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arXiv · 0705.1978

A Radio Nebula Surrounding the Ultra-luminous X-ray Source in NGC 5408

Cornelia C. Lang·Philip Kaaret·Stephane Corbel·Allison Mercer
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Abstract

New radio observations of the counterpart of the ultraluminous X-ray source in NGC 5408 show for the first time that the radio emission is resolved with an angular size of 1.5 to 2.0 arcseconds. This corresponds to a physical size of 35-46 pc, and rules out interpretation of the radio emission as beamed emission from a relativistic jet. In addition, the radio spectral index of the counterpart is well determined from three frequencies and found to be alpha=-0.8 pm 0.2. The radio emission is likely to be optically-thin synchrotron emission from a nebula surrounding the X-ray source. The radio luminosity of the counterpart is 3.8 x 10^34 erg/s and the minimum energy required to power the nebula is ~1 x 10^49 erg. These values are two orders of magnitude larger than in any Galactic nebula powered by an accreting compact object.

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Cornelia C. Lang, Philip Kaaret, Stephane Corbel, Allison Mercer. 2007-05-14. A Radio Nebula Surrounding the Ultra-luminous X-ray Source in NGC 5408. https://doi.org/10.1086/519553

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