Astrophys. J., 577, 738-756 (2002/October-1)
X-ray point sources in the central region of M31 as seen by Chandra.
KONG A.K.H., GARCIA M.R., PRIMINI F.A., MURRAY S.S., DI STEFANO R. and McCLINTOCK J.E.
Abstract (from CDS):
We report on Chandra observations of the central region of M31. By combining eight Chandra ACIS-I observations taken between 1999 and 2001, we have identified 204 X-ray sources within the central ∼17'x17' region of M31, with a detection limit of ∼2x1035 ergs.s–1. Of these 204 sources, 22 are identified with globular clusters, two with supernova remnants, nine with planetary nebula, and nine with supersoft sources. By comparing individual images, about 50% of the sources are variable on timescales of months. We also found 13 transients, with light curves showing a variety of shapes. We also extracted the energy spectra of the 20 brightest sources; they can be well fitted by a single power law with a mean photon index of 1.8. The spectral shapes of 12 sources are shown to be variable, suggesting that they went through state changes. The luminosity function of all the point sources is consistent with previous observations (a broken power law with a luminosity break at 1.7x1037 ergs.s–1). However, when the X-ray sources in different regions are considered separately, different luminosity functions are obtained. This indicates that the star formation history might be different in different regions.
Galaxies: Individual: Messier Number: M31 - X-Rays: Galaxies - X-Rays: Stars
VizieR on-line data:
<Available at CDS (J/ApJ/577/738): table2.dat table4.dat table5.dat>
Table 2, col(1): [KGP2002] rN-NNN (Nos r1-1 to r1-33, r2-1 to r2-59, r3-1 to r3-112) = Table 2, col(2): CXOM31 JHHMMSS.s+DDMMSS N=204.
Table 4: mita NNN = [M93b] NNN in SIMBAD.
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