:00 PM CST [Webinar]

Title: Precision Cosmology at Nonlinear Scales
Speaker: Prof. Aurel Schneider
Institutions: University of Zurich, Switzerland

Short-bio:
Prof. Aurel Schneider is an assistant professor at the University of Zurich, Switzerland, predominantly working on weak lensing and 21cm reionization science. Before this, he held research positions at ETH Zurich and the University of Sussex, United Kingdom.

Abstract:
Upcoming weak lensing and galaxy clustering surveys will push the frontier of cosmology towards small, highly nonlinear scales. I will discuss how to develop new theoretical tools to predict nonlinear structure formation (including baryons) at high precision. I will furthermore discuss how to apply these methods to current and future weak lensing surveys in order to learn something about cosmology, astrophysics, and the nature of dark matter.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-10-13 (Thursday) 9:00 AM CST [Webinar]

Title: Scale-invariant enhancement of gravitational waves during inflation
Speaker: Dr. Atsuhisa Ota
Institutions: The HKUST Jockey Club Institute for Advanced Study

Short-bio:
Ph.D. in Physics, Tokyo institute of Technology, March 2017

IAS Postdoctoral Fellow, The HKUST Jockey Club Institute for Advanced Study, October 2021-present

Postdoctral researcher, Physics & Astronomy Department, Ohio University, April 2020- September 2021

Oversea Research Fellow of the Japan Society for the Promotion of Science, DAMTP, University of Cambridge (main), April 2018 – March 2020

Research Fellow of the Japan Society for the Promotion of Science (PD), Department of Physics, Tokyo Institute of Technology, April 2017 – March 2018

Research Fellow of the Japan Society for the Promotion of Science (DC2), Department of Physics, Tokyo Institute of Technology, April 2016 – March 2017

Research interest: cosmological perturbation theory and aim to find new observational approaches to the early Universe and high energy physics.

Abstract:
The inflationary 1-loop tensor power spectrum from an excited spectator scalar field is calculated. Recent studies on primordial black holes suggest that the inflationary curvature perturbation may be huge on small scales. An enhanced curvature perturbation may arise from a drastic enhancement of spectator scalar field fluctuations. In this letter, using the in-in formalism, we calculate 1-loop quantum corrections to primordial gravitational waves by such an excited spectator field with a sharp peak in momentum space. We find scale-invariant loop corrections in this full quantum setup, in contrast to the sharply peaked corrections in the previously calculated scalar-induced tensor modes. Especially, on super Hubble scales, the primordial gravitational waves are also amplified, which can be understood as a Bogolyubov transformation of the vacuum due to the excited scalar field. This mechanism allows us to probe the scalar field properties on extremely short-distance scales with the current and future cosmic microwave background and gravitational wave experiments, opening a novel window for inflationary cosmology.

Zoom Meeting: 819 0963 7699 Password: 607973
https://dooyle.zoom.us/j/81909637699?pwd=NUdycmV6Ny9NWElOVzRBLzNUNHQ4dz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-09-28 (Wednesday) 3:00 PM CST [Webinar]

Title: LOFAR+GMRT+ MeerKAT+VLA: Radio spectral properties at 150—5000MHz of star-forming galaxies
Speaker: Dr. Fangxia An
Institutions: Purple Mountain Observatory

Short-bio:
Dr. Fangxia An is a postdoc fellow based at the Purple Mountain Observatory in Nanjing China from July 2022. She obtained her Doctoral degree from the Purple Mountain Observatory in Nov. 2018. During Oct. 2016 to Oct. 2018, she studied at Durham University in UK as a joint PhD student. During Feb. 2019 to May 2022, she worked at Inter-University Institute for Data Intensive Astronomy in South Africa as a postdoc fellow.

Her research interests are galaxies formation and evolution, galaxy clusters/proto-clusters, large-scale structures of galaxies.

Abstract:
A well-determined radio spectrum for star-forming galaxy (SFG) is critically important for studies that are based on rest-frame radio power, especially those at high-redshift where k-corrections are generally extrapolated the most. In this talk, I will introduce two of our recently completed projects based on the MeerKAT(SKA pathfinder)+VLA+GMRT data in the COSMOS field and the LOFAR+GMRT+JVLA data in the ELAIS-N1 field. I will present our measured radio spectral indices between the observer-frame frequencies of 150-400, 400-610, 400-1300MHz, 1.3-3GHz, and 610-5000MHz and show the correlations between radio spectrum and physical properties of radio-selected SFGs. With these results, I will discuss the possible physical mechanisms that determine the radio spectrum of SFGs. I will also show how the adoption of these different radio spectral indices (from low- and high-frequency) in k-correction affects the study of far-infrared-radio correlation of SFGs.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-09-14 (Wednesday) 3:00 PM CST [Webinar]

Title: Primordial Black Holes and Leptogenesis: An unexpected interplay
Speaker: Dr. Yuber Perez-Gonzalez
Institutions: Fermi National Accelerator Laboratory

Short-bio:
PhD --- University of São Paulo, Brazil, December 2017

Research Associate --- Fermi National Accelerator Laboratory, 2018 - 2021

Postdoctoral Researcher Associate --- Northwestern University, 2018 - 2021

Postdoctoral Researcher Associate --- IPPP, Durham University, 2021 - present.

Research Interests: Neutrimo Physics, Black Hole Physics, Particle Phenomenology in the Early Universe.

Abstract:
Black Hole evaporation offers a unique method of particle production, unlike any other interaction process. In the Early Universe, such an evaporation can affect the baryon asymmetry produced via leptogenesis since heavy right-handed neutrinos can be emitted independently of the properties of the primordial plasma. However, there is also a large amount of entropy injected, which could dilute the generated asymmetry. We will explore in detail this interplay between Primordial Black Holes and Leptogenesis, determining the regions of the parameter space where the evaporation increases or erases the asymmetry.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-08-17 (Wednesday) 3:00 PM CST [Webinar]

Title: What can we learn from primordial gravitational waves?
Speaker: Dr. Tomohiro Fujita
Institutions: Waseda Institute for Advanced Study, Waseda University

Short-bio:
PhD—Kavli IPMU, University of Tokyo, Chiba, Japan in March 2015

Postdoctoral Research Fellow— Tokyo Institute of Technology(April 2015) —Stanford Institute for Theoretical Physics(October 2015)—Kyoto University(2017) —Institute for Cosmic Ray Research (April 2020 )

In April 2021, he joined Waseda Institute for Advanced Study, Waseda University as an assistant professor. Won Young Scientist Award The Physical Society of Japan(2022)

Research Interests—Inflation, Gravitational waves, Dark matter, Large scale structure

Abstract:
Having many on-going and upcoming experiments to detect them, we hope primordial gravitational waves (PGWs) imprinted in CMB B-mode will be observed in the near future. PGWs produced during inflation are the unique probe for very high energy physics beyond the reach of particle accelerators, and now is a good time to study what we can learn from them. In this webinar, I will discuss that much more information than the energy scale of inflation can be extracted from PGWs by using a model as an example. In the model, SU(2) gauge fields coupled to axion generate detectable PGWs with distinguishable signatures such as non-Gaussianity and circular polarization.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-08-08 (Monday) 3:00 PM CST [Webinar]

Title: Pulsar Polarization Arrays
Speaker: Dr. Tao Liu
Institutions: Hong Kong University of Science and Technology

Short-bio:
Dr. Tao Liu's research focuses on particle physics and its connection with astronomy and cosmology. Dr. Tao Liu received his PhD in Physics at University of Pennsylvania in 2007. Then he hold a position of ``McCormick Fellow'' in Enrico Fermi Institute at University of Chicago during 2007-2010. After that, he moved to University of California at Santa Barbara to continue his postdoctoral research. He joined the Hong Kong University of Science and Technology (HKUST) in 2013 as a junior faculty. Now he is an associate professor at HKUST. He received the HKUST ``School of Science Research Award'' in 2016, and currently is the Project Coordinator/Principal Investigator of the Hong Kong UGC/RGC Collaborative Research Fund project ``Dark Matter and the Universe''.

