Symbiosis or not: the interplay of massive black holes and their host galaxies
Final Report Abstract
Bright and massive galaxies harbour very massive black holes. These black holes are found in the nuclei of galaxies, the very central regions also characterised with high density of stars. While the ratio of the masses of host galaxies and central black holes is about 10^-3, the size ratio spans some 8 orders of magnitudes. The existence of tight relation between the mass of the central black hole and various properties of host galaxies (e.g. its mass), suggest that the evolution of both the central black hole and the host galaxies, spanning such large scales, are intertwined. A major open issue is to understand to what extent these objects evolve in a synchronous way. The evolutionary interplay can be probed by investigating how massive black holes grow (increase their mass). This happens by two processes: accretion of inter-stellar gas, or by coalescence of black holes. These processes are closely connected to the processes governing the growth of galaxies: star-formation (fuelled by gas accretion) and merger of galaxies. It is also necessary to establish the properties of the relations between host galaxies and black holes, such as their extent, scatter and demographics. These were the main goals of the project. The results of the project increased our knowledge in four-fold way: 1) This project increased by approximately 20% the number of measured black hole masses on the scaling relation between the massive black holes and galaxies. This increase is especially important for galaxies with lower masses, as they were previously not well represented. 2) We found evidence that some galaxies either have central black holes that are significantly less massive than expected (from general scaling relations) or might not even have a central black hole. About 25% of galaxies in our sample fall in this category. This finding can be directly used to put limits to the models of black hole evolution, which expect that some galaxies will have ‘underdeveloped’ black holes, but until now there were no observational constraints to these estimates. 3) We showed that black holes in massive galaxies increase their mass via the channel of black hole mergers. These mergers occur during merger of galaxies, but are only significant when both galaxies and black holes are already very massive (above 1011 M@ and 109 M@, respectively), and galaxies do not contain gas (so there is no possibility for star formation or black hole growth via gas accretion). Such results were anticipated based on other properties of galaxies, but this is the first observational evidence of such processes on a statistical basis. 4) The project showed that there is a systematic discrepancy between masses of central black holes estimated using different types of dynamical models. In particular, the difference is found between dynamical models, which aim at reproducing motions of stars or gas. The mass difference at the level of a factor of 2 might be representative of a current precision achieved by the data and the models, or it can indicate fundamental limitations of current models.
Publications
- “A low upper mass limit for the central black hole in the late-type galaxy NGC 4414", 2017, A&A, 597, 18
Thater, Sabine; Krajnovic, Davor; Bourne, M. A.; Cappellari, M.; de Zeeuw, T.; Emsellem, E.; Magorrian, J.;McDermid, R. M.; Sarzi, M.; van de Ven, G.
(See online at https://doi.org/10.1051/0004-6361/201629480) - “A quartet of black holes and a missing duo: probing the low end of the MBH-σ relation with the adaptive optics assisted integral-field spectroscopy’’, 2018, MNRAS, 477, 3030
Krajnovi´c, Davor; Cappellari, Michele; McDermid, Richard M.; Thater, Sabine; Nyland, Kristina; de Zeeuw, P. T.; Falcón-Barroso, Jesús; Khochfar, Sadegh; Kuntschner, Harald; Sarzi, Marc; Young, Lisa M.
(See online at https://doi.org/10.1093/mnras/sty778) - “Two channels of supermassive black hole growth as seen on the galaxies mass-size plane’’, 2018, MNRAS, 473, 5237
Krajnovi´c, Davor; Cappellari, Michele; McDermid, Richard M.
(See online at https://doi.org/10.1093/mnras/stx2704) - “Six new supermassive black hole mass determinations from adaptive-optics assisted SINFONI observations", 2019, A&A, 625, 62
Thater, Sabine; Krajnovic, Davor; Cappellari, Michele; Davis, Timothy A.; de Zeeuw, P. Tim; McDermid, Richard M.; Sarzi, Marc
(See online at https://doi.org/10.1051/0004-6361/201834808) - “The interplay between supermassive black holes and their host galaxies", PhD Thesis, University of Potsdam, 2019
Sabine Thater
(See online at https://doi.org/10.25932/publishup-43757)
