J/MNRAS/453/1965 Star-forming compact groups (Hernandez-Fernandez+, 2015)
Star-forming compact groups (SFCGs): an ultraviolet search for a local sample.
Hernandez-Fernandez J.D., Mendes de Oliveira C.
<Mon. Not. R. Astron. Soc., 453, 1965-1980 (2015)>
=2015MNRAS.453.1965H 2015MNRAS.453.1965H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; Photometry, ultraviolet
Keywords: galaxies: clusters: general - galaxies: evolution -
galaxies: star formation - ultraviolet: galaxies
Abstract:
We present a local sample (z<0.15) of 280 star-forming compact groups
(SFCGs) of galaxies identified in the ultraviolet Galaxy Evolution
EXplorer (GALEX) All-sky Imaging Survey (AIS). So far, just one
prototypical example of SFCG, the Blue Infalling Group, has been
studied in detail in the Local Universe. The sample of SFCGs is mainly
the result of applying a Friends-of-Friends group finder in the space
of celestial coordinates with a maximum linking-length of 1.5 arcmin
and choosing groups with a minimum number of four members of bright
UV-emitting 17<FUV<20.5 sources (mostly galaxies) from the GALEX/AIS
catalogue. The result from the search are 280 galaxy groups composed
by 226, 39, 11 and 4 groups of four, five, six and seven bright
ultraviolet (UV) members, respectively. Only 59 of these 280 newly
identified SFCGs have a previous catalogued group counterpart. Group
redshifts are available for at least one member in 75 per cent of the
SFCGs, and over 40 per cent of the SFCGs have redshifts measured for
two or more galaxies. 26 of the SFCGs appear to be located in the
infalling regions of clusters with known redshift. The SFCG sample
presents a combination of properties different from the group samples
studied up to now, such as low-velocity dispersions
(sigmal-o-s∼120km/s), small crossing-times (H0tc∼0.05) and high
star formation content (95 per cent of star-forming galaxies). This
points to the SFCGs being in an evolutionary stage distinct from those
groups selected in the optical and near-infrared ranges. Once
redshifts are obtained to discard interlopers, SFCGs will constitute a
unique sample of SFCGs.
Description:
This article provides a local sample (z≲0.15) of compact groups of
star-forming galaxies. In this type of groups, galaxies strongly
interact among themselves and with the rest of the group components
(ICM, dark matter halo). This induces morphological changes and star
formation events which are currently taking place. The peculiar
evolutionary stage of these groups provides a wealth of galaxy
observables that may clarify the theoretical framework about galaxy
evolution in groups.
We have performed an all-sky search for compact groups of star-forming
galaxies in the GALEX UV catalogues.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 64 280 SFCG catalogue
table2.dat 60 1193 SFCG galaxy catalogue
table10.dat 62 280 Additional redshift counterparts
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Group Identification number of the SFCG ordered by
increasing UV richness
5- 6 I2 h RAh Right ascension of group centre (J2000)
8- 9 I2 min RAm Right ascension of group centre (J2000)
11- 15 F5.2 s RAs Right ascension of group centre (J2000)
17 A1 --- DE- Declination sign of group centre (J2000)
18- 19 I2 deg DEd Declination of group centre (J2000)
21- 22 I2 arcmin DEm Declination of group centre (J2000)
24- 27 F4.1 arcsec DEs Declination of group centre (J2000)
29- 36 F8.6 --- zUV ?=0 Group redshift
38 I1 --- nUV Number of UV members
40 I1 --- ngal Number of UV members compiled as 'galaxy' by NED
42 I1 --- nz Number of UV members with a redshift counterpart
44 I1 --- mz Number of UV with a known l-o-s velocity within
2000km/s centred at the group redshift
46- 50 F5.3 arcmin rθ Group angular radius
52- 57 F6.2 kpc Rij ?=-1 Median intergalaxy physical separation
59- 64 F6.2 km/s sigmalos ?=-1 l-o-s velocity dispersion derived by the
gapper method (Beers, Flynn & Gebhardt,
1990AJ....100...32B 1990AJ....100...32B) (1)
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Note (1): For mz=3, the relative uncertainty in σl-o-s corresponds to
50 per cent and for mz=4 corresponds to 41 per cent following
(σ/δσ)=sqrt(2(mz-1)) (e.g. Proctor et al.,
2011MNRAS.418.2054P 2011MNRAS.418.2054P, Cat. J/MNRAS/418/2054).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Group Identification number of the SFCG
5 I1 --- Gal Identification number of the SFCG galaxy
ordered by increasing right ascension
7- 8 I2 h RAh Right ascension of UV-bright galaxy member
(J2000)
10- 11 I2 min RAm Right ascension of UV-bright galaxy member
(J2000)
13- 17 F5.2 s RAs Right ascension of UV-bright galaxy member
(J2000)
19 A1 --- DE- Declination sign of UV-bright galaxy member
(J2000)
20- 21 I2 deg DEd Declination of UV-bright galaxy member (J2000)
23- 24 I2 arcmin DEm Declination of UV-bright galaxy member (J2000)
26- 29 F4.1 arcsec DEs Declination of UV-bright galaxy member (J2000)
31- 38 F8.6 --- zmemb Galaxy redshift
41- 42 I2 --- gmemb [-1/1] Group membership code (1)
45- 51 F7.4 mag FUV FUV magnitude (AB) corrected for Galactic
extinction
54- 60 F7.4 mag NUV NUV magnitude (AB) corrected for Galactic
extinction
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Note (1): Group membership code as follows:
1 = velocity-accordant galaxy member
0 = non-member galaxy or unknown redshift
-1 = non-NED galaxy
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Group ID number of the SFCG
5- 34 A30 --- Name Preferred NED name of a previously identified
group counterpart
36- 43 F8.6 --- zNED ? NED group redshift
45- 49 F5.3 arcmin Dsep ? Angular separation distance between the SFCG
and the previously identified galaxy group
52- 59 F8.6 --- ? Median redshift for galaxies with known
redshift given by NED inside Dsep=2.5arcmin
61- 62 I2 --- ngz ? Number of galaxies to derive the redshift
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 18-Mar-2016