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arXiv · 1402.3802

Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44

Long Ji·Shu Zhang·YuPeng Chen·Shuang-Nan Zhang·Peter Kretschmar·Jian-Min Wang·Jian Li
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Abstract

Aims: A hard X-ray shortage, implying the cooling of the corona, was observed during bursts of IGR J17473-272, 4U 1636-536, Aql X-1, and GS 1826-238. Apart from these four sources, we investigate here an atoll sample, in which the number of bursts for each source is larger than 5, to explore the possible additional hard X-ray shortage during {\it Rossi X-ray timing explorer (RXTE)} era. Methods: According to the source catalog that shows type-I bursts, we analyzed all the available pointing observations of these sources carried out by the {\it RXTE} proportional counter array (PCA). We grouped and combined the bursts according to their outburst states and searched for the possible hard X-ray shortage while bursting. Results: We found that the island states of KS 1731-260 and 4U 1705-44 show a hard X-ray shortage at significant levels of 4.5 and 4.7 $\sigma$ and a systematic time lag of $0.9 \pm 2.1$ s and $2.5 \pm 2.0$ s with respect to the soft X-rays, respectively. While in their banana branches and other sources, we did not find any consistent shortage.

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Long Ji, Shu Zhang, YuPeng Chen, Shuang-Nan Zhang, Peter Kretschmar, Jian-Min Wang, Jian Li. 2014-02-16. Possible hard X-ray shortages in bursts from KS 1731-260 and 4U 1705-44. https://doi.org/10.1051/0004-6361/201322981

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