Abstract:
Pulsar timing arrays (PTAs) consisting of widely distributed and well-timed millisecond pulsars can serve as a galactic interferometer to measure gravitational waves. With the same data acquired for PTAs, we have proposed (https://arxiv.org/abs/2111.10615) to develop pulsar polarization arrays (PPAs), to explore astrophysics and fundamental physics. As in the case of PTAs, PPAs are best suited to reveal temporal and spatial correlations at large scales that are hard to mimic by local noise. As a demonstration of the physical potential of PPAs, we considered the detection of ultralight axion-like dark matter (ALDM), through cosmic birefringence induced by its Chern-Simons coupling. Because of its tiny mass, the ultralight ALDM can be generated as a Bose-Einstein condensate, characterized by a strong wavy nature. In this talk, the speaker will give a detailed introduction to this topic and show how the PPAs can significantly enhance the detection of ALDM by correlating the their polarization data. 

Zoom Meeting: 879 6329 4916 Password: 129582
https://dooyle.zoom.us/j/87963294916?pwd=K2RSbmc0VnZPZWpkc1hTM2FyYi9nUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/235406

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2022-07-27 (Wednesday) 3:00 PM CST [Webinar]

Title: Minimal theories and modified gravity models
Speaker: Prof. Antonio De Felice
Institutions: Kyoto University

Short-bio:
Prof.Antonio took his Ph.D. in Syracuse University (NY, USA) with prof. Trodden. He has been a postdoctoral researcher in Sussex U. (Brighton, UK), Louvain U. (Louvain-la-Neuve, Belgium). Then he got a JSPS fellowship working at Tokyo U. of Science. Then he became a lecturer at IF (Naresuan U., Phitsanulok, Thailand). From the end of 2013 he has joined the Yukawa Institute For Theoretical Physics (Kyoto U.) as an associate professor. His research focuses on modified gravity models (applied to dark energy as well as inflation).

Abstract:
"I will describe the minimal theories and modified gravity I have been working recently on. In particular, I will describe why minimal theories might help resolve today's tensions in cosmology."

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-07-13 (Wednesday) 3:00 PM CST [Webinar]

Title: Emergent Cosmology from Matrix Theory
Speaker: Prof. Robert Brandenberger
Institutions: McGill University

Short-bio:
Professor of Physics, McGill University Department of Physics McGill University
Ph.D. in Physics, Harvard University, November 1983——

Professor of Physics, McGill University, Sept. 2004 -present
Professor of Physics, Brown University, July 1997 - June 2005
Associate Professor of Physics, Brown University, July 1991 to June 1997
Assistant Professor of Physics, Brown University, Sept. 1986 to June 1991
Postdoctoral Fellow, Dept. of Applied Mathematics and Theoretical Physics University of Cambridge, UK, October 1985 to August 1987
Postdoctoral Fellow, Institute for Theoretical Physics, University of California, Santa Barbara, Sept. 1983 to Sept. 1985

More than 400 publications with around 26000 citations.
More than 900 invited seminar and conference talks

Canadian Association of Physicists CAP Lifetime Achievement Award, 2021—
Canada Research Chair (Tier 1), Oct. 1 2004 - present

Research field: Theoretical cosmology

Abstract:
The Trans-Planckian Censorship Criterion and other arguments indicate that we need to go beyond an effective field theory analysis in order to understand the evolution of the very early universe. I will present a proposal to obtain an emergent metric space-time and an emergent early universe scenario from the BFSS matrix model, a proposed non-perturbative definition of superstring theory.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

Image

2022-06-29 (Wednesday) 3:00 PM CST [Webinar]

Title: Dark Matter in the Time of Primordial Black Holes
Speaker: Prof. Nicolas Bernal
Institutions: Universidad Antonio Nariño in Bogotá, Colombia

Short-bio:
Dr. Nicolás Bernal received his Ph.D. from Paris-Saclay University in 2008. After postdoctoral appointments at the University of Barcelona, Lisboa University, Bonn University, and ICTP-SAIFR, he joined Universidad Antonio Nariño in Bogotá, Colombia, as an associate professor. His research interests are dark matter, beyond standard model phenomenology, and particle cosmology.

Abstract:
Rotating black holes (BHs) can efficiently transfer energy to the surrounding environment via superradiance. In particular, when the Compton length of a particle is comparable to the gravitational radius of a BH, the particle’s occupation number can be exponentially amplified. In this work, we investigate the effect of the primordial-black-hole (PBH) superradiant instabilities on the generation of heavy bosonic dark matter (DM) with a mass above ∼ 1 TeV. Additionally, we analyze its interplay with other purely gravitational and therefore unavoidable DM production mechanisms such as Hawking emission and the ultraviolet freeze-in. We find that superradiance can significantly increase the DM density produced by PBHs with respect to the case that only considers Hawking emission, and hence lower initial PBH densities are required.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

Image

2022-06-22 (Wednesday) 9:00 AM CST [Webinar]

Title: Compact Star in F(R) Gravity: Degeneracy Problem and Non-Integer Power Correction
Speaker: Dr. Taishi Katsuragawa
Institutions: Institute of Astrophysics of Central China Normal University

Short-bio:
Dr. Taishi Katsuragawa received his Ph.D. from Nagoya University in 2017. After working in postdoctoral research positions at Kobayashi-Maskawa Institute and Central China Normal University, he joined in Institute of Astrophysics of Central China Normal University as an associate professor. His research interests are the modified gravity theory and its applications to particle cosmology and astrophysics.

Abstract:
The F(R) gravity is one of the extensions of general relativity, and it has been investigated in various research fields. This talk focuses on the astrophysical application and demonstrates that adjusting the F(R) function can construct an arbitrary mass-radius relation of the compact star because the model-dependence of the equation of state and modification of gravity degenerate to each other. We also see that a non-integer curvature power correction is naturally introduced when the Schwarzschild spacetime is chosen as a boundary condition, which gives guidelines for model-building in F(R) gravity. Comparing with the reconstruction method known in cosmology and higher-curvature corrections to avoid curvature singularities in the dark energy model, we consider some problems in the existing studies on compact stars and discuss the prospects for future studies.

Zoom Meeting: 874 6858 5677 Password: 838803
https://dooyle.zoom.us/j/87468585677?pwd=OHNsTkJCRktWRkZhekw3Y1MrVkhoZz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

Image

2022-06-15 (Wednesday) 3:00 PM CST [Webinar]

Title: Universal relation in the gravitational lensing of gravitational waves
Speaker: Prof. Teruaki Suyama
Institutions: Tokyo Institute of Technology, Tokyo (Japan)

Short-bio:
Prof. Teruaki Suyama is an associate professor at Tokyo Institute of Technology since 2018. He obtained his doctorate from Kyoto University in 2007, after which he did postdoctoral research at the University of Tokyo and Louvain University. Since 2012, he has been a faculty member at the Research Center for the Early Universe (U.Tokyo), until he was appointed the current position. His research interest is to (mainly theoretically) investigate the horizon of our understanding of cosmology and gravitational physics we could reach in the era of the gravitational-wave astronomy. He is a lover of Belgian beers.

