University of Cambridge > > Galaxies Discussion Group > Feeding and feedback from little monsters: black holes in dwarf galaxies

Feeding and feedback from little monsters: black holes in dwarf galaxies

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If you have a question about this talk, please contact Ricarda Beckmann.

Supermassive black holes of 10E10 solar masses already existed when the Universe was only 0.8 Gyr old. To reach this mass they should have started as seed intermediate-mass black holes (IMBHs) of 100-10E6 solar masses. Detecting such IMB Hs in the early Universe is extremely challenging; however, those that did not grow into supermassive black holes should be found in local dwarf galaxies resembling the first galaxies formed at early epochs.

I will show that a population of actively accreting IMB Hs exists in local dwarf galaxies and that they can be detected out to z~3 with the use of deep multiwavelength surveys like COSMOS . The black hole occupation fraction of these dwarf galaxies suggests that the early Universe seed black holes formed from direct collapse of pre-galactic gas disk, which is reinforced by the finding that the M-sigma relation flattens at the low-mass end. This scenario is however challenged by the recent finding that AGN feedback can have a very strong impact on dwarf galaxies (e.g. in the form of jet mechanical feedback), which implies that those AGN hosted in dwarf galaxies might not be the untouched relics of the early seed black holes. This has important implications for seed black hole formation models.

This talk is part of the Galaxies Discussion Group series.

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