- ID:
- ivo://nasa.heasarc/euvexrtcat
- Title:
- All-Sky Catalog of Faint EUV Sources
- Short Name:
- EUV/Faint
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The All-Sky Catalog of Faint Extreme-Ultraviolet (EUV) Sources is a list of 534 objects detected jointly in the Extreme Ultraviolet Explorer (EUVE) (100 Angstrom (AA) band) All-Sky Survey and in the ROSAT X-ray Telescope (XRT) (0.25 keV band) All-Sky Survey. The joint selection criterion within a 1.5 arcminute positional tolerance permitted the use of a low count rate threshold in each survey. This low threshold was roughly 60% of the threshold used in the previous EUVE all-sky surveys, and 166 of the objects listed in this table were new EUV sources, appearing neither in the Second EUVE Source Catalog nor in the ROSAT Wide Field Camera Second Catalog. Preliminary identifications are offered for 105 of the 166 sources not previously reported in any EUV catalog: by far the most numerous (81) of the identifications are late-type (F-M) stars, while 18 are other stellar types, only 5 are white dwarfs, and none are extragalactic. The paucity of WDs and extragalactic objects may be explained by a strong horizon effect wherein interstellar absorption strongly limits the effective new-source search volume, and, thereby, selectively favors low-luminosity nearby sources over more luminous but distant objects. Notice that, with the adopted 1.5 arcminute acceptance criterion, about 50 spurious detections are expected. This Browse table was created in July 2003 based on CDS table IX/35/faint.dat. This is a service provided by NASA HEASARC .
« Previous |
1 - 10 of 119
|
Next »
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/511/595
- Title:
- An X-Ray Survey of Galaxies in Pairs
- Short Name:
- J/ApJ/511/595
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Results are reported from the first survey of X-ray emission from galaxies in pairs. The sample consists of 52 pairs of galaxies from the Catalog of Paired Galaxies (Cat. <VII/77>) whose coordinates overlap the ROSAT Position Sensitive Proportional Counter pointed observations. The mean observed log(L_x_) for early-type pairs is 41.35+/-0.21, while the mean log(L_x_) predicted using the (L_X_-L_b_) relationship for isolated early-type galaxies is 42.10+/-0.19. With 95% confidence, the galaxies in pairs are underluminous in the X-ray, compared with isolated galaxies, for the same L_b_. A significant fraction of the mixed pair sample also appears similarly underluminous. A spatial analysis shows that the X-ray emission from pairs of both types typically has an extent of 10 - 50 kpc, much smaller than the group intergalactic medium, and thus likely originates from the galaxies. CPG 564, the most X-ray luminous early-type pair, 4.7x10^42^ergs/s, is an exception. The extent of its X-ray emission, greater than 169 kpc, and HWHM, {~}80 kpc, is comparable to that expected from an intergalactic medium. The sample shows only a weak correlation, {~}81% confidence, between L_X_ and L_b_, presumably due to variations in gas content within the galaxies. No correlation between L_X_ and the pair velocity difference ({delta}v), separation ({delta}r), or far-infrared luminosity (L_fir_) is found, although the detection rate is low, 22%.
