J/ApJ/883/10ivo://CDS.VizieR/J/ApJ/883/10doi:10.26093/cds/vizier.18830010CDSPutko J.Sanchez Almeida J.Munoz-Tunon C.Asensio Ramos A.,Elmegreen B.G.Elmegreen D.M.2021-07-05T08:38:23Z2021-03-16T08:26:11ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomygalaxy-classification-systemsThe three-dimensional (3D) shape of a galaxy inevitably is tied to how it has formed and evolved and to its dark matter halo. Local extremely metal-poor galaxies (XMPs; defined as having an average gas-phase metallicity <0.1 solar) are important objects for understanding galaxy evolution largely because they appear to be caught in the act of accreting gas from the cosmic web, and their 3D shape may reflect this. Here, we report on the 3D shape of XMPs as inferred from their observed projected minor-to-major axial ratios using a hierarchical Bayesian inference model, which determines the likely shape and orientation of each galaxy, while simultaneously inferring the average shape and dispersion. We selected a sample of 149 XMPs and divided it into three subsamples according to physical size and found that (1) the stellar component of XMPs of all sizes tends to be triaxial, with an intermediate axis ~0.7 times the longest axis and that (2) smaller XMPs tend to be relatively thicker, with the shortest axis going from ~0.15 times the longest axis for the large galaxies to ~0.4 for the small galaxies. We provide the inferred 3D shape and inclination of the individual XMPs in electronic format. We show that our results for the intermediate axis are not clouded by a selection effect against face-on XMPs. We discuss how an intermediate axis significantly smaller than the longest axis may be produced by several mechanisms, including lopsided gas accretion, non-axisymmetric star formation, or coupling with an elongated dark matter halo. Large relative thickness may reflect slow rotation, stellar feedback, or recent gas accretion.2019ApJ...883...10Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/883/10CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)J/ApJ/631/85 : Galaxy morphologies in the Hubble UDF (Elmegreen+, 2005)J/ApJS/162/49 : UBV imaging of irregular galaxies (Hunter+, 2006)J/ApJ/743/77 : Extremely metal-poor (XMP) gal. in SDSS (Morales-Luis+, 2011)J/A+A/558/A18 : HI spectra of extremely metal-poor (XMP) gal. (Filho+, 2013)J/ApJ/772/135 : 3.6um surface brightness from S4G (Zaritsky+, 2013)J/MNRAS/444/3015 : Morphologies of S4G galaxies (Laine+, 2014)J/ApJ/819/110 : Extremely metal-poor gal. in SDSS. II. (Sanchez Almeida+ 2016)J/MNRAS/468/703 : Abell 168 ultra-diffuse galaxies distribution (Roman+, 2017)http://www.sdss.org/ : SDSS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/883/10https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/883/10http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/883/10https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/883/10https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/883/10http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/883/10GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/883/10/table3 (3-D shape parameters for individual galaxies)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/883/10/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/883/10/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/883/10/table3?GETtext/xml+votable180.050000true9.42130.555610.0055555555555555566/0 4145 4251 4425 4441 5018 5044 5176 5180 5358 5359 5392 5501 5556 5600 5617 5618 5635 5647 5877 5916 5924 5942 5964 5983 6010 6011 6014 6087 6115 6406 7254 7272 7281 7445 7504 8272 8321 8379 8683 8705 8718 8747 8897 8935 9192 9382 9870 10028 10213 10215 10247 10301 10494 10565 10587 10639 10766 10768 10844 10896 10999 11005 11062 11143 11177 11254 11776 12404 17558 17752 17768 17769 17771 18066 18071 18085 18087 18392 18581 18765 18787 18789 19086 19096 19108 19417 23193 23196 23201 23204 23206 23213 23216 25593 25910 25952 25965 25981 26049 26251 26287 26297 26320 26377 26877 27090 27223 27342 27347 27387 27401 27482 27510 27654 27719 27745 27765 27775 27801 27809 27840 28129 28154 28178 28240 28312 28353 28358 28396 28435 28537 30044 31419 32415 36861https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/883/10?format=asciiOpticaldefaultJ/ApJ/883/10/table33-D shape parameters for individual galaxiesSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension in decimal degrees (J2000) (1)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000) (1)degpos.eq.dec;meta.mainC[0.14/0.4] Thickness normalized to the axis lengthsrc.morph.paramfloate_C[0.03/0.06] The 16th percentile uncertainty in Cstat.errorfloatE_C[0.02/0.09] The 84th percentile uncertainty in Cstat.error;stat.maxfloatB[0.66/0.72] Widthsrc.morph.paramfloate_B[0.04/0.1] The 16th percentile uncertainty in Bstat.errorfloatE_B[0.04/0.1] The 84th percentile uncertainty in Bstat.error;stat.maxfloatInc[33/86] Inclination of major axis with respect to the line-of-sightdegphys.angSizefloate_Inc[4/26] The 16th percentile uncertainty in Incdegstat.errorfloatE_Inc[2/27] The 84th percentile uncertainty in Incdegstat.error;stat.maxfloatSetSub-sample (2)meta.codecharID[1/195] Sanchez Almeida+ 2016, J/ApJ/819/110 identifiermeta.id;meta.mainintNEDNED column added by the CDSmeta.ref.urlchar