Tidal disruption event (TDE), where a star is ripped apart by the strong tidal forces of a supermassive black hole (SMBH), creates an impulse of accretion, resulting in bright flare that decays in time-scales of months to years, thus provides a unique tool to detect dormant black holes and investigate the accretion process around SMBH. We have built a sample of highly variable X-ray sources,...
Tidal Disruption Events (TDEs) were first investigated as theoretical possibilities in the 1970s-1980s, exploring what would happen if a black hole devours an unlucky star. The first detection in 1996 was consistent with the formation of an accretion disk emitting primarily in the X-rays as predicted by theory. However, in recent decades, the situation has become much more complicated. There...
A star will be destroyed by tidal forces when it passes close enough by a supermassive black hole (SMBH). These events known as TDEs are expected to produce luminous flare emission in the UV to X-ray band. The observations of Sw J1644+57, in particular, suggest that at least some TDEs can launch an on-axis relativistic jet. A common speculation is that these rare events are related to rapidly...
During the inspiralling of a white dwarf (WD) into an intermediate-mass black hole ($\sim 10^{2-5}\ M_{\odot}$), both gravitational waves (GWs) and electromagnetic (EM) radiation are emitted. Once the eccentric orbit's pericenter radius approaches the tidal radius, the WD would be tidally stripped upon each pericenter passage. The accretion of these stripped mass would produce EM radiation. It...
In this talk, the GW and EM radiation from a compact object orbiting an SMBH are discussed. First, I will present a new formation channel of EMRIs with tidal disruption flares as EM counterparts. In this scenario, flares can be produced from the tidal stripping of the helium (He) envelope of amassive star by an SMBH. The remaining compact core of the massive star then evolves into an EMRI....
In changing-look AGNs, the optical-to-X-ray continuum flux typically increases significantly as broad emission lines appear. The changing-look AGN 1ES 1927+654, hosting already a highly accreting black hole, displays peculiar X-ray properties after its optical changing-look event in early 2018. We carried out a follow-up campaign to probe its extreme accretion physics, using 34 optical...
