Access to Astronomical Catalogues

← Click to display the menu
J/AJ/137/4795    Dynamical state of brightest cluster galaxies  (Coziol+, 2009)

The dynamical state of brightest cluster galaxies and the formation of clusters. Coziol R., Andernach H., Caretta C.A., Alamo Martinez K.A., Tago E. <Astron. J. 137, 4795 (2009)> =2009AJ....137.4795C (erratum in 2011AJ....142..142C)
ADC_Keywords: Clusters, galaxy ; Velocity dispersion Keywords: galaxies: clusters: general; galaxies: formation; large-scale structure of universe Abstract: A large sample of Abell clusters of galaxies, selected for the likely presence of a dominant galaxy, is used to study the dynamical properties of the brightest cluster members (BCMs). From visual inspection of Digitized Sky Survey images combined with redshift information we identify 1426 candidate BCMs located in 1221 different redshift components associated with 1169 different Abell clusters. This is the largest sample published so far of such galaxies. From our own morphological classification we find that ∼92% of the BCMs in our sample are early-type galaxies and 48% are of cD type. We confirm what was previously observed based on much smaller samples, namely, that a large fraction of BCMs have significant peculiar velocities. From a subsample of 452 clusters having at least 10 measured radial velocities, we estimate a median BCM peculiar velocity of 32% of their host clusters' radial velocity dispersion. This suggests that most BCMs are not at rest in the potential well of their clusters. This phenomenon is common to galaxy clusters in our sample, and not a special trait of clusters hosting cD galaxies. We show that the peculiar velocity of the BCM is independent of cluster richness and only slightly dependent on the Bautz-Morgan type. We also find a weak trend for the peculiar velocity to rise with the cluster velocity dispersion. The strongest dependence is with the morphological type of the BCM: cD galaxies tend to have lower relative peculiar velocities than elliptical galaxies. This result points to a connection between the formation of the BCMs and that of their clusters. Our data are qualitatively consistent with the merging-groups scenario, where BCMs in clusters formed first in smaller subsystems comparable to compact groups of galaxies. In this scenario, clusters would have formed recently from the mergers of many such groups and would still be in a dynamically unrelaxed state. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 143 1426 Identification and Properties of the BCMs (brightest cluster members) and their host cluster table2.dat 77 238 Identification of discarded BCMs (brightest cluster members) and the clusters on which they are projected table3.dat 51 38 List of Discarded Clusters
Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 7 A7 --- BCM-ID Galaxy identification by rank (1) 9- 10 I2 h RAh Hour of Right Ascension (J2000) 11- 12 I2 min RAm Minute of Right Ascension (J2000) 13- 17 F5.2 s RAs Second of Right Ascension (J2000) 18 A1 --- DE- Sign of the Declination (J2000) 19- 20 I2 deg DEd Degree of Declination (J2000) 21- 22 I2 arcmin DEm Arcminute of Declination (J2000) 23- 26 F4.1 arcsec DEs Arcsecond of Declination (J2000) 28 I1 --- R Abell richness class 30- 33 A4 --- BM Bautz-Morgan type of Abell cluster (2) 35- 39 A5 --- RS Rood-Sastry type or ACO1989 note (2) 41- 46 I6 km/s Vcl Heliocentric cluster mean velocity 47 A1 --- f_Vcl [en*:] Note on Vcl origin or problems (G1) 49 A1 --- l_Nz Limit flag on Nz 50- 52 I3 --- Nz ? Number of galaxies used to determine redshift 54- 57 I4 km/s sigV ? Cluster velocity dispersion (4) 60- 64 I5 km/s VBCM ? Heliocentric velocity of brightest cluster member 65 A1 --- f_VBCM [*?:] Note on VBCM origin or problems (G2) 67- 71 I5 km/s Vpec ? Peculiar velocity of galaxy (5) 73- 77 F5.2 --- Ratio ? Ratio Vpec/sigV (6) 79- 85 A7 --- Morph Optical morphological type of the galaxy 87-105 A19 --- 2MASX The 2MASX identification of the galaxy 107-143 A37 --- OName Other identification of the galaxy
Note (1): The first 5 bytes are the Abell cluster name, followed by the redshift component of the cluster (A,B,C,...), followed by the rank of the galaxy within this component (a,b,c,...). Either of the last two characters may be blank. Note (2): BM types were converted from roman numbers I, I-II, ... III, to 1, 2, ... 5, and are given in parenthesis if this cluster has a discarded BCM candidate in Table 2. BM type is taken from Abell et al. (1989, Cat. VII/110). For southern clusters without RS type, we indicate whether the notes in Tables 7A, B, or C of ACO 1989 suggest the presence of a galaxy of cD type (listed as "NcD") or one with a "corona" (listed as "Ncor"). Note (4): the cluster velocity dispersion is taken from the literature whenever Vcl is also taken from literature Note (5): calculated according to Vpec=(VBCM-Vcl)/[1+(Vcl/c]) Note (6): Note that the online journal table incorrectly says "Ratio is calculated as Vpec/(1+z)/sigV"-------------------------------------------------------------------------------- Byte-by-byte Description of file: table2.dat
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Abell Abell identification number 7- 8 I2 h RAh Hour of Right Ascension (J2000) 9- 10 I2 min RAm Minute of Right Ascension (J2000) 11- 15 F5.2 s RAs Second of Right Ascension (J2000) 16 A1 --- DE- Sign of the Declination (J2000) 17- 18 I2 deg DEd Degree of Declination (J2000) 19- 20 I2 arcmin DEm Arcminute of Declination (J2000) 21- 24 F4.1 arcsec DEs Arcsecond of Declination (J2000) 26- 31 I6 km/s Vcl Heliocentric cluster mean velocity (1) 32- 33 A2 --- f_Vcl Note on Vcl origin or problems (G1) 35- 39 I5 km/s VBCM ? Heliocentric velocity of discarded object 40- 41 A2 --- f_VBCM Note on VBCM origin or problems (G2) 43- 77 A35 --- OName Other identification(s) of the discarded object
Note (1): Only one radial velocity for a representative cluster component is given for clusters with known superposition; we made sure that VBCM is incompatible with all redshift components known to us.
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 5 A5 --- Abell Abell identification number 7- 51 A45 --- Reason Reason for discarding the cluster
Global Notes: Note (G1): flag as follows: n = taken from literature; e = photometric estimate; : = uncertain, or poor spectrum; * = factor 2 to 4 different from photometric estimate. Note (G2): flag as follows: : = poor spectrum; * = taken from Andernach & Tago's database; b = in the background of the cluster. e = photometric estimate
History: Reformatted more economically from electronic version of the journal; Tables 1 and 2 from erratum AJ, 142, 142 (2011).
(End) H. Andernach (Univ. Guanajuato) 23-Oct-2011
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

catalogue service

© UDS/CNRS

Contact