- ID:
- ivo://CDS.VizieR/J/PAZh/42/313
- Title:
- 3XMM-DR4 QSO candidates at 3<z<5.5
- Short Name:
- J/PAZh/42/313
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of quasar candidates at redshifts 3<z<5.5 is presented. These candidates have been selected among X-ray sources in the XMM-Newton Serendipitous Source Catalog (3XMM-DR4) in the 0.5-2keV band, located at high galactic latitudes |b|>20deg in the Sloan Digital Sky Survey (SDSS) area. The total overlapping area is about 300 sq. deg. The SDSS, 2MASS and WISE photometric catalogs were used. Only SDSS point sources were considered. X-ray sources having an optical counterpart with magnitude error in SDSS z band of less than 0.2 and color i-z<0.6 were chosen. Their photometric redshifts were determined with the EAZY code using a library of spectral templates. A sample of quasar candidates with photometric redshifts in the range 2.75<z<5.5 has been composed. Objects whose spectral energy distributions are better described by stellar templates have been excluded. The selection completeness of known quasars is about 80%. The normalized median absolute deviation of the differences between the photometric and spectroscopic redshifts of known quasars is 0.07 (with 9% outliers). The sky density of quasar candidates in our sample is 1.5 times that of the spectroscopic SDSS sample in the same fields. Follow-up spectroscopy should clarify the purity of the sample.
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Search Results
- ID:
- ivo://CDS.VizieR/J/PAZh/45/464
- Title:
- 3XMM-DR4 QSO candidates optical spectroscopy
- Short Name:
- J/PAZh/45/464
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present the results of optical spectroscopy for 58 quasar candidates at photometric redshifts z>~3, 57 of which enter into the Khorunzhev et al. (2016, Cat. J/PAZh/42/313) catalog (K16). This is a catalog of quasar candidates and known type 1 quasars selected among the X-ray sources of the 3XMM-DR4 catalog of the XMM-Newton serendipitous survey. At first we have performed spectroscopy for a quasi-random sample of 19 candidates at the 1.6-m AZT-33IK telescope of the Sayan Solar Observatory and the 6-m BTA telescope of the Special Astrophysical Observatory (SAO RAS). Then we have continued the observation for 39 X-ray bright candidates that could be used for the X-ray luminosity function construction (see Khorunzhev et al. 2018AstL...44..500K). The spectra at AZT-33IK were taken with the new low- and medium-resolution ADAM spectrograph that was produced and installed on the telescope in 2015. One of the most distant (z=5.08) optically bright (i=21) quasars ever detected in X-ray surveys has been discovered.
- ID:
- ivo://CDS.VizieR/J/A+A/527/A126
- Title:
- 2XMMi/SDSS DR7 cross-correlation
- Short Name:
- J/A+A/527/A126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Survey Science Centre of the XMM-Newton satellite released the first incremental version of the 2XMM catalogue in August 2008. Containing more than 220000 X-ray sources, the 2XMMi was at that time the largest catalogue of X-ray sources ever published and thus constitutes an unprecedented resource for studying the high-energy properties of various classes of X-ray emitters such as AGN and stars. Thanks to the high throughput of the EPIC cameras on board XMM-Newton accurate positions, fluxes, and hardness ratios are available for a substantial fraction of the X-ray detections. The advent of the 7th release of the Sloan Digital Sky Survey offers the opportunity to cross-match two major surveys and extend the spectral energy distribution of many 2XMMi sources towards the optical bands. This implies building extensive homogeneous samples with a statistically controlled rate of spurious matches and completeness. We here present a cross-matching algorithm based on the classical likelihood ratio estimator. The method developed has the advantage of providing true probabilities of identifications without resorting to heavy Monte-Carlo simulations.
- ID:
- ivo://CDS.VizieR/J/A+A/490/879
- Title:
- XMM-LSS field optical identifications
- Short Name:
- J/A+A/490/879
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XMM-Large Scale Structure survey field (XMM-LSS) is an extragalactic window surveyed in the X-ray with the XMM-Newton satellite. It has also been observed in the optical with the Canada-France Hawaii Telescope (CFHTLS survey), and in the infrared with the Spitzer Space Telescope (SWIRE survey). These surveys have been carried out to study the structure and evolution of both baryonic and dark matter on cosmological scales. In two previous papers, we presented deep low frequency radio surveys of the XMM-LSS field, with limiting flux density levels of ~4 and ~1.5mJy/beam at 325 and 610MHz respectively (5{sigma}). These radio surveys were motivated by the need to understand the various connections between the host galaxies of radio sources and their environments. In this paper, we identify optical counterparts to the low frequency radio sources, using the CFHTLS optical catalogue and images, that have an i-band limiting magnitude of i_AB_~25.
