- ID:
- ivo://nasa.heasarc/etgalxray
- Title:
- Early-Type Galaxies X-Ray Luminosities Catalog
- Short Name:
- ETGALXRAY
- Date:
- 07 Mar 2025
- 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 <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/328/461">CDS catalog J/MNRAS/328/461</a> file table3.dat. This is a service provided by NASA HEASARC .
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Search Results
- 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.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/197
- Title:
- F, G and K stars BVRI photometry
- Short Name:
- J/A+AS/131/197
- Date:
- 15 Dec 2021 08:12:40
- Publisher:
- CDS
- Description:
- We present accurate BV(RI)c photometry for a sample of F, G and K stars detected in selected areas of the ROSAT all-sky survey (RASS). We have used the photometry, in addition to low-resolution spectroscopy, to estimate spectral classifications, distances and X-ray luminosities. The log(L_X_/L_V_) in the sample lies below -2. Although the sample contains also nearby, inactive stars, it is dominated by active objects. The median X-ray luminosity in our sample is <L_X_>=29.88 and the mean value of the hardness ratios <HR1>=0.13+/-0.35. We compare the derived X-ray luminosity function with similar functions obtained from the serendipitous samples of the Einstein Observatory medium sensitivity survey (EMSS, Cat. <IX/15>) and EXOSAT (Cat. <J/A+AS/115/41>). Our sample is completely consistent with the EMSS sample of solar type stars, indicating that both our sources and the EMSS sources are representative of the high galactic latitude X-ray stellar population. We do not find extremely active stars (log(L_X_)>=32), as are found in the EMSS sample, and we argue that these objects are rare.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/251
- Title:
- Giants and supergiants ROSAT data
- Short Name:
- J/A+AS/127/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present X-ray data for all late-type (A,F,G,K,M) giants and supergiants (luminosity classes I to III-IV) listed in the Bright Star Catalogue that have been detected in the ROSAT all-sky survey. The selection of the sample stars, the data analysis, the criteria for an accepted match between star and X-ray source, and the determination of X-ray fluxes are described.
- ID:
- ivo://CDS.VizieR/J/A+A/309/116
- Title:
- 10 globular cluster ROSAT observations
- Short Name:
- J/A+A/309/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present X-ray observations of ten globular clusters observed with the ROSAT PSPC. The clusters were chosen to have large core radii and to be nearby. Three clusters contain X-ray sources which are probably associated with the cluster. One is the previously discovered X-ray transient H1825-331 in NGC 6652. The other two, in NGC 6366 and NGC 6809, are new members of the class of low-luminosity sources, with luminosities in the region of 10^32^erg/s. Upper limits can be placed on the source temperatures of both sources, making them similar to sources found in other globular clusters by ROSAT.
- ID:
- ivo://nasa.heasarc/hrassoptid
- Title:
- Hamburg/RASS Catalog: Optical Identifications
- Short Name:
- HRASS/Opt
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table is a representation of part of the Hamburg/ROSAT All-Sky Survey (RASS) Catalog (HRC) of optical identifications of X-ray sources at high-galactic latitude, namely the list of proposed and possible optical identifications. (The list of the X-ray sources themselves is given in the linked Browse table HRASSCAT). The HRC includes all X-ray sources from the ROSAT Bright Source Catalog (RASS-BSC) with galactic latitude |b| >= 30 degrees and declination Dec >= 0 degrees. In this part of the sky covering ~10,000 square degrees, the RASS-BSC contains 5341 X-ray sources. For the optical identification, the HRC authors used blue Schmidt prism and direct plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) which are now available in digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82% of the selected RASS-BSC, an identification could be given. For the rest, either no counterpart was visible in the error circle, or a plausible identification was not possible. With ~42%, AGN represent the largest group of X-ray emitters, ~31% have a stellar counterpart, whereas galaxies and cluster of galaxies comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources, no object was visible on the blue direct plates within 40" around the X-ray source position. The catalog has been used as a source for the selection of (nearly) complete samples of the various classes of X-ray emitters. This table was produced by the HEASARC in February 2005 based on the CDS Catalog table J/A+A/406/353/optical.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/hrasscat
- Title:
- Hamburg/RASS Catalog: X-Ray Sources
- Short Name:
- RASS/HRC
