J/A+A/486/9 Redshifts in z∼0.25 clusters (Verdugo+, 2008)
The galaxy populations from the centers to the infall regions in
z∼0.25 clusters.
Verdugo M., Ziegler B.L., Gerken B.
<Astron. Astrophys. 486, 9 (2008)>
=2008A&A...486....9V 2008A&A...486....9V
ADC_Keywords: Clusters, galaxy ; Redshifts ; Galaxies, photometry ;
Equivalent widths
Keywords: galaxies: general - galaxies: evolution -
galaxies: fundamental parameters - galaxies: clusters: general
Abstract:
We investigate the relation between star-formation activity and
environment in six intermediate redshift clusters (z∼0.25) out to
large clustercentric distances (∼4Rvir). For that, we conducted a
panoramic spectroscopic campaign with MOSCA at the Calar Alto
observatory. We acquired spectra of more than 500 objects.
Approximately 150 of these spectra were of galaxies that are members
of the clusters. Other ∼150 are field galaxies or galaxies belonging to
groups, serendipitously found during the investigation. The rest of
the spectra did not met the quality criteria or were stars. The
wavelength range allows us to quantify the star formation activity by
using the [OII] and the Hα lines. This activity is examined in
terms of the large-scale environment expressed by the clustercentric
distance of the galaxies as well as on local scales given by the
spatial galaxy densities. The suppression of the star-formation
activity is observed at large clustercentric distances and low
projected densities. Galaxies with current star-formation show similar
activity, regardless of the environment, Therefore, the decline of the
star-formation activity inside the investigated clusters is driven
mainly by the significant change in the fraction of active versus
passive populations. This suggests that the suppression of the
star-formation activity occurs on short timescales. We also detect a
significant population of red star-forming galaxies whose colors are
consistent with the red-sequence of passive galaxies. They appear to
be in an intermediate evolutionary stage between active and passive
types.
Description:
We present measurements for all objects for which we were able to
derive secure redshifts. This includes galaxies belonging to the six
aforementioned clusters, four serendipitously found groups and the
general field (see the paper and below). For each object, table3.dat
provides the identification code, membership, right ascension and
declination (J2000.0); redshift, I-band magnitude and V-I color from
Gilbank et al. (2004MNRAS.348..551G 2004MNRAS.348..551G); B and R-band absolute magnitude
derived with k-correct (Blanton and Roweis, 2007AJ....133..734B 2007AJ....133..734B);
stellar mass also derived using k-correct and the equivalent widths of
the [OII] and the Hα emission lines and associated errors.
Objects are sorted by membership to facilitate any specific search.
The clusters studied are the following:
VMF194 or RX J1729.0+7440;
XDCS220, short for XDCS cmJ172333+744410;
VMF131 or RX J1309.9+3222;
VMF132 or RX J1313.2+3229;
VMF73 or RX J0943.5+1640;
VMF74 or RX J0943.7+1644;
Galaxies belonging to the groups candidates are tagged with a group
number which corresponds to one of the following identifications:
group1 is r220_1J 172604+742830;
group2 is r220_2J 172518+742844;
group3 is r220_3J 172958+744204;
group4 is r265_1J 131030+322840.
Galaxies without any identifiable membership are tagged as belonging
to the field.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 105 286 Individual data for 286 galaxies at intermediate
redshifts
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- [VZG2008] Galaxy identification code (1)
11- 17 A7 --- Memb Galaxy membership (2)
19- 20 I2 h RAh Right ascension (J2000.0)
22- 23 I2 min RAm Right ascension (J2000.0)
25- 29 F5.2 s RAs Right ascension (J2000.0)
31 A1 --- DE- Declination sign (J2000.0)
32- 33 I2 deg DEd Declination (J2000.0)
35- 36 I2 arcmin DEm Declination (J2000.0)
38- 41 F4.1 arcsec DEs Declination (J2000.0)
43- 49 F7.5 --- z Spectroscopic Redshift
51- 55 F5.2 mag Icmag Cousins I-band apparent magnitude (3)
57- 61 F5.3 mag V-Ic Johnson-Cousins V-I color index (3)
63- 68 F6.2 mag BMAG B-band absolute magnitude (4)
70- 75 F6.2 mag RMAG V-band absolute magnitude (4)
77- 81 F5.2 [solMass] log(M) logarithm of the Stellar Mass (4)
83- 88 F6.2 0.1nm EW(OII) ? Equivalent width of [OII] emission line
90- 93 F4.2 0.1nm e_EW(OII) ? Error in EW(OII)
95-100 F6.2 0.1nm EW(Ha) ? Equivalent width of Hα emission line
102-105 F4.2 0.1nm e_EW(Ha) ? Error in EW(Ha)
--------------------------------------------------------------------------------
Note (1): All galaxies with identification codes beginning with 'r' are
original of this work (r22NN_NNA, r26NN_NNA and r28NN_NNA).
The prefixes r22, r26 and r28 correspond to the fields R220, R265 and
R285 respectively. The following numbers are mask and slit number.
Galaxies with a prefix 'ba' (ba_NN) come from Balogh et al.,
2002ApJ...566..123B 2002ApJ...566..123B.
Galaxy with a prefix 'xdc' (xdc29_04) is from Gilbank et al.,
2004MNRAS.348..551G 2004MNRAS.348..551G.
Note (2): Galaxy membership as follows:
field = field galaxy
group1 = group candidate r220_1J 172604+742830
group2 = group candidate r220_2J 172518+742844
group3 = group candidate r220_3J 172958+744204
group4 = r265_1J 131030+322840
vmf131 = VMF131 or RX J1309.9+3222 cluster
vmf132 = VMF132 or RX J1313.2+3229 cluster
vmf194 = VMF194 or RX J1729.0+7440 cluster
vmf73 = VMF73 or RX J0943.5+1640 cluster
vmf74 = VMF74 or RX J0943.7+1644 cluster
xdcs220 = XDCS220, short for XDCS cmJ172333.0+744410 cluster
Note (3): The apparent magnitudes are from the project of
Gilbank et al., 2004MNRAS.348..551G 2004MNRAS.348..551G
Note (4): The absolute magnitudes and stellar masses were calculated for a
cosmology H0=70km/s/Mpc, ΩΛ=0.7 and Ωmatter=0.3.
--------------------------------------------------------------------------------
Acknowledgements:
Miguel Verdugo, mverdugo(at)astro.physik.uni-goettingen.de
(End) Miguel Verdugo [IAG, Germany], Patricia Vannier [CDS] 21-Apr-2008