- ID:
- ivo://CDS.VizieR/J/A+A/459/199
- Title:
- XMM-Newton survey of two Upper Scorpius regions
- Short Name:
- J/A+A/459/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied X-ray emission from young stars by analyzing the deep XMM-Newton observations of two regions of the Upper Scorpius association with an age of 5Myr. Based on near infrared and optical photometry we identified 22 Upper Scorpius photometric members among the 224 detected X-ray sources. We derived coronal properties of Upper Scorpius stars by performing X-ray spectral and timing analyses. The study of four strong and isolated stellar flares allowed us to derive the length of the flaring loops.
- ID:
- ivo://CDS.VizieR/J/A+A/395/499
- Title:
- XMM observations in M8 and NGC6530
- Short Name:
- J/A+A/395/499
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an XMM-Newton observation of the Lagoon Nebula (M 8). Our EPIC images of this region reveal a cluster of point sources, most of which have optical counterparts inside the very young open cluster NGC 6530. The bulk of these X-ray sources are probably associated with low and intermediate mass pre-main sequence stars.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A150
- Title:
- XMM observations of {lambda} Ori cluster
- Short Name:
- J/A+A/530/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We studied the X-ray properties of the young (~1-8Myr) open cluster around the hot (O8 III) star {lambda} Ori and compared them with those of the similarly-aged sigma Ori cluster to investigate possible effects of the different ambient environment. We analysed an XMM-Newton observation of the cluster using EPIC imaging and low-resolution spectral data. We studied the variability of detected sources, and performed a spectral analysis of the brightest sources in the field using multi-temperature models.
- ID:
- ivo://CDS.VizieR/J/MNRAS/367/781
- Title:
- XMM observations of NGC 2547
- Short Name:
- J/MNRAS/367/781
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The following tables describe the results of a survey for X-ray (0.3-3 keV) sources in the young (30Myr) NGC 2547 open cluster using the XMM-Newton EPIC instrument. Table 1 lists the details of X-ray sources which are correlated with optical cluster members. Table 2 catalogues the cross-identifications with optical catalogues for the sources in Table 1 and derives their X-ray luminosities and X-ray to bolometric flux ratios. Table 3 lists the X-ray properties of sources which are uncorrelated with cluster members. Table 7 lists the correlations between cluster members detected by XMM-Newton and those detected 7 years earlier by the ROSAT HRI instrument, along with the X-ray luminosities and flux ratios as determined by the HRI.
- ID:
- ivo://CDS.VizieR/J/A+A/456/977
- Title:
- XMM observations of NGC 2516 stars
- Short Name:
- J/A+A/456/977
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the characteristics of the X-ray variability of stars in the cluster NGC 2516 as derived from XMM-Newton/EPIC/pn data. The X-ray variations on short (hours), medium (months), and long (years) time scales have been explored. We detected 303 distinct X-ray sources by analysing six EPIC/pn observations; 194 of them are members of the cluster. Stars of all spectral types, from the early-types to the late-M dwarfs, were detected.
- ID:
- ivo://CDS.VizieR/J/ApJ/821/54
- Title:
- XMM spectral analysis of Draco dSph
- Short Name:
- J/ApJ/821/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectral analysis of an 87ks XMM-Newton observation of Draco, a nearby dwarf spheroidal galaxy. Of the approximately 35 robust X-ray source detections, we focus our attention on the brightest of these sources, for which we report X-ray and multiwavelength parameters. While most of the sources exhibit properties consistent with active galactic nuclei, few of them possess the characteristics of low-mass X-ray binaries (LMXBs) and cataclysmic variable (CVs). Our analysis places constraints on the population of X-ray sources with LX>3x10^33^erg/s in Draco, suggesting that there are no actively accreting black hole and neutron star binaries. However, we find four sources that could be quiescent state LMXBs/CVs associated with Draco. We also place constraints on the central black hole luminosity and on a dark matter decay signal around 3.5keV.
