J/A+A/657/A41ivo://CDS.VizieR/J/A+A/657/A41doi:10.26093/cds/vizier.36570041CDSRejkuba M.Harris W.E.Greggio L.Crnojevic D.Harris G.L.H.2022-10-12T08:45:37Z2022-01-06T08:51:46ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryccd-photometryvisible-astronomyhalo-starsThe extended stellar halos of galaxies contain important clues for investigating their assembly history and evolution. We investigate the resolved stellar content and the extended halo of NGC 5128 as a function of galactocentric distance, and trace the halo outward to its currently detectable limits. We used Hubble Space Telescope images obtained with the WFPC2, ACS, and WFC3 cameras equipped with F606W and F814W filters to resolve individual red giant branch (RGB) stars in 28 independent pointings across the halo of NGC 5128. The stellar halo analysis for 14 of these pointings is presented here for the first time. Star counts from deep VI color-magnitude diagrams reaching at least 1.5mag below the tip of the RGB are used to derive the surface density distribution of the halo. The contamination by Milky Way stars is assessed with a new control field, with models, and by combining optical and near-IR photometry. We present a new calibration of the WFC3 F606W + F814W photometry to the ground-based VI photometric system. The photometry shows that the stellar halo of NGC 5128 is dominated by old RGB stars that are present in all fields. The V-band surface brightness of fields changes from 23 to 32mag/arcsec^2^ between the innermost field only 8.3kpc from the galaxy center to our outermost halo fields, which are located 140 kpc away from the center along the major axis and 92 kpc along the minor axis. Within the inner ~30kpc, we also find evidence for a 2-3Gyr old population traced by asymptotic giant branch stars that are brighter than the tip of the RGB. This population contributes only up to 10% in total stellar mass if it is 2Gyr old, but a larger fraction of 30-40% is required if its age is 3Gyr. The stellar surface density profile is well fit by a classic r^1/4^ curve or a simple power-law form ~r^-3.1^ over the full radial range, with no obvious break in the slope, but with large field-to-field scatter. The ellipticity measured from integrated-light photometry in the inner parts, e=(b/a)=0.77, flattens to e=0.54+/-0.02 beyond 30kpc. Considering the flattening of the outer halo, the projection of the elliptical isophote on the semimajor axis for our most distant field reaches nearly 30 effective radii.2022A&A...657A..41Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/657/A41CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/369/812 : NGC 5128 globular clusters UVKs photometry (Rejkuba, 2001)J/A+A/406/75 : JHKs magnitudes of variables in NGC 5128 (Rejkuba+, 2003)J/A+A/447/71 : CHANDRA X-ray point sources in Cen A (NGC 5128) (Voss+, 2006)J/A+A/574/A109 : Spectroscopy of Planetary Nebulae in NGC 5128 (Walsh+, 2015)J/ApJ/600/716 : NGC 5128 Chandra X-ray point sources (Minniti+, 2004)J/AJ/134/494 : NGC 5128 globular clusters UBVRICMT1 phot. + RVJ/ApJ/805/65 : NGC 5128 globular clusters FLAMES observations (Taylor+, 2017)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/657/A41https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/657/A41http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/657/A41https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/657/A41https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/657/A41http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/657/A41GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/657/A41/fields (Field IDs, coordinates, E(B-V) and instrument)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/657/A41/fields?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/657/A41/fields?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/657/A41/fields?GETtext/xml+votable180.050000true201.2125-43.075830.0055555555555555565/10815 10901 6/43259 43434 43776https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/657/A41?format=asciiOpticaldefaultJ/A+A/657/A41/fieldsField IDs, coordinates, E(B-V) and instrumentrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFieldIDField pointing identifier (FNNA or WNN)meta.id;obs.fieldcharRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.mainE(B-V)Galactic reddening (1)magphot.color.excessfloatInstInstrumentmeta.id;instrcharJ/A+A/657/A41/catalogPhotometry for stellar sources in 30 fieldsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFieldIDField pointing identifier (FNNA or WNN)meta.id;obs.fieldcharVmagV-band magnitude without correction for galactic extinctionmagphot.mag;em.opt.Vfloate_VmagV-band magnitude measurement errormagstat.error;phot.magfloatImagI-band magnitude without correction for galactic extinctionmagphot.mag;em.opt.Ifloate_ImagI-band magnitude measurement errormagstat.error;phot.magfloat