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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 (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). 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). 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). 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) adopted in this paper. Objects: ---------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------- 17 12 50.04 +64 03 10.6 A2255 = ACO 2255 ---------------------------------------------------------- File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table2.dat 65 579 Cluster Membership
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
Bytes Format Units Label Explanations
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)
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) 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) 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.
History: From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 24-Apr-2017
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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