J/ApJ/938/16ivo://CDS.VizieR/J/ApJ/938/16doi:10.26093/cds/vizier.19380016CDSOlivier G.M.Berg D.A.Chisholm J.Erb D.K.Pogge R.W.Skillman E.D.2024-11-06T20:27:48Z2024-09-17T08:23:36ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frgalaxiesspectroscopyredshiftedline-intensitiesultraviolet-astronomyvisible-astronomyObservations of high-redshift galaxies (z>5) have shown that these galaxies have extreme emission lines with equivalent widths much larger than their local star-forming counterparts. Extreme emission line galaxies (EELGs) in the nearby universe are likely analogs to galaxies during the Epoch of Reionization and provide nearby laboratories to understand the physical processes important to the early universe. We use Hubble Space Telescope/Cosmic Origins Spectrograph and Large Binocular Telescope/Multi-Object Double Spectrographs spectra to study two nearby EELGs, J104457 and J141851. The far-UV spectra indicate that these two galaxies contain stellar populations with ages <~10Myr and metallicities <=0.15Z_{sun}_. We use photoionization modeling to compare emission lines from models of single-age bursts of star formation to observed emission lines and find that the single-age bursts do not reproduce high-ionization lines including [OIII] or very-high-ionization lines like HeII or OIV]. Photoionization modeling using the stellar populations fit from the UV continuum similarly is not capable of reproducing the very-high-energy emission lines. We add a blackbody to the stellar populations fit from the UV continuum to model the necessary high-energy photons to reproduce the very-high-ionization lines of HeII and OIV]. We find that we need a blackbody of 80000K and ~45%-55% of the luminosity from the blackbody and young stellar population to reproduce the very-high-ionization lines while simultaneously reproducing the low-, intermediate-, and high-ionization emission lines. Our self-consistent model of the ionizing spectra of two nearby EELGs indicates the presence of a previously unaccounted-for source of hard ionizing photons in reionization analogs.2022ApJ...938...16Ohttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/938/16CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/103/97 : Grids of stellar models V. (Meynet+ 1994)J/A+AS/125/229 : A standard stellar library (Lejeune+ 1997)J/ApJS/161/240 : High-ionization em. in metal-deficient BCDs (Thuan+, 2005)J/ApJ/636/214 : HII regions in dwarf irregular galaxies (van Zee+, 2006)J/ApJ/742/111 : Extreme emission-line galaxies in CANDELS (van der Wel+, 2011)J/ApJ/795/165 : Line ratios in z~2-3 gal. from KBSS-MOSFIRE (Steidel+, 2014)J/ApJ/806/16 : CHemical Abund. of Spirals (CHAOS). I. NGC628 (Berg+, 2015)J/ApJ/803/34 : z~4-10 galaxies from HST legacy fields (Bouwens+, 2015)J/ApJ/810/71 : UV mag of candidate galaxies at 3~<z~<8.5 (Finkelstein+, 2015)J/ApJ/813/82 : z<0.06 broad-line AGN emission-line measures (Reines+, 2015)J/ApJ/814/L6 : CIII] emission in near & far star-forming gal. (Rigby+, 2015)J/ApJ/835/113 : Gal. >~6 from the Hubble Frontier Fields (Livermore+, 2017)J/AJ/155/104 : MEGaSaURA. I. The sample and the spectra (Rigby+, 2018)J/ApJ/853/87 : MEGaSaURA. II. Stacked spectra (Rigby+, 2018)J/A+A/629/A134 : Radiative contribution from stripped stars (Goetberg+, 2019)J/ApJ/888/36 : SDSS/FIRST dwarf gal. with VLA high res. obs. (Reines+, 2020)J/ApJ/921/91 : Catastrophic cooling in superwinds. II. (Danehkar+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/938/16https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/938/16http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/938/16https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/938/16https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/938/16http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/938/16GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/938/16/table1 (Extreme UV emission-line galaxy properties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/938/16/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/938/16/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/938/16/table1?GETtext/xml+votable180.050000true161.24079173.88698610.0055555555555555560/https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/938/16?format=asciiUVOpticaldefaultJ/ApJ/938/16/table1Extreme UV emission-line galaxy propertiesEWCIV1550CIV{lambda}1550 equivalent width0.1nmspect.line.eqWidthfloatEWHeII[-2.82/-2.75] HeII{lambda}1640 equivalent width0.1nmspect.line.eqWidthfloatDelVOIII[64.7/87.3] Velocity width (FWHM), {Delta}V, of OIII]{lambda}1666km/sspect.line.width;em.line.OIIIfloatDelVCIVbVelocity width (FWHM), {Delta}V, of CIV{lambda}1548 bluekm/sspect.line.widthfloatDelVCICrVelocity width (FWHM), {Delta}V, of CIV{lambda}1548 redkm/sspect.line.widthfloatFWHM[103.5/188.4] Spectral resolution from COS used in our continuum fittingkm/sspect.resolutionfloatSpInteractive plot of spectrummeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDGalaxy identifier (JHHMMSS)meta.id;meta.maincharRefReference (1)meta.bibcharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainz[0.009/0.013] Redshiftsrc.redshiftfloatlogMass[6.6/6.8] Log of total stellar masslog(solMass)phys.massfloatlogSFR[-1.2/-0.8] Log of stellar formation ratelog(solMass.yr**-1)arith.rate;phys.SFRfloatlogsSFR[-7.8/-7.6] Log of specific stellar formation ratelog(yr**-1)arith.rate;phys.SFRfloatE(B-V)[0.07/0.14] Reddening E (B-V)magphot.color.excessfloatZMetallicity, 12+log (O/H)phys.abund.Zfloate_ZZ uncertaintystat.error;phys.abund.ZfloatlogU[-2.42/-1.7] Ionization parameterphys.ionizParamfloatEWOIII1661OIII]{lambda}1661 equivalent width0.1nmspect.line.eqWidth;em.line.OIIIfloatEWOIII1666OIII]{lambda}1666 equivalent width0.1nmspect.line.eqWidth;em.line.OIIIfloatEWCIV1548CIV{lambda}1548 equivalent width0.1nmspect.line.eqWidthfloatNEDNED column added by the CDSmeta.ref.urlcharLEDAmeta.ref.urlcharSimbadNameSimbad column added by the CDSmeta.idcharnullable