2004A&A...413..879P -
Astronomy and Astrophysics, volume 413, 879-887 (2004/1-3)
The eclipsing massive X-ray binary M 33 X-7: New X-ray observations and optical identification.
PIETSCH W., MOCHEJSKA B.J., MISANOVIC Z., HABERL F., EHLE M. and TRINCHIERI G.
Abstract (from CDS):
The eclipsing X-ray binary
M 33 X-7 was in the field of view during several observations of our XMM-Newton
M 33 survey and in the archival Chandra observation 1730 which cover a large part of the 3.45d orbital period. We detect emission of
M 33 X-7 during eclipse and a soft X-ray spectrum of the source out of eclipse that can best be described by bremsstrahlung or disk blackbody models. No significant regular pulsations of the source in the range 0.25-1000s were found. The average source luminosity out of eclipse is 5x10
37erg/s (0.5-4.5keV). In a special analysis of DIRECT observations we identify as optical counterpart a B0I to O7I star of 18.89mag in V which shows the ellipsoidal heating light curve of a high mass X-ray binary with the
M 33 X-7 binary period. The location of the X-ray eclipse and the optical minima allow us to determine an improved binary period and ephemeris of mid-eclipse as HJD (2 451760.61±0.09)±Nx(3.45376±0.00021). The mass of the compact object derived from orbital parameters and the optical companion mass, the lack of pulsations, and the X-ray spectrum of
M 33 X-7 may indicate that the compact object in the system is a black hole.
M 33 X-7 would be the first detected eclipsing high mass blackhole X-ray binary.
Abstract Copyright:
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Journal keyword(s):
galaxies: individual: M 33 - X-rays: individuals: M 33 X-7 - X-rays: binaries - binaries: eclipsing
Simbad objects:
7
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