Can We Detect Electromagnetically a Supermassive Black Hole in the Milky Way Satellite Leo I?

A supermassive black hole (SMBH) of ~3 million solar masses was recently detected via dynamical measurements at the center of the dwarf galaxy Leo I. Standing ~2 orders of magnitude above standard scaling relations, this SMBH is hosted by a galaxy devoid of gas and with no significant star formation in the last ~1 Gyr. This detection can profoundly impact the formation models for black holes and their hosts. We proposed that winds from a population of ~100 evolved stars within the Bondi radius of the SMBH produce a sizable accretion rate, with Eddington ratios 1-10 times higher than those characterizing Sgr A*. These rates are typical of SMBHs accreting in advection-dominated accretion flow mode. The predicted spectrum peaks in the microwaves at ~0.1-1 THz (300-3000 μm) and exhibits significant variations at higher energies depending on the accretion rate. We predict a radio flux of ~0.1 mJy at 6 GHz, mildly dependent on the accretion properties. Deep imaging with Chandra, the Very Large Array, and the Atacama Large Millimeter/submillimeter Array can confirm the presence of this SMBH and constrain its accretion flow.

In this talk, I will present the status of the observational campaign directed at this fascinating object. New radio, sub-mm, infrared, optical, and X-ray data and insights into its optical variability will be presented.