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J/A+A/449/461       Radial velocities in A2744               (Boschin+, 2006)

Internal dynamics of the radio-halo cluster A2744. Boschin W., Girardi M., Spolaor M., Barrena R. <Astron. Astrophys. 449, 461 (2006)> =2006A&A...449..461B
ADC_Keywords: Clusters, galaxy ; Radial velocities Keywords: galaxies: clusters: general - galaxies: clusters: individual: Abell 2744 - galaxies: distances and redshifts - intergalactic medium - cosmology: observations Abstract: We present a detailed dynamical analysis of the rich galaxy cluster A2744, containing a powerful diffuse radio-halo. Our analysis is based on redshift data for 102 galaxies, part of them recovered from unexplored spectra in the ESO archive. We combine galaxy velocity and position information to select the cluster members and determine global dynamical properties of the cluster. We use a variety of statistical tests to detect possible substructures. We find that A2744 appears as a well isolated peak in the redshift space at <z≥0.306, which includes 85 galaxies recognized as cluster members. We compute the line-of-sight (LOS) velocity dispersion of galaxies, sigmaV=1767-99121km/s, which is significantly larger than what is expected in the case of a relaxed cluster with an observed X-ray temperature of 8 keV. We find evidence that this cluster is far from dynamical equilibrium, as shown by the non Gaussianity of the velocity distribution, the presence of a velocity gradient and a significant substructure. Our analysis shows the presence of two galaxy-clumps of different mean LOS velocities DeltaV∼4000km/s. We detect a main, low-velocity clump with sigmaV∼1200-1300km/s and a secondary, high-velocity clump with sigmaV=500-800km/s and located in the S-SW cluster region. We estimate a cluster mass within 1Mpc of 1.4-2.4M, depending on the model adopted to describe the cluster dynamics. Our results suggest a merging scenario of two clumps with a mass ratio of 3:1 and a LOS impact velocity of DeltaVrf∼3000km/s, likely observed just after the core passage. The merging is occuring roughly in the NS direction with the axis close to the LOS. This scenario agrees with that proposed on the basis of recent Chandra results in its general lines although pointing out for a somewhat more advanced merging phase. Our conclusions support the view of the connection between extended radio emission and energetic merging phenomena in galaxy clusters. Description: Spectroscopic redshifts for 102 galaxies in the central region of the galaxy cluster Abell 2744 are presented. For each galaxy equatorial coordinates and radial velocity are given. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 58 102 Velocity catalog of 102 spectroscopically measured galaxies
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 3 I3 --- Seq Galaxy identification number 4 A1 --- n_Seq [*] *: non-member galaxy 8- 9 I2 h RAh Right ascension J2000 (hours) 11- 12 I2 min RAm Right ascension J2000 (minutes) 14- 18 F5.2 s RAs Right ascension J2000 (seconds) 21 A1 --- DE- Declination J2000 (sign) 22- 23 I2 deg DEd Declination J2000 (degrees) 25- 26 I2 arcmin DEm Declination J2000 (minutes) 28- 31 F4.1 arcsec DEs Declination J2000 (seconds) 33- 38 I6 km/s HRVN ?=- Heliocentric radial velocity from NTT data 40- 42 I3 km/s e_HRVN ?=- 1-sigma error on the HRVN 44- 49 I6 km/s HRV Heliocentric radial velocity 52- 54 I3 km/s e_HRV 1-sigma error on the HRV 56- 58 I3 --- CN ?=- Couch & Newell (1984ApJS...56..143C) identification number, CN A2744 NNN in Simbad
Acknowledgements: Walter Boschin, boschin(at)
(End) Walter Boschin [Fundacion Galileo Galilei], P. Vannier [CDS] 22-Nov-2005
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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