The relation between outburst rate and orbital period in low-mass X-ray binary transients. (arXiv:1901.00239v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Lin_J/0/1/0/all/0/1">Jie Lin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yan_Z/0/1/0/all/0/1">Zhen Yan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Han_Z/0/1/0/all/0/1">Zhanwen Han</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yu_W/0/1/0/all/0/1">Wenfei Yu</a>
We have investigated the outburst properties of low-mass X-ray binary
transients (LMXBTs) based on a comprehensive study of the outbursts observed in
the past few decades. The outburst rates were estimated based on the X-ray
monitoring data from Swift/BAT, RXTE/ASM and MAXI, and previous reports in the
literature. We found that almost all LMXBTs with the orbital period below
$sim$12 hr showed only one outburst in these observations. There are
systematic difference in the outburst rate between long-period ($P_{rm orb}
gtrsim$ 12 hr) and short-period ($P_{rm orb} lesssim$ 12 hr) systems. We
infer that mass transfer rate is responsible for the systematic difference,
since the disk instability model (DIM) suggested that the mass transfer rate is
a key factor affecting the quiescence time. The difference in outburst rate
between long-period and short-period LMXBTs is probably due to the different
mass transfer mechanism at different evolutionary stages of the donors. Based
on the evolutionary tracks of single stars, we derived the critical orbital
period for X-ray binaries that harbor a subgiant donor in various metallicity.
The critical orbital period ($P_{rm orb,crit}=$12.4 hr) is consistent with the
above orbital period boundary obtained from the statistics of outburst rates.
Furthermore, we found a negative correlation between the outburst rate and the
orbital period in the samples for which the luminosity class of the donor star
is III/IV. The best-fitting power-law index for the black hole subsamples is
roughly consistent with the theoretical prediction for those systems with a
donor star evolved off the main sequence.
We have investigated the outburst properties of low-mass X-ray binary
transients (LMXBTs) based on a comprehensive study of the outbursts observed in
the past few decades. The outburst rates were estimated based on the X-ray
monitoring data from Swift/BAT, RXTE/ASM and MAXI, and previous reports in the
literature. We found that almost all LMXBTs with the orbital period below
$sim$12 hr showed only one outburst in these observations. There are
systematic difference in the outburst rate between long-period ($P_{rm orb}
gtrsim$ 12 hr) and short-period ($P_{rm orb} lesssim$ 12 hr) systems. We
infer that mass transfer rate is responsible for the systematic difference,
since the disk instability model (DIM) suggested that the mass transfer rate is
a key factor affecting the quiescence time. The difference in outburst rate
between long-period and short-period LMXBTs is probably due to the different
mass transfer mechanism at different evolutionary stages of the donors. Based
on the evolutionary tracks of single stars, we derived the critical orbital
period for X-ray binaries that harbor a subgiant donor in various metallicity.
The critical orbital period ($P_{rm orb,crit}=$12.4 hr) is consistent with the
above orbital period boundary obtained from the statistics of outburst rates.
Furthermore, we found a negative correlation between the outburst rate and the
orbital period in the samples for which the luminosity class of the donor star
is III/IV. The best-fitting power-law index for the black hole subsamples is
roughly consistent with the theoretical prediction for those systems with a
donor star evolved off the main sequence.
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