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Chandra Observation of LMXBs in the elliptical galaxy M84

A. Finoguenov·C. Jones
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Abstract

We present characteristics of the X-ray point source population in the M84 galaxy, observed by Chandra ACIS-S. We find an excess in the number of sources centered on M84, with a spatial distribution closely corresponding to the M84 stellar light. Given an absence of recent star-formation, accreting binaries are the only candidates for the M84 X-ray sources. The majority of M84 sources (with luminosities exceeding 10^38 ergs/s) exhibit hardness ratios expected from multi-temperature black-body disk emission. The most luminous sources, which we attribute to accreting black holes exhibit X-ray colors typical of a black body spectrum. We also identify the sources whose X-ray colors match the expectations for constituents of the Cosmic X-ray Background. The number of such sources agrees with that expected to be background sources. After correcting for incompleteness in the source detection, we find a log(N)-log(S) for M84 similar to that of the elliptical galaxy NGC4697, i.e. having a break at a luminosity of L_b=2.4 (+0.6 -0.3) x10^38 ergs/s, approximately the Eddington limit on the isotropic luminosity for accretion onto a neutron star. The slope of the luminosity function above the break provides evidence for a mass distribution in the M84 accreting black holes.

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A. Finoguenov, C. Jones. 2002-04-03. Chandra Observation of LMXBs in the elliptical galaxy M84. https://doi.org/10.1086/340997

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