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Breaking the limit: Super-Eddington accretion onto black holes and neutron stars

Brightman, M. and Bachetti, M. and Earnshaw, H. P. and Fürst, F. and García, J. and Grefenstette, B. and Heida, M. and Kara, E. and Madsen, K. K. and Middleton, M. J. and Stern, D. and Tombesi, F. and Walton, D. J. (2019) Breaking the limit: Super-Eddington accretion onto black holes and neutron stars. Astro2020 Science White Paper, . (Unpublished)

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With the recent discoveries of massive and highly luminous quasars at high redshifts (z∼7; e.g. Mortlock et al. 2011), the question of how black holes (BHs) grow in the early Universe has been cast in a new light. In order to grow BHs with M_(BH) > 10^9 M⊙ by less than a billion years after the Big Bang, mass accretion onto the low-mass seed BHs needs to have been very rapid (Volonteri & Rees, 2005). Indeed, for any stellar remnant seed, the rate required would need to exceed the Eddington limit. This is the point at which the outward force produced by radiation pressure is equal to the gravitational attraction experienced by the in-falling matter. In principle, this implies that there is a maximum luminosity an object of mass M can emit; assuming spherical accretion and that the opacity is dominated by Thompson scattering, this Eddington luminosity is L_E = 1.38×10^(38)(M/M⊙) erg s^(−1). In reality, it is known that this limit can be violated, due to non-spherical geometry or various kinds of instabilities. Nevertheless, the Eddington limit remains an important reference point, and many of the details of how accretion proceeds above this limit remain unclear. Understanding how this so-called super-Eddington accretion occurs is of clear cosmological importance, since it potentially governs the growth of the first supermassive black holes (SMBHs) and the impact this growth would have had on their host galaxies (‘feedback') and the epoch of reionization, as well as improving our understanding of accretion physics more generally.

Item Type:Report or Paper (White Paper)
Related URLs:
URLURL TypeDescription Paper
Brightman, M.0000-0002-8147-2602
Bachetti, M.0000-0002-4576-9337
Earnshaw, H. P.0000-0001-5857-5622
Fürst, F.0000-0003-0388-0560
García, J.0000-0003-3828-2448
Grefenstette, B.0000-0002-1984-2932
Heida, M.0000-0002-1082-7496
Kara, E.0000-0003-0172-0854
Madsen, K. K.0000-0003-1252-4891
Middleton, M. J.0000-0002-8183-2970
Stern, D.0000-0003-2686-9241
Tombesi, F.0000-0002-6562-8654
Walton, D. J.0000-0001-5819-3552
Group:Space Radiation Laboratory
Series Name:Astro2020 Science White Paper
Record Number:CaltechAUTHORS:20190617-141021193
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96477
Deposited By: Tony Diaz
Deposited On:17 Jun 2019 21:26
Last Modified:20 May 2021 22:59

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