A Possible X-Ray Periodicity at Several Tens Hours of a Ultra-Luminous Compact X-Ray Source in IC 342

M. Sugiho; J. Kotoku; K. Makishima; A. Kubota; T. Mizuno; Y. Fukazawa; M. Tashiro

doi:10.1086/324456

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A Possible X-Ray Periodicity at Several Tens Hours of a Ultra-Luminous Compact X-Ray Source in IC 342

M. Sugiho·J. Kotoku·K. Makishima·A. Kubota·T. Mizuno·Y. Fukazawa·M. Tashiro

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Abstract

A long (155 hours) ASCA observation was performed of two ultra luminous compact X-ray sources, Source 1 and Source 2, in the spiral galaxy IC 342. While Source 1 that was in a hard spectral state varied little, Source 2 that was in its soft spectral state varied significantly on a time scale of about one day. The rms variation amplitude amounts to 5% in the 2-10 keV band, but is less than 4% in 0.7-2 keV. The variation involves statistically significant changes in the parameters describing multi-color disk blackbody emission from this source. The variation is possibly periodic, with a period of either 31 $\pm$ 2, hours or 41 $\pm$ 3 hours. Both are consistent with the orbital period of a semi-detached binary formed by a black hole and a main-sequence star of several tens solar masses. These results reinforce the interpretation of these X-ray objects in terms of accreting massive stellar black holes.

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M. Sugiho, J. Kotoku, K. Makishima, A. Kubota, T. Mizuno, Y. Fukazawa, M. Tashiro. 2001-09-22. A Possible X-Ray Periodicity at Several Tens Hours of a Ultra-Luminous Compact X-Ray Source in IC 342. https://doi.org/10.1086/324456

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