- ID:
- ivo://nasa.heasarc/bmwhricat
- Title:
- Brera Multi-scale Wavelet ROSAT HRI Source Catalog
- Short Name:
- BMW-HRI
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Brera Multi-scale Wavelet ROSAT High Resolution Imager Source Catalog (BMW-HRI) is derived from all ROSAT HRI pointed observations with exposure time longer than 100 seconds available in the ROSAT public archives. The data were analyzed automatically using a wavelet detection algorithm suited to the detection and characterization of both point-like and extended sources. This algorithm is able to detect and disentangle sources in very crowded fields and/or in presence of extended or bright sources. Images have been also visually inspected after the analysis to ensure verification. The final catalog, derived from 4,303 observations, consists of 29,089 sources detected with a detection probability of greater or equal 4.2 sigma. For each source, the primary catalog entries provide name, position, count rate, flux and extension along with the relative errors. In addition, results of cross-correlations with existing catalogs at different wavelengths (FIRST, IRAS, 2MASS, and GSC2) are also reported. As an external check, the authors compared their catalog with the previously available ROSHRICAT catalog (both in its short and long versions) and were able to recover, for the short version, ~90% of the entries. The sky coverage of the entire HRI data set was computed by means of simulations. The complete BMW-HRI catalog provides a sky coverage of 732 square degrees down to a limiting flux of ~1x10<sup>-12</sup> erg/s/cm<sup>2</sup> and of 10 square degrees down to ~1x10<sup>-14</sup> erg/s/cm<sup>2</sup>. The authors were able to compute the cosmological log(N)-log(S) distribution down to a flux of about 1.2x10<sup>-14</sup> erg/s/cm<sup>2</sup>. This catalog was ingested by the HEASARC in March 2003, based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/IX/34">CDS Catalog IX/34</a> file catalog.dat.gz. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJS/126/209
- Title:
- Bright SHARC survey cluster catalog
- Short Name:
- J/ApJS/126/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the Bright SHARC (Serendipitous High-Redshift Archival ROSAT Cluster) Survey, which is an objective search for serendipitously detected extended X-ray sources in 460 deep ROSAT PSPC pointings. The Bright SHARC Survey covers an area of 178.6 deg^2^ and has yielded 374 extended sources. We discuss the X-ray data reduction, the candidate selection and present results from our on-going optical follow-up campaign. The optical follow-up concentrates on the brightest 94 of the 374 extended sources and is now 97% complete. We have identified 37 clusters of galaxies, for which we present redshifts and luminosities. The clusters span a redshift range of 0.0696<z<0.83 and a luminosity range of 0.065<L_X_< 8.3x10^44^ergs/s [0.5-2.0keV] (assuming H_0_=50km/s/Mpc and q_0_=0.5). Twelve of the clusters have redshifts greater than z=0.3, eight of which are at luminosities brighter than L_X_=3x10^44^ergs/s. Seventeen of the 37 optically confirmed Bright SHARC clusters have not been listed in any previously published catalog. We also report the discovery of three candidate "fossil groups" of the kind proposed by Ponman et al. (1994Natur.369..462P)
- ID:
- ivo://nasa.heasarc/bhrfscid
- Title:
- Byurakan/Hamburg/ROSAT Catalog of Optical IDs
- Short Name:
- BHROSATOpt.
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Byurakan/Hamburg/ROSAT Catalog (BHRC) of the optical identifications of X-ray sources. The BHRC includes all 2791 X-ray sources from the ROSAT Faint Source Catalog (ROSAT-FSC, CDS Catalog <IX/29>) with galactic latitude |b| >= 30 degrees, declination >= 0 degrees, and ROSAT PSPC count rate CR > 0.04 ct/s. The optical identifications were carried out using the Hamburg Quasar Survey (HQS) digitized spectroscopic plates, the DSS1 and DSS2 (blue, red, and IR) images, the MAPS photometric data, the USNO-B1.0 (for proper motion), the NVSS and FIRST radio, and the IRAS and 2MASS infrared catalogs. From the DSS images, positional, brightness, color, extension, variability, and proper-motion information, the optical-to-X-ray positional offsets were obtained and a morphological classification was made. Available SIMBAD and NED data were also utilized. Cross-correlations were made with AGN, white dwarf, and cataclysmic variable catalogs (322, 8 and 7 associations, respectively). The authors managed to identify 97% of the sources (2696/2791 sources) that are associated with 3202 optical objects. 