J/ApJ/834/186 Metallicity of MPA-JHU SDSS-DR7 dwarf galaxies (Douglass+, 2017)
Determining the large-scale environmental dependence of gas-phase metallicity
in dwarf galaxies.
Douglass K.A., Vogeley M.S.
<Astrophys. J., 834, 186-186 (2017)>
=2017ApJ...834..186D 2017ApJ...834..186D (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, spectra ; Abundances ; Redshifts
Keywords: galaxies: abundances; galaxies: dwarf; galaxies: evolution
Abstract:
We study how the cosmic environment affects galaxy evolution in the
universe by comparing the metallicities of dwarf galaxies in voids
with dwarf galaxies in more dense regions. Ratios of the fluxes of
emission lines, particularly those of the forbidden [OIII] and [SII]
transitions, provide estimates of a region's electron temperature and
number density. From these two quantities and the emission line fluxes
[OII]λ3727, [OIII]λ4363, and
[OIII]λλ4959,5007, we estimate the abundance of oxygen
with the direct Te method. We estimate the metallicity of 42 blue,
star-forming void dwarf galaxies and 89 blue, star-forming dwarf
galaxies in more dense regions using spectroscopic observations from
the Sloan Digital Sky Survey Data Release 7, as reprocessed in the
MPA-JHU value-added catalog. We find very little difference between
the two sets of galaxies, indicating little influence from the
large-scale environment on their chemical evolution. Of particular
interest are a number of extremely metal-poor dwarf galaxies that are
less prevalent in voids than in the denser regions.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 68 135 Dwarf galaxy properties
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See also:
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012)
J/AJ/119/32 : Survey of galaxies within nearby voids. II (Grogin+, 2000)
J/A+A/448/955 : Abundances of emission galaxies in SDSS-DR3 (Izotov+, 2006)
J/A+A/462/535 : Low-metallicity HII regions and galaxies (Yin+, 2007)
J/AJ/144/16 : Optical & HI properties of galaxies in voids (Kreckel+, 2012)
J/ApJ/765/140 : Stacked spectra of SDSS star forming galaxies (Andrews+, 2013)
J/ApJS/208/10 : κ-distribution effects in HII regions (Dopita+, 2013)
J/A+A/550/A115 : Oxygen abundances and properties of galaxies (Hughes+, 2013)
J/A+A/559/A114 : Updated O3N2 and N2 abundance indicators (Marino+, 2013)
http://www.sdss.org/ : SDSS home page
http://wwwmpa.mpa-garching.mpg.de/SDSS/DR7/ : MPA-JHU for the SDSS-DR7 release
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 I7 --- Seq KIAS-VAGC galaxy index number (1)
9 A1 --- f_Seq [e] e = extreme low gas-phase metallicity
(12+log(O/H)<7.6) galaxy; flag added by CDS
according to table 3
11- 12 I2 h RAh Hour of Right Ascension (J2000)
14- 15 I2 min RAm Minute of Right Ascension (J2000)
17- 21 F5.2 s RAs Second of Right Ascension (J2000)
23 A1 --- DE- Sign of the Declination (J2000)
24- 25 I2 deg DEd Degree of Declination (J2000)
27- 28 I2 arcmin DEm Arcminute of Declination (J2000)
30- 34 F5.2 arcsec DEs Arcsecond of Declination (J2000)
36- 41 F6.4 --- zsp [0.02/0.03] Spectroscopic redshift
43- 48 F6.2 mag rMag [-17/-16.3] Absolute r band magnitude
50- 53 F4.2 [-] O/H [7/8.6] The 12+log(O/H) abundance (2)
55- 58 F4.2 [-] e_O/H [0/0.7] Uncertainty in O/H
60- 68 A9 --- Loc Location code (3)
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Note (1): The flux values for all required emission lines can be found in the
MPA-JHU value-added catalog.
Note (2): Metallicity values are calculated using the Direct Te method, with
error estimates via a Monte Carlo method.
Note (3): The void catalog of Pan et al. (2012MNRAS.421..926P 2012MNRAS.421..926P) is used
to classify the galaxies as either Void or Wall. If a galaxy is
located too close to the boundary of the SDSS survey to identify
whether or not it is inside a void, it is labeled as Uncertain.
Among the 21 extremely metal-poor galaxies, four are located in voids
(about 10% of the void dwarf population measured) and seventeen are
in more dense regions (about 19% of the wall dwarf population
measured); thus, there does not seem to be a special population of
extreme low-metallicity galaxies in voids. Further study of these
galaxies is recommended, to confirm metallicity values and identify
any shared characteristics.
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History:
From electronic version of the journal
10-Aug-2017: Insert into VizieR
17-Nov-2017: Declination coordinates corrected,
following positions in Paper II.
References:
Douglass & Vogeley Paper II 2017ApJ...837...42D 2017ApJ...837...42D Cat. J/ApJ/837/42
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Jul-2017