Abstract:
Gravitational waves from the distant sources are gravitationally lensed during their propagation through the intervening matter inhomogeneities before arriving at detectors. In this talk, I first give an overview of the gravitational lensing of gravitational waves, followed by a proposal made in the literature that the variance of the lensed waveform can be used to extract information of the matter power spectrum at very small scales and of low-mass dark halos. I will then show that the variance of the amplitude fluctuation and that of the phase fluctuation of the lensed waveform obey a simple consistency relation irrespective of the shape of the matter power spectrum. I will discuss about conditions under which this relation can be violated and provide some potential applications of the relation.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/413819

Image

2022-06-08 (Wednesday) 7:00 PM CST [Webinar]

Title: Bootstrapping inflation: A new perspective towards cosmological correlators
Speaker: Dr. Dong-Gang Wang
Institutions: University of Cambridge, UK

Short-bio:
Dr. Dong-Gang Wang was a master student in USTC from 2013 to 2016. After that, he moved to Leiden University in the Netherlands for PhD as a de Sitter Fellow from 2016 to 2020. Now he is a postdoctoral researcher as a Rubicon Fellow at the Department of Applied Mathematics and Theoretical Physics in the University of Cambridge, UK. His research mainly focuses on the primordial cosmology. In particular he is interested in dissecting non-Gaussian statistics of primordial fluctuations by using the effective field theory and bootstrap approaches.

Abstract:
Correlation functions of primordial fluctuations provide us an exciting avenue into the physics with extremely high energy in the very early Universe. Recently the bootstrap approach has offered new perspectives and powerful tools to study these cosmological correlators. In this talk, I will first briefly review this subject. Then, by incorporating the latest developments, I will “bootstrap” two types of inflationary correlators, which are most relevant for the next-generation observations. The first one is the contact correlators arising from large self-interactions of the inflaton. The second is the cosmological collider bispectra from the massive exchange diagrams with all possible boost-breaking interactions. Applying the bootstrap approach, we derive for the first time not only a complete set of these correlators systematically, but also their full shape information analytically. Since the de Sitter boost symmetries are broken in our consideration, the sizes of signals are boosted to be detectable for near-future experiments. We identify new features in these non-Gaussianity shapes, which provide interesting targets for the data analysis of upcoming surveys.

Zoom Meeting: 834 6695 7596 Password: 395040
https://dooyle.zoom.us/j/83466957596?pwd=cDg2eURyd25BRUtGZjN5M1dZZGFJZz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

Image

2022-06-01(Wednesday) 9:00 PM CST [Webinar]

Title: Alternative for Black Hole Paradoxes
Speaker: Dr Reinoud Jan Slagter
Institutions: Asfyon, Astronomisch Fysisch Onderzoek Nederland and University of Amsterdam, The Netherland

Short-bio:
Researcher since 1974 in the field of cosmology, general relativity and quantum field theory
1980:Master at University of Utrecht, supervisor Prof. G, ‘t Hooft
1986: PhD at University of Amsterdam. Promotors Prof. K. Gaemers and Prof E. v/d Heuvel
Copromotor Prof G. ‘t Hooft
www.asfyon.com

Abstract:
A throughout investigation is made of the exact black hole solution in five-dimensional warped conformal dilaton gravity, found in an earlier investigation. The singularities of the dynamical black hole spacetime are determined by the zeros of a meromorphic quintic polynomial, which has no essential singularities.
The solutions of the polynomial are analyzed in the complex plane in relation to the icosahedron group and by the Hopf-fibrations of the Klein surface.
The model fits the antipodal boundary condition, i.e., antipodal points in the projected space are identified using the embedding of a Klein surface in ${C}^2$, using the ${Z}_2$ symmetry on the two sides of the brane.
If one writes $^{(5)}g_{\mu\nu}=\omega^{4/3}{^{(5)}}{\tilde g_{\mu\nu}}, {^{(5)}}{\tilde g_{\mu\nu}}={^{(4)}}{\tilde g_{\mu\nu}}+n_\mu n_\nu$, $ ^{(4)}\tilde g_{\mu\nu}=\bar\omega^2 {^{(4)}}\bar g_{\mu\nu}$, with $n_\mu$ the normal to the brane and $\omega$ the dilaton field, then ${^{(4)}}\bar g_{\mu\nu}$ is conformally flat.
It is the contribution from the bulk which determines the real pole on the effective four-dimensional spacetime.
There is no objection applying 't Hooft's back reaction method in constructing the unitary S-matrix for the Hawking radiation.
Again, there is no "inside" of the black hole.

Zoom Meeting: 840 9109 6731 Password: Ustc1234
https://dooyle.zoom.us/j/84091096731?pwd=d1JtRkVJRlBGV09xZ2g5SDRFZFVRQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/831059

Image

2022-05-25 (Wednesday) 4:30 PM CST  [Colloquium]

Title: Beyond Einstein: a journey in the swamp
Speaker: Prof Chunshan Lin
Institutions: Jagiellonian university 雅盖隆大学

Short-bio:
Prof. Chunshan Lin obtained his PhD degree in 2011, from the University of Science and Technology of China. He successively held postdoc positions in Tokyo University and Kyoto University between 2011 - 2017. In 2017 he joined the university of Warsaw as an assistant professor. He moved to Jagiellonian university, which is his current affiliation, in 2020. His research interests lie primarily in the gravitational waves, early universe, modified gravity, and dark energy.

Abstract:
This is a colloquium talk for students and non-experts (the experts on the topic may find it boring). In this talk I will review several attempts beyond Einstein's general relativity, including the massive gravity whose history can be traced all the way back to 1939, the Horndeski theory which was discovered in 1974 and then rediscovered in 2011, and 4-dimensional Einstein-Gauss-Bonnet theory which was proposed recently yet has stimulated an extensive discussion and controversy among colleagues in the field. The focuses will be on the theoretical consistency of these theories, as well as the experimental testability (or falsifiability). 

Zoom Meeting: 872 5593 6961 Password: 879097
https://dooyle.zoom.us/j/87255936961?pwd=TWYrT1B2YlhiNmtWTXBGN3pucno1QT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/366119

Image

2022-05-21(Saturday)4:00pm Beijing time [Open Lecture]

Title: 银河系中心的脉动——人马座A*黑洞照片的全面解读
Speaker: 袁业飞教授、薛涌泉教授、蔡一夫教授
Institutions: 中国科学技术大学

Abstract:
袁业飞教授:银心黑洞吸积及成像
薛涌泉教授:黑洞照片又双叒叕来啦——直击银心黑洞
蔡一夫教授:银河系的心跳——理论解读

2022-05-18 [Colloquium]

Title: Current and Future Millimeter Wave Surveys of the Sky – From the Cosmic Microwave Background to the Local Universe
Speaker: Prof Mark Devlin
Institutions: Reese W. Flower Professor of Astronomy and Astrophysics, University of Pennsylvania

Short-bio:
Prof. Mark Devlin did his PhD from University of California at Berkeley (1993). Later on Postdoctoral Research from Princeton University and University of California at Berkeley. Currently Prod. Mark Devlin is at University of Pennsylvania as a Reese W. Flower Professor of Astronomy and Astrophysics. His research focuses on experimental cosmology at millimeter and submillimeter wavelengths. He design and build sophisticated instrumentation and telescopes which he use to observe from high-altitude balloons and the high-plateaus of Chile. Current work on four major projects include the Atacama Cosmology Telescope (ACT), the Simons Observatory (SO), The Balloon-borne Large Aperture Telescope (BLAST), and the MUSTANG-2 Instrument on the Green Bank Telescope.

Abstract:
Millimeter-wave surveys of the sky have the potential for yielding a wealth of information about our universe from the first instants of its existence to our own solar system.  I will describe how modern measurements of the cosmic microwave background (CMB) are being used to measure how our universe has evolved over cosmic time leading to a better understand the fundamental parameters governing its nature.  I will present recent results from the Atacama Cosmology Telescope (ACT) and future plans for the Simons Observatory program.

