SIMBAD references

2002MNRAS.334..553A - Mon. Not. R. Astron. Soc., 334, 553-562 (2002/August-2)

X-rays from isolated black holes in the Milky Way.


Abstract (from CDS):

Galactic stellar-population-synthesis models, chemical-enrichment models, and possibly gravitational microlensing indicate that about Ntot=108-109 stellar-mass black holes reside in our Galaxy. We study X-ray emission from accretion from the interstellar medium on to isolated black holes. Although black holes may be fewer in number than neutron stars, NNS∼109, their higher masses, <M >∼9M, and smaller space velocities, σv∼40km.s–1, result in Bondi-Hoyle accretion rates ∼4x103 times higher than for neutron stars. Given a total number of black holes Ntot=N9109 within the Milky Way, we estimate that ∼103N9should accrete at M{dot}>1015g.s–1, comparable to accretion rates inferred for black hole X-ray binaries. If black holes accrete at the Bondi-Hoyle rate with efficiencies only ∼10–4(NNS/Ntot)0.8 of the neutron-star accretion efficiency, a comparable number of each may be detectable. We make predictions for the number of isolated accreting black holes in our Galaxy that can be detected with X-ray surveys as a function of efficiency, concluding that all-sky surveys at a depth of F =F–1510–15–2.s–1.dex–1 can find N(>F)∼104 N9(F–15–5)–1.2 isolated accreting black holes for a velocity dispersion of 40km.s–1 and an X-ray accretion efficiency of ε=ε–510–5. Deeper surveys of the Galactic plane with Chandra or XMM-Newton may find tens of these objects per year, depending on the efficiency. We argue that a mass estimate can be derived for microlensing black hole candidates with an X-ray detection.

Abstract Copyright: 2002 Blackwell Science Ltd

Journal keyword(s): accretion, accretion discs - black hole physics - Galaxy: stellar content - X-rays: ISM - X-rays: stars

Simbad objects: 25

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