J/ApJ/693/152 Abell 851 and the role of starbursts (Oemler+, 2009)
Abell 851 and the role of starbursts in cluster galaxy evolution.
Oemler A., Dressler A., Kelson D., Rigby J., Poggianti B.M., Fritz J.,
Morrison G., Smail I.
<Astrophys. J., 693, 152-173 (2009)>
=2009ApJ...693..152O 2009ApJ...693..152O
ADC_Keywords: Clusters, galaxy ; Equivalent widths ; Redshifts ; Morphology
Keywords: galaxies: clusters: general - galaxies: evolution
Abstract:
We use extensive new observations of the very rich z∼0.4 cluster of
galaxies A851 (Cl 0939+47) to examine the nature and origin of
starburst galaxies in intermediate-redshift clusters. New HST
observations, 24um Spitzer photometry and ground-based spectroscopy
cover most of a region of the cluster about 10' across, corresponding
to a cluster-centric radial distance of about 1.6Mpc. This spatial
coverage allows us to confirm the existence of a morphology-density
relation within this cluster, and to identify several large,
presumably infalling, subsystems. We confirm our previous conclusion
that a very large fraction of the star-forming galaxies in A851 has
recently undergone starbursts. We argue that starbursts are mostly
confined to two kinds of sites: infalling groups and the cluster
center.
Description:
We make use of four sets of HST-imaging observations of A851. Cycle 1
WFPC1 imaging of the center of A851 is described in Dressler et al.
(1994ApJ...430..107D 1994ApJ...430..107D). Cycle 4 HST imaging of the central field and
one outer field in Abell 851 were part of the "Morphs" study of 10
clusters (Smail et al. 1997, Cat. J/ApJS/110/213). Cycle 6 observation
consisted of two orbits of exposure (4400s total exposure time) with
the F702W filter, providing the equivalent to a rest-frame band
between Johnson B and V. Finally, in Cycle 16, two additional fields
were observed with ACS, for 2235s each, using the F606W filter.
Spectroscopic observations of galaxies in the outer fields were
obtained with the COSMIC spectrograph on the 200-inch Hale telescope
at Palomar Observatory, as described in Dressler et al. (1999, Cat
J/ApJS/122/51), during six observing runs in 1999 December, 2001
January, 2001 April, 2002 February, 2003 January, and 2003 February.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 74 224 A851 region spectroscopic sample
table2.dat 78 113 A851 cluster sample
table3.dat 57 95 Field galaxy sample 0.30≤z≤0.55
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See also:
J/ApJS/142/153 : Distant galaxy clusters photometry (Stanford+, 2002)
J/ApJS/122/51 : Spectroscopic catalog of 10 rich galaxy clusters (Dressler+,
1999)
J/ApJS/110/213 : Morphological Types in 10 Distant Rich Clusters (Smail+ 1997)
J/A+A/323/337 : Abell 851 morphological segregation (Andreon+ 1997)
J/A+AS/118/65 : BRI + redshifts in Cl0939+472 + Cl0016+161 (Belloni+, 1996)
J/A+A/297/61 : E+A galaxies in Cl0939+472 (Belloni+, 1995)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID Galaxy index number (<[ODK2009] NNN> in Simbad)
5- 6 I2 h RAh Hour of right ascension (J2000)
8- 9 I2 min RAm Minute of right ascension (J2000)
11- 15 F5.2 s RAs Second of right ascension (J2000)
17 A1 --- DE- Declination sign (J2000)
18- 19 I2 deg DEd Degree of declination (J2000)
21- 22 I2 arcmin DEm Arcminute of declination (J2000)
24- 27 F4.1 arcsec DEs Arcsecond of declination (J2000)
29- 34 F6.4 --- z Redshift (spectroscopic)
36 I1 --- q_z Spectrum/redshift quality indicator
(1=excellent; 4=poor)
38- 41 I4 0.1nm [OII] ? Rest frame equivalent widths of [OII]
43- 46 F4.1 0.1nm W(Hd) ? Rest frame equivalent widths of Hδ
48- 51 F4.1 --- W(Hd)a ? Rest frame width of the Hδ absorption
line, only measured for stronger lines
53- 58 A6 --- Class Spectral class (G1)
60- 64 F5.2 mag rmag Gunn r magnitude (1)
66- 74 A9 --- SpecID Spectrum id (2)
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Note (1): rmag=0.30 for object ID 236 is likely a misprint for 20.30;
corrected at CDS.
