J/MNRAS/518/3999ivo://CDS.VizieR/J/MNRAS/518/3999CDSLiao L.-W.Cooper A.P.2026-03-05T12:02:38Z2026-03-05T12:49:33ZCDS support team

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

cds-question@unistra.frgalaxiesphotometryspectroscopyvisible-astronomyastrometryredshiftedeffective-temperaturestellar-massesstar-forming-regionsRadial colour gradients within galaxies arise from gradients of stellar age, metallicity, and dust reddening. Large samples of colour gradients from wide- area imaging surveys can complement smaller integral-field spectroscopy data sets and can be used to constrain galaxy formation models. Here, we measure colour gradients for low-redshift galaxies (z < 0.1) using photometry from the DESI Legacy Imaging Survey DR9. Our sample comprises ~93000 galaxies with spectroscopic redshifts and ~574000 galaxies with photometric redshifts. We focus on gradients across a radial range 0.5R_eff_ to R_eff_, which corresponds to the inner disc of typical late-type systems at low redshift. This region has been the focus of previous statistical studies of colour gradients and has recently been explored by spectroscopic surveys such as MaNGA. We find that the colour gradients of most galaxies in our sample are negative (redder towards the centre), consistent with the literature. We investigate empirical relationships between colour gradient, average g-r and r-z colour, Mr, M*, and sSFR. Trends of gradient strength with M_r_ (M*) show an inflection around Mr~-21(log_10_M*/M_{Sun}_ ~10.5). Below this mass, colour gradients become steeper with increasing M*, whereas colour gradients in more massive galaxies become shallower. We find that positive gradients (bluer stars at smaller radii) are typical for galaxies of M_*_~10^8^M_{Sun}_. We compare our results to age and metallicity gradients in two data sets derived from fits of different stellar population libraries to MaNGA spectra, but find no clear consensus explanation for the trends we observe. Both MaNGA data sets seem to imply a significant contribution from dust reddening, in particular, to explain the flatness of colour gradients along the red sequence.2023MNRAS.518.3999Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/518/3999CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/506/928 : Stellar mass-size relation for low M* galaxiesJ/MNRAS/491/3562 : CALIFA ETGs spatially resolved stellar pop. (Zibetti+, 2020)J/MNRAS/483/1862 : Metallicity gradient across the Hubble sequenceJ/MNRAS/476/1765 : MaNGA E and S galaxies properties (Li+, 2018)J/MNRAS/371/703 : MILES library of empirical spectra (Sanchez-Blazquez+, 2006)J/A+A/581/A103 : CALIFA survey across the Hubble sequence (Gonzalez+, 2015)J/A+A/313/377 : Near-IR photometry of 86 galaxies. IV. (de Jong 1996)J/ApJ/907/85 : The SAGA Survey. II. Satellite systems around galaxiesJ/ApJ/883/175 : First release of the MaNGA Stellar Library (MaStar)J/ApJ/766/109 : Color/age/metallicity gradients of E galaxies (Kim+, 2013)J/ApJ/527/573 : Line Strengths in Elliptical Galaxies (Kobayashi+, 1999)J/AJ/154/86 : MaNGA catalog, DR15 (Wake+, 2017)J/AJ/112/2471 : The Ursa Major cluster. I. (Tully+ 1996)J/ApJS/126/271 : Surface photometry of nearby field galaxies (Jansen+ 2000)II/294 : The SDSS Photometric Catalog, Release 7https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/518/3999https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/518/3999http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/518/3999https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/518/3999https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/518/3999http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/518/3999GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/518/3999/szdr9 (The colour gradient measurements for spectroscopic redshifts from LS DR9)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/518/3999/szdr9?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/518/3999/szdr9?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/518/3999/szdr9?GETtext/xml+votable180.050000true256.282555068926262.7009056106704250.005555555555555556Cone search capability for table J/MNRAS/518/3999/pzdr9 (The colour gradient measurements for photometric redshifts from LS DR9)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/518/3999/pzdr9?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/518/3999/pzdr9?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/518/3999/pzdr9?GETtext/xml+votable180.050000true35.91191635780212-0.58648088173207510.0055555555555555561/4-5 8-10 17 27 35 2/25 28-29 44-46 73-78 101-103 105-107 123 126 131 133-138 179-180 3/8 10-11 32 97 99 105 108-109 120-121 124-125 188 190 192-193 196-197 208 234-235 238-239 250 260-261 269-271 289-291 316 322 328 341 343 354-355 360 399 403 419 491 510-511 519 523 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49071https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/518/3999?format=asciiOpticaldefaultJ/MNRAS/518/3999/szdr9The colour gradient measurements for spectroscopic redshifts from LS DR9J/MNRAS/518/3999/pzdr9The colour gradient measurements for photometric redshifts from LS DR9