2248 X-ray sources have a single optical counterpart, 144 have a double or multiple optical counterpart (binaries, galaxy groups, etc.), and 304 have ambiguous identifications (some of the latter might actually be blends of two X-ray sources that were not resolved by ROSAT). The QSOs and AGN represent the largest group of X-ray counterparts (56.2%); bright stars (including late-type stars, but excluding WDs and CVs) are counterparts for 33.2% of the sources, and bright galaxies and groups of galaxies comprise 9.2%. A number of close galaxy pairs (possibly interacting/merging galaxies) are found as counterparts for X-ray sources (3.0%), as well as 1.0% WDs and 0.4% CVs. The BHRC may be used for the selection and study of samples of the various classes of X-ray emitters: the table gives all the available multiwavelength data for the identified sources. This table was created by the HEASARC in June 2006 based on CDS table J/A+A/449/425/table1.dat This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/502/558
- Title:
- Catalog of ROSAT galaxy clusters
- Short Name:
- J/ApJ/502/558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 203 clusters of galaxies serendipitously detected in 647 ROSAT PSPC high Galactic latitude pointings covering 158deg^2^. This is one of the largest X-ray-selected cluster samples, comparable in size only to the ROSAT All-Sky Survey sample of nearby clusters (Ebeling et al., 1997ApJ...479L.101E). We detect clusters in the inner 175 of the ROSAT PSPC field of view using the spatial extent of their X-ray emission. Fluxes of detected clusters range from 1.6x10^-14^ to 8x10^-12^ergs/s/cm^2^ in the 0.52keV energy band. X-ray luminosities range from 10^42^ergs/s, corresponding to very poor groups, to ~5x10^44^ergs/s, corresponding to rich clusters. The cluster redshifts range from z=0.015 to z>0.5. The catalog lists X-ray fluxes, core radii, and spectroscopic redshifts for 73 clusters and photometric redshifts for the remainder.
- ID:
- ivo://CDS.VizieR/J/A+A/316/147
- Title:
- Catalogue of ROSAT White Dwarfs
- Short Name:
- J/A+A/316/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table1 lists all white dwarf stars, both previously-catalogued and newly discovered, which have been detected in the ROSAT All-Sky Survey. The positions and count rates of the X-ray sources associated with each star are given, as well as spectral types and other star names for those stars which have been previously catalogued. Table2 lists distances estimated via Balmer line profile fitting, corrected (for IS absorption) X-ray luminosities, and each star's contribution to the X-ray luminosity function for all DA white dwarfs which were detected in the ROSAT All-Sky Survey.
- ID:
- ivo://CDS.VizieR/J/A+AS/114/109
- Title:
- Cha X-ray sources & optical identifications
- Short Name:
- J/A+AS/114/109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the observations of the ROSAT all-sky survey (RASS) in the direction of the Chamaeleon cloud complex, as well as the spectroscopic identifications of the detected X-ray sources. The main purpose of this identification program was the search for low mass pre-main sequence stars. Sixteen previously known PMS stars were detected with high confidence by ROSAT. Eight are classical T Tauri stars and eight are weak-line T Tauri stars. Seventy-seven new weak-line T Tauri stars were identified on the basis of the presence of strong Li {lambda}6707 absorption, spectral type later than F0 and chromospheric emission. We give coordinates and count rates of the X-ray sources, and present optical spectra and finding charts for the sources identified optically as new pre-main sequence stars. Optical UBV(RI)c and near-infrared JHKLM photometry for this sample of stars is also provided. In addition, 6 new dKe-dMe candidates are found among the RASS sources.
