Oral Presentation
The Second Black Hole near the Galactic Center?
Presenter: Masato Tsuboi (ISAS, JAXA)
The Galactic Center IRS 13E complex is a very intriguing IR object identified within 0.2 pc from Sgr A$^¥ast$. Although the complex should be disrupted by the strong tidal force of Sgr A$^¥ast$ ($M¥sim10^6$ M$_¥sun$), the main member stars seem to be physically bound. Then one of the possible speculation is that a dark mass, like an intermediate mass black hole (IMBH) in the complex prevents its disruption although there are some objections to accept the presence of the IMBH.We analyzed the DDT observation of the Galactic Center with ALMA and obtained the channel maps with very high resolution ($0.4¥arcsec¥times0.3¥arcsec$) and very high sensitivity (0.8 mJy/beam) in Hydrogen recombination line, H30$¥alpha$. We found an ionized gas with a very wide velocity width ($¥Delta >500$ km/s) toward the IRS13E complex with ALMA. Our detected ionized gas associated with the IRS 13E is very compact ($¥lesssim0.4¥arcsec$). The ionized gas is presumably accreting onto the IMBH embedded in the IRS 13E complex. The enclosed mass is estimated to be $10^{4-5}$ M$_¥sun$ from these data. This mass is enough to bound the main member stars. However, the mass apparently conflicts with the upper limit mass of the IMBH around Sgr A$^¥ast$ which is derived by the long-term astrometry with VLBA.
asiaa.sinica.edu.tw