Detection of a very low hard X-ray pulse fraction in the bright state of GX 1+4

Rao, A. R. ; Paul, B. ; Chitnis, V. R. ; Agrawal, P. C. ; Manchanda, R. K. (1994) Detection of a very low hard X-ray pulse fraction in the bright state of GX 1+4 Astronomy & Astrophysics, 289 (3). L43-L46. ISSN 0004-6361

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Official URL: http://articles.adsabs.harvard.edu/cgi-bin/nph-iar...

Abstract

We have observed the Galactic center hard X-ray pulsar GX 1+4 on 1993 December 11, in the energy range of 20 - 100 keV with a balloon-borne Xenon filled Multi-cell Proportional Counter (XMPC) telescope. The source was detected in a bright state, the average observed source count rate being 10.1 ±0.2 s-1 per detector. X-ray pulsations with a period of 121.0 ± 0.4 s were detected in the source at a very high significance level. This, compared with the Burst and Transient Source Experiment (BATSE) observations, gives a spin down rate of dot-P = 1.6 ± 1.4 s yr -1. The pulse fraction in the hard X-ray range is low (35%), and the observed spectrum is very hard (power law energy index 0.54 ± 0.18). The observed source luminosity in the 20 - 100 keV range is 7.9 ± 0.3 x 1037 erg/s. These properties are similar to those seen during high luminosity spin up state of early 1970s and suggest that the source should revert back to a a spin-up episode.

Item Type:Article
Source:Copyright of this article belongs to EDP Sciences.
Keywords:X Ray; Stars-Pulsars; Individual; GX 1+4
ID Code:85562
Deposited On:03 Mar 2012 14:47
Last Modified:19 May 2016 01:33

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