Journal Article

A curious source of extended X-ray emission in the outskirts of globular cluster GLIMPSE-C01

N. Mirabal

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 402, issue 2, pages 1391-1396
Published in print February 2010 | ISSN: 0035-8711
Published online February 2010 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2009.15984.x
A curious source of extended X-ray emission in the outskirts of globular cluster GLIMPSE-C01

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We report the discovery of an unusual source of extended X-ray emission CXOU J184846.3–013040 (‘The Stem’) located on the outskirts of the globular cluster GLIMPSE-C01. No point-like source falls within the extended emission which has an X-ray luminosity LX(0.3–8 keV) ∼ 1032 erg s−1 and a physical size of ∼0.1 pc at the inferred distance to the cluster. These X-ray properties are consistent with the pulsar wind nebula of an unseen pulsar located within the 95 per cent confidence error contour of an unidentified Fermiγ-ray source 0FGL J1848.6–0138. However, we cannot exclude an alternative interpretation that postulates X-ray emission associated with a bow shock produced from the interaction of the globular cluster and interstellar gas in the Galactic plane. Analysis of the X-ray data reveals that ‘The Stem’ is most significant in the 2–5 keV band, which suggests that the emission may be dominated by non-thermal bremsstrahlung from suprathermal electrons at the bow shock. If the bow shock interpretation is correct, these observations would provide compelling evidence that GLIMPSE-C01 is shedding its intracluster gas during a galactic passage. Such a direct detection of gas stripping would help clarify a crucial step in the evolutionary history of globular clusters. Intriguingly, the data may also accommodate a new type of X-ray source.

Keywords: stars: neutron; globular clusters: general; gamma-rays: observations; X-rays: general

Journal Article.  4720 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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