<p>Such objects are surrounded by an accretion disk, that is a disk of gas, the gas being accreted onto the central object. However, at this stage of its life, the accretion disk around the black hole of a binary system like GRS-1915+105 is strongly depleted. Therefore, the accretion rate is not sufficient to support a coutinuous burst. Matter fills the outer disk until a critical density is reached, that triggered an outburst. Mass from the companion star is lost by a <a href="http://astronomy.swin.edu.au/cosmos/R/roche-lobe+overflow" rel="nofollow">Roche lobe overflow mechanism</a>.</p>

<p><strong>References:</strong></p>

<ul>
<li>X-ray binaries in general: <a href="http://cdsads.u-strasbg.fr/abs/2006ARA%26A..44...49R" rel="nofollow">Remillard &amp; McClintock 2006</a></li>
<li>For the outburst X-ray transients in particular: <a href="http://adsabs.harvard.edu/abs/2001A%26A...373..251D" rel="nofollow">Dubus et al. 2001</a></li>
</ul>

CC BY-SA 3.0
2013-10-09T15:18:13.703Z
2013-10-09T15:18:13.703Z
MBR
<p>X-ray binaries such as GRS-1915 feature a black hole and a regular star. The x-ray luminosity is likely related to the rate of mass flow into the black hole from the star so when there is a lot of mass flow the x-ray luminosity is high but this explanation seems to just beg the question as to why the mass flow would change over time.</p>

<black-hole><binary-star>
Why do X-ray binaries such as GRS-1915 have active and quiet states?
ehsteve
# Why do X-ray binaries such as GRS-1915 have active and quiet states?

(Asked by: username_0 on 2013-10-08)

X-ray binaries such as GRS-1915 feature a black hole and a regular star. The x-ray luminosity is likely related to the rate of mass flow into the black hole from the star so when there is a lot of mass flow the x-ray luminosity is high but this explanation seems to just beg the question as to why the mass flow would change over time.

**Tags:** black-hole, binary-star

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## 1 answers

### Answer by username_1 on 2013-10-09. Score: 4 | Accepted answer

Such objects are surrounded by an accretion disk, that is a disk of gas, the gas being accreted onto the central object. However, at this stage of its life, the accretion disk around the black hole of a binary system like GRS-1915+105 is strongly depleted. Therefore, the accretion rate is not sufficient to support a coutinuous burst. Matter fills the outer disk until a critical density is reached, that triggered an outburst. Mass from the companion star is lost by a [Roche lobe overflow mechanism](http://astronomy.swin.edu.au/cosmos/R/roche-lobe+overflow).

**References:**

* X-ray binaries in general: [Remillard & McClintock 2006](http://cdsads.u-strasbg.fr/abs/2006ARA%26A..44...49R)
* For the outburst X-ray transients in particular: [Dubus et al. 2001](http://adsabs.harvard.edu/abs/2001A%26A...373..251D)


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