Lunch talk on Dec. 14, 2020

The black hole spin in coalescing binary black holes and high-mass X-ray binaries

Speaker: Ying Qin（Northwestern University）

Venue: Video conference

Time: 12:30 PM, Monday, Dec. 14, 2020

Abstract: 

In this talk, I'll introduce the black hole(BH) spin in two different BH binaries, i.e., the coalescing binary BHs(BBHs) and BH high-mass X-ray binaries (HMXBs). The BHs in these two types of systems have very different spin measurements, which can be explained well by introducing different formation channels. For the “Common Envelope” binary evolution channel, the first-born BH has a negligible spin, while the second-born one covers the whole range of the spin (from 0 to 1). On the other hand, With an assumption that the inefficient angular momentum transport is implemented after the main sequence of the BH progenitor, the currently observed BH spins in HMXBs can be well explained via the Case-A mass transfer(MT) and the chemically homogeneously evolution(CHE) channel. Compared to the CHE channel, the Case-A MT can form a HMXB in a tight orbit, which is consistent with the current observations. Hence The Case-A MT can be considered a potential channel to explain the current properties of Cygnus X-1, LMC X-1 and M33 X-7. Finally, we expect the nitrogen surface abundance of the BH companion star can be challenged from the observational point of view to distinguish the two channels.

Report PPT:  SWIFAR_Ying Qin.pdf