Program: GN-2007B-Q-61

Binary black holes (BBHs), the predicted result of galaxy-galaxy mergers, are expected to be common throughout the Universe and may be the cause of many astrophysical phenomena. However, only a handful of BBHs have to date been confirmed to exist, and none at a separation < 1 kpc. A pair of variable UV point sources in the nearby LINER, NGC4736, separated by only 60 pc, are by far the smallest-separation spatially-resolved BBH candidates yet discovered, but virtually nothing is known about the off-nuclear source of the pair. We propose GMOS long-slit spectroscopy to investigate the possibility that this source may in fact be the second supermassive black hole in a long-sought-after close BBH pair. These observations can be scheduled under conditions of 90%-ile cloud cover and are intended for Band 4.