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تسجيل مستخدم جديدClassification of X-ray Sources in the XMM-Newton Serendipitous Source Catalog: Objects of Special Interest
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Dacheng Lin
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We analyze 18 sources that were found to show interesting properties of periodicity, very soft spectra and/or large long-term variability in X-rays in our project of classification of sources from the 2XMMi-DR3 catalog but were poorly studied in the literature, in order to investigate their nature. Two hard sources show X-ray periodicities of ~1.62 hr (2XMM J165334.4-414423) and ~2.1 hr (2XMM J133135.2-315541) and are probably magnetic cataclysmic variables. The source 2XMM J123103.2+110648 is an active galactic nucleus (AGN) candidate showing very soft X-ray spectra (kT~0.1 keV) and exhibiting an intermittent ~3.8 hr quasi-periodic oscillation. There are six other very soft sources (with kT<0.2 keV), which might be in other galaxies with luminosities between ~10^{38}-10^{42} erg/s. They probably represent a diverse group that might include objects such as ultrasoft AGNs and cool thermal disk emission from accreting intermediate-mass black holes. Six highly variable sources with harder spectra are probably in nearby galaxies with luminosities above 10^{37} erg/s and thus are great candidates for extragalactic X-ray binaries. One of them (2XMMi J004211.2+410429, in M 31) is probably a new-born persistent source, having been X-ray bright and hard in 0.3--10 keV for at least four years since it was discovered to enter an outburst in 2007. Three highly variable hard sources appear at low galactic latitudes and have maximum luminosities below ~10^{34} erg/s if they are in our Galaxy, thus great candidates for cataclysmic variables or very faint X-ray transients harboring a black hole or neutron star. Our interpretations of these sources can be tested with future long-term X-ray monitoring and multi-wavelength observations.
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We present a new method to identify luminous off-nuclear X-ray sources in the outskirts of galaxies from large public redshift surveys, distinguishing them from foreground and background interlopers. Using the 3XMM-DR5 catalog of X-ray sources and th
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Sky surveys produce enormous quantities of data on extensive regions of the sky. The easiest way to access this information is through catalogues of standardised data products. {em XMM-Newton} has been surveying the sky in the X-ray, ultra-violet, an
d optical bands for 20 years. The {em XMM-Newton} Survey Science Centre has been producing standardised data products and catalogues to facilitate access to the serendipitous X-ray sky. Using improved calibration and enhanced software, we re-reduced all of the 14041 {em XMM-Newton} X-ray observations, of which 11204 observations contained data with at least one detection and with these we created a new, high quality version of the {em XMM-Newton} serendipitous source catalogue, 4XMM-DR9. 4XMM-DR9 contains 810795 detections down to a detection significance of 3 $sigma$, of which 550124 are unique sources, which cover 1152 degrees$^{2}$ (2.85%) of the sky. Filtering 4XMM-DR9 to retain only the cleanest sources with at least a 5 $sigma$ detection significance leaves 433612 detections. Of these detections, 99.6% have no pileup. Furthermore, 336 columns of information on each detection are provided, along with images. The quality of the source detection is shown to have improved significantly with respect to previo
XMM-Newton has observed the X-ray sky since early 2000. The XMM-Newton Survey Science Centre Consortium has published catalogues of X-ray and ultraviolet sources found serendipitously in the individual observations. This series is now augmented by a
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