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J/MNRAS/427/2047  Formation of cD Galaxies and their Clusters (Tovmassian+ 2012)

On the Formation of cD Galaxies and their Parent Clusters Tovmassian H.M., Andernach H. <Mon. Not. R. Astron. Soc. 427, 2047 (2012)> =2012MNRAS.427.2047T
ADC_Keywords: Clusters, galaxy Keywords: galaxies: clusters -- clusters: general -- galaxies: formation -- galaxies: cD galaxies Abstract: In order to study the mechanism of formation of cD galaxies we search for possible dependencies between the K-band luminosity of cDs and the parameters of their host clusters which we select to have a dominant cD galaxy, corresponding to a cluster morphology of Bautz-Morgan (BM) type I. As a comparison sample we use cD galaxies in clusters where they are not dominant, which we define here as non-BM I (NBMI) type clusters. We find that for 71 BM I clusters the absolute K-band luminosity of cDs depends on the cluster richness, but less strongly on the cluster velocity dispersion. Meanwhile, for 35 NBMI clusters the correlation between cD luminosity and cluster richness is weaker, and is absent between cD luminosity and velocity dispersion. In addition, we find that the luminosity of the cD galaxy hosted in BM I clusters tends to increase with the cD's peculiar velocity with respect to the cluster mean velocity. In contrast, for NBMI clusters the cD luminosity decreases with increasing peculiar velocity. Also, the X-ray luminosity of BM I clusters depends on the cluster velocity dispersion, while in NBMI clusters such a correlation is absent. These findings favour the cannibalism scenario for the formation of cD galaxies. We suggest that cDs in clusters of BM I type were formed and evolved preferentially in one and the same cluster. In contrast, cDs in NBMI type clusters were either originally formed in clusters that later merged with groups or clusters to form the current cluster, or are now in the process of merging. Description: For 128 Abell clusters selected as hosting a cD galaxy as well as having a minimum number of members with measured redshifts, we extracted the Ks(tot) magnitude from 2MASS for the cD galaxy and the 2nd-brightest member of the cluster. Depending on the magnitude difference between these two galaxies we subdivide the sample into 71 clusters with a dominant cD (BM I), 22 clusters of intermediate type, and 35 clusters with a non-dominant cD (NBMI). The table contains cluster name, mean redshift, number of members with redshift, difference in Ks(tot) magnitude between the cD galaxy and the 2nd-brightest cluster member, the absolute Ks(tot) magnitude of the cD galaxy, the Abell count, the cluster velocity dispersion, the peculiar velocity of the cD galaxy, and the names in NED of the cD galaxy and the 2nd-brightest galaxy. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 174 128 Data on the 71 clusters of type BM I, 22 of intermediate type, and 35 of type NBMI
See also: J/AJ/137/4795 : Dynamical state of brightest cluster galaxies (Coziol+, 2009) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1 A1 --- Smpl [abc] Subsample the cluster belongs to (1) 3- 8 A6 --- cluID Cluster identification (2) 10- 15 F6.4 --- z Mean galactocentric redshift of the cluster 17- 19 I3 --- Nz Number of galaxies used to determine redshift 21- 25 F5.2 mag DK Difference in Ks,tot mag between cD and 2nd-brightest galaxy ΔK 27- 32 F6.2 mag KMAG Absolute Ks,tot magnitude of cD galaxy (H_0=72) 34- 36 I3 --- NA Abell richness count 37 A1 --- f_NA [* ] Corrected Abell richness count (3) 40- 43 I4 km/s sigV ? Cluster velocity dispersion (4) 45- 49 I5 km/s Vpec ? Peculiar velocity of cD galaxy wrt to the cluster mean velocity (5) 51- 73 A23 --- Name1 NED name of cD galaxy 75- 76 I2 h RAB.h Right ascension (B1950) of cD galaxy 77- 78 I2 min RAB.m Right ascension (B1950) of cD galaxy 79- 82 F4.1 s RAB.s Right ascension (B1950) of cD galaxy 83 A1 --- DEB.