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J/ApJ/790/16  X-ray ETGs properties in the Chandra COSMOS survey (Civano+, 2014)

Early-type galaxies in the Chandra COSMOS survey. Civano F., Fabbiano G., Pellegrini S., Kim D.-W., Paggi A., Feder R., Elvis M. <Astrophys. J., 790, 16 (2014)> =2014ApJ...790...16C (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; X-ray sources ; Redshifts Keywords: galaxies: evolution - galaxies: formation - surveys - X-rays: galaxies Abstract: We study a sample of 69 X-ray detected early-type galaxies (ETGs), selected from the Chandra COSMOS survey, to explore the relation between the X-ray luminosity of hot gaseous halos (L_X, gas_) and the integrated stellar luminosity (LK) of the galaxies, in a range of redshift extending out to z = 1.5. In the local universe, a tight, steep relationship has been established between these two quantities (Lx.gas ∼ LK4.5), suggesting the presence of largely virialized halos in X-ray luminous systems. We use well-established relations from the study of local universe ETGs, together with the expected evolution of the X-ray emission, to subtract the contribution of low-mass X-ray binary populations from the X-ray luminosity of our sample. Our selection minimizes the presence of active galactic nuclei (AGNs), yielding a sample representative of normal passive COSMOS ETGs; therefore, the resulting luminosity should be representative of gaseous halos, although we cannot exclude other sources such as obscured AGNs or enhanced X-ray emission connected with embedded star formation in the higher-z galaxies. We find that most of the galaxies with estimated LX< 1042 erg/s and z < 0.55 follow the L_X, gas-LK_ relation of local universe ETGs. For these galaxies, the gravitational mass can be estimated with a certain degree of confidence from the local virial relation. However, the more luminous (1042 erg/s <LX< 1043.5 erg/s) and distant galaxies present significantly larger scatter; these galaxies also tend to have younger stellar ages. The divergence from the local L_X, gas-LK_relation in these galaxies implies significantly enhanced X-ray emission up to a factor of 100 larger than predicted from the local relation. We discuss the implications of this result for the presence of hidden AGNs, and the evolution of hot halos, in nuclear and star formation feedback. Description: The galaxies in our sample were selected from the C-COSMOS X-ray source identification catalog (Civano et al. 2012, J/ApJS/201/30) to have a rest-frame X-ray luminosity of LX < 5 x 1043 erg/s in the 0.5-10 keV band (using the spectral assumptions in Elvis et al. 2009, J/ApJS/184/158) and to be classified as elliptical or S0 from their optical to near-infrared spectral energy distribution (SED). Of the 69 galaxies in the X-ray ETG sample, 53 have spectroscopic redshifts. For the remaining 16 galaxies, we used the available photometric redshifts reported in the C-COSMOS identification catalog (Civano et al. 2012, J/ApJS/201/30; Salvato et al. 2011, J/ApJ/742/61). Given the high quality of the photometry available for the sources in the COSMOS field (see Salvato et al. 2011, J/ApJ/742/61), we are confident that we can use photometric redshifts when spectroscopic ones are not available. Although not uniform, an optical spectroscopic classification is available for the C-COSMOS sources (see Civano et al. 2012, J/ApJS/201/30 for the details on observing programs). According to the spectroscopic classification, our sample includes 24 absorption line galaxies (ALGs) and 29 narrow emission line (NL) objects. Moreover, using standard diagnostic diagrams (Bongiorno et al. 2010, J/A+A/510/A56), we find that of the 29 NL sources, 5 are classified as NL active galactic nuclei (i.e., Type 2 AGNs) and 7 as star-forming galaxies, while 17 spectra remain unclassified. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 84 69 COSMOS X-Ray ETGs Properties
See also: J/MNRAS/328/461 : X-ray luminosities of early-type galaxies (O'Sullivan+, 2001) J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009) J/A+A/510/A56 : zCOSMOS type-2 AGN (Bongiorno, 2010) J/ApJ/725/480 : Stellar X-ray sources in the COSMOS survey (Wright+, 2010) J/ApJ/742/61 : Photometric redshift of AGNs from XMM- and C-COSMOS (Salvato+ 2011) J/ApJS/201/30 : The Chandra COSMOS survey. III. (Civano+, 2012) J/MNRAS/422/494 : X-ray properties of optically selected ETGs (Danielson+, 2012) J/ApJ/819/62 : The COSMOS-Legacy Survey (CLS) catalog (Civano+, 2016) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 4 I4 --- CID Chandra identifier according to Elvis et al. (2009, Cat. J/ApJS/184/158) [ECV2009] NNNNN in Simbad 6- 10 F5.3 --- z Redshift 11 A1 --- n_z [d] Note on z (1) 13- 18 A6 --- MType Spectral type (2) 20- 27 E8.3 ct/s CR Count rates in the 0.5-7 keV band 29- 35 E7.3 ct/s e_CR Error in count rates 37- 41 F5.2 [10-7W] logL(X-lmxb) Log of the X-ray luminosity in the 0.3-8 keV band (3) 43- 47 F5.2 [10-7W] logL(X) Log of the remaining X-ray luminosity in the 0.3-8 keV band (4) 49 A1 --- l_HR Limit flag on HR 50- 54 F5.2 --- HR Hardness ratio (5) 56- 57 I2 --- Ext [0/10] Extension of X-ray emission 59- 63 F5.2 [Lsun] logL(K) Log of K band luminosity 65- 68 F4.2 [Lsun] e_logL(K) Error in logL(K) 70- 74 F5.2 [Msun] logM* Log of stellar mass 76- 80 E5.1 Gyr Age Age of early type galaxy 82 I1 --- Group [1]?=- Group relevance 84 I1 --- Radio [1]?=- Radio emission flag
Note (1): d for Photometric redshift. Note (2): Spectral type as follows : ALG = absorption line galaxies NL = narrow emission line NLAGN = NL active galactic nuclei SF gal = star forming galaxies Note (3): X-lmxb is the X-ray luminosity computed using Fragos et al. (2013ApJ...776L..31F) relation. Note (4): LX is the remaining X-ray luminosity after subtracting the LMXB contribution to the total and it is computed using a thermal model as in Section 3.1. Note (5): defined as HR = (H-S/H+S), where H and S are the number of net counts in the hard band (2-7 keV) and soft band (0.5-2 keV), respectively, to study the spectral shape of the sources.
History: From electronic version of the journal
(End) Prepared by Tiphaine Pouvreau [CDS] 16-Mar-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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