Sasaki M, Pietsch W, Haberl F, Hatzidimitriou D, Stiele H, Williams BF, Kong A, Kolb U (2012)
Publication Status: Published
Publication Type: Journal article
Publication year: 2012
Publisher: EDP SCIENCES S A
Book Volume: 544
DOI: 10.1051/0004-6361/201219025
Context. We carried out new observations of two fields in the
star-forming northern ring of M 31 with XMM-Newton with each one of them
consisting of two exposures of about 100 ks each. A previous XMM-Newton
survey of the entire M 31 galaxy revealed extended diffuse X-ray
emission in these regions.
Aims: We study the population of X-ray
sources in the northern disc of M 31 by compiling a complete list of
X-ray sources down to a sensitivity limit of ̃7 × 1034 erg s-1
(0.5-2.0 keV) and improve the identification of the X-ray sources. The
major objective of the observing programme was the study of the hot
phase of the interstellar medium (ISM) in M 31. The analysis of the
diffuse emission and the study of the ISM is presented in a separate
paper.
Methods: We analysed the spectral properties of all detected
sources using hardness ratios and spectra if the statistics were high
enough. We also checked for variability. In order to classify the
sources detected in the new deep XMM-Newton observations, we
cross-correlated the source list with the source catalogue of a new
survey of the northern disc of M 31 carried out with the Chandra X-ray
Observatory and the Hubble Space Telescope (Panchromatic Hubble
Andromeda Treasury, PHAT) as well as with other existing catalogues.
Results: We detected a total of 389 sources in the two fields of the
northern disc of M 31 observed with XMM-Newton. We identified 43
foreground stars and candidates and 50 background sources. Based on a
comparison with the results of the Chandra/PHAT survey, we classify 24
hard X-ray sources as new candidates for X-ray binaries. In total, we
identified 34 X-ray binaries and candidates and 18 supernova remnants
(SNRs) and candidates. We studied the spectral properties of the four
brightest SNRs and confirmed five new X-ray SNRs. Three of the four
SNRs, for which a spectral analysis was performed, show emission mainly
below 2 keV, which is consistent with shocked ISM. The spectra of two of
them also require an additional component with a higher temperature.
The SNR [SPH11] 1535 has a harder spectrum and might suggest that there
is a pulsar-wind nebula inside the SNR. For all SNRs in the observed
fields, we measured the X-ray flux or calculated upper limits. We also
carried out short-term and long-term variability studies of the X-ray
sources and found five new sources showing clear variability. In
addition, we studied the spectral properties of the transient source
SWIFT J004420.1+413702, which shows significant variation in flux over a
period of seven months (June 2015 to January 2016) and associated
change in absorption. Based on the likely optical counterpart detected
in the Chandra/PHAT survey, the source is classified as a low-mass X-ray
binary.
APA:
Sasaki, M., Pietsch, W., Haberl, F., Hatzidimitriou, D., Stiele, H., Williams, B.F.,... Kolb, U. (2012). Supernova remnants and candidates detected in the XMM-Newton M31 large survey. Astronomy & Astrophysics, 544. https://doi.org/10.1051/0004-6361/201219025
MLA:
Sasaki, Manami, et al. "Supernova remnants and candidates detected in the XMM-Newton M31 large survey." Astronomy & Astrophysics 544 (2012).
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