Abstract.In an XMM-Newton raster observation of the bright Local Group spiral galaxy M 33 we study the population of X-ray sources (X-ray binaries, supernova remnants) down to a 0.2-4.5 keV luminosity of 10 35 erg s −1 -more than a factor of 10 deeper than earlier ROSAT observations. EPIC hardness ratios and optical and radio information are used to distinguish between different source classes. The survey detects 408 sources in an area of 0.80 square degree. We correlate these newly detected sources with earlier M 33 X-ray catalogues and information from optical, infra-red and radio wavelengths. As M 33 sources we detect 21 supernova remnants (SNR) and 23 SNR candidates, 5 super-soft sources and 2 X-ray binaries (XRBs). There are 267 sources classified as hard, which may either be XRBs or Crab-like SNRs in M 33 or background AGN. The 44 confirmed and candidate SNRs more than double the number of X-ray detected SNRs in M 33. 16 of these are proposed as SNR candidates from the X-ray data for the first time. On the other hand, there are several sources not connected to M 33: five foreground stars, 30 foreground star candidates, 12 active galactic nucleus candidates, one background galaxy and one background galaxy candidate. Extrapolating from deep field observations we would expect 175 to 210 background sources in this field. This indicates that about half of the sources detected are within M 33.
We present an analysis of the individual observations of a deep XMM-Newton survey of the Local Group spiral galaxy M 33. We detected a total of 350 sources with fluxes (in the 0.2-4.5 keV energy band) in the range 6.7 × 10 −16 −1.5 × 10 −11 erg s −1 . This comprehensive study considers flux variability, spectral characteristics, and classification of the detected objects. Thirty-nine objects in our catalogue are new sources, while 311 were already detected in a previous analysis of most of the same data using combined images. We present improved positions of these sources and the X-ray parameters of each source in each individual observation that covers the source. We then used these parameters to systematically search for flux variability on time scales of hours to months or years. The long-term light-curves were generated for the 61 sources showing a significant variability of the (0.2-4.5) keV flux, by a factor of 1.2 to 144. The detected variability was then used to classify 8 new X-ray binary candidates in M 33. Together with the hardness ratio method and cross-correlation with optical, infrared, and radio data, we also classify or confirm previous classification of 25 supernova remnants and candidates, 2 X-ray binaries, and 11 super-soft source candidates (7 of which are new SSS candidates). In addition, we classify 13 active galactic nuclei and background galaxies, 6 stars, and 23 foreground star candidates in the direction of M 33. Further 206 objects are classified as "hard", approximately half of which are sources intrinsic to M 33. The relative contribution of the classified XRB and SSS in M 33 is now comparable to M 31. The luminosity distribution of SNRs in both spiral galaxies is almost the same, although the number of the detected SNRs in M 33 remains much higher.
Chandra and XMM-Newton resolved extremely long tails behind two middle-aged pulsars, J1509-5850 and J1740+1000. The tail of PSR J1509-5850 is discernible up to 5.6 from the pulsar, which corresponds to the projected length l ⊥ = 6.5d 4 pc, where d = 4d 4 kpc is the distance to the pulsar. The observed tail flux is 2 × 10 −13 erg s −1 cm −2 in the 0.5-8 keV band. The tail spectrum fits an absorbed power-law (PL) model with the photon index Γ = 2.3 ± 0.2, corresponding to the 0.5-8 keV luminosity of 1 × 10 33 d 2 4 ergs s −1 , for n H = 2.
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