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QUASAR FEEDBACK AND THE ORIGIN OF EXTENDED LYđ¶ GLOW IN Z > 6 QUASARS
17 fĂ©vrier 2022 | 11h00 – 12h00
Tiago Costa – MPE Garching
The detection of quasars out to zâ7.5 shows that supermassive black holes with masses of â109 Mâ have already assembled by the time the Universe was only â680 Myr old. These observations strenuously test theoretical models of galaxy evolution, which have to explain how such rapid black hole growth comes about. I will start by reviewing results from state-of-the-art cosmological simulations that show that black hole growth to â109 Mâ can be accommodated by galaxy evolution models. These black holes, however, must evolve inside rare, massive dark matter haloes tracing extreme overdensities. Zooming-in on the quasar host galaxies, I will argue that the required rapid black hole growth is expected to ignite powerful quasar feedback in the form of large-scale outflows. I will illustrate how these outflows, which are characterized by a multi-phase structure resembling that of the interstellar medium, affect quasar environments in a myriad of ways. I will then demonstrate how the same cosmological simulations that succeed in reproducing â109 Mâ black holes also account for recent observations of bright, extended Lyα nebulae around z > 6 quasars. I will make the case that the uncanny match between theoretical models and observations is only possible if quasar feedback already operates efficiently in z > 6 quasars. I will conclude my talk by highlighting new theoretical insights into the nature of Lyα nebulae at z=6, explaining their detailed observational properties, their dominant physical mechanism, and the potential to detect them at z=7.5.