X-ray variability with spectral state transitions in NS-LMXBs observed with MAXI/GSC and Swift/BAT

被引：8

作者：

Asai, Kazumi ^{[1
]}

Mihara, Tatehiro ^{[1
]}

Matsuoka, Masaru ^{[1
]}

Sugizaki, Mutsumi ^{[1
]}

机构：

[1] RIKEN, MAXI Team, Wako, Saitama 3510198, Japan

来源：

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN | 2015年 / 67卷 / 05期

关键词：

accretion; accretion disks; stars: neutron; X-rays: binaries; IRRADIATED ACCRETION DISKS; SLIT CAMERA GSC; NEUTRON-STAR; DWARF NOVAE; INSTABILITY MODEL; AQUILA X-1; 4U; 1636-53; BINARIES; TRANSIENTS; OUTBURSTS;

D O I：

10.1093/pasj/psv060

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

X-ray variabilities with spectral state transitions in bright low-mass X-ray binaries containing a neutron star are investigated by using the one-day bin light curves of MAXI/GSC (Gas Slit Camera) and Swift/BAT (Burst Alert Telescope). Four sources (4U 1636-536, 4U 1705-44, 4U 1608-52, and GS 1826-238) exhibited small-amplitude X-ray variabilities with spectral state transitions. Such "mini-outbursts" were characterized by smaller amplitudes (several times) and shorter duration (less than several tens of days) than those of "normal outbursts." A theoretical model of disk instability by Mineshige and Osaki (PASJ, 37, 1, 1985) predicts both large-amplitude outbursts and small-amplitude variabilities. We interpret the normal outbursts as the former prediction of this model, and the mini-outbursts as the latter. Here, we can also call the mini-outburst a "purr-type outburst" referring to the theoretical work. We suggest that similar variabilities lasting for several tens of days without spectral state transitions, which are often observed in the hard state, may be repeats of mini-outbursts.

引用

页数：14

共 57 条

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