Kavli Affiliate: Ke Wang
| First 5 Authors: Chunyang Cao, Fukun Liu, Shuo Li, Xian Chen, Ke Wang
| Summary:
When a binary of early-type stars from the young stellar populations in the
Galactic center (GC) region is scattered to the vicinity of the supermassive
black hole (SMBH) Sgr~$rm{A}^{*}$, one of the components would be tidally
ejected as an early-type hypervelocity star (HVS) and the counterpart would be
captured on a tight orbit around Sgr~$rm{A}^{*}$. Dozens of B-type HVSs moving
faster than the Galactic escape speed have been discovered in the Galactic halo
and are produced most likely by the SMBH Sgr~$rm{A}^{*}$. However, the
velocity distribution and in particular the deficit of the HVSs above $700,
rm{km, s^{-1}}$ is seriously inconsistent with the expectations of the
present models. Here we show that the high-velocity deficit is due to the
deficiency in close interactions of stars with the SMBH Sgr~$rm{A}^{*}$,
because an orbiting intermediate-mass black hole (IMBH) of about 15,000 Solar
mass kicked away slowly approaching stars 50–250 million years ago. The
SMBH-IMBH binary formed probably after the merger of the Milky Way with the
Gaia-Sausage-Enceladus dwarf galaxy, and coalesced about 10 million years ago,
leading to a gravitational recoil of Sgr~$rm{A}^{*}$ at a velocity of
0.3–0.5$, rm{km, s^{-1}}$ and to a change of the HVS ejection scenarios.
The SMBH-IMBH binary scenario predicts the formation of the S-star cluster at
the GC with the distribution of the orbital size and stellar ages that are well
consistent with the observations.
| Search Query: ArXiv Query: search_query=au:”Ke Wang”&id_list=&start=0&max_results=3