J/ApJ/860/83 22 extreme [OIII] emitters at z∼0.5 from SDSS-DR14 (Li+, 2018)
Extreme [OIII] emitters at z∼0.5.
Li Z., Malkan M.A.
<Astrophys. J., 860, 83 (2018)>
=2018ApJ...860...83L 2018ApJ...860...83L
ADC_Keywords: Photometry, SDSS ; Galaxies, spectra ; Equivalent widths ;
Redshifts
Keywords: galaxies: dwarf ; galaxies: luminosity function ; galaxies: ISM ;
galaxies: starburst
Abstract:
We have found a sample of extreme emission-line galaxies (EELGs) with
strong [OIII]λ5007 emission at z∼0.5. Using broadband
photometric selection and requiring small uncertainties in photometry,
we searched the 14th Data Release of the Sloan Digital Sky Survey
(SDSS) and found 2658 candidates with strong i-band excess (i-z≤r-i-0.7).
We further obtained 649 SDSS spectra of these objects, and visually
identified 22 [OIII] emitters lying at 0.40<z<0.63. Having constructed
their ultraviolet-infrared spectral energy distributions, we found
that they have fairly blue r-W2 and red W1-W4 colors, indicative of
strong, warm dust emission. Their rest-frame [OIII]λ5007
equivalent widths are mostly 200-600Å, and their high
[OIII]λ5007/Hβ ratios put them at the boundary of
star-forming galaxies and active galactic nuclei on line ratio
classification diagrams. The typical E(B-V) and electron temperature
of [OIII] emitters are ∼0.1-0.3mag and ∼104K, respectively. The lowest
metallicity of our [OIII] emitters with S/N[OIII]λ4363>3 is
12+log(O/H)=7.98-0.02+0.12, with a median value of
8.24-0.04+0.05. Our [OIII] emitters exhibit remarkably high line
luminosity-18/22 have L[OIII]λ5007>5x1042erg/s and 5/22 have
L[OIII]λ5007>1043erg/s. Their estimated volume number density
at z∼0.5 is ∼2x10-8Mpc-3, with L[OIII]λ5007 down to
∼3x1042erg/s. The cumulative number distribution of EELGs across
different redshifts is indicative of a strong redshift evolution at
the bright end of the [OIII] luminosity function.
Description:
Our parent sample is constructed from the ugriz photometry in
PhotoPrimary catalog of the Sloan Digital Sky Survey (SDSS) 14th Data
Release (DR14, Abolfathi+ 2018ApJS..235...42A 2018ApJS..235...42A). We have searched in
the PhotoObjAll catalog (where multiple photometry of a certain object
could exist) and it yielded a list of 2658 unique objects (the "total
sample" --see Table 2), of which 649 have observed SDSS spectra.
See section 2.
We have constructed UV-IR SEDs for each of our 22 [OIII] emitters by
collecting GALEX, SDSS, UKIDSS and WISE data from their corresponding
online catalogs. See section 3 (and Tables 5 and 6).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 33 2658 Positions, r-band magnitudes, Petrosian radii, and
clean photometry flags of our total sample
of [OIII] candidates
table5.dat 59 22 Stellar masses, burst ages and color excesses
derived from SED fitting and Ha-derived SFRs of
22 [OIII] emitters
table6.dat 82 22 Emission line properties of 22 [OIII] emitters
fig3.dat 19 91151 Average rest-frame spectrum of 22 [OIII] emitters
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See also:
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
J/A+A/448/955 : Abundances of emission galaxies in SDSS-DR3 (Izotov+, 2006)
J/ApJ/657/738 : SDF galaxies multi-photometry (Ly+, 2007)
J/ApJ/737/71 : The [OIII] emission line in SDSS AGNs (Zhang+, 2011)
J/ApJ/765/140 : Stacked spectra of SDSS star forming galaxies (Andrews+, 2013)
J/A+A/561/A33 : SDSS star-forming gal. multi-wavelength study (Izotov+, 2014)
J/MNRAS/452/4153 : SDSS DR12 QSOs [OIII] doublet (Albareti+, 2015)
J/ApJS/226/5 : MACT survey I. Opt. spectrosc. in Subaru Deep Field (Ly+, 2016)
J/ApJ/844/171 : Lyα profile in 43 Green Pea galaxies (Yang+, 2017)
J/ApJ/847/38 : Extreme emission line galaxies at z≲0.05 (Yang+, 2017)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 7 F7.3 deg RAdeg Right Ascension in decimal degrees (J2000)
9- 16 F8.4 deg DEdeg [-23/85] Declination in decimal degrees (J2000)
18- 22 F5.2 mag rmag [18.5/32.3] SDSS r-band magnitude
24- 29 F6.2 arcsec rRad [0.06/259] SDSS r-band Petrosian radius
31 I1 --- clean [0/1] Clean photometry flag; 1 when clean
33 I1 --- PFlag [0/1] Catalog flag (1)
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Note (1): 1 when in the primary sample: 968 objects in total as our
"parent sample" of [OIII] candidates with i-band excess.