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table is a representation of part of the Hamburg/ROSAT All-Sky Survey (RASS) Catalog (HRC) of optical identifications of X-ray sources at high-galactic latitude, namely the list of X-ray sources. (The list of proposed and possible optical counterparts is given in the linked Browse table HRASSOPTID). The HRC includes all X-ray sources from the ROSAT Bright Source Catalog (RASS-BSC) with galactic latitude |b| >= 30 degrees and declination Dec >= 0 degrees. In this part of the sky covering ~10,000 square degrees, the RASS-BSC contains 5341 X-ray sources. For the optical identification, the HRC authors used blue Schmidt prism and direct plates taken for the northern hemisphere Hamburg Quasar Survey (HQS) which are now available in digitized form. The limiting magnitudes are 18.5 and 20, respectively. For 82% of the selected RASS-BSC, an identification could be given. For the rest, either no counterpart was visible in the error circle, or a plausible identification was not possible. With ~42%, AGN represent the largest group of X-ray emitters, ~31% have a stellar counterpart, whereas galaxies and cluster of galaxies comprise only ~4% and ~5%, respectively. In ~3% of the RASS-BSC sources, no object was visible on the blue direct plates within 40" around the X-ray source position. The catalog has been used as a source for the selection of (nearly) complete samples of the various classes of X-ray emitters. This table was produced by the HEASARC in February 2005 based on the CDS Catalog table J/A+A/406/353/x-ray.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/A+A/325/647
- Title:
- High-resolution spectra south of Taurus
- Short Name:
- J/A+A/325/647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Listed are results from our high-resolution data for all stars in our study area which were listed by either Magazzu et al. (1997A&AS..124..449M) or Alcala et al. (1996A&AS..119....7A), i.e. T Tauri candidates from the ROSAT All-Sky Survey. In table 1, we list all stars for which lithium was found either by Magazzu et al. (1997A&AS..124..449M) or in our CASPEC spectra, as well as two stars identified as wTTS by Alcala et al. (1996A&AS..119....7A). Listed are the designation, number of single-order echelle spectra taken, effective temperatures, projected rotational velocities, mean heliocentric radial velocities with errors, radial velocities in the local standard of rest, and remarks on variability in radial velocity as found in our high-resolution spectra. For comparison, we also list the results on spectral types of the stars (with `e' for H{alpha} emission) as found by Magazzu et al. (1997A&AS..124..449M) (or Alcala et al., 1996A&AS..119....7A) with low- and medium-resolution spectroscopy. In the last two columns, we list the (NLTE) lithium abundance (given on a scale where logN(H)=12) and the lithium excess above the relevant Pleiades upper envelope; upper limits indicate stars where the Magazzu et al. (1997A&AS..124..449M) spectra suffer from either low S/N or low resolution. In table 2, we list all stars where no lithium was detected -- neither by Magazzu et al. (1997A&AS..124..449M) nor in our CASPEC spectra.
- ID:
- ivo://CDS.VizieR/J/A+AS/126/509
- Title:
- HS 47.5/22: X-ray catalogue
- Short Name:
- J/A+AS/126/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 4 contains the parameters of the PSPC pointings which form the medium deep survey in HS 47.5/22, table 5 is the final X-ray source catalogue, and table 6 gives the results of the optical follow-up observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/448/683
- Title:
- Hyades RASS observations
- Short Name:
- J/ApJ/448/683
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a complete X-ray survey of the Hyades cluster region using the ROSAT All-Sky Survey (RASS). Our survey covers over 900deg^2^ of the sky. Over 185 optically identified Hyades were detected down to a limiting X-ray luminosity of ~1-2x10^28^ergs/s (0.1-1.8keV); among solar-like stars, i.e., main-sequence stars of spectral type G, the RASS detection rate is ~90%. The presence of many binary systems in the cluster is a key factor influencing the X-ray luminosity function. Short-period (~ a few days or less) binaries are anomalously X-ray bright, as might be expected; however, the X-ray luminosity functions of K and possibly M binaries of all types are significantly different from their single counterparts, confirming the results of Pye et al. (1994MNRAS.266..798P) for a smaller K star sample drawn from deep ROSAT pointings. Comparison with Einstein Observatory studies of a subset of Hyades stars demonstrates a general lack of significant (> a factor of 2) long-term X-ray variability. This may be the result of the dominance of a small-scale, turbulent dynamo in the younger Hyades stars compared to the large-scale, cyclic dynamo observed in the Sun.
