J/A+A/629/A18ivo://CDS.VizieR/J/A+A/629/A18doi:10.26093/cds/vizier.36290018CDSMueller O.Rejkuba M.Pawlowski M.S.Ibata R.Lelli F.Hilker M.,Jerjen H.2019-11-27T12:27:22Z2019-08-26T08:25:14ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryDwarf galaxy satellite systems are essential probes to test models of structure formation, making it necessary to establish a census of dwarf galaxies outside of our own Local Group. We present deep FORS2 VI band images from the ESO Very Large Telescope (VLT) for 15 dwarf galaxy candidates in the Centaurus group of galaxies. We confirm nine dwarfs to be members of Cen A by measuring their distances using a Bayesian approach to determine the tip of the red giant branch luminosity. We have also fit theoretical isochrones to measure their mean metallicities. The properties of the new dwarfs are similar to those in the Local Group in terms of their sizes, luminosities, and mean metallicities. Within our photometric precision, there is no evidence of a metallicity spread, but we do observe possible extended star formation in several galaxies, as evidenced by a population of asymptotic giant branch stars brighter than the red giant branch tip. The new dwarfs do not show any signs of tidal disruption. Together with the recently reported dwarf galaxies by the complementary PISCeS survey, we study the luminosity function and 3D structure of the group. By comparing the observed luminosity function to the high-resolution cosmological simulation IllustrisTNG, we find agreement within a 90% confidence interval.However, Cen A seems to be missing its brightest satellites and has an overabundance of the faintest dwarfs in comparison to its simulated analogs. In terms of the overall 3D distribution of the observed satellites, we find that the whole structure is flattened along the line-of-sight, with a root-mean-square (rms) height of 130kpc and an rms semi-major axis length of 330kpc. Future distance measurements of the remaining dwarf galaxy candidates are needed to complete the census of dwarf galaxies in the Centaurus group.2019A&A...629A..18Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/629/A18CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/629/A18https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/629/A18http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/629/A18https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/629/A18https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/629/A18http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/629/A18GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/629/A18/catalog (Photometric catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/629/A18/catalog?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/629/A18/catalog?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/629/A18/catalog?GETtext/xml+votable180.050000true200.6900154-33.605459860.005555555555555556Cone search capability for table J/A+A/629/A18/list (List of fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/629/A18/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/629/A18/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/629/A18/list?GETtext/xml+votable180.050000true200.73321-33.571530.005555555555555556Cone search capability for table J/A+A/629/A18/table1 (Observation summary for 15 dwarf galaxy candidates)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/629/A18/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/629/A18/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/629/A18/table1?GETtext/xml+votable180.050000true198.98333-45.750560.0055555555555555566/43252 43254 43256-43257 43259 43403 43424-43425 43607 43613 43789 43796 43832 43921https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/629/A18?format=asciidefaultJ/A+A/629/A18/catalogPhotometric catalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameDwarf galaxy candidate namemeta.id;meta.maincharChipChip number (chipN)meta.id;instrcharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainindexedDEJ2000Declination (J2000)degpos.eq.dec;meta.mainindexedVmag? V magnitude (Vega)magphot.mag;em.opt.Vfloatnullablee_Vmag? rms uncertainty on V magnitudemagstat.error;phot.mag;em.opt.VfloatnullableImag? I magnitude (Vega)magphot.mag;em.opt.Ifloatnullablee_Imag? rms uncertainty on I magnitudemagstat.error;phot.mag;em.opt.IfloatnullablechiCHI estimation from DAOPHOTstat.fit.chi2floatSharpSharp estimation from DAOPHOTstat.fit.paramdoubleJ/A+A/629/A18/listList of fits imagesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainscaleScale of the imagearcsec/pixinstr.scalefloatNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitscharJ/A+A/629/A18/table1Observation summary for 15 dwarf galaxy candidatesSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameDwarf galaxy candidate namemeta.id;meta.maincharRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000declination (J2000)pos.eq.dec;meta.mainObs.dateObservation date (DD/DD MMM YYYY)time.epoch;obscharInstInstrumentmeta.id;instrcharExpTimeExposure timestime.duration;obs.exposurecharFilt[VI] Filter used for the observationinstr.setup;instr.filtercharAirmass? Mean airmass during the observationobs.airMassfloatnullablel_ImgQualLimit flag on ImgQualmeta.code.errorcharImgQual? Average image qualityarcsecinstr.fov;instr.pixelcharNote[*] *: KK198 V-band exposure on 19 and 20 Apr was aborted - here we report it for completeness, but the data was not usedmeta.notecharPhotomDisplay the VI photmetry for this galaxymeta.ref.urlcharImageDisplay the images list for this galaxymeta.ref.urlchar