Maximally accreting supermassive stars

• Verfasst von: Haemmerlé, Lionel [VerfasserIn]
• Verfasst von: Klessen, Ralf S. [VerfasserIn]
• Titel: Maximally accreting supermassive stars
• Titelzusatz: a fundamental limit imposed by hydrostatic equilibrium
• Verf.angabe: L. Haemmerlé, G. Meynet, L. Mayer, R.S. Klessen, T.E. Woods, and A. Heger
• E-Jahr: 2019
• Jahr: 02 December 2019
• Umfang: 5 S.
• Fussnoten: Gesehen am 24.01.2020
• Titel Quelle: Enthalten in: Astronomy and astrophysics
• Ort Quelle: Les Ulis : EDP Sciences, 1969
• Jahr Quelle: 2019
• Band/Heft Quelle: 632(2019) Artikel-Nummer L2, 5 Seiten
• ISSN Quelle: 1432-0746
• DOI: doi:10.1051/0004-6361/201936716
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1688477349

Abstract

Context: Major mergers of gas-rich galaxies provide promising conditions for the formation of supermassive black holes (SMBHs; ≳105 M⊙) by direct collapse because they can trigger mass inflows as high as 104 − 105 M⊙ yr−1 on sub-parsec scales. However, the channel of SMBH formation in this case, either dark collapse (direct collapse without prior stellar phase) or supermassive star (SMS; ≳104 M⊙), remains unknown. Aims: Here, we investigate the limit in accretion rate up to which stars can maintain hydrostatic equilibrium. Methods: We compute hydrostatic models of SMSs accreting at 1–1000 M⊙ yr−1, and estimate the departures from equilibrium a posteriori by taking into account the finite speed of sound. Results: We find that stars accreting above the atomic cooling limit (≳10 M⊙ yr−1) can only maintain hydrostatic equilibrium once they are supermassive. In this case, they evolve adiabatically with a hylotropic structure, that is, entropy is locally conserved and scales with the square root of the mass coordinate. Conclusions: Our results imply that stars can only become supermassive by accretion at the rates of atomically cooled haloes (∼0.1 − 10 M⊙ yr−1). Once they are supermassive, larger rates are possible.