Letter. Population x: are the super-Eddington x-ray sources beamed jets in microblazars or intermediate mass black holes?

Koerding, E., Falcke, H. and Markoff, S. (2002) Letter. Population x: are the super-Eddington x-ray sources beamed jets in microblazars or intermediate mass black holes? Astronomy & Astrophysics, 382 (1), L13-L17. (doi:10.1051/0004-6361:20011776).

Abstract

Recent x-ray observations reveal an increasing number of x-ray sources in nearby galaxies exceeding luminosities of L_x >~ 2 x 10³⁹ erg s^-1. Assuming isotropic emission, the Eddington limit suggests a population of intermediate-mass black holes of M. >> 10 M_sun. However, Markoff et al. proposed that jets may be contributing to the x-ray emission from x-ray binaries (XRBs), implying that some x-ray sources may be relativistically beamed. This could reduce the required black hole masses to standard values. To test this hypothesis, we investigate a simple x-ray population synthesis model for x-ray point sources in galaxies with relativistic beaming and compare it with an isotropic emission model. The model is used to explain a combined data set of x-ray point sources in nearby galaxies. We show that the current distributions are consistent with black hole masses M < ~10 M_sun and bulk Lorentz factors for jets in microquasars of γ_j ~ 5. Alternatively, intermediate mass black holes up to 1000 M_sun are required which are distributed in a power law with roughly (dN)/(dM) ~ M^-2.

This record has no associated files available for download.

Contributors

Download statistics