Journal Article

The bright unidentifiedγ-ray source 1FGL J1227.9−4852: can it be associated with a low-mass X-ray binary?

A. B. Hill, A. Szostek, S. Corbel, F. Camilo, R. H. D. Corbet, R. Dubois, G. Dubus, P. G. Edwards, E. C. Ferrara, M. Kerr, E. Koerding, D. Kozieł and Ł. Stawarz

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 415, issue 1, pages 235-243
Published in print July 2011 | ISSN: 0035-8711
Published online July 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2011.18692.x
The bright unidentifiedγ-ray source 1FGL J1227.9−4852: can it be associated with a low-mass X-ray binary?

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We present an analysis of high energy (HE; 0.1–300 GeV) γ-ray observations of 1FGL J1227.9−4852 with the Fermi Gamma-ray Space Telescope, follow-up radio observations with the Australia Telescope Compact Array, Giant Metrewave Radio Telescope and Parkes radio telescopes of the same field and follow-up optical observations with the ESO VLT. We also examine archival XMM–Newton and INTEGRAL X-ray observations of the region around this source. The γ-ray spectrum of 1FGL J1227.9−4852 is best fitted with an exponentially cut-off power law, reminiscent of the population of pulsars observed by Fermi. A previously unknown, compact radio source within the 99.7 per cent error circle of 1FGL J1227.9−4852 is discovered and has a morphology consistent either with an AGN core/jet structure or with two roughly symmetric lobes of a distant radio galaxy. A single bright X-ray source XSS J12270−4859, a low-mass X-ray binary, also lies within the 1FGL J1227.9−4852 error circle and we report the first detection of radio emission from this source. The potential association of 1FGL J1227.9−4852 with each of these counterparts is discussed. Based upon the available data we find the association of the γ-ray source to the compact double radio source unlikely and suggest that XSS J12270−4859 is a more likely counterpart to the new HE source. We propose that XSS J12270−4859 may be a millisecond binary pulsar and draw comparisons with PSR J1023+0038.

Keywords: pulsars: general; galaxies: active; gamma-rays: general; radio continuum: galaxies; X-rays: individual: XSS J12270−4859

Journal Article.  7132 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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