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.