See section 2 for further explanations.
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [OIII-]
6- 7 I2 --- Seq Sequential number of the [OIII] emitter
9- 13 F5.2 [Msun] logM* [9.2/10.2] Log of stellar mass
15- 18 F4.2 [Msun] e_logM* [0.1/1.4]? Negative uncertainty on logM*
19 A1 --- f_logM* i=inf
21- 24 F4.2 [Msun] E_logM* [0.08/0.4] Positive uncertainty on logM*
26- 28 I3 Myr Age [50/148] Age of the recent burst
30- 31 I2 Myr e_Age [5/58] Age uncertainty
33- 36 F4.2 mag E(B-V) [0.05/0.3] Color excess
38- 42 F5.3 mag e_E(B-V) [0.005/0.06] E(B-V) uncertainty
44- 48 F5.1 Msun/yr SFR [9/129] Hα-derived star formation rate
50- 53 F4.1 Msun/yr e_SFR [0.3/37] SFR negative uncertainty
(68% confidence level)
55- 59 F5.1 Msun/yr E_SFR [0.1/104] SFR positive uncertainty
(68% confidence level)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- --- [OIII-]
6- 7 I2 --- Seq Sequential number of the [OIII] emitter
9- 17 F9.5 deg RAdeg Right ascension (J2000)
19- 26 F8.5 deg DEdeg [-1.2/61] Declination (J2000)
28- 32 F5.3 --- z [0.4/0.7] Redshift
34- 38 F5.2 [-] logNIII/Ha [-1.6/-1]? log of [NIII]/Hα
emission line ratio
40- 43 F4.2 [-] e_logNIII/Ha [0.02/0.07]? logNIII/Ha uncertainty
45- 48 F4.1 [-] logSII/Ha [-1/-0.8]? log of [SII]/Hα
emission line ratio
50- 53 F4.2 [-] e_logSII/Ha [0.02/0.1]? logSII/Ha uncertainty
55 A1 --- l_logOI/Ha Limit flag on logOI/Ha
56- 60 F5.2 [-] logOI/Ha [-2.7/-1.4]? log of [OI]/Hα
emission line ratio
62- 65 F4.2 [-] e_logOI/Ha [0.03/0.9]? logOI/Ha uncertainty
67- 70 I4 0.1nm EWOIII [132/1252] Observed-frame equivalent
width of [OIII]λ5007 (1)
72- 75 I4 10-20W/m2 FOIII [210/1695] [OIII]λ5007 emission
line flux (1)
77- 82 E6.2 10-7W LOIII [3.2e+42/1.7e+43] [OIII]λ5007
line luminosity
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Note (1): Taken from the default emission line fits in SDSS DR14. The
uncertainties correspond to 68% confidence levels. The median relative
uncertainties of EWOIII and FOIII are 9 per thousand and 4 per thousand,
with a maximum of 2% and 1%, respectively, according to the SDSS DR14
catalog.
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Byte-by-byte Description of file: fig3.dat
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Bytes Format Units Label Explanations
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1- 8 F8.5 mJy Flux [0.3/80.2] Flux
10- 19 F10.5 0.1nm lambda [2269/7240] Rest-frame wavelength; Angstroms
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 04-Jul-2019