A transient high-coherence oscillation in 4U 1820-30

被引：9

作者：

Belloni, T

Parolin, I

Casella, P

机构：

[1] Osserv Astron Brera, INAF, I-23807 Merate, Italy

[2] Osserv Astron Roma, INAF, I-00040 Monte Porzio Catone, Italy

[3] Univ Roma Tre, Dipartimento Fis, I-00146 Rome, Italy

来源：

ASTRONOMY & ASTROPHYSICS | 2004年 / 423卷 / 03期

关键词：

accretion : accretion disks; stars : neutron; X-rays : binaries;

D O I：

10.1051/0004-6361:20040335

中图分类号：

P1 [天文学];

学科分类号：

0704 ;

摘要：

We re-analyzed two Rossi X-Ray Timing Explorer archival observations of the atoll source 4U 1820-30 in order to investigate the detailed time-frequency properties of the source during the intervals when a similar to7 Hz QPO was detected by Wijnands et a]. (1999, ApJ, 512, L39). We find that in both observations, in addition to a QPO signal lasting a couple of minutes as previously reported, there is a much narrower transient oscillation with a life time of only a few seconds. Within this time, the oscillation is consistent with being coherent. Its integrated fractional rms is around 10% and its frequency 7.3 Hz and 5.7 Hz in the two observations. We discuss the possible association of this QPO with other oscillations known both in Neutron-Star and Black-Hole systems, concentrating on the similarities with the narrow 5-7 Hz oscillations observed at high flux in Black-Hole Candidates.

引用

页码：969 / 973

页数：5

共 20 条

[1] A unified description of the timing features of accreting X-ray binaries [J].