- Declination sign (B1950) of cD galaxy 84- 85 I2 deg DEB.d Declination (B1950) of cD galaxy 86- 87 I2 arcmin DEB.m Declination (B1950) of cD galaxy 88- 89 I2 arcsec DEB.s Declination (B1950) of cD galaxy 91- 92 I2 h RAh Right ascension (J2000) of cD galaxy 93- 94 I2 min RAm Right ascension (J2000) of cD galaxy 95- 98 F4.1 s RAs Right ascension (J2000) of cD galaxy 99 A1 --- DE- Declination sign (J2000) of cD galaxy 100-101 I2 deg DEd Declination (J2000) of cD galaxy 102-103 I2 arcmin DEm Declination (J2000) of cD galaxy 104-105 I2 arcsec DEs Declination (J2000) of cD galaxy 107-111 F5.4 --- z1 Heliocentric redshift of cD galaxy 112 A1 --- r_z1 [*] Origin of z1: * from our own unpublished measurement, blank for NED 113-135 A23 --- Name2 NED name of 2nd-brightest cluster member 137-138 I2 h RA2B.h Right ascension (B1950) of 2nd-brightest galaxy 139-140 I2 min RA2B.m Right ascension (B1950) of 2nd-brightest galaxy 141-144 F4.1 s RA2B.s Right ascension (B1950) of 2nd-brightest galaxy 145 A1 --- DE2B.- Declination sign (B1950) of 2nd-brightest galaxy 146-147 I2 deg DE2B.d Declination (B1950) of 2nd-brightest galaxy 148-149 I2 arcmin DE2B.m Declination (B1950) of 2nd-brightest galaxy 150-151 I2 arcsec DE2B.s Declination (B1950) of 2nd-brightest galaxy 153-154 I2 h RA2h Right ascension (J2000) of 2nd-brightest galaxy 155-156 I2 min RA2m Right ascension (J2000) of 2nd-brightest galaxy 157-160 F4.1 s RA2s Right ascension (J2000) of 2nd-brightest galaxy 161 A1 --- DE2- Declination sign (J2000) of 2nd-brightest galaxy 162-163 I2 deg DE2d Declination (J2000) of 2nd-brightest galaxy 164-165 I2 arcmin DE2m Declination (J2000) of 2nd-brightest galaxy 166-167 I2 arcsec DE2s Declination (J2000) of 2nd-brightest galaxy 169-173 F5.4 --- z2 ? heliocentric redshift of 2nd-brightest galaxy (NED) 174 A1 --- f_z2 ? redshift flag from NED (6)
Note (1): subsamples are as follows: a = Clusters of BM I type (ΔK ≥ 1.00 mag); b = Clusters of intermediate type (0.70 mag < ΔK < 1.00 mag); c = Clusters of NBMI type (ΔK ≤ 0.70 mag). Note (2): The first 5 bytes are the Abell cluster name, followed by the redshift component of the cluster (A,B,C,...), according to Andernach's Abell cluster redshift compilation (cf. 2005ASPC..329..283A). The last byte may be blank. Note (3): taken from 1989ApJS...70....1A; * indicates a downward correction for an overlap of two or more redshift components of a cluster (see text). Note (4): value taken from Andernach's Abell cluster redshift compilation (cf. 2005ASPC..329..283A) or from the literature. Note (5): calculated according to Vpec = (c * z1 - Vcl)/[1 + (Vcl/c)] where Vcl is the mean heliocentric velocity of the cluster; note also that we used weighted averages for z1, not directly the NED value; most peculiar velocities are taken from 2009AJ....137.4795C Note (6): an F means a Friends-of-Friends (FoF) type of redshift
History: * 26-Nov-2012: The positions and redshifts of the cD and 2nd-brightest galaxies were not included in the printed version, but appear only in the electronic version. * 29-Nov-2012: The electronic version published by MNRAS on 20-Nov-2012 had an error in the name of the 2nd-brightest galaxy for A0690A, which was corrected here and also in the electronic journal version on 29-Nov-2012, as well as in the printed version. * 02-Dec-2012: the 2nd-brightest galaxy in A1149 (record#99) was corrected to 2MASX J11032040+0730463 at z=0.0714, implying ΔK=0.15. This does not change the cluster's category as NBMI. * 01-Apr-2014: the brightest galaxy of A0193 (record#6) was incorrectly given identical to the 2nd-brightest one. The name, coordinates and redshift of the brightest one were replaced with those of IC 1695. (found by Marion Schmitz of NED) Acknowledgements: Heinz Andernach heinz(at)
(End) Heinz Andernach [Univ. Guanajuato, Mexico] 26-Nov-2012
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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