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  每周简讯
 
19/06/2017-23/06/2017

SHAO Astrophysics Colloquia

Title: The UV/Optical Variation in Active Galactic Nuclei

Speaker: Prof. Junxian Wang (Univ. of Science and Technology of China)

Time: 3 PM, June 22 (Thursday)

Location: Lecture Hall, 3rd floor

Abstract:  Stochastic variation is one of the most prominent characteristics of AGNs. The UV/optical emission, which is believed from the accretion disk, is variable on timescales of days to years,the origin of which remains unclear for decades. I will present our recent works in the field, aimed to explore the origin of the variations and address the following key questions:

1)  Why AGNs appear bluer when they brighten?

2)  Why the variations in various UV/optical bands are well coordinated,  with the short wavelength variations leading the long wavelength ones?

3)  Which factors control the variation amplitude?

I will also show that variations provide a unique probe to spatially “resolve” the accretion disc. With this tool, we find the inner accretion disc in radio loud quasars clearly differ from that in radio quiet ones, offering an exciting clue to jet launching in quasars.

Group meetings

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

Location: 1608

Time: 14:00-16:00, Wednesday(Jun 21th)

Speaker: Prof. Fulai Guo

Title: Sound wave generation by a spherically symmetric outburst and AGN feedback in galaxy clusters

http://adsabs.harvard.edu/abs/2017MNRAS.468.3516T

Speaker: Zhaoming Gan
Title: Backflows by active galactic nuclei jets: global properties and influence on supermassive black hole accretion

http://adsabs.harvard.edu/abs/2017MNRAS.467.4526C

Galactic Dynamics Group Journal Club

Speaker: Ramya Sethuram

Location: Room 1608

Time: June 22 (Thursday) 9:45 AM

Title: New methods to constrain the mass ratio of minor mergers in Elliptical galaxies.
Abstract :Many recent observations and numerical simulations suggest that nearby massive, early-type galaxies (ETGs) were formed through a “two-phase” process. In the proposed second phase, the extended stellar envelope was accumulated through many dry mergers. However, details of the past merger history of present-day ellipticals, such as typical merger mass ratio is difficult to constrain observationally. Within the context and assumptions of the two-phase formation scenario, a photometric method to estimate the average mass ratio of mergers that contributes to the build-up of massive elliptical galaxies will be reviewed in this journal club talk.
References : 2013ApJ...773...34G and 2016ApJ...821...114H
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