Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes
Recent studies have indicated that the ratio between