J/MNRAS/423/422 Early-type BCGs with star formation (Liu+, 2012)
Star formation activities in early-type brightest cluster galaxies.
Liu F.S., Mao S., Meng X.M.
<Mon. Not. R. Astron. Soc., 423, 422-436 (2012)>
=2012MNRAS.423..422L 2012MNRAS.423..422L
ADC_Keywords: Clusters, galaxy ; Spectroscopy ; Redshifts
Keywords: galaxies: clusters: general -
galaxies: elliptical and lenticular, cD - galaxies: star formation
Abstract:
We identify a total of 120 early-type brightest cluster galaxies
(BCGs) at 0.1<z<0.4 in two recent large cluster catalogues selected
from the Sloan Digital Sky Survey (SDSS). They are selected with
strong emission lines in their optical spectra, with both Hα and
[OII]λ3727 line emission, which indicates significant ongoing
star formation. They constitute about ∼0.5 per cent of the largest,
optically selected, low-redshift BCG sample, and the fraction is a
strong function of cluster richness. Their star formation history can
be well described by a recent minor and short starburst superimposed
on an old stellar component, with the recent episode of star formation
contributing on average only less than 1 per cent of the total stellar
mass. We show that the more massive star-forming BCGs in richer
clusters tend to have higher star formation rate (SFR) and specific
SFR (SFR per unit galaxy stellar mass). We also compare their
statistical properties with a control sample selected from X-ray
luminous clusters, and show that the fraction of star-forming BCGs in
X-ray luminous clusters is almost one order of magnitude larger than
that in optically selected clusters. BCGs with star formation in
cooling flow clusters usually have very flat optical spectra and show
the most active star formation, which may be connected with cooling
flows.
Description:
We identify early-type BCGs with significant SF from two large
optically selected cluster catalogues of SDSS-WHL (Wen et al., 2009,
Cat. J/ApJS/183/197) and GMBCG (Hao et al., 2010, Cat. J/ApJS/191/254).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 156 120 Basic parameters for the 120 identified
early-type BCGs with ongoing star formation
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See also:
J/ApJS/183/197 : Galaxy clusters identified from the SDSS-DR6 (Wen+, 2009)
J/ApJS/191/254 : GMBCG galaxy cluster catalog from SDSS-DR7 (Hao+, 2010)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 25 A25 --- Cluster SDSS-WHL cluster name or GMBCG cluster name
26- 28 A3 --- n_Cluster Note on Cluster (1)
30- 46 A17 --- XCluster X-ray cluster name
48- 56 F9.5 deg RAdeg Brightest galaxy right ascension (J2000)
58- 66 F9.5 deg DEdeg Brightest galaxy (BCG) declination (J2000)
68- 73 F6.4 --- zBCG Spectroscopic redshift of the BCG
75- 79 F5.2 [Msun] logM*f Stellar mass inside the fibre aperture
81- 85 F5.2 [Msun] logM*t Total stellar mass
87- 93 F7.2 10-20W/m2 F[NII] Flux of [NII]λ6584 line (2)
95-101 F7.2 10-20W/m2 FHa Flux of Hα line (2)
103-109 F7.2 10-20W/m2 F[OIII] Flux of [OIII]λ5007 line (2)
111-117 F7.2 10-20W/m2 FHb Flux of Hβ line (2)
119-126 F8.2 10-20W/m2 F[OII] Flux of [OII]λ3727 line (2)
128-133 F6.2 Msun/yr SFRa Derived SFR by the Hα emission line
135-140 F6.2 Msun/yr SFRo Derived SFR by the [OII] emission line
142-145 F4.2 --- Dn(4000) Amplitude of the Balmer break Dn(4000Å)
147-151 F5.2 --- HdA Absorption line index HδA
153-156 A4 --- Class Galaxy type classified by the BPT diagnostic
diagrams: sb (starburst) or comp (composite)
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Note (1): Notes as follows:
a = SDSS-WHL objects also in the GMBCG catalogue
b = galaxies in the 13 identified candidates of X-ray luminous clusters
Note (2): The flux of all emission lines used in this paper have been applied
the dust correction. In 10-17erg/cm2/s.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 06-Sep-2013