- ID:
- ivo://nasa.heasarc/etgalxray
- Title:
- Early-Type Galaxies X-Ray Luminosities Catalog
- Short Name:
- ETGALXRAY
- Date:
- 10 May 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains a catalog of X-ray luminosities for 401 early-type galaxies (and 24 other galaxies which were listed in previuous studies as early but which have LEDA T-types >= -1.5), of which 136 are based on newly analysed ROSAT PSPC pointed observations. The remaining luminosities are taken from the literature and converted to a common energy band, spectral model and distance scale. In their paper, the authors use this sample to fit the L<sub>X</sub>/L<sub>B</sub> relation for early-type galaxies and find a best-fit slope for the catalog of ~ 2.2. The authors demonstrate the influence of group-dominant galaxies on the fit and present evidence that the relation is not well modeled by a single power-law fit. They also derive estimates of the contribution to galaxy X-ray luminosities from discrete-sources and conclude that they provide L<sub>(discrete-source-contribution)</sub>/L<sub>B</sub> ~ 29.5 erg s<sup>-1</sup>/L<sub>Bsun</sub>. The authors compare this result with luminosities from their catalog. Lastly, they examine the influence of environment on galaxy X-ray luminosity and on the form of the L<sub>X</sub>/L<sub>B</sub> relation. They conclude that although environment undoubtedly affects the X-ray properties of individual galaxies, particularly those in the centres of groups and clusters, it does not change the nature of whole populations. The sample of early-type galaxies was selected from the Lyon-Meudon Extragalactic Data Archive (LEDA). This catalog at that time contained information on ~ 100,000 galaxies, of which ~ 40,000 had redshift and morphological data. Galaxies were selected using the following criteria: (i) Morphological Type T < -1.5 (i.e. E, E-S0 and S0 galaxies). (ii) Virgo-corrected recession velocity V <= 9,000 km s<sup>-1</sup>. (iii) Apparent Magnitude B<sub>T</sub> <= 13.5. The redshift and apparent magnitude restrictions were chosen in order to minimize the effects of incompleteness on their sample. The LEDA catalogue is known to be 90 per cent complete at B<sub>T</sub> = 14.5, so the selection should be close to statistical completeness. The selection process produced ~ 700 objects. The authors then cross-correlated this list with a list of public ROSAT PSPC pointings. Only pointings within 30 arcminutes of the target were accepted, as, further off-axis, the PSPC point-spread function becomes large enough to make analysis problematic. This left 209 galaxies with X-ray data available. The authors also added data from previously published catalogs, ROSAT PSPC All-Sky Survey values from Beuing et al. (1999, MNRAS, 302, 209), and Einstein IPC values from Fabbiano et al. (1992, ApJS, 80, 531) and Roberts et al. (1991, ApJS, 75, 751). These other references use a range of models to fit the data, different wavebands, distances and blue luminosities. O'Sullivan et al. corrected for these differences by converting the catalogs to a common set of values, as used for their own results. All of the X-ray luminosities have been converted to a common format based on a reliable distance scale (assuming H<sub>0</sub> = 75 km s<sup>-1</sup> Mpc<sup>-1</sup>), and correcting for differences in spectral fitting techniques and waveband. This table was created by the HEASARC in October 2010 based on CDS catalog J/MNRAS/328/461 file table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/MNRAS/318/333
- Title:
- Extended ROSAT Bright Cluster Sample
- Short Name:
- J/MNRAS/318/333
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a low-flux extension of the X-ray-selected ROSAT Brightest Cluster Sample (BCS) published in Paper I of this series. Like the original BCS and employing an identical selection procedure, the BCS extension is compiled from ROSAT All-Sky Survey (RASS) data in the northern hemisphere ({delta}>=0{deg}) and at high Galactic latitudes (|b|>=20{deg}). It comprises 99 X-ray-selected clusters of galaxies with measured redshifts z<=0.3 (as well as eight more at z>0.3) and total fluxes between 2.8x10^-12^ and 4.4x10^-12^erg/cm^2^/s in the 0.1-2.4keV band (the latter value being the flux limit of the original BCS). The extension can be combined with the main sample published in 1998 to form the homogeneously selected extended BCS (eBCS), the largest and statistically best understood cluster sample to emerge from the RASS to date. The nominal completeness of the combined sample (defined with respect to a power-law fit to the bright end of the BCS logN-logS distribution) is relatively low at 75per cent (compared with 90per cent for the high-flux sample of Paper I). However, just as for the original BCS, this incompleteness can be accurately quantified, and thus statistically corrected for, as a function of X-ray luminosity and redshift. In addition to its importance for improved statistical studies of the properties of clusters in the local Universe, the low-flux extension of the BCS is also intended to serve as a finding list for X-ray-bright clusters in the northern hemisphere which we hope will prove useful in the preparation of cluster observations with the next generation of X-ray telescopes such as Chandra and XMM-Newton.
