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XMM-NEWTON OBSERVATIONS OF NGC 247: X-RAY POPULATION AND A SUPERSOFT ULTRALUMINOUS X-RAY SOURCE
Journal article   Open access   Peer reviewed

XMM-NEWTON OBSERVATIONS OF NGC 247: X-RAY POPULATION AND A SUPERSOFT ULTRALUMINOUS X-RAY SOURCE

JING Jin, HUA Feng, Philip Kaaret and Shuang-Nan Zhang
The Astrophysical journal, Vol.737(2), 87
2011
DOI: 10.1088/0004-637X/737/2/87

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Abstract

We report on a new XMM-Newton observation of NGC 247 from 2009 December. The galaxy contains a supersoft, ultraluminous X-ray source whose spectrum consists of a thermal component with a temperature about 0.1keV and a power-law tail with a photon index around 2.5. The thermal emission is absolutely the dominant component, contributing 96% of the total luminosity in the 0.3-10keV band. Variability is detected at timescales of 102 s and longer with a ν-1 power spectrum. These properties are consistent with black hole binaries in the thermal state and suggest the presence of an intermediate-mass black hole of at least 600 solar masses. However, the integrated root-mean-square power is much higher than typically found in the thermal state. An alternative explanation of the emission could be a photosphere with a radius about 109cm. A possible absorption feature around 1keV is detected, which may be due to absorption of highly ionized winds. X-ray sources within the disk of NGC 247 have a luminosity function consistent with that found in low-mass X-ray binaries. We confirm previous results that X-rays from the quasar PHL 6625 may be absorbed by gas in NGC 247, mainly at energies below 0.3keV. © 2011. The American Astronomical Society. All rights reserved..
 Astronomy Earth, ocean, space Exact sciences and technology

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