J/ApJ/794/31 Post-merger cluster A2255 membership (Tyler+, 2014)
Star formation trends in the unrelaxed, post-merger cluster A2255.
Tyler K.D., Bai L., Rieke G.H.
<Astrophys. J., 794, 31 (2014)>
=2014ApJ...794...31T 2014ApJ...794...31T (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; Photometry, infrared ;
Photometry, H-alpha
Keywords: galaxies: clusters: individual: A2255 - galaxies: evolution -
galaxies: photometry - galaxies: star formation - infrared: galaxies
Abstract:
The effects of dense environments on normal field galaxies are still
up for debate despite much study since Abell published his catalog of
nearby clusters in 1958 (1958ApJS....3..211A 1958ApJS....3..211A). There are changes in
color, morphology, and star formation properties when galaxies fall
into groups and clusters, but the specifics of how and where these
modifications occur are not fully understood. To look for answers, we
focused on star-forming galaxies in A2255, an unrelaxed cluster
thought to have recently experienced a merger with another cluster or
large group. We used Hα, MIPS 24 µm, and WISE 22 µm to
estimate total star formation rates (SFRs) and Sloan Digital Sky
Survey photometry to find stellar masses (M*) for galaxies out to
∼5 r200. We compared the star-forming cluster galaxies with the
field SFR-mass distribution and found no enhancement or suppression of
star formation in currently star-forming galaxies of high mass
(log(M*/M☉)≳10). This conclusion holds out to very large
distances from the cluster center. However, the core (rproj<3 Mpc)
has a much lower fraction of star-forming galaxies than anywhere else
in the cluster. These results indicate that for the mass range studied
here, the majority of the star formation suppression occurs in the
core on relatively short timescales, without any enhancement prior to
entering the central region. If any significant enhancement or
quenching of star formation occurs, it will be in galaxies of lower
mass (log(M*/M☉)<10).
Description:
A2255 was initially chosen from the Popesso et al. (2007, J/A+A/461/397)
sample because it is a large cluster with complete SDSS photometric
and spectroscopic coverage out to ∼3 r200. It has incomplete areal
spectroscopic coverage from 3 r200≲rproj≲5 r200 - about half of
this region is covered. The SDSS photometric survey provides a uniform
data set to study galaxy properties in the cluster. The model
magnitudes are the linear combinations of best-fit exponential and
de Vaucouleurs profiles and are recommended as the best estimates of
magnitude by SDSS. As such, we use the model magnitudes (except where
explicitly stated otherwise) and correct them for Galactic extinction
(O'Donnell, 1994ApJ...422..158O 1994ApJ...422..158O). We used these photometric data to
estimate galactic stellar masses with the SDSS_KCORRECT routine within
KCORRECT (v. 4.2; Blanton & Roweis 2007AJ....133..734B 2007AJ....133..734B). KCORRECT uses
different cosmological values and initial mass function, so we
corrected the original stellar mass output to the cosmology and
initial mass function (Kroupa, 2001MNRAS.322..231K 2001MNRAS.322..231K) adopted in this paper.
Objects:
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RA (ICRS) DE Designation(s)
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17 12 50.04 +64 03 10.6 A2255 = ACO 2255
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 65 579 Cluster Membership
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See also:
J/ApJS/132/37 : Spectroscopy of Southern warm IR galaxies (Kewley+, 2001)
J/ApJS/149/53 : Multicolor photometry of A2255 galaxies (Yuan+, 2003)
J/A+A/461/397 : RASS-SDSS galaxy cluster survey. V. (Popesso+, 2007)
J/ApJ/714/1256 : Far-IR star formation rate indicators (Calzetti+, 2010)
J/ApJ/727/14 : Merging galaxy cluster A2255 in mid-IR (Shim+, 2011)
J/other/JApA/32.567 : Rotation measures in A2255 at 18, 21, 25, 85cm
(Pizzo+ 2011)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension in decimal degrees (J2000)
11- 19 F9.6 deg DEdeg Declination in decimal degrees (J2000)
21- 26 F6.4 --- z Redshift
28- 32 F5.2 [Msun] logM* ? Log of the stellar mass
34 I1 --- 24Cov [0/1] The 24 micron coverage flag (1)
36- 40 F5.2 [10-7W] logL24 ? Log of 24 micron band luminosity
42- 46 F5.2 [10-7W] logL22 ? Log of 22 micron band luminosity
48- 52 F5.2 [10-7W] logLHa ? Log of Hα luminosity
54- 57 F4.2 Msun/yr SFR24 ? Star Formation Rate from 24 micron band (2)
59- 63 F5.2 Msun/yr SFR22 ? Star Formation Rate from 22 micron band (3)
65 I1 --- AGN ? [1/3] AGN flag (4)
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Note (1): Flag as follows:
1 = source was included in the 24 micron image;
0 = source was not included in the 24 micron image.
Note (2): Calculated using the Calzetti et al. (2010, J/ApJ/714/1256) conversion
using 24 micron or both 24 micron and Hα. SFRs for galaxies detected in
Hα but not 24 micron were calculated using the Brinchmann et al.
(2004MNRAS.351.1151B 2004MNRAS.351.1151B) method mentioned in the text.
Note (3): Calculated the same way as for SFR24 but using WISE 22 micron instead
of MIPS 24 micron.
Note (4): Flag as follows:
1 = Defined as an AGN using the Kewley et al. (2001, J/ApJS/132/37) limits
(Figure 3);
2 = defined using the Kauffmann et al. (2003MNRAS.346.1055K 2003MNRAS.346.1055K) limits (not
including Kewley et al. (2001, J/ApJS/132/37) AGN; Figure 3);
3 = identified using WISE color-color values (Figure 4). The SFRs listed
for AGN should be treated as upper limits due to the AGN contribution,
though we exclude the Kewley et al. (2001, J/ApJS/132/37) and WISE AGN
from our analysis.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 24-Apr-2017