Quasi-periodic X-ray brightness oscillations of GRO J1744-28

被引:47
作者
Zhang, W
Morgan, EH
Jahoda, K
Swank, JH
Strohmayer, TE
Jernigan, G
Klein, RI
机构
[1] UNIV SPACE RES ASSOC,WASHINGTON,DC
[2] MIT,SPACE RES CTR,CAMBRIDGE,MA 02139
[3] UNIV CALIF BERKELEY,SPACE SCI LAB,BERKELEY,CA 94720
[4] UNIV CALIF BERKELEY,DEPT ASTRON,BERKELEY,CA 94720
[5] LAWRENCE LIVERMORE NATL LAB,LIVERMORE,CA 94550
关键词
binaries; general; pulsars; stars; individual (GRO J1744-28); neutron; X-rays; bursts;
D O I
10.1086/310259
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
The newly discovered source GRO J1744-28 is remarkable in many respects. It is a low-mass X-ray binary system that shows 2.1 Hz coherent pulsations. It also produces type II X-ray bursts similar to those seen in the Rapid Burster. In this Letter we report results from a series of observations with the Rossi X-Ray Timing Explorer (RXTE) during which GRO J1744-28 showed quasi-periodic X-ray brightness oscillations (QPOs) at 20, 40, and 60 Hz. Their fractional rms amplitudes are 0.19%, 5.9%, and 0.42%, respectively. The QPO centroid frequency and its rms amplitude as a function of source brightness in the band of 2-60 keV indicate that these QPOs are of a different kind from the beat-frequency QPOs that have been observed among Z sources as well as X-ray pulsars, We discuss possible interpretations of these QPOs in the context of neutron star g-mode oscillations and photon bubble oscillations.
引用
收藏
页码:L29 / L32
页数:4
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