2022-05-11 [Colloquium]

Title: Primordial Black Holes from Inflation
Speaker: Prof. Misao Sasaki (佐佐木节 教授)
Institutions: IPMU 数物连携宇宙物理学研究所

Short-bio:
Currently Prof. Misao Sasaki is working as Deputy Director and Project Professor in KAVLI IPMU. His main research interest is in general relativity and cosmology. He is particularly interested in the theory of the inflationary universe. What he is interested in now is looking for new observational signatures that can distinguish differences between different models, to identify the physics behind inflation, and to possibly find traces from physics beyond inflation. In this respect, in addition to electromagnetic waves as an observational tool, gravitational waves will certainly play a central role in cosmology, particularly in exploring early universe physics in coming years. He is currently working on gravitational wave cosmology with this expectation . according to IHeP, .He has around 34 articles as a single author and around 400 as a group !!

Abstract:
The existence of primordial black holes (PBHs) was suggested more than half a century ago. However, studies on the PBH formation have remained at a qualitative level until recently. The situation has changed in the last few years. Thanks to the rapid progress in gravitational wave (GW) astrophysics/cosmology, we have begun to realize that we may actually detect signatures of PBHs by GW observations, in addition to classic gravitational lensing observations. Thus it has become highly important to study possible early universe models for the PBH formation and their observational signatures. In this talk, I discuss some of the recently proposed models of inflation that may lead to a copious production of PBHs.

2022-05-04 [Webinar]

Title: Emergent inflation from a Nambu–Jona-Lasinio mechanism in gravity with non-dynamical torsion
Speaker: Prof. Antonino Marciano
Institutions: Fudan University 复旦大学

Short-bio:
Antonino Marciano’ is currently Tenured Associate Professor at Fudan University, Full Professor for the Italian Ministry of University and Research, and member of the Italian Institute of Nuclear Physics (INFN), assigned to the theory division of the Frascati laboratories.
As a theoretical physicist, Antonino focuses his scientific research on a variety of topics, ranging mainly from quantum field theories and theories of gravity, to their neighboring research areas as well as analogous applications to Solid State Physics, Artificial Intelligence and Quantum Computation.
Antonino has published so far about 100 articles in international scientific journals with the highest impact factors. He serves as referee for Nature, the American Physical Society, and several Chinese and European journals to assess publications of scientific papers, and as a reviewer for the Italian Minister of the University and Research, for the Dutch Royal Academy of Science, and for the National Science Centre of Poland, to evaluate tenure-track applications and assess scientific grants up to one million euros.

Abstract:
We discuss how inflation can emerge from a four-fermion interaction induced by torsion. Inflation can arise from coupling torsion to Standard Model fermions, without any need of introducing new scalar particles beyond the Standard Model. Within this picture, the inflaton field can be a composite field of the SM-particles and arises from a Nambu-Jona-Lasinio mechanism in curved space-time, non-minimally coupled with the Ricci scalar. The model we specify predicts small value of the r-parameter, namely r ~ 10−4 ÷ 10−2, which nonetheless would be detectable by the next generation of experiments, including BICEP 3 and the AliCPT projects.

Contact Us

Bo Wang (王博) email:ymwangbo@ustc.edu.cn

Amara Ilyas email:aarks@mail.ustc.edu.cn

Batool Imtiaz email:batool24@mail.ustc.edu.cn

2022-05-04 [Webinar]

Title: Emergent inflation from a Nambu–Jona-Lasinio mechanism in gravity with non-dynamical torsion
Speaker: Prof. Antonino Marciano
Institutions: Fudan University 复旦大学

Short-bio:
Antonino Marciano’ is currently Tenured Associate Professor at Fudan University, Full Professor for the Italian Ministry of University and Research, and member of the Italian Institute of Nuclear Physics (INFN), assigned to the theory division of the Frascati laboratories.
As a theoretical physicist, Antonino focuses his scientific research on a variety of topics, ranging mainly from quantum field theories and theories of gravity, to their neighboring research areas as well as analogous applications to Solid State Physics, Artificial Intelligence and Quantum Computation.
Antonino has published so far about 100 articles in international scientific journals with the highest impact factors. He serves as referee for Nature, the American Physical Society, and several Chinese and European journals to assess publications of scientific papers, and as a reviewer for the Italian Minister of the University and Research, for the Dutch Royal Academy of Science, and for the National Science Centre of Poland, to evaluate tenure-track applications and assess scientific grants up to one million euros.

Abstract:
We discuss how inflation can emerge from a four-fermion interaction induced by torsion. Inflation can arise from coupling torsion to Standard Model fermions, without any need of introducing new scalar particles beyond the Standard Model. Within this picture, the inflaton field can be a composite field of the SM-particles and arises from a Nambu-Jona-Lasinio mechanism in curved space-time, non-minimally coupled with the Ricci scalar. The model we specify predicts small value of the r-parameter, namely r ~ 10−4 ÷ 10−2, which nonetheless would be detectable by the next generation of experiments, including BICEP 3 and the AliCPT projects.

2022-05-11 [Colloquium]

Title: Primordial Black Holes from Inflation
Speaker: Prof. Misao Sasaki (佐佐木节 教授)
Institutions: IPMU 数物连携宇宙物理学研究所

Short-bio:
Currently Prof. Misao Sasaki is working as Deputy Director and Project Professor in KAVLI IPMU. His main research interest is in general relativity and cosmology. He is particularly interested in the theory of the inflationary universe. What he is interested in now is looking for new observational signatures that can distinguish differences between different models, to identify the physics behind inflation, and to possibly find traces from physics beyond inflation. In this respect, in addition to electromagnetic waves as an observational tool, gravitational waves will certainly play a central role in cosmology, particularly in exploring early universe physics in coming years. He is currently working on gravitational wave cosmology with this expectation . according to IHeP, .He has around 34 articles as a single author and around 400 as a group !!

Abstract:
The existence of primordial black holes (PBHs) was suggested more than half a century ago. However, studies on the PBH formation have remained at a qualitative level until recently. The situation has changed in the last few years. Thanks to the rapid progress in gravitational wave (GW) astrophysics/cosmology, we have begun to realize that we may actually detect signatures of PBHs by GW observations, in addition to classic gravitational lensing observations. Thus it has become highly important to study possible early universe models for the PBH formation and their observational signatures. In this talk, I discuss some of the recently proposed models of inflation that may lead to a copious production of PBHs.

2022-05-18 [Colloquium]

Title: Current and Future Millimeter Wave Surveys of the Sky – From the Cosmic Microwave Background to the Local Universe
Speaker: Prof Mark Devlin
Institutions: Reese W. Flower Professor of Astronomy and Astrophysics, University of Pennsylvania

Short-bio:
Prof. Mark Devlin did his PhD from University of California at Berkeley (1993). Later on Postdoctoral Research from Princeton University and University of California at Berkeley. Currently Prod. Mark Devlin is at University of Pennsylvania as a Reese W. Flower Professor of Astronomy and Astrophysics. His research focuses on experimental cosmology at millimeter and submillimeter wavelengths. He design and build sophisticated instrumentation and telescopes which he use to observe from high-altitude balloons and the high-plateaus of Chile. Current work on four major projects include the Atacama Cosmology Telescope (ACT), the Simons Observatory (SO), The Balloon-borne Large Aperture Telescope (BLAST), and the MUSTANG-2 Instrument on the Green Bank Telescope.

Abstract:
Millimeter-wave surveys of the sky have the potential for yielding a wealth of information about our universe from the first instants of its existence to our own solar system.  I will describe how modern measurements of the cosmic microwave background (CMB) are being used to measure how our universe has evolved over cosmic time leading to a better understand the fundamental parameters governing its nature.  I will present recent results from the Atacama Cosmology Telescope (ACT) and future plans for the Simons Observatory program.

