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J/ApJ/681/1017      Chandra observations of lens groups       (Fassnacht+, 2008)

The X-ray properties of moderate-redshift galaxy groups selected by association with gravitational lenses. Fassnacht C.D., Kocevski D.D., Auger M.W., Lubin L.M., Neureuther J.L., Jeltema T.E., Mulchaey J.S., McKean J.P. <Astrophys. J., 681, 1017-1034 (2008)> =2008ApJ...681.1017F
ADC_Keywords: X-ray sources ; Clusters, galaxy ; Redshifts Keywords: galaxies: clusters: general - gravitational lensing - X-rays: galaxies: clusters Abstract: We present results from a systematic investigation of the X-ray properties of a sample of moderate-redshift (0.3<z<0.6) galaxy groups. These groups were selected not by traditional X-ray or optical search methods, but rather by an association, either physical or along the line of sight, with a strong gravitational lens. We calculate the properties of seven galaxy groups in the fields of six lens systems. Diffuse X-ray emission from the intragroup medium is detected in four of the groups. All of the detected groups have X-ray luminosities greater than 1042h-2ergs/s and lie on the LXv_^ relations defined by local groups and clusters. The upper limits for the nondetections are also consistent with the local LXv_^ relationships. Although the sample size is small and deeper optical and X-ray data are needed, these results suggest that lens-selected groups are similar to X-ray-selected samples and thus are more massive than the typical poor-group environments of local galaxies. Description: The systems analyzed for this paper are all strong lenses for which we have obtained new observations with Chandra or for which data are available in the Chandra archive. Observation parameters as follows: ---------------------------------------------------------------- Target ObsID Exp (s) Obs.Date PI ---------------------------------------------------------------- B0712 4199 97742 2004/12/17 Fassnacht PG 1115 363 26489 2000/06/02 Garmire B1422 367 16888a 2000/06/02 Garmire B1600 3460 30176 2003/10/07 Kochanek B1608 3461 29717 2003/09/09 Kochanek B2108 6971 45507 2006/07/14 Fassnacht ---------------------------------------------------------------- a = Reduced from 28429s due to flaring events. ---------------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file group.dat 99 8 Properties of diffuse group emission (tables 2 and 3 of the paper) table6.dat 69 51 Serendipitous sources detected in the field of B0712+472 table7.dat 69 34 Serendipitous sources detected in the field of B2108+213
See also: B/chandra : The Chandra Archive Log (CXC, 1999-) J/ApJ/658/865 : Redshifts of galaxies in X-ray-luminous groups (Jeltema+, 2007) J/ApJ/496/39 : Properties of poor groups of galaxies. I. (Zabludoff+ 1998) Byte-by-byte Description of file: group.dat
Bytes Format Units Label Explanations
1- 7 A7 --- Group Group name 10- 11 I2 h RAh ? Hour of right ascension (J2000) 13- 14 I2 min RAm ? Minute of right ascension (J2000) 16- 19 F4.1 s RAs ? Second of right ascension (J2000) 21 A1 --- DE- ? Declination sign (J2000) 22- 23 I2 deg DEd ? Degree of declination (J2000) 25- 26 I2 arcmin DEm ? Arcminute of declination (J2000) 28- 29 I2 arcsec DEs ? Arcsecond of declination (J2000) 31- 34 F4.1 10+20cm-2 nH Neutral hydrogen column densities of Dickey & Lockman (1990ARA&A..28..215D) 36- 38 I3 --- Cts ? Net counts in x-ray 40- 43 F4.2 10-3/s CtR ? Count rate in x-ray 45 A1 --- l_Flux Limit flag on Flux 46- 49 F4.1 aW/m2 Flux Soft band flux corrected from Galactic absorption (1) 51- 53 F3.1 aW/m2 e_Flux ? Uncertainty in Flux 55 A1 --- l_Lx Limit flag on Lx 56- 59 F4.2 10+35W Lx Rest-frame bolometric luminosity in 1042h-2ergs/s units 61- 64 F4.2 10+35W e_Lx ? Uncertainty in Lx 66 A1 --- l_Lx500 Limit flag on Lx500 67- 70 F4.1 --- Lx500 ? Rest-frame bolometric luminosity within R500 (in 1042h-2ergs/s) 72- 74 F3.1 --- e_Lx500 ? Uncertainty in Lx500 76- 77 I2 --- N ? Group optical number of members 78 A1 --- n_N [a] a = optical data in B2108-1 are for B2108 80- 84 F5.3 --- z ? Group optical redshift 86- 88 I3 km/s sigma ? Group optical radial velocity dispersion 90- 91 I2 km/s e_sigma ? σ uncertainty 93- 95 I3 kpc R500 ? Group optical radius at 500 times critical density, in h-1kpc units (2) 97- 99 I3 arcsec the500 ? Group optical position angle at 500 times critical density
Note (1): We determined the soft-band flux of the group emission by normalizing a Raymond-Smith spectral model in the CIAO package Sherpa to the net counts detected above the background in each system. Units are 10-15erg/cm2/s = aW/m2. Note (2): The value of R500 for each system was estimated from the radial velocity dispersion that had been determined from the group galaxy redshifts as R500=2σv/[500H(z)^0.5]
Byte-by-byte Description of file: table6.dat table7.dat
Bytes Format Units Label Explanations
1- 3 A3 --- --- [CXO] 5- 20 A16 --- CXO Name (JHHMMSS.s+DDMMSS, <CXOU JHHMMSS.s+DDMMSS> in Simbad) 21 A1 --- f_CXO [b] extended source flag 23- 31 F9.5 deg RAdeg Right ascension in decimal degree (J2000) 33- 40 F8.5 deg DEdeg Declination in decimal degree (J2000) 42- 45 I4 ct Scts Soft (0.5-2.0keV) band net counts 47- 49 I3 ct Hcts Hard (2.0-8.0keV) band net counts 51- 54 I4 ct Fcts Full (0.5-8.0keV) band net counts 56- 59 F4.1 --- Ssig Soft (0.5-2.0keV) band significance (3) 61- 64 F4.1 --- Hsig Hard (2.0-8.0keV) band significance (3) 66- 69 F4.1 --- Fsig Full (0.5-8.0keV) band significance (3)
Note (3): The significances are calculated as the net counts from each source divided by the error of the background counts in the measurement aperture.
History: From electronic version of the journal
(End) Emmanuelle Perret [CDS] 27-Oct-2010
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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