X-ray scattered halo around IGR J17544-2619

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Mao, Junjie and Ling, Zhixing and Zhang, Shuang-Nan (2014) X-ray scattered halo around IGR J17544-2619. The Astrophysical Journal, 785 (1). pp. 1-10. ISSN 1538-4357 (https://doi.org/10.1088/0004-637X/785/1/23)

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Abstract

X-ray photons coming from an X-ray point source not only arrive at the detector directly, but also can be strongly forward-scattered by the interstellar dust along the line of sight (LOS), leading to a detectable diffuse halo around the X-ray point source. The geometry of small angle X-ray scattering is straightforward, namely, the scattered photons travel longer paths and thus arrive later than the unscattered ones; thus the delay time of X-ray scattered halo photons can reveal information of the distances of the interstellar dust and the point source. Here we present a study of the X-ray scattered around IGR J17544-2619, which is one of the so-called supergiant fast X-ray transients. IGR J17544-2619 underwent a striking outburst when observed with Chandra on 2004 July 3, providing a near delta-function lightcurve. We find that the X-ray scattered halo around IGR J17544-2619 is produced by two interstellar dust clouds along the LOS. The one which is closer to the observer gives the X-ray scattered at larger observational angles; whereas the farther one, which is in the vicinity of the point source, explains the halo with a smaller angular size. By comparing the observational angle of the scattered halo photons with that predicted by different dust grain models, we are able to determine the normalized dust distance. With the delay times of the scattered halo photons, we can determine the point source distance, given a dust grain model. Alternatively we can discriminate between the dust grain models, given the point source distance.

ORCID iDs

Mao, Junjie ORCID logoORCID: https://orcid.org/0000-0001-7557-9713, Ling, Zhixing and Zhang, Shuang-Nan;
  • Item type:Article
    ID code:70867
    Dates:
    Date
    Event
    20 February 2014
    Published
    17 February 2014
    Accepted
    Subjects:Science > Astronomy
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:13 Dec 2019 09:35
    Last modified:11 Nov 2024 12:31
    URI:https://strathprints.strath.ac.uk/id/eprint/70867
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