Zoom Meeting: 868 5838 7813 Password: 390176
https://dooyle.zoom.us/j/86858387813?pwd=bWV6cjVqQ1Jra1pPMXZhbjhpaEFLQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

Image

2022-05-21 [Open Lecture]

Title: 银河系中心的脉动——人马座A*黑洞照片的全面解读
Speaker: 袁业飞教授、薛涌泉教授、蔡一夫教授
Institutions: 中国科学技术大学

Abstract:
袁业飞教授:银心黑洞吸积及成像 薛涌泉教授:黑洞照片又双叒叕来啦——直击银心黑洞 蔡一夫教授:银河系的心跳——理论解读

2022-05-25 [Colloquium]

Title: Beyond Einstein: a journey in the swamp
Speaker: Prof. Chunshan Lin
Institutions: Jagiellonian university 雅盖隆大学

Short-bio:
Prof. Chunshan Lin obtained his PhD degree in 2011, from the University of Science and Technology of China. He successively held postdoc positions in Tokyo University and Kyoto University between 2011 - 2017. In 2017 he joined the university of Warsaw as an assistant professor. He moved to Jagiellonian university, which is his current affiliation, in 2020. His research interests lie primarily in the gravitational waves, early universe, modified gravity, and dark energy.

Abstract:
This is a colloquium talk for students and non-experts (the experts on the topic may find it boring). In this talk I will review several attempts beyond Einstein's general relativity, including the massive gravity whose history can be traced all the way back to 1939, the Horndeski theory which was discovered in 1974 and then rediscovered in 2011, and 4-dimensional Einstein-Gauss-Bonnet theory which was proposed recently yet has stimulated an extensive discussion and controversy among colleagues in the field. The focuses will be on the theoretical consistency of these theories, as well as the experimental testability (or falsifiability).

Zoom Meeting: 872 5593 6961 Password: 879097
https://dooyle.zoom.us/j/87255936961?pwd=TWYrT1B2YlhiNmtWTXBGN3pucno1QT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/366119

Image

2022-06-01(Wednesday) 9:00 PM CST [Webinar]

Title: Alternative for Black Hole Paradoxes
Speaker: Dr Reinoud Jan Slagter
Institutions: Asfyon, Astronomisch Fysisch Onderzoek Nederland and University of Amsterdam, The Netherland

Short-bio:
Researcher since 1974 in the field of cosmology, general relativity and quantum field theory
1980:Master at University of Utrecht, supervisor Prof. G, ‘t Hooft
1986: PhD at University of Amsterdam. Promotors Prof. K. Gaemers and Prof E. v/d Heuvel
Copromotor Prof G. ‘t Hooft
www.asfyon.com

Abstract:
A throughout investigation is made of the exact black hole solution in five-dimensional warped conformal dilaton gravity, found in an earlier investigation. The singularities of the dynamical black hole spacetime are determined by the zeros of a meromorphic quintic polynomial, which has no essential singularities.
The solutions of the polynomial are analyzed in the complex plane in relation to the icosahedron group and by the Hopf-fibrations of the Klein surface.
The model fits the antipodal boundary condition, i.e., antipodal points in the projected space are identified using the embedding of a Klein surface in ${C}^2$, using the ${Z}_2$ symmetry on the two sides of the brane.
If one writes $^{(5)}g_{\mu\nu}=\omega^{4/3}{^{(5)}}{\tilde g_{\mu\nu}}, {^{(5)}}{\tilde g_{\mu\nu}}={^{(4)}}{\tilde g_{\mu\nu}}+n_\mu n_\nu$, $ ^{(4)}\tilde g_{\mu\nu}=\bar\omega^2 {^{(4)}}\bar g_{\mu\nu}$, with $n_\mu$ the normal to the brane and $\omega$ the dilaton field, then ${^{(4)}}\bar g_{\mu\nu}$ is conformally flat.
It is the contribution from the bulk which determines the real pole on the effective four-dimensional spacetime.
There is no objection applying 't Hooft's back reaction method in constructing the unitary S-matrix for the Hawking radiation.
Again, there is no "inside" of the black hole.

Zoom Meeting: 840 9109 6731 Password: Ustc1234
https://dooyle.zoom.us/j/84091096731?pwd=d1JtRkVJRlBGV09xZ2g5SDRFZFVRQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/831059

Image

2022-06-08 (Wednesday) 7:00 PM CST [Webinar]

Title: Bootstrapping inflation: A new perspective towards cosmological correlators
Speaker: Dr. Dong-Gang Wang
Institutions: University of Cambridge, UK

Short-bio:
Dr. Dong-Gang Wang was a master student in USTC from 2013 to 2016. After that, he moved to Leiden University in the Netherlands for PhD as a de Sitter Fellow from 2016 to 2020. Now he is a postdoctoral researcher as a Rubicon Fellow at the Department of Applied Mathematics and Theoretical Physics in the University of Cambridge, UK. His research mainly focuses on the primordial cosmology. In particular he is interested in dissecting non-Gaussian statistics of primordial fluctuations by using the effective field theory and bootstrap approaches.

Abstract:
Correlation functions of primordial fluctuations provide us an exciting avenue into the physics with extremely high energy in the very early Universe. Recently the bootstrap approach has offered new perspectives and powerful tools to study these cosmological correlators. In this talk, I will first briefly review this subject. Then, by incorporating the latest developments, I will “bootstrap” two types of inflationary correlators, which are most relevant for the next-generation observations. The first one is the contact correlators arising from large self-interactions of the inflaton. The second is the cosmological collider bispectra from the massive exchange diagrams with all possible boost-breaking interactions. Applying the bootstrap approach, we derive for the first time not only a complete set of these correlators systematically, but also their full shape information analytically. Since the de Sitter boost symmetries are broken in our consideration, the sizes of signals are boosted to be detectable for near-future experiments. We identify new features in these non-Gaussianity shapes, which provide interesting targets for the data analysis of upcoming surveys.

Zoom Meeting: 834 6695 7596 Password: 395040
https://dooyle.zoom.us/j/83466957596?pwd=cDg2eURyd25BRUtGZjN5M1dZZGFJZz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

Image

2022-06-15 (Wednesday) 3:00 PM CST [Webinar]

Title: Universal relation in the gravitational lensing of gravitational waves
Speaker: Prof. Teruaki Suyama
Institutions: Tokyo Institute of Technology, Tokyo (Japan)

Short-bio:
Prof. Teruaki Suyama is an associate professor at Tokyo Institute of Technology since 2018. He obtained his doctorate from Kyoto University in 2007, after which he did postdoctoral research at the University of Tokyo and Louvain University. Since 2012, he has been a faculty member at the Research Center for the Early Universe (U.Tokyo), until he was appointed the current position. His research interest is to (mainly theoretically) investigate the horizon of our understanding of cosmology and gravitational physics we could reach in the era of the gravitational-wave astronomy. He is a lover of Belgian beers.

Abstract:
Gravitational waves from the distant sources are gravitationally lensed during their propagation through the intervening matter inhomogeneities before arriving at detectors. In this talk, I first give an overview of the gravitational lensing of gravitational waves, followed by a proposal made in the literature that the variance of the lensed waveform can be used to extract information of the matter power spectrum at very small scales and of low-mass dark halos. I will then show that the variance of the amplitude fluctuation and that of the phase fluctuation of the lensed waveform obey a simple consistency relation irrespective of the shape of the matter power spectrum. I will discuss about conditions under which this relation can be violated and provide some potential applications of the relation.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/413819

Image

2022-06-22 (Wednesday) 9:00 AM CST [Webinar]

Title: Compact Star in F(R) Gravity: Degeneracy Problem and Non-Integer Power Correction
Speaker: Dr. Taishi Katsuragawa
Institutions: Institute of Astrophysics of Central China Normal University

Short-bio:
Dr. Taishi Katsuragawa received his Ph.D. from Nagoya University in 2017. After working in postdoctoral research positions at Kobayashi-Maskawa Institute and Central China Normal University, he joined in Institute of Astrophysics of Central China Normal University as an associate professor. His research interests are the modified gravity theory and its applications to particle cosmology and astrophysics.

