SHAO Astrophysics Colloquia

Title: Acceleration of High-energy Particles in Supernova Remnants

Speaker: Prof. Siming Liu (Purple Mountain Observatory)

Time: 3 PM, Dec. 15 (Thursday)

Location: Lecture Hall, 3rd floor

Abstract: Supernova remnants (SNRs) are considered the dominant contributors to Galactic cosmic rays. Although there is increasing evidence that shock of SNRs can indeed accelerate particles to hundreds of TeV,  this standard paradigm for high-energy particle acceleration in SNRs is far from complete. Outstanding issues include 1) gradual hardening of radio spectral index with the aging of SNRs, 2) the relative acceleration of electrons and protons, 3) importance of particle acceleration at the forward shock, reverse shock, and shock downstream. I will discuss how future multi-wavelength and cosmic ray observations, in combination with comprehensive modeling, may help to address these issues.

Seminar talk

Title: The Extremely Luminous Dust-Obscured Galaxies

Time & Date: 2:00pm, Dec. 14th (Wednesday)

Place: Middle Conference Room, 3rd floor. （中会议室）

Speaker: Chao-Wei Tsai

Abstract: I present a class of distant dust-enshrouded galaxies with extremely high luminosity, including several "Extremely Luminous Infrared Galaxies" (ELIRGs) that reach 10^14 L_Sun. Selected by their extreme red colors in WISE bands, their SEDs incorporating WISE, Spitzer, and Herschel photometry indicate hot dust dominates the bolometric luminosity. These sources are likely powered by highly obscured active galactic nuclei (AGN), are unlikely to be lensed. The existence of ELIRGs at z > 3 constrains the supermassive black hole (SMBH) growth history, suggesting that these SMBH's are born with large mass, or have a very rapid mass assembly, presumably by chaotic accretion. Their low source density (~ 10^-5 of LIRGs' at similar redshift) implies that these objects are intrinsically rare, or are a short-lived phase in a more numerous population. These sources have absorption-corrected X-ray luminosity significantly fainter than the mid-IR/X-ray correlation for AGNs, likely to be intrinsically X-ray weak. The ALMA C+ observation on selected sample shows a large, homogeneous velocity dispersion across few kpc, suggesting that gas is being blown away isotropically, possibility reflecting the stage of becoming unsecured quasars.  I will also discuss some of the follow-up effort using the Keck IFU to study the dynamics of the ionized gas in hyper-luminous systems.

Galaxy Seminar

Location: 1714

Time: 10:30，Dec.14 ( Wednesday)

Title: The effects of Kozai oscillations in various astrophysical systems

Speaker: 刘斌

Contact: Jian Fu, Fangting Yuan, Chunyan Jiang, Zhaoyu Li, Ting Xiao

Group meetings

Black hole Accretion and High-energy Astrophysics /Black Hole Feedback and Cosmic Ray Astrophysics Seminar

Location：1608

Time：14:00-16:00, Dec.14 ( Wednesday)

Speaker: Feng Gao (高峰)

Title: AGN accretion disk and outflow revealed by H2O megamaser disks

Galactic Dynamics Group Journal Club

Location：1608

Time：9:30-11:00, Dec. 15 (Thursday)

Speaker: Chenxu Liu

Title: The HI gas and molecular gas in galaxies in the cosmic voids.

Abstract:

He will talk about the HI gas and molecular gas in galaxies in the cosmic voids and their implications on the star formation of the void galaxies.