Note (2): As described in Dressler et al., 1999 (Cat. J/ApJS/122/51).
The new spectroscopic data are flagged as 0939_3 ms_1, ms_2, ms_3,
nw1, and nw2.
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID Galaxy index number
5- 10 F6.4 --- z Redshift
12 I1 --- q_z Spectrum quality/redshift reliability
(1=excellent; 3=fair)
14- 17 I4 0.1nm [OII] ?=0 [OII] rest frame equivalent width
19- 22 F4.1 0.1nm W(Hd) ? Hδ rest frame equivalent width
24- 28 F5.1 --- Hd ? Excess Hδ strength (1)
30- 31 I2 --- W(Hd)a ? Rest frame width of the Hδ absorption
line, only measured for stronger lines
33- 38 A6 --- Class Spectral class (G1)
40 A1 --- l_F24 Limit flag on F24 (2)
41- 47 E7.3 Jy F24 ? Spitzer/MIPS 24um flux
49- 55 A7 --- Morph Morphological type (3)
57- 59 A3 --- Int Out best guess about the nature of
distortions (4)
61- 66 F6.1 arcsec alpha Δα galaxy coordinate relative to
the cluster center
68- 73 F6.1 arcsec delta Δδ galaxy coordinate relative to
the cluster center
75- 78 A4 --- Group Subgroup membership (Core, N or NW) (5)
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Note (1): As defined in Section 5.
Note (2): Upper limits from Dressler et al., 2009ApJ...693..140D 2009ApJ...693..140D
Note (3): If not available, indicates that the object is outside of the HST
fields; "*" = stellar
Note (4): As follows:
T = tidal tail,
I = interaction with neighbor,
M = merger,
? = uncertain case
Note (5): As determined in Section 3; main properties as follows:
-------------------------------------------
Subcluster Ngal σ(km/s)
-------------------------------------------
Core 80 0.4068 1079
N group 11 0.3946 295
NW group 10 0.4021 412
-------------------------------------------
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- Cl Cluster field from which the galaxy was obtained
12- 14 I3 --- ID Galaxy index number (1)
16- 21 F6.4 --- z Redshift
23 I1 --- q_z Spectrum quality/redshift reliability
(1=excellent; 3=fair)
25- 27 I3 0.1nm [OII] ?=0 [OII] rest-frame equivalent width
29- 32 F4.1 0.1nm W(Hd) ? Hδ rest-frame equivalent width in Å
34- 37 F4.1 --- Hd ? Excess Hδ strength
39- 40 I2 --- W(Hd)a ? Rest-frame width of the Hδ absorption
line, only measured for stronger lines
42- 46 A5 --- Class Spectral class (G1)
48- 54 A7 --- Morph Morphological type (2)
56- 57 A2 --- Int Out best guess about the nature of the
distortion (3)
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Note (1): From Table 1 for A851 (<[ODK2009] NNN> in Simbad) or from
Dressler et al. 1999 (Cat. J/ApJS/122/51) for other clusters
(<[DSP99] A 370 NNN>, <[DSP99] Cl HHMM+DD NNN> or
<[DSP99] 3C 295 NNN> in Simbad).
Note (2): If not available, indicates that the object is outside of the
HST fields, "x" = stellar
Note (3): As follows:
T = tidal tail,
I = interaction with neighbor,
M = merger,
? = uncertain case.
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Global Notes:
Note (G1): Classes as defined in Dressler et al., 1999 (Cat. J/ApJS/122/51),
and described in Section 5 as follows:
------------------------------------------------------------------------
Class EW([OII]) EW(Hδ) Stellar population
------------------------------------------------------------------------
k = absent <3Å Passive
k+a = absent 3-8Å Weak post-starburst
a+k = absent ≥8Å Strong post-starburst
e(c) = -40-5 <4Å Continuous star formation
e(a) = -40-5 ≥4Å Ongoing starburst
e(b) = ←40 Any Ongoing starburst or low z star formation
e(n) = --- --- AGN spectrum
------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 08-Mar-2011