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J/AJ/125/2427       1.4GHz flux densities of Abell 2255 galaxies (Miller+, 2003)

Abell 2255: increased star formation and AGN activity in a cluster-cluster merger. Miller N.A., Owen F.N. <Astron. J., 125, 2427-2446 (2003)> =2003AJ....125.2427M
ADC_Keywords: Clusters, galaxy ; Galaxies, radio ; Radial velocities Keywords: galaxies: clusters: general - galaxies: evolution - radio continuum - galaxies: clusters: individual (Abell 2255) Abstract: Deep VLA 1.4GHz radio continuum imaging of Abell 2255 is presented. This cluster is among the better nearby candidates for rich cluster-cluster merger systems, with evidence including an elongated X-ray morphology, the presence of a radio halo, and substructure present in its galaxy distribution. Our radio observations reach an rms sensitivity of ∼40µJy/beam, enabling us to detect (at 5σ) star formation rates as low as 1.4M/yr from the center of the cluster out to a radial distance of 3h-175Mpc. The radio data are complemented by optical imaging and a large spectroscopic database, allowing us to separate all galaxies with MRc≤-20 0 into cluster members and foreground/background galaxies. The spectra are also used to associate the galaxies' radio emission with either star formation or active galactic nuclei (AGNs). We compare the resulting cluster radio galaxy population with those of 19 other nearby Abell clusters and find strong evidence for an increase in the frequency of radio galaxies in Abell 2255. This increase is seen in two separate types of galaxies: powerful radio AGNs and optically faint star-forming galaxies. The optical spectra of the latter often indicate current or recent starbursts, and these galaxies appear to be distributed along an axis perpendicular to the probable merger axis. We assess these factors in light of models of galaxy evolution and suggest that the cluster-cluster merger is responsible for triggering galaxy activity in Abell 2255. Description: Radio observations at 1.4GHz were made with the VLA in two configurations. The higher resolution observations were performed during 1998 July while the VLA was in its B configuration, and lower resolution observations were performed during 1999 May in the D configuration. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 73 46 Cluster radio galaxies table2.dat 68 36 Additional radio galaxies
See also: J/AJ/123/567 : SDSS quasar catalog, I: Early Data Release (Schneider+, 2002) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Right ascension (J2000.0) (G1) 4- 5 I2 min RAm Right ascension (J2000.0) (G1) 7- 10 F4.1 s RAs Right ascension (J2000.0) (G1) 12 A1 --- DE- Declination sign (J2000.0) (G1) 13- 14 I2 deg DEd Declination (J2000.0) (G1) 16- 17 I2 arcmin DEm Declination (J2000.0) (G1) 19- 20 I2 arcsec DEs Declination (J2000.0) (G1) 22- 26 I5 km/s cz Heliocentric radial velocity (1) 28- 29 I2 km/s e_cz rms uncertainty on cz 31- 35 F5.2 mag Rcmag Cousins R magnitude, calculated for the Gunn-Oke aperture, with an error of ≲0.05mag 37- 40 F4.2 Mpc Dist Radial distance (2) 42- 48 F7.3 mJy S1.4GHz Flux density at 1.4GHz 50- 54 F5.3 mJy e_S1.4GHz rms uncertainty on S1.4GHz 56- 58 F3.1 arcsec Sep ? Separation betwen optical and radio emission 59 A1 --- n_Sep [c] Note on Sep (3) 61- 64 A4 --- Class Classification (4) 66 A1 --- n_Class [b] Note on Class (5) 68- 71 A4 --- Morph Morphology 73 A1 --- n_Morph Note on Morph (6)
