Massive metal-poor stars might form massive stellar black holes (BHs) with mass 25 lt;= mBHMsolar lt;= 80 via direct collapse. We derive the number of massive BHs (N_BH) that are expected to form per galaxy through this mechanism. Such massive BHs might power most of the observed ultra-luminous X-ray sources (ULXs). We select a sample of 64 galaxies with X-ray coverage measurements of the star formation rate (SFR) and of the metallicity. We find that N_BH correlates with the number of observed ULXs per galaxy (N_ULX) in this sample. We discuss the dependence of our model on the SFR and on the metallicity.
Ultra-luminous X-ray sources and remnants of massive metal-poor stars / Mapelli, M.; Ripamonti, E.; Zampieri, L.; Colpi, M.; Bressan, A.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 408:1(2010), pp. 234-253. [10.1111/j.1365-2966.2010.17048.x]
Ultra-luminous X-ray sources and remnants of massive metal-poor stars
Bressan, A.
2010-01-01
Abstract
Massive metal-poor stars might form massive stellar black holes (BHs) with mass 25 lt;= mBHMsolar lt;= 80 via direct collapse. We derive the number of massive BHs (N_BH) that are expected to form per galaxy through this mechanism. Such massive BHs might power most of the observed ultra-luminous X-ray sources (ULXs). We select a sample of 64 galaxies with X-ray coverage measurements of the star formation rate (SFR) and of the metallicity. We find that N_BH correlates with the number of observed ULXs per galaxy (N_ULX) in this sample. We discuss the dependence of our model on the SFR and on the metallicity.File | Dimensione | Formato | |
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