Abstract:
The F(R) gravity is one of the extensions of general relativity, and it has been investigated in various research fields. This talk focuses on the astrophysical application and demonstrates that adjusting the F(R) function can construct an arbitrary mass-radius relation of the compact star because the model-dependence of the equation of state and modification of gravity degenerate to each other. We also see that a non-integer curvature power correction is naturally introduced when the Schwarzschild spacetime is chosen as a boundary condition, which gives guidelines for model-building in F(R) gravity. Comparing with the reconstruction method known in cosmology and higher-curvature corrections to avoid curvature singularities in the dark energy model, we consider some problems in the existing studies on compact stars and discuss the prospects for future studies.

Zoom Meeting: 874 6858 5677 Password: 838803
https://dooyle.zoom.us/j/87468585677?pwd=OHNsTkJCRktWRkZhekw3Y1MrVkhoZz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-06-29 (Wednesday) 3:00 PM CST [Webinar]

Title: Dark Matter in the Time of Primordial Black Holes
Speaker: Prof. Nicolas Bernal
Institutions: Universidad Antonio Nariño in Bogotá, Colombia

Short-bio:
Dr. Nicolás Bernal received his Ph.D. from Paris-Saclay University in 2008. After postdoctoral appointments at the University of Barcelona, Lisboa University, Bonn University, and ICTP-SAIFR, he joined Universidad Antonio Nariño in Bogotá, Colombia, as an associate professor. His research interests are dark matter, beyond standard model phenomenology, and particle cosmology.

Abstract:
Rotating black holes (BHs) can efficiently transfer energy to the surrounding environment via superradiance. In particular, when the Compton length of a particle is comparable to the gravitational radius of a BH, the particle’s occupation number can be exponentially amplified. In this work, we investigate the effect of the primordial-black-hole (PBH) superradiant instabilities on the generation of heavy bosonic dark matter (DM) with a mass above ∼ 1 TeV. Additionally, we analyze its interplay with other purely gravitational and therefore unavoidable DM production mechanisms such as Hawking emission and the ultraviolet freeze-in. We find that superradiance can significantly increase the DM density produced by PBHs with respect to the case that only considers Hawking emission, and hence lower initial PBH densities are required.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-07-13 (Wednesday) 3:00 PM CST [Webinar]

Title: Emergent Cosmology from Matrix Theory
Speaker: Prof. Robert Brandenberger
Institutions: McGill University

Short-bio:
Professor of Physics, McGill University Department of Physics McGill University
Ph.D. in Physics, Harvard University, November 1983——

Professor of Physics, McGill University, Sept. 2004 -present
Professor of Physics, Brown University, July 1997 - June 2005
Associate Professor of Physics, Brown University, July 1991 to June 1997
Assistant Professor of Physics, Brown University, Sept. 1986 to June 1991
Postdoctoral Fellow, Dept. of Applied Mathematics and Theoretical Physics University of Cambridge, UK, October 1985 to August 1987
Postdoctoral Fellow, Institute for Theoretical Physics, University of California, Santa Barbara, Sept. 1983 to Sept. 1985

More than 400 publications with around 26000 citations.
More than 900 invited seminar and conference talks

Canadian Association of Physicists CAP Lifetime Achievement Award, 2021—
Canada Research Chair (Tier 1), Oct. 1 2004 - present

Research field: Theoretical cosmology

Abstract:
The Trans-Planckian Censorship Criterion and other arguments indicate that we need to go beyond an effective field theory analysis in order to understand the evolution of the very early universe. I will present a proposal to obtain an emergent metric space-time and an emergent early universe scenario from the BFSS matrix model, a proposed non-perturbative definition of superstring theory.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-07-27 (Wednesday) 3:00 PM CST [Webinar]

Title: Minimal theories and modified gravity models
Speaker: Prof. Antonio De Felice
Institutions: Kyoto University

Short-bio:
Prof.Antonio took his Ph.D. in Syracuse University (NY, USA) with prof. Trodden. He has been a postdoctoral researcher in Sussex U. (Brighton, UK), Louvain U. (Louvain-la-Neuve, Belgium). Then he got a JSPS fellowship working at Tokyo U. of Science. Then he became a lecturer at IF (Naresuan U., Phitsanulok, Thailand). From the end of 2013 he has joined the Yukawa Institute For Theoretical Physics (Kyoto U.) as an associate professor. His research focuses on modified gravity models (applied to dark energy as well as inflation).

Abstract:
"I will describe the minimal theories and modified gravity I have been working recently on. In particular, I will describe why minimal theories might help resolve today's tensions in cosmology."

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-08-08 (Monday) 3:00 PM CST [Webinar]

Title: Pulsar Polarization Arrays
Speaker: Dr. Tao Liu
Institutions: Hong Kong University of Science and Technology

Short-bio:
Dr. Tao Liu's research focuses on particle physics and its connection with astronomy and cosmology. Dr. Tao Liu received his PhD in Physics at University of Pennsylvania in 2007. Then he hold a position of ``McCormick Fellow'' in Enrico Fermi Institute at University of Chicago during 2007-2010. After that, he moved to University of California at Santa Barbara to continue his postdoctoral research. He joined the Hong Kong University of Science and Technology (HKUST) in 2013 as a junior faculty. Now he is an associate professor at HKUST. He received the HKUST ``School of Science Research Award'' in 2016, and currently is the Project Coordinator/Principal Investigator of the Hong Kong UGC/RGC Collaborative Research Fund project ``Dark Matter and the Universe''.

Abstract:
Pulsar timing arrays (PTAs) consisting of widely distributed and well-timed millisecond pulsars can serve as a galactic interferometer to measure gravitational waves. With the same data acquired for PTAs, we have proposed (https://arxiv.org/abs/2111.10615) to develop pulsar polarization arrays (PPAs), to explore astrophysics and fundamental physics. As in the case of PTAs, PPAs are best suited to reveal temporal and spatial correlations at large scales that are hard to mimic by local noise. As a demonstration of the physical potential of PPAs, we considered the detection of ultralight axion-like dark matter (ALDM), through cosmic birefringence induced by its Chern-Simons coupling. Because of its tiny mass, the ultralight ALDM can be generated as a Bose-Einstein condensate, characterized by a strong wavy nature. In this talk, the speaker will give a detailed introduction to this topic and show how the PPAs can significantly enhance the detection of ALDM by correlating the their polarization data. 

