J/ApJ/775/125 Metallicity of galaxies from colors (Sanders+, 2013)
Using colors to improve photometric metallicity estimates for galaxies.
Sanders N.E., Levesque E.M., Soderberg A.M.
<Astrophys. J., 775, 125 (2013)>
=2013ApJ...775..125S 2013ApJ...775..125S
ADC_Keywords: Galaxies, photometry ; Abundances ; Models
Keywords: galaxies: abundances; galaxies: ISM; galaxies: photometry
Abstract:
There is a well known correlation between the mass and metallicity of
star-forming galaxies. Because mass is correlated with luminosity,
this relation is often exploited, when spectroscopy is not available,
to estimate galaxy metallicities based on single band photometry.
However, we show that galaxy color is typically more effective than
luminosity as a predictor of metallicity. This is a consequence of the
correlation between color and the galaxy mass-to-light ratio and the
recently discovered correlation between star formation rate (SFR) and
residuals from the mass-metallicity relation. Using Sloan Digital Sky
Survey spectroscopy of ∼180000 nearby galaxies, we derive "LZC
relations," empirical relations between metallicity (in seven common
strong line diagnostics), luminosity, and color (in 10 filter pairs
and four methods of photometry). We show that these relations allow
photometric metallicity estimates, based on luminosity and a single
optical color, that are ∼50% more precise than those made based on
luminosity alone; galaxy metallicity can be estimated to within
∼0.05-0.1 dex of the spectroscopically derived value depending on the
diagnostic used. Including color information in photometric
metallicity estimates also reduces systematic biases for populations
skewed toward high or low SFR environments, as we illustrate using the
host galaxy of the supernova SN 2010ay. This new tool will lend more
statistical power to studies of galaxy populations, such as supernova
and gamma-ray burst host environments, in ongoing and future
wide-field imaging surveys.
Description:
We used spectroscopic data and derived quantities from the MPA/JHU
catalog of 927552 star-forming galaxies from the SDSS-DR7.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 91 241 *Parameters of the LZC relations
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Note on table2.dat: Parameters of the LZC relations defined in Equation (1) as:
µ=Mi-α*(mi-mj) where i,j are choices of filters.
(See section 3).
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See also:
J/ApJ/765/140 : Stacked spectra of SDSS star forming galaxies (Andrews+, 2013)
J/ApJ/758/133 : Metallicity profile of M31 HII regions and PNe (Sanders+, 2012)
J/ApJ/743/149 : Color-metallicity relations. II. M87 GCs (Yoon+, 2011)
J/ApJ/673/999 : Supernova and host galaxies metallicities (Prieto+, 2008)
J/MNRAS/385/1270 : Age-metallicity relation via photometry (Li+, 2008)
http://www.mpa-garching.mpg.de/SDSS : MPA/JHU SDSS studies home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- r_Type Model type/description reference (1)
6- 17 A12 --- Type Model type/description
20 A1 --- Filt Photometric band of luminosity (u, g, r or i)
22- 24 A3 --- Color Color relation (SDSS colors)
26- 29 F4.1 --- alpha Optimal value of color weighting factor α
(minimize the scatter in metallicity) (2)
31- 37 F7.2 10-5 p3 The p3 parameter times 105 (2)
39- 45 F7.2 10-3 p2 The p2 parameter times 103 (2)
47- 54 F8.2 10-3 p1 The p1 parameter times 103 (2)
56- 61 F6.2 --- p0 The p0 parameter (2)
63- 67 F5.3 --- sigZ0 Scatter in Z residual σZ,0 of LZ relation
69- 73 F5.3 --- sigZ Scatter in Z residual σZ of LZC relation
75- 79 F5.3 --- Ratio [[0.68/0.98] Ratio of σZ/σZ,0 (3)
81- 85 F5.1 mag mu2 [-35/-22] The 2nd percentile in the µ range
87- 91 F5.1 mag mu98 [-24/-17] The 98th percentile in the µ range
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Note (1): References are (see section 2)
M91 = McGaugh, S.S. 1991ApJ...380..140M 1991ApJ...380..140M
KD02 = Kewley & Dopita 2002ApJS..142...35K 2002ApJS..142...35K
KK04 = Kobulnicky & Kewley 2004ApJ...617..240K 2004ApJ...617..240K
PP04 = Pettini & Pagel 2004MNRAS.348L..59P 2004MNRAS.348L..59P
T04 = Tremonti et al. 2004ApJ...613..898T 2004ApJ...613..898T
PVT = Pilyugin, Vilchez and Thuan 2010ApJ...720.1738P 2010ApJ...720.1738P
Note (2): the relations are, if the indices i and j are choices of filters:
µ = Mi-α*(mi-mj)
12+log(O/H) = p0+p1µ+p2µ2+p3µ3
Note (3): Expresses the reduction in the scatter relative to the LZ relation
(without color term).
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 17-Mar-2015