NASA/IPAC EXTRAGALACTIC DATABASE
Date and Time of the Query: 2019-05-26 T07:38:05 PDT
Help | Comment | NED Home

For refcode 2006A&A...454..447T:
Retrieve 38 NED objects in this reference.
Please click here for ADS abstract

NED Abstract

Copyright by European Southern Observatory (ESO). Reproduced by permission
2006A&A...454..447T Searching for X-ray luminous "normal" galaxies in 2dFGRS P. Tzanavaris; I. Georgantopoulos; A. Georgakakis Received 2 December 2005 / Accepted 26 February 2006 Aims. We cross-correlated the Chandra XASSIST and XMM-Newton Serendipitous Source Catalogues with the 2 degree Field Galaxy Redshift Survey (2dFGRS) database. Our aim was to identify the most X-ray luminous (L_X_ > 10^42^ erg s^-1^) examples of galaxies in the local Universe whose X-ray emission is dominated by stellar processes rather than AGN activity ("normal" galaxies), as well as to test the empirical criterion log (f_X_/f_O_) < -2 for separating AGN from NGs. We also performed a similar search in two nearby-galaxy samples from the literature. Methods. With XMM-Newton (Chandra) we covered an area of ~ 8.2 (~ 5.8) deg^2^ down to a flux limit of ~ 10^-15^ (~ 1.6 x 10^-15^) erg cm^-2^ s^-1^. We classified 2dFGRS spectra using emission-line intensity ratios. Results. We found 18 (20) 2dFGRS galaxies with XMM-Newton (Chandra), which constitute our XMM-Newton-2dFGRS (Chandra-2dFGRS) correlation sample. We classified 6 2dFGRS spectra as star-forming, H II nuclei, and 2 spectra as possible H II nuclei. The rest of the objects are absorption-line galaxies and AGN, including 3 possible LINERs. No luminous "normal" galaxies have been found, but out of 19 "normal" galaxies in this sample, 5 H II and 3 absorption-line galaxies have log (f_X_/f_O_) > -2. Furthermore, all 44 galaxies in the first literature sample have log (f_X_/f_O_) < -2 and L_X_ < 10^42^ erg s^-1^. In the second literature sample, out of a total of 170 "normal" galaxies, we found 16 galaxies with log (f_X_/f_O_) >-2, the majority of which are massive ellipticals. Three of these have L_X_ > 10^42^ erg s^-1^. Conclusions. We found no luminous "normal" galaxies in our XMM-Newton-2dFGRS and Chandra-2dFGRScorrelation samples. We found three such galaxies in the second literature sample. Considering all samples, we find that the log (f_X_/f_O_) < -2 criterion seems to select primarily against the brightest, massive ellipticals. Key words: X-rays: galaxies, galaxies: starburst, galaxies: active
Retrieve 38 NED objects in this reference.
Please click here for ADS abstract

Back to NED Home