Zoom Meeting: 879 6329 4916 Password: 129582
https://dooyle.zoom.us/j/87963294916?pwd=K2RSbmc0VnZPZWpkc1hTM2FyYi9nUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/lives/room/235406

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2022-08-17 (Wednesday) 3:00 PM CST [Webinar]

Title: What can we learn from primordial gravitational waves?
Speaker: Dr. Tomohiro Fujita
Institutions: Waseda Institute for Advanced Study, Waseda University

Short-bio:
PhD—Kavli IPMU, University of Tokyo, Chiba, Japan in March 2015

Postdoctoral Research Fellow— Tokyo Institute of Technology(April 2015) —Stanford Institute for Theoretical Physics(October 2015)—Kyoto University(2017) —Institute for Cosmic Ray Research (April 2020 )

In April 2021, he joined Waseda Institute for Advanced Study, Waseda University as an assistant professor. Won Young Scientist Award The Physical Society of Japan(2022)

Research Interests—Inflation, Gravitational waves, Dark matter, Large scale structure

Abstract:
Having many on-going and upcoming experiments to detect them, we hope primordial gravitational waves (PGWs) imprinted in CMB B-mode will be observed in the near future. PGWs produced during inflation are the unique probe for very high energy physics beyond the reach of particle accelerators, and now is a good time to study what we can learn from them. In this webinar, I will discuss that much more information than the energy scale of inflation can be extracted from PGWs by using a model as an example. In the model, SU(2) gauge fields coupled to axion generate detectable PGWs with distinguishable signatures such as non-Gaussianity and circular polarization.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-09-14 (Wednesday) 3:00 PM CST [Webinar]

Title: Primordial Black Holes and Leptogenesis: An unexpected interplay
Speaker: Dr. Yuber Perez-Gonzalez
Institutions: Fermi National Accelerator Laboratory

Short-bio:
PhD --- University of São Paulo, Brazil, December 2017

Research Associate --- Fermi National Accelerator Laboratory, 2018 - 2021

Postdoctoral Researcher Associate --- Northwestern University, 2018 - 2021

Postdoctoral Researcher Associate --- IPPP, Durham University, 2021 - present.

Research Interests: Neutrimo Physics, Black Hole Physics, Particle Phenomenology in the Early Universe.

Abstract:
Black Hole evaporation offers a unique method of particle production, unlike any other interaction process. In the Early Universe, such an evaporation can affect the baryon asymmetry produced via leptogenesis since heavy right-handed neutrinos can be emitted independently of the properties of the primordial plasma. However, there is also a large amount of entropy injected, which could dilute the generated asymmetry. We will explore in detail this interplay between Primordial Black Holes and Leptogenesis, determining the regions of the parameter space where the evaporation increases or erases the asymmetry.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-09-28 (Wednesday) 3:00 PM CST [Webinar]

Title: LOFAR+GMRT+ MeerKAT+VLA: Radio spectral properties at 150—5000MHz of star-forming galaxies
Speaker: Dr. Fangxia An
Institutions: Purple Mountain Observatory

Short-bio:
Dr. Fangxia An is a postdoc fellow based at the Purple Mountain Observatory in Nanjing China from July 2022. She obtained her Doctoral degree from the Purple Mountain Observatory in Nov. 2018. During Oct. 2016 to Oct. 2018, she studied at Durham University in UK as a joint PhD student. During Feb. 2019 to May 2022, she worked at Inter-University Institute for Data Intensive Astronomy in South Africa as a postdoc fellow.

Her research interests are galaxies formation and evolution, galaxy clusters/proto-clusters, large-scale structures of galaxies.

Abstract:
A well-determined radio spectrum for star-forming galaxy (SFG) is critically important for studies that are based on rest-frame radio power, especially those at high-redshift where k-corrections are generally extrapolated the most. In this talk, I will introduce two of our recently completed projects based on the MeerKAT(SKA pathfinder)+VLA+GMRT data in the COSMOS field and the LOFAR+GMRT+JVLA data in the ELAIS-N1 field. I will present our measured radio spectral indices between the observer-frame frequencies of 150-400, 400-610, 400-1300MHz, 1.3-3GHz, and 610-5000MHz and show the correlations between radio spectrum and physical properties of radio-selected SFGs. With these results, I will discuss the possible physical mechanisms that determine the radio spectrum of SFGs. I will also show how the adoption of these different radio spectral indices (from low- and high-frequency) in k-correction affects the study of far-infrared-radio correlation of SFGs.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-10-13 (Thursday) 9:00 AM CST [Webinar]

Title: Scale-invariant enhancement of gravitational waves during inflation
Speaker: Dr. Atsuhisa Ota
Institutions: The HKUST Jockey Club Institute for Advanced Study

Short-bio:
Ph.D. in Physics, Tokyo institute of Technology, March 2017

IAS Postdoctoral Fellow, The HKUST Jockey Club Institute for Advanced Study, October 2021-present

Postdoctral researcher, Physics & Astronomy Department, Ohio University, April 2020- September 2021

Oversea Research Fellow of the Japan Society for the Promotion of Science, DAMTP, University of Cambridge (main), April 2018 – March 2020

Research Fellow of the Japan Society for the Promotion of Science (PD), Department of Physics, Tokyo Institute of Technology, April 2017 – March 2018

Research Fellow of the Japan Society for the Promotion of Science (DC2), Department of Physics, Tokyo Institute of Technology, April 2016 – March 2017

Research interest: cosmological perturbation theory and aim to find new observational approaches to the early Universe and high energy physics.

Abstract:
The inflationary 1-loop tensor power spectrum from an excited spectator scalar field is calculated. Recent studies on primordial black holes suggest that the inflationary curvature perturbation may be huge on small scales. An enhanced curvature perturbation may arise from a drastic enhancement of spectator scalar field fluctuations. In this letter, using the in-in formalism, we calculate 1-loop quantum corrections to primordial gravitational waves by such an excited spectator field with a sharp peak in momentum space. We find scale-invariant loop corrections in this full quantum setup, in contrast to the sharply peaked corrections in the previously calculated scalar-induced tensor modes. Especially, on super Hubble scales, the primordial gravitational waves are also amplified, which can be understood as a Bogolyubov transformation of the vacuum due to the excited scalar field. This mechanism allows us to probe the scalar field properties on extremely short-distance scales with the current and future cosmic microwave background and gravitational wave experiments, opening a novel window for inflationary cosmology.

Zoom Meeting: 819 0963 7699 Password: 607973
https://dooyle.zoom.us/j/81909637699?pwd=NUdycmV6Ny9NWElOVzRBLzNUNHQ4dz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-10-26 (Wednesday) 3:00 PM CST [Webinar]

Title: Precision Cosmology at Nonlinear Scales
Speaker: Prof. Aurel Schneider
Institutions: University of Zurich, Switzerland

Short-bio:
Prof. Aurel Schneider is an assistant professor at the University of Zurich, Switzerland, predominantly working on weak lensing and 21cm reionization science. Before this, he held research positions at ETH Zurich and the University of Sussex, United Kingdom.

Abstract:
Upcoming weak lensing and galaxy clustering surveys will push the frontier of cosmology towards small, highly nonlinear scales. I will discuss how to develop new theoretical tools to predict nonlinear structure formation (including baryons) at high precision. I will furthermore discuss how to apply these methods to current and future weak lensing surveys in order to learn something about cosmology, astrophysics, and the nature of dark matter.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-11-16 (Wednesday) 3:00 PM CST [Webinar]

Title: Testing a key foundation of the concordance model
Speaker: Prof. Roy Maartens
Institutions: University of Western Cape, South Africa

Short-bio:
Prof. Roy has held a Research Chair at the University of the Western Cape since 2011, which supports a team of students and postdocs working on cosmology with the SKA and other surveys. He got his PhD from the University of Cape Town in 1980 (advisor George Ellis). He was at the University of Portsmouth in the UK during 1994-2010, where he was the founding Director of the Institute of Cosmology & Gravitation, one of the top cosmology research groups in the UK. His main interests are in the nature and applications of general relativistic effects in cosmology.

Abstract:
Tensions in the observed values of some key parameters of the concordance model of cosmology may indicate problems in the model itself. This motivates further independent tests of the model. I will describe a test of a key foundation of the concordance model - the Cosmological Principle. According to the Cosmological Principle, the Universe should be statistically isotropic. In particular, isotropy in the CMB must be consistent with isotropy in the galaxy distribution. This means that the dipole in the CMB should agree in direction and amplitude with the dipole in the galaxies. Current results suggest that there is a significant tension between the amplitudes of these dipoles. I will discuss some theoretical and observational issues that remain to be clarified before this can be declared as a new tension.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-11-30 (Wednesday) 3:00 PM CST [Webinar]

Title: Cosmological Weak Lensing
Speaker: Prof. Alexandre Refregier
Institutions: ETH Zürich, Switzerland

Short-bio:
Prof. Alexandre Refregier obtained his PhD in Physics from Columbia University, New York, NY, USA in 1997. Following this, he was a postdoc at Princeton University, Princeton, NJ, USA (1997 – 1999) and the University of Cambridge, Cambridge, UK (1999 - 2002). He was then Astrophysicist at CEA Saclay, France (2002 – 2011) and is currently Professor at ETH Zürich, Switzerland since 2011. His research interest are cosmology, structure formation, gravitation lensing and statistical methods.

