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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

 
中心简介
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    天体物理研究室是上海天文台从事基础天体物理研究的主要机构,包括12个科研团组。研究室的研究方向涉及黑洞和高能天体物理、星系形成与演化、宇宙大尺度 结构、星团和银河系结构、恒星形成、以及行星天体物理等领域,在黑洞吸积与喷流理论、黑洞和星系的共同演化、银河系结构与动力学、计算天体物理等方向具有一定的国际影响力。研究室现有固定研究人员固定研究人员46名,博士后11名,研究生65名。固定研究人员中包括国家杰出青年基金获得者3人、优秀青年基金获得者2人、科学院“百人计划”入选者9人。
    研究室与国内外的天文研究机构有着密切的合作关系,与中国科技大学联合成立了“中国科学院星系和宇宙学重点实验室”,与厦门大学成立了天体物理联合中心。研究室还参与了多项国际、国内天文项目和观测计划,如LAMOST、HXMT、SDSS-IV、TMT、LSST、FAST等。
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