http://arxiv.org/abs/1602.05554
The Advanced Laser Interferometer Gravitational-Wave Observatory (aLIGO) has detected direct signals of gravitational waves (GWs) from GW150914. The event was a merger of a binary black holes whose masses are $36^{+5}_{-4}M_{\odot}$ and $29^{+4}_{-4}M_{\odot}$. Such binary systems are expected to be formed in either isolated binary systems or dense stellar environments. Here we derived the binary black hole merger rate for isolated binary systems based on the nearby ultra-luminous X-ray source (ULX) luminosity function (LF). We obtained the binary black hole merger rate as $1.9 ({t}_{\rm ULX}/{1 \ \rm Myr})^{-1} \lambda^{-0.6} \exp{(-0.30\lambda)} \ {\rm Gpc^{-3}\ yr^{-1}}$, where $t_{\rm ULX}$ is the typical duration of the ULX phase and $\lambda$ is the Eddington ratio. This is comparable to the event rate inferred from the detection of GW150914 as well as the predictions based on binary population synthesis models. Although we are currently unable to constrain $\lambda$ due to the uncertainties of our models and measured binary black hole merger event rates, further X-ray and GW data will allow us to constrain $\lambda$ of ULXs.
Y. Inoue, Y. Tanaka and N. Isobe
Thu, 18 Feb 16
38/44
Comments: 4 pages, 1 figure
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