THE MAIN CHARACTERISTICS OF GRO J1744-28 OBSERVED BY THE PROPORTIONALCOUNTER ARRAY EXPERIMENT ON THE ROSSI X-RAY TIMING EXPLORER

Citation
Ab. Giles et al., THE MAIN CHARACTERISTICS OF GRO J1744-28 OBSERVED BY THE PROPORTIONALCOUNTER ARRAY EXPERIMENT ON THE ROSSI X-RAY TIMING EXPLORER, The Astrophysical journal, 469(1), 1996, pp. 25-28
Citations number
30
Categorie Soggetti
Astronomy & Astrophysics
Journal title
ISSN journal
0004637X
Volume
469
Issue
1
Year of publication
1996
Part
2
Pages
25 - 28
Database
ISI
SICI code
0004-637X(1996)469:1<25:TMCOGJ>2.0.ZU;2-F
Abstract
In this Letter, we provide an introduction to the main features seen i n a series of observations of the bursting pulsar GRO J1744-28. The ob servations were made from 1996 January through May with the proportion al counter array on the Rossi X-Ray Timing Explorer spacecraft. In the 2-10 keV band, GRO J1744-28 emitted large bursts of similar to 10 s d uration at a rate of about 2 per hour. The peak flux during these burs ts was similar to 6-40 times greater than that in the quiescent, or no nbursting, periods. For the earliest bursts, the inferred peak luminos ity approaches 100 times the Eddington limit, which is suggestive of s ome kind of beaming mechanism. A range of smaller bursts and quasi-per iodic oscillation features were also seen. All this activity was super posed on an almost perfect sinusoidal modulation at a frequency of 2.1 4 Hz with an amplitude of similar to 10% of the nonbursting flux. The source's persistent flux declined in a roughly linear trend from late January until mid-May, by which time its intensity was confused with s everal other sources.