Optically thick winds of very massive stars suppress intermediate-mass black hole formation

Fuente: arXiv
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Main Authors: Torniamenti, Stefano, Mapelli, Michela, Boco, Lumen, Simonato, Filippo, Iorio, Giuliano, Korb, Erika
Format: Preprint
Published: 2025
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author Torniamenti, Stefano
Mapelli, Michela
Boco, Lumen
Simonato, Filippo
Iorio, Giuliano
Korb, Erika
author_facet Torniamenti, Stefano
Mapelli, Michela
Boco, Lumen
Simonato, Filippo
Iorio, Giuliano
Korb, Erika
contents Intermediate-mass black holes (IMBHs) are the link between stellar-mass and supermassive black holes. Gravitational waves have started unveiling a population of IMBHs in the $\sim 100-300 \, \mathrm{M_{\odot}}$ range. Here, we investigate the formation of IMBHs from non-rotating very massive stars (VMSs, $>100\,{} \mathrm{M_{\odot}}$). We calculate new VMS models that account for the transition from optically thin to optically thick winds, and study how this enhanced mass loss affects IMBH formation and the black hole mass function at intermediate and high metallicity ($Z=10^{-4}-0.02$). We show that optically thick winds suppress the formation of IMBHs from direct VMS collapse at metallicities $Z>0.001$, one order of magnitude lower than predicted by previous models. Our models indicate that the stellar progenitors of GW231123 must have had a metallicity $Z<0.002$, if the primary black hole formed via direct VMS collapse.
format Preprint
id arxiv_https___arxiv_org_abs_2510_12465
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optically thick winds of very massive stars suppress intermediate-mass black hole formation
Torniamenti, Stefano
Mapelli, Michela
Boco, Lumen
Simonato, Filippo
Iorio, Giuliano
Korb, Erika
High Energy Astrophysical Phenomena
Astrophysics of Galaxies
Intermediate-mass black holes (IMBHs) are the link between stellar-mass and supermassive black holes. Gravitational waves have started unveiling a population of IMBHs in the $\sim 100-300 \, \mathrm{M_{\odot}}$ range. Here, we investigate the formation of IMBHs from non-rotating very massive stars (VMSs, $>100\,{} \mathrm{M_{\odot}}$). We calculate new VMS models that account for the transition from optically thin to optically thick winds, and study how this enhanced mass loss affects IMBH formation and the black hole mass function at intermediate and high metallicity ($Z=10^{-4}-0.02$). We show that optically thick winds suppress the formation of IMBHs from direct VMS collapse at metallicities $Z>0.001$, one order of magnitude lower than predicted by previous models. Our models indicate that the stellar progenitors of GW231123 must have had a metallicity $Z<0.002$, if the primary black hole formed via direct VMS collapse.
title Optically thick winds of very massive stars suppress intermediate-mass black hole formation
topic High Energy Astrophysical Phenomena
Astrophysics of Galaxies
url https://arxiv.org/abs/2510.12465