ETGALXRAY - Early-Type Galaxies X-Ray Luminosities Catalog
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-1.
(iii) Apparent Magnitude BT <= 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 BT = 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 H0 = 75 km s-1 Mpc-1), and correcting for differences in spectral fitting techniques and waveband.
A catalogue and analysis of X-ray luminosities of early-type galaxies. O'Sullivan E., Forbes D.A., Ponman T.J. <Mon. Not. R. Astron. Soc. 328, 461 (2001)> =2001MNRAS.328..461O
The name of the galaxy. Two of the original object names, 'ESO-LV 109-0221' and 'ESO-LV 92-0130', were changed (to 'ESO-LV 1090221' and 'ESO-LV 0920130', respectively) to conform to the current NED name standards. The HEASARC also notes that the names in the original Table 3 as published and in the CDS table from which this HEASARC table is based are different: e.g., in the paper, these 2 objects are called 'E1090221' and 'E920130', respectively.
An alternate name for the galaxy.
The Right Ascension of the galaxy in the selected equinox. The HEASARC added positions to this table using the NED name resolver.
The Declination of the galaxy in the selected equinox. The HEASARC added positions to this table using the NED name resolver.
The Galactic Longitude of the galaxy.
The Galactic Latitude of the galaxy.
The distance to the galaxy, in Mpc. Where possible, the authors take the distances from Prugniel and Simien (1996, A&A, 309, 749). These are computed using the model of Faber and Burstein (1988), which accounts for the influence of the Great Attractor and Virgocentric flow. For galaxies not listed in Prugniel & Simien they used distances from LEDA, which are corrected only for Virgocentric motion.
The logarithm of the B-band luminosity of the galaxy, in units of the solar B-band luminosity of 5.2 x 1032 erg s-1. This parameter is based on the BT magnitude given in Prugniel and Simien, where possible. When these were unavailable, the authors used BT values, or in some cases (indicated by log_lb_flag = 'Y') mB values, from NED.
This flag parameter is set to 'Y' to indicates that the log_lb value (the logarithm of the B-band luminosity of the galaxy) is based on an mB magnitude rather than a BT magnitude.
This limit parameter is set to '<' if the corresponding log_lx parameter value is an upper limit rather than a detection.
The logarithm of the X-ray luminosity of the galaxy, in erg s-1. This is given in a pseudo-bolometric broad band in order to properly normalize the IPC and PSPC measurements.
This parameter contains a reference code which indicates the source of the log_lx value as follows:
B = Beuing et al. 1999, MNRAS, 302, 209 F = Fabianno et al. 1992, ApJS, 80, 531 R = Roberts et al. 1991, ApJS, 75, 751 N = new values from this paper
The galaxy's T-type (Hubble stage), as taken from LEDA.
The HEASARC Browse object classification for the galaxy, based on the value of the t_type parameter, as follows:
-5 < t_type < -3 = Elliptical Galaxy -2.99 < t_type < -1.5 = Lenticular (S0) Galaxy -1.49 < t_type < 8 = Spiral Galaxy