J/MNRAS/458/3443 Cl0939+4713 Hα z∼0.4 star-forming galaxies (Sobral+ 2016)
The nature of Hα star-forming galaxies at z ∼ 0.4 in and around
Cl 0939+4713: the environment matters.
Sobral D., Stroe A., Koyama Y., Darvish B., Calhau J., Afonso A.,
Kodama T., Nakata F.
<Mon. Not. R. Astron. Soc., 458, 3443-3454 (2016)>
=2016MNRAS.458.3443S 2016MNRAS.458.3443S (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, galaxy ; Redshifts ; Spectroscopy
Keywords: galaxies: clusters: general - galaxies: evolution -
intergalactic medium - cosmology: observations -
large-scale structure of Universe
Abstract:
Cluster star-forming galaxies are found to have an excess of
far-infrared emission relative to Hα, when compared to those in
the field, which could be caused by intense active galactic nuclei
(AGN) activity, dust and/or declining star formation histories. Here
we present spectroscopic observations of Hα emitters in the Cl
0939+4713 (Abell 851) super-cluster at z=0.41, using AF2+ WYFFOS on
the William Herschel Telescope. We measure [OII], Hβ, [OIII],
Hα and [NII] for a sample of 119 Hα emitters in and
around the cluster. We find that 17±5 per cent of the Hα
emitters are AGN, irrespective of environment. For star-forming
galaxies, we obtain Balmer decrements, metallicities and ionization
parameters with different methods, individually and by stacking. We
find a strong mass-metallicity relation at all environments, with no
significant dependence on environment. The ionization parameter
declines with increasing stellar mass for low-mass galaxies. Hα
emitters residing in intermediate environments show the highest
ionization parameters (along with high [OIII]/Hα and high
[OIII]/[OII] line ratios, typically twice as large as in the highest
and lowest densities), which decline with increasing environmental
density. Dust extinction (AHα) correlates strongly with
stellar mass, but also with environmental density. Star-forming
galaxies in the densest environments are found to be significantly
dustier (AHα~=1.5-1.6) than those residing in the
lowest density environments (AHα~=0.6), deviating
significantly from what would be predicted given their stellar masses.
Description:
We followed up 214 candidate Hα line emitters from Koyama et al.
(2011ApJ...734...66K 2011ApJ...734...66K) using AF2 on the WHT in La Palma (program ID:
W14BN020) on the second half of four nights during 2015 January 22-25.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 152 119 Hα emitters in our spectroscopic sample
with Flags 1,2,3
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See also:
J/MNRAS/416/2041 : Hα emitters at z=2.23 (Matsuda+, 2011)
J/ApJ/765/26 : Very low-z SDSS galaxies with Hα emission (Shim+ 2013)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- ID Name (DUSQ_NNN)
10- 11 I2 h RAh Right ascension (J2000)
13- 14 I2 min RAm Right ascension (J2000)
16- 21 F6.3 s RAs Right ascension (J2000)
23 A1 --- DE- Declination sign (J2000)
24- 25 I2 deg DEd Declination (J2000)
27- 28 I2 arcmin DEm Declination (J2000)
30- 34 F5.2 arcsec DEs Declination (J2000)
36- 43 F8.6 --- zsp Spectroscopic redshift
45- 52 F8.6 --- e_zsp rms uncertainty on zsp
54- 59 F6.3 mag zmag SDSS z' magnitude
61- 68 F8.4 [mW/m2] logF(Ha) Flux in Hα
70- 74 F5.3 [Mpc-2] logSigma10 Local environmental density
76- 83 F8.6 --- [NII]/Ha ?=- [NII]6584/Hα line flux ratio
85- 92 F8.6 --- [OIII]/Hb ?=- [OIII]5007/Hβ line flux ratio
94-101 F8.6 --- [OIII]/Ha ?=- [OIII]5007/Hα line flux ratio
103-110 F8.6 --- [OII]/Ha ?=- [OII]3727/Hα line flux ratio
112-119 F8.5 [Msun] logM* Stellar mass
121 I1 --- Flag [1/3] Flag (1)
123-125 I3 --- AGN [-1/2]?=-99 AGN flag (2)
127 I1 --- Point [1/4] Pointing identification number
129-133 F5.3 mag B-I B-I colour index
135-142 F8.4 0.1nm EWrest Rest-frame Hα+[NII] equivalent width
144-152 F9.6 arcmin Rc Radius used to calculate logSigma10
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Note (1): Flag as follows:
1 = Hα and at least two other emission lines
2 = Hα and at least another emission line detected at S/N>5
3 = at least one emission line detected at S/N>5
4 = a potential Hα line but at too low S/N (S/N<5)
Note (2): AGN flag as follows:
-1 = Unclass
0 = SFGs
1 = Others
2 = AGN
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 01-Jun-2017