Friday, 29 March 2024

Two Astronomy Colloquia on Wednesday (22.03/2023)

Calendar
研讨会日历
Date
03.22.2023 10:00 am - 11:00 am

Description

Title: Demystifying the AGN IR emission and hunting obscured SMBHs in the JWST era
Speaker: Jianwei Lyu
 
Abstract:
Completing the census of active galactic nuclei (AGN) activity is the key to study the build-up of supermassive black holes (SMBHs) and understand their relations with the host galaxy properties. Nevertheless, many AGNs are obscured by dust and gas, making the identification of such systems a challenging task even today. In this talk, I will summarize our current understanding of the AGN obscuring structures and how we can use this knowledge to pick out obscured AGNs in the JWST era. For the former, I will describe a relatively simple framework that intergrates the studies of the IR spectral energy distributions (SEDs), time variability and spatially-resolved observations covering large ranges of AGN luminosity and redshift. For the latter, I will talk about what have been learned from selecting AGNs in the GOODS-S/HUDF with archival X-ray to the radio-band data and introduce our JWST NIRCam and MIRI surveys of the same field.
 
Bio:
Jianwei Lyu is a postdoctoral researcher at the Steward Observatory, University of Arizona and a member of JWST MIRI science team. His major research area is the study of galaxy evolution with a focus on AGN/quasar, extragalactic ISM and IR astronomy with ground- and space-based observing facilities as well as necessary computer simulations.  Right now, he is leading several JWST GTO/GO projects ranging from the study of dust grains in the nearby starburst galaxies to the host galaxy properties of most distant quasars in the reionization age. He recevied his PhD degree in 2020 at the University of Arizona with Dr. George Rieke on the reconcliation of AGN IR properties from z~0 to z~6.
 
Time: 10:00-11:00AM, 22/Mar, Wednesday
Venue: Room 508 (large seminar room), Department of Astronomy
 
 
Title: Discovery of the Higgs boson and Future Higgs Factory
Speaker: Haijun Yang (SJTU/TDLI)
 
Abstract: 
The Higgs boson explains the mass origin of elementary particles, it was discovered at CERN’s LHC in 2012. It is a great triumph of the Standard Model and opens up a new era of particle physics. In the past 10 years, tremendous efforts and progress have been made to deepen our understanding of the electroweak symmetry breaking mechanism through Higgs properties measurement at the LHC. On the other hand, the Standard Model can not explain and accommodate dark matter and dark energy which compose of about 95% of the universe. It may indicate new physics and more fundamental physics laws beyond the Standard Model. The newly discovered Higgs boson has spin 0 and may act as a mediator of a new kind of interaction. Higgs boson is widely considered as a portal to dark matter or dark sector. Study of the Higgs boson properties with unprecedented precision at future Higgs factories could significantly enhance new physics detection sensitivity, helps to reveal the secret of the dark matter, and may shed light on baryon asymmetry of the universe through the electroweak phase transition in the early universe. In this talk, I will present the Higgs mechanism, the brief history of the Higgs discovery and recent progresses, status of e+e- Higgs factories worldwide, and recent progress of the CEPC project.
 
 
Bio: Haijun Yang, Professor at SJTU and TDLI, Director of the Institute of Nuclear and Particle Physics, Deputy project director of the CEPC.  He received his Ph.D. in Particle and Nuclear Physics in 2000 from IHEP. In 2000-2012, he was a postdoctoral research fellow and later promoted as a research scientist at the University of Michigan, Ann Arbor. His major research focus is high energy collider physics including the CERN/LHC/ATLAS experiment and future Higgs factory CEPC R&D. He made significant contributions to the discovery of the Higgs boson and its property measurements, the discovery of the vector boson scattering  process. He is a pioneer to develop and apply an advanced multivariate machine learning technique Boosted Decision Trees (BDT) for particle identification and physics analysis since 2004. BDT is widely used by many particle physics experiments, including the LHC experiments as a primary tool for Higgs discovery and new physics searches.
 
Time: 14:00-15:00PM, 22/Mar, Wednesday
Venue: Room 508 (large seminar room), Department of Astronomy