Super-Massive Black Holes

The masses of the super massive black holes in the centers of galaxies appear to correlate with several properties of the host galaxy. The best known correlations are black hole mass with the stellar velocity dispersion and total luminosity of the host galaxy. These relations extend from the biggest galaxies to globular clusters. And they strongly suggest that there is a fundamental link between galaxy and black hole evolution, The relations tie together quantities that probe very different length- and mass-scales. Important questions remain about the demography of the super-massive black holes, with direct implications for galaxy evolution, black hole fueling and feedback from AGN.

The black hole correlations are based on a small number (~90) of black hole mass estimates, the large majority of which were derived with dynamical Schwarzschild models. To understand the physical origin of the the black hole scaling relations more black hole mass we need more measurements. However, we can only do this for very few nearby galaxies, as the gravitational sphere-of-influence of the black hole needs to be spatially resolved to be able to probe the region near the black hole. The HET Massive Galaxy Survey was started to find all possible galaxies suitable for black hole mass estimates in the Northern Hemisphere. The HETMGS has allowed us to find galaxies with extremely big black holes and we are currently following those up with the Calor alto 3.5m, Harlan J. Smith, Keck, Gemini and Hubble telescopes.

An Over-Massive Black Hole in the Compact Lenticular Galaxy NGC1277

NGC 1277 is a compact little galaxy with one of the biggest black holes known to date. Its black hole weighs 5 billion times the mass of the Sun, which is 2% of this galaxies total mass. Most of the stars in this galaxy are strongly affected by the gravitational pull of this black hole. And the black hole itself is bigger than our solar system. The original research paper is published in Nature on November 29, 2012 and it describes a further 5 galaxies with similar properties. And we published an updated analysis in 2016 in this paper by Jonelle Walsh.

A very nice popular level article can be found at ScienceNOW by Ken Croswell.

Follow-up work is in progress. Akin Yildirim, PhD student at MPIA, is currently leading the follow up with the PPAK integral field spectograph at Calar Alto 3.5m to find out if these systems also have extraordinarily large dark matter halos. Jonelle Walsh (University of Texas) is leading the Laser-assisted Adaptive Optics observations with both Gemini-North and a Keck telescope.

This animation has been made by Remco van den Bosch and is released under creative commons and can be freely embedded. Credit for the background Hubble Space Telescope image is NASA/ESA/Fabian/Remco C. E. van den Bosch (MPIA)

The animation shows representative orbits of the stars in this galaxy from the dynamical model used to measure the black hole mass. The green orbit shows the orbit of the stars in the disk. The red orbit shows the strong gravitational pull near the black hole. The blue orbit is strongly influenced by the (round) dark matter halo. One second in this animation represents 22 million years of simulated time and the horizontal size of this image is 41 million lightyears (36 arcsec)

Press Coverage (November 29, 2012)

The Nature paper is generating quite some press interest. Here are the links that (will have) coverage. If you find others please let me know.

English coverage:

German Coverge:

Dutch Coverage:

Foreign Coverage:

This story is also appearing in several newspapers, including NRC, Trouw and LAtimes.