Research
 
Newsletter

SHAO Astrophysics Colloquium

Title: Supersoft AGNs: signature of super Eddington accretion, IMBH, TDE or new AGN spectral state?

Speaker: Xinwen Shu (Anhui Normal University)

Time: 3 pm, April 26 (Thursday)

Location: Lecture Hall, 3rd floor

Abstract:

Supersoft AGNs are a special class of AGNs which lack significant hard X-ray emission above ~2 keV. They may host intermediate mass black holes (IMBH) accreting in a poorly explored regime of parameter space, such as super Eddingtong accretion and extreme coronal condition. Their X-ray spectra are dominated by a soft thermal component, a form similar to disk blackbody emission in stellar-mass BHs in their high/soft state. Though only three supersoft AGNs are reported to date, they show distinct X-ray variability behavior, some of them could be associated with TDEs.  In this talk, I will present the multi-wavelength characteristics of RX J1301.9+2746, the most distinct source of this kind. In particular, I will show our follow-up JVLA observations which reveal fast intraday radio variability, confining its origin likely from a compact jet. This is further supported by the unresolved radio emission observed with our VLBA observations. Such the unexpected presence of compact jet in a supersoft AGN challenges canonical theories of jet formation, but may have implications on the origin of radio emission in radio-quiet AGNs. All the results suggest that this AGN is an ideal laboratory for studying the universality of accretion/ejection coupling in BH accreting systems.

 

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 (Apr 25th)

Speaker: Maochun Wu

Revisiting the Cooling Flow Problem in Galaxies, Groups, and Clusters of Galaxies

http://adsabs.harvard.edu/abs/2018arXiv180304972M

Speaker: Can Cui 

https://arxiv.org/pdf/1802.10306.pdf

http://adsabs.harvard.edu/abs/2018NatAs...2..198H

 

Seminar talk

Time:  4pm on Fri (Apr 27th)

Location: The lecture room on 17th floor

Speaker: Jerry Sellwood

Title: Two-body scattering and relaxation in disk systems
Abstract: The formula for the rate of relaxation in a gravitating system of point mass particles that is given in standard text books implicitly assumes that system is roughly spherical. I will derive a modified expression for rotationally-supported disks, and discuss its implications for real galaxy disks and for simulations.

Ref: http://adsabs.harvard.edu/abs/2013ApJ...769L..24S

 
About
img_ex1.jpg

The Astrophysics division is the main group engaged in astrophysical research at Shanghai Astronomical Observatory. Research areas include active galactic nuclei and high energy astrophysics, galaxy formation and evolution, cosmology and large scale structure, star clusters and the structure of the Milk Way, star formation, and planetary astrophysics. There are now 45 faculty members, 16 postdocs, and 65 graduate students in the division.

The Astrophysics division maintains close partnerships with many astronomical research institutes, including the joint Key laboratory of research in galaxies and cosmology of CAS with University of Science and Technology of China, the joint astrophysics center with Xiamen University. Members of the astrophysics division also participate in many international and domestic astronomical projects, including LAMOST, HXMT, FAST, the Sloan Digital Sky Survey IV, TMT, LSST, etc.

 

Shanghai Astronomical Observatory, All Rights Reserved
80 Nandan Road, Shanghai 200030, China Email:shao@shao.ac.cn