Formation of the First Stars and Black Holes

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Formation of the First Stars and Black Holes L. Haemmerlé1 · L. Mayer2 · R.S. Klessen3 · T. Hosokawa4 · P. Madau5 · V. Bromm6

Received: 13 March 2020 / Accepted: 9 April 2020 © Springer Nature B.V. 2020

Abstract We review the current status of knowledge concerning the early phases of star formation during cosmic dawn. This includes the first generations of stars forming in the lowest mass dark matter halos in which cooling and condensation of gas with primordial composition is possible at very high redshift (z > 20), namely metal-free Population III stars, and the first generation of massive black holes forming at such early epochs, the so-called black hole seeds. The formation of black hole seeds as end states of the collapse of Population III stars, or via direct collapse scenarios, is discussed. In particular, special emphasis is given to the physics of supermassive stars as potential precursors of direct collapse black holes, in light of recent results of stellar evolution models, and of numerical simulations of the early stages of galaxy formation. Furthermore, we discuss the role of the cosmic radiation produced by the early generation of stars and black holes at high redshift in the process of reionization. Keywords Star formation · Population III · Black holes · Supermassive stars · Supermassive black holes · Quasars · Cosmology Star Formation Edited by Andrei Bykov, Corinne Charbonnel, Patrick Hennebelle, Alexandre Marcowith, Georges Meynet, Maurizio Falanga and Rudolf von Steiger

B L. Haemmerlé 1

Département d’Astronomie, Université de Genève, chemin des Maillettes 51, 1290 Geneva, Switzerland

2

Center for Theoretical Astrophysics and Cosmology, Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland

3

Zentrum für Astronomie, Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle-Str. 2, 69120 Heidelberg, Germany

4

Department of Physics, Kyoto University, Kyoto 606-8502, Japan

5

Department of Astronomy and Astrophysics, University of California, 1156 High Street, Santa Cruz, CA 95064, USA

6

Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA

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L. Haemmerlé et al.

1 First Stars The first generation of stars, the so-called Population III (or Pop. III) built up from truly metal-free primordial gas. They have long been thought to live short, solitary lives, with only one extremely massive star forming in each dark matter halo with about 100 solar masses or more (Omukai 2001; Abel et al. 2002; Bromm et al. 2002; O’Shea and Norman 2007). The idea was that first star formation is simple and one only needs to know the initial Gaussian density perturbations of material at very high-redshift which are very well understood, e.g. from measuring cosmic microwave background (CMB) anisotropies (Planck Collaboration et al. 2016a), the growth of cosmological structures, and the heating and cooling processes in the primordial gas. However, this simple picture has undergone substantial r