Abstract:
Weak gravitational lensing is a unique technique to map the distribution of dark matter in the universe. It is also a sensitive probe of dark energy, large scale structures in the universe, and cosmological parameters. We will first briefly describe the principles of weak lensing. We will then review the current observational status of this field, highlighting several new measurements and the resulting sigma8 tension between different cosmological probes. We will then present recent measurements of non-gaussian statistics based on human-made summaries and machine  learning at map-level.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-12-07 (Wednesday) 9:00 AM CST [Webinar]

Title: Do we need to move beyond Cold Dark Matter?
Speaker: Prof. Andrea Valerio Macciò
Institutions: New York University, Abu Dhabi

Short-bio:
Andrea V. Macciò is a Professor of Physics at New York University, Abu Dhabi and the Director of the Center for Astro, Particle and Planetary Physics.

Professor  Macciò is interested in understanding the nature and origin of the mysterious dark components of our cosmos: dark energy and dark matter, which account for 95 percent of the total energy/matter budget of the universe. In order to achieve this goal, he studies the formation and evolution of galaxies in such a dark universe via large computer numerical simulations

Abstract:
Our current understanding of galaxy formation is based on the presence of an elusive matter component: the Cold Dark Matter (CDM) This simple model has ben challenged many times in the past decade, mainly by galaxy observations on small scales: from the abundance of satellites, to the distribution of dark matter within galaxies, and more recently by the discovery of galaxies "without" dark matter. In my talk I will first revise all these claims with the help of cosmological numerical simulations of galaxy formation from the NIHAO project. I will then discuss whether there is indeed an observationally motivated need to abandon Cold Dark Matter and move beyond such a simple model.

Zoom Meeting: 865 7871 0701 Password: Ustc1234
https://dooyle.zoom.us/j/86578710701?pwd=Q2p5UEsxWjJ4ZWs4RmlPbnRpczNsdz09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2022-12-21 (Wednesday) 3:00 PM CST [Webinar]

Title: Simulation of Primordial Black Hole formation
Speaker: Dr. Albert Escrivà
Institutions: Nagoya University, Japan

Short-bio:
Albert Escrivà is a JSPS postdoctoral fellow in the QG-lab at Nagoya University (Japan) since November 2022. Previously, he was a postdoctoral researcher at Brussels University (Belgium) for one year and finished his PhD in 2021 at the University of Barcelona (Spain). His current main research interest is devoted to the numerical simulation of primordial black holes.

Abstract:
Primordial Black Holes (PBHs) are black holes that could have been formed in the very early universe due to the collapse of large curvature fluctuations after inflation. PBHs are nowadays one of the most attractive and fascinating research areas in cosmology for their possible theoretical and observational implications. In this talk, I will review the physical process of PBH formation and its numerical simulation, focusing on the definition of "threshold for PBH formation" and its analytical estimation, which is essential to estimate the abundance of PBHs correctly. Moreover, I will present recent results about the formation of PBHs when a time-dependent equation of state is considered, which has a significant phenomenological impact compared with the standard case of a radiation-dominated era.

Zoom Meeting: 891 4812 4260 Password: 076606
https://dooyle.zoom.us/j/89148124260?pwd=d0prSjFnT3JRY1crSk9jNzVxV3MxUT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2023-01-11 (Wednesday) 9:00 PM CST [Webinar]

Title: Primordial black holes and axions: a tale of (galactic and extragalactic) light
Speaker: Dr. Ricardo Z. Ferreira
Institutions: Institute for High Energy Physics, Autonomous University of Barcelona

Short-bio:
Ricardo is a Beatriu de Pinós fellow at IFAE, the Institute for High Energy Physics at the U. Autónoma of Barcelona in Spain. He obtained his PhD in 2016 at the CP3-Origins Institute, University of Southern Denmark, and has held postdoctoral positions at the U. Barcelona, Nordita (Stockholm) and IFAE (Barcelona). His research has been devoted to topics in the interface between cosmology, axion physics and gravity including inflation, gravitational waves and the cosmic microwave background.

Abstract:
Primordial black holes with asteroid-like masses (10^{14-18} kg) can still account for all the dark matter. In this talk, I will discuss a new indirect probe of PBH dark matter. I will show that axions with masses in the 0.1eV-MeV range can form in clouds around such PBHs, via superradiance, and ultimately decay, if coupled to photons. The decay products will contribute to the galactic or extragalactic background flux at frequencies between the UV and the gamma-rays, depending on the axion mass. I will show that current data already constraints a large range of parameters and that searches for narrow lines with future experiments such as the Athena X-ray telescope will further test this co-existence of PBH dark matter and axions. If time allows I will also discuss recent work on another probe of axion physics: gravitational waves.

Zoom Meeting: 833 9022 1307 Password: 782677
https://dooyle.zoom.us/j/83390221307?pwd=MGpnQWgzS3IzWmFjbGd4d2RXWWZzQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2023-01-25 (Wednesday) 9:00 PM CST [Webinar]

Title: Tidal Love Numbers of Black Holes
Speaker: Dr. Valerio De Luca
Institutions: University of Pennsylvania

Short-bio:
Bachelor and Master degree at the University of Pisa (Italy);

PhD at the University of Geneva (Switzerland) under the supervision of Prof. Antonio Riotto;

Postdoc researcher at the University of Pennsylvania (United States).

Abstract:
Tidal Love numbers describe the deformability of compact objects under the presence of external tidal perturbations, and are found to be exactly zero for black holes. We discuss about their connection to the weak gravity conjecture and investigate the scenario of black holes dressed with an ultralight scalar field, addressing their detectability at future gravitational wave experiments.

Zoom Meeting: 833 9022 1307 Password: 782677
https://dooyle.zoom.us/j/83390221307?pwd=MGpnQWgzS3IzWmFjbGd4d2RXWWZzQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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2023-02-15 (Wednesday) 9:00 PM CST [Webinar]

Title: Tensions in cosmology and implications for the standard model
Speaker: Dr. Eleonora Di Valentino
Institutions: University of Sheffield (UK)

Short-bio:
Regarding my bio, I am a Royal Society Dorothy Hodgkin Research Fellow at the University of Sheffield (UK). Previous to this I've been an Addison-Wheeler fellow at Durham University (UK), a postdoc at the University of Manchester (UK), and a Lagrange fellow at the IAP in Paris (France). I had my PhD in Rome at "La Sapienza" University.

Abstract:
The scenario that has been selected as the standard cosmological model is Lambda Cold Dark Matter (ΛCDM), which provides a remarkable fit to the bulk of available cosmological data. However, discrepancies among key cosmological parameters of the model have emerged with different statistical significance. While some portion of these discrepancies may be due to systematic errors, their persistence across probes can indicate a failure of the canonical ΛCDM model. I will review these tensions, showing some interesting extended cosmological scenarios that can alleviate them.

Zoom Meeting: 833 9022 1307 Password: 782677
https://dooyle.zoom.us/j/83390221307?pwd=MGpnQWgzS3IzWmFjbGd4d2RXWWZzQT09
Koushare live broadcast 蔻享直播 :
https://www.koushare.com/topic-hd/i/Euade

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