Note (1): All velocities and associated errors have been taken from Paper I (Hill et al., 2003, in prep.), which includes SDSS EDR (Schneider et al., 2002, Cat. J/AJ/123/567) data. Note (2): Radial distances are calculated based on a central position of RA = 17 12 45 (J2000.0) DE = +64 03 54. Note (3): Note on Sep: c: See Figs. 2-6 of the paper. Note (4): The classes are determined from the galaxy spectra and are defined as follows: SF: star-forming galaxy AGNl: AGNs with optical spectrum dominated by an old stellar population but with weak emission of [N II] and sometimes [S II] AGNo: AGNs with pure absorption-line spectrum representative of old stellar population stars AGNs: AGNs with emission-line spectrum (Seyfert) Note (5): Note on Class: b: The lack of optical emission lines formally places this galaxy in the AGN category. However, there is evidence that these galaxies are heavily dust-obscured star-forming galaxies (see text). Note (6): Note on Morph: a: Hδ absorption is sufficient for classification as an e(a) galaxy, but measurement is noisy and we tentatively classify the galaxy as e(c). d: Wavelength coverage of spectrum misses [O II]; strong emission lines suggest this is a potential e(b) galaxy. e: Potential k + a galaxy, although spectrum is relatively noisy
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 2 I2 h RAh Right ascension (J2000.0) (G1) 4- 5 I2 min RAm Right ascension (J2000.0) (G1) 7- 10 F4.1 s RAs Right ascension (J2000.0) (G1) 12 A1 --- DE- Declination sign (J2000.0) (G1) 13- 14 I2 deg DEd Declination (J2000.0) (G1) 16- 17 I2 arcmin DEm Declination (J2000.0) (G1) 19- 20 I2 arcsec DEs Declination (J2000.0) (G1) 22- 27 I6 km/s cz Heliocentric radial velocity (1) 28- 29 A2 --- n_cz Reference and notes for cz (2) 31- 33 I3 km/s e_cz rms uncertainty on cz 35- 39 F5.2 mag Rcmag ? Cousins R magnitude, calculated for the Gunn-Oke aperture, with an error of ≲0.05mag 41- 47 F7.3 mJy S1.4GHz Flux density at 1.4GHz 49- 53 F5.3 mJy e_S1.4GHz rms uncertainty on S1.4GHz 55- 57 F3.1 arcsec Sep ? Separation 59- 62 A4 --- Class Classification (3) 64- 68 A5 --- Notes Notes (4)
Note (1): All velocities and associated errors have been taken from Paper I (Hill et al., 2003, in prep.), unless otherwise noted. Note (2): References for cz, if not Paper I: b: velocity and error from Strauss et al. (1992, Cat. II/174). Galaxy pair (UGC 10731 or VV726), where each galaxy is a radio source but the flux measurement and velocity correspond to the system. e: velocity and error taken from the SDSS EDR (Cat. J/AJ/123/567). j: See Fig. 7 of the paper Note (3): The classes are determined from the galaxy spectra and are defined as follows: SF: star-forming galaxy AGNl: AGNs with optical spectrum dominated by an old stellar population but with weak emission of [N II] and sometimes [S II] AGNo: AGNs with pure absorption-line spectrum representative of old stellar population stars AGNs: AGNs with emission-line spectrum (Seyfert) QSO: quasar designation from SDSS EDR. Note that J170902+641728, J170911+632940, J171010+642257, J171118+643902, and J171346+641447 are compact starbursts misidentified as QSOs by the automated routines of the SDSS EDR. False identifications of this type are among the principal contaminants of the SDSS QSO sample (Richards et al., 2002AJ....123.2945R). Note (4): Notes: a: Background galaxy. c: Foreground galaxy. d: Outside the 3 Mpc radial limit of the study. f: Cluster member. g: Optical magnitude too faint to be formally included in the radio galaxy study. h: See Fig. 8 of the paper. i: The SDSS velocity for this galaxy was flagged because of inconsistent measurements by their automated routines. Inspection of the spectrum and a prior velocity measurement from NED clearly indicate it is consistent with cluster membership.
Global notes: Note (G1): Galaxies are identified as [MO2003] JHHMMSS.s+DDMMSS in Simbad
History: From electronic version of the journal
(End) James Marcout, Patricia Bauer [CDS] 09-Feb-2004
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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