J/MNRAS/421/2982 Optical and UV colors of Coma galaxies (Smith+, 2012)
What drives the ultraviolet colours of passive galaxies?
Smith R.J., Lucey J.R., Carter D.
<Mon. Not. R. Astron. Soc., 421, 2982-2997 (2012)>
=2012MNRAS.421.2982S 2012MNRAS.421.2982S
ADC_Keywords: Clusters, galaxy ; Velocity dispersion ; Abundances ;
Photometry, SDSS ; Photometry, ultraviolet
Keywords: galaxies: elliptical and lenticular, cD - galaxies: stellar content -
ultraviolet: galaxies
Abstract:
We present and analyse optical and ultraviolet (UV) colours for
passive and optically-red Coma cluster galaxies for which we have
spectroscopic age and element abundance estimates. Our sample of 150
objects covers a wide range in mass, from giant ellipticals down to
the bright end of the dwarf-galaxy regime. Galaxies with ongoing star
formation have been removed using strict Hα emission-line
criteria. We focus on the colours FUV-i, NUV-i, FUV-NUV, u*-g and g-i.
We find that all of these colours are correlated with both luminosity
and velocity dispersion at the >5σ level, with FUV-i and FUV-NUV
becoming bluer with increasing 'mass' while the other colours become
redder. We perform a purely empirical analysis to assess what fraction
of the variation in each colour can be accounted for by variations in
the average stellar populations, as traced by the optical spectra.
Description:
Our approach is to measure UV/optical colours for galaxies drawn
from a catalogue of galaxies with measured spectroscopic ages and
metallicities. Full details of the spectroscopy are given in
related papers (Smith et al. 2012MNRAS.419.3167S 2012MNRAS.419.3167S; Smith et al.,
in preparation). Broadly the parent sample comprises spectra for 242
bright Coma cluster members from SDSS (analysed in Price et al. 2010,
Cat. J/MNRAS/411/2558) and 169 fainter members observed using long
integrations with Hectospec at the 6.5-m MMT. The MMT sample is an
extended version of that reported by Smith et al. (2009, cat.
J/MNRAS/392/1265). Velocity dispersions were compiled from a variety
of literature sources, supplemented with new observations from
VLT/FLAMES, and combined using observations from multiple data sources
to determine relative systematic offsets.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 152 The galaxy properties used for the analysis in
Section 3
table2.dat 96 152 The 10" diameter aperture magnitudes from which
colours were derived for the analysis in Section 3
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See also:
J/MNRAS/392/1265 : Coma cluster faint red galaxies spectroscopy (Smith+, 2009)
J/MNRAS/411/2558 : Coma cluster galaxies absorption-line indices (Price+, 2011)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- Name Galaxy name (1)
9- 10 I2 h RAh Right ascension (J2000)
12- 13 I2 min RAm Right ascension (J2000)
15- 19 F5.2 s RAs Right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 31 F4.1 arcsec DEs Declination (J2000)
33- 37 F5.2 [Lsun] log(Lr) [9.4/11.1] r-band luminosity from SDSS
39- 43 F5.3 [km/s] logsig Velocity dispersion σ (2)
45- 49 F5.3 [km/s] e_logsig rms uncertainty on logsig
51- 55 F5.3 [10Gyr] logTssp [0.22/1.39] SSP-equivalent age (2)
57- 61 F5.3 [10Gyr] e_logTssp rms uncertainty on logTssp (3)
63- 68 F6.3 [Sun] [Mg/H] [-0.04/0.5] Abundance [Mg/H] (2)
70- 74 F5.3 [Sun] e_[Mg/H] rms uncertainty on [Mg/H] (3)
76- 80 F5.2 --- rhoerr [-1/-0.72] Error coefficient ρerr (3)
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Note (1): The identifications are from Godwin, Metcalfe & Peach (1983, VII/42)
where available, with coordinates derived from matching to SDSS.
Note (2): SSP = Simple Stellar Population; from Smith et al.
(2012MNRAS.419.3167S 2012MNRAS.419.3167S). The errors on logTssp and [Mg/H] parameters are
highly anticorrelated.
Note (3): The errors on logTssp and [Mg/H] are highly anti-correlated; this
correlation coefficient is needed when computing errors on combinations
of age and metallicity.
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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- 7 A7 --- Name Galaxy name
9- 31 A23 --- Tile GALEX tile
33- 38 F6.3 mag FUV GALEX FUV magnitude in 10" diameter aperture (AB)
40- 44 F5.3 mag e_FUV Error on FUV (2)
46- 51 F6.3 mag NUV GALEX NUV magnitude in 10" diameter aperture (AB)
53- 57 F5.3 mag e_NUV Error on NUV (2)
59- 64 F6.3 mag u*mag CFHT u* magnitude in 10" diameter aperture (AB) (1)
66- 70 F5.3 mag e_u*mag Error on u* (2)
72- 77 F6.3 mag gmag SDSS g magnitude in 10" diameter aperture (AB)
79- 83 F5.3 mag e_gmag Error on gmag (2)
85- 90 F6.3 mag imag SDSS i magnitude in 10" diameter aperture (AB)
92- 96 F5.3 mag e_imag Error on imag (2)
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Note (1): this passband is centred ∼20nm redder than SDSS u (at 380nm).
Note (2): The quoted errors include a contribution from confusion noise,
but not for calibration uncertainty. Neither extinction corrections
nor k-corrections have been applied.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 07-Mar-2013