Five Billion Solar Mass Supermassive Black Hole

NGC 1277 is a nearby lenticular galaxy that is thought to host one of the largest supermassive black holes known in the Universe. This black hole was first reported to contain a whopping 17 billion solar mass. Using more recent measurements of the motion of stars within ~1500 light years of the galaxy’s nucleus, the mass of the supermassive black hole in the centre of NGC 1277 has been revised downwards to 4.9 ± 1.6 billion solar mass, ~3 times smaller than previously claimed. Still, the supermassive black hole is an order of magnitude more massive than expected for a galaxy with the luminosity of NGC 1277.

Figure 1: Artist’s impression of a black hole.

NGC 1277 hosts an over-massive black hole in its center and it joins several other galaxies that are known to be positive outliers on the correlation between a supermassive black hole’s mass and the luminosity of its host galaxy’s central bulge. NGC 1277 appears similar in morphology to galaxies in the early Universe. If over-massive black holes are common in the centres of galaxies in the early Universe, then NGC 1277 could be a relic from the early Universe where the present black hole scaling relations did not apply. It can also imply that the growth of a supermassive black hole precedes that of its host galaxy.

Figure 2: The location of NGC 1277 (red square) and other similar galaxies with over-massive black holes (red asterisks) on the black hole to host galaxy correlations. The left panel shows the relationship between a black hole’s mass and the velocity dispersion of stars in its host galaxy. The right panel shows the relationship between a black hole’s mass and the luminosity of its host galaxy’s central bulge. Walsh et al. (2015)

Reference:
Walsh et al. (2015), “A 5x10^9 Solar Mass Black Hole in NGC 1277 from Adaptive Optics Spectroscopy”, arXiv:1511.04455 [astro-ph.GA]