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Register a new userXMMFITCAT: The XMM-Newton spectral-fit database
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Authors
A. Corral
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The XMM-Newton spectral-fit database (XMMFITCAT) is a catalogue of spectral fitting results for the source detections within the XMM-Newton Serendipitous source catalogue with more than 50 net (background-subtracted) counts per detector in the 0.5-10 keV energy band. Its most recent version, constructed from the latest version of the XMM-Newton catalogue, the 3XMM Data Release 4 (3XMM-DR4), contains spectral-fitting results for $gtrsim$ 114,000 detections, corresponding to $simeq$ 78,000 unique sources. Three energy bands are defined and used in the construction of XMMFITCAT: Soft (0.5-2 keV), Hard (2-10 keV), and Full (0.5-10 keV) bands. Six spectral models, three simple and three more complex models, were implemented and applied to the spectral data. Simple models are applied to all sources, whereas complex models are applied to observations with more than 500 counts (30%). XMMFITCAT includes best-fit parameters and errors, fluxes, and goodness of fit estimates for all fitted models. XMMFITCAT has been conceived to provide the astronomical community with a tool to construct large and representative samples of X-ray sources by allowing source selection according to spectral properties, as well as characterise the X-ray properties of samples selected in different wavelengths. We present in this paper the main details of the construction of this database, and summarise its main characteristics.
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The XMM-Newton spectral-fit database is an ongoing ESA funded project aimed to construct a catalogue of spectral-fitting results for all the sources within the XMM-Newton serendipitous source catalogue for which spectral data products have been pipeline-extracted (~ 120,000 X-ray source detections). The fundamental goal of this project is to provide the astronomical community with a tool to construct large and representative samples of X-ray sources by allowing source selection according to spectral properties.
We present the results of a 500 ksec long XMM-Newton observation and a 120 ksec long quasi-simultaneous Chandra observation of the Narrow Line Seyfert 1 galaxy 1H0707-495 performed in 2010 September. Consistent with earlier results by Fabian et al. (2009) and Zoghbi et al. (2010), the spectrum is found to be dominated by relativistically broadened reflection features from an ionised accretion disc around a maximally rotating black hole. Even though the spectra changed between this observation and earlier XMM-Newton observations, the physical parameters of the black hole and accretion disc (i.e., spin and inclination) are consistent between both observations. We show that this reflection spectrum is slightly modified by absorption in a mildly relativistic, highly ionised outflow which changed velocity from around 0.11c to 0.18c between 2008 January and 2010 September. Alternative models, in which the spectral shape is dominated by absorption, lead to spectral fits of similar quality, however, the parameters inferred for the putative absorber are unphysical.
Thanks to the large collecting area (3 x ~1500 cm$^2$ at 1.5 keV) and wide field of view (30 across in full field mode) of the X-ray cameras on board the European Space Agency X-ray observatory XMM-Newton, each individual pointing can result in the detection of hundreds of X-ray sources, most of which are newly discovered. Recently, many improvements in the XMM-Newton data reduction algorithms have been made. These include enhanced source characterisation and reduced spurious source detections, refined astrometric precision, greater net sensitivity and the extraction of spectra and time series for fainter sources, with better signal-to-noise. Further, almost 50% more observations are in the public domain compared to 2XMMi-DR3, allowing the XMM-Newton Survey Science Centre (XMM-SSC) to produce a much larger and better quality X-ray source catalogue. The XMM-SSC has developed a pipeline to reduce the XMM-Newton data automatically and using improved calibration a new catalogue version has been produced from XMM-Newton data made public by 2013 Dec. 31 (13 years of data). Manual screening ensures the highest data quality. This catalogue is known as 3XMM. In the latest release, 3XMM-DR5, there are 565962 X-ray detections comprising 396910 unique X-ray sources. For the 133000 brightest sources, spectra and lightcurves are provided. For all detections, the positions on the sky, a measure of the quality of the detection, and an evaluation of the X-ray variability is provided, along with the fluxes and count rates in 7 X-ray energy bands, the total 0.2-12 keV band counts, and four hardness ratios. To identify the detections, a cross correlation with 228 catalogues is also provided for each X-ray detection. 3XMM-DR5 is the largest X-ray source catalogue ever produced. Thanks to the large array of data products, it is an excellent resource in which to find new and extreme objects.
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, and 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
Most of the X-ray binary systems containing neutron stars classified as Atoll sources show two different spectral states, called soft and hard. Moreover, a large number of these systems show a reflection component relativistically smeared in their spectra, which gives information on the innermost region of the system. Our aim is to investigate the poorly studied broadband spectrum of the low mass X-ray binary system 4U 1702-429, which was recently analysed combining XMM-Newton and INTEGRAL data. The peculiar value of the reflection fraction brought us to analyse further broadband spectra of 4U 1702-429. We re-analysed the spectrum of the XMM-Newton/INTEGRAL observation of 4U 1702-429 in the 0.3-60 keV energy range and we extracted three 0.1-100 keV spectra of the source analysing three observations collected with the BeppoSAX satellite. We find that the XMM-Newton/INTEGRAL spectrum is well fitted using a model composed of a disc blackbody plus a Comptonised component and a smeared reflection component. We used the same spectral model for the BeppoSAX spectra, finding out that the addition of a smeared reflection component is statistically significant. The best-fit values of the parameters are compatible to each other for the BeppoSAX spectra. We find that the reflection fraction is $0.05^{+0.03}_{-0.01}$ for the XMM-Newton/INTEGRAL spectrum and between 0.15 and 0.4 for BeppoSAX ones. The relative reflection fraction and the ionisation parameter are incompatible between the XMM-Newton/INTEGRAL and the BeppoSAX observations and the characteristics of the Comptonising corona suggest that the source was in a soft state in the former observation and in a hard state in the latter.
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