Lunch talk on Apr. 24, 2023

Tidal Stripping of a White Dwarf by an Intermediate-Mass Black Hole

Speaker: Jinhong Chen (SYSU)

Venue: Video Conference

Time: 12:30 PM, Monday, Apr. 24, 2023

Abstract: 

During the inspiralling of a white dwarf (WD) into an intermediate-mass black hole, 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 is suspected that the recently discovered new types of transients, namely the quasi-periodic eruptions and the fast ultraluminous X-ray bursts, might originate from such systems. Modeling these flares requires a prediction of the amount of stripped mass from the WD and the details of the mass supply to the accretion disk. We run hydrodynamical simulations to study the orbital parameter dependence of the stripped mass. We find that our simulation results match the analytical estimate. The corresponding fallback rate of the stripped mass is calculated, which may be useful in interpreting the individual flaring light curve in candidate EM sources. We further calculate the long-term mass-loss evolution of a WD during its inspiral and the detectability of the GW and EM signals. The EM signal from the mass-loss stage should be easily detected. The GW signal, for the space-borne detectors such as Laser Interferometer Space Antenna (LISA) or TianQin, can be detected only within the Local Supercluster (~ 33 Mpc).