Program: GS-2016A-Q-20

Intermediate-mass black holes (IMBH, ~10^2-10^5 solar mass) have been long sought after because they are predicted to exist in several important astrophysical processes such as the collapse of massive population III stars. They are also leading candidates for gravitational wave emission. The strongest IMBH candidates are hyperluminous off-nuclear X-ray sources (HLX) with Lx > 10^{41} erg/s. However, there are only about a dozen marginal candidates found around this limit, and only ESO 243-49 HLX-1 reaches a luminosity of 10^{42} erg/s. We have identified a new HLX candidate with an estimated X-ray luminosity of 10^{43} erg/s, assuming its association with a galaxy at 244 Mpc. We propose a Gemini spectroscopic observation to measure the spectroscopic redshifts of the source and a nearby satellite galaxy, in order to confirm its IMBH nature and check whether it is formed through tidal stripping of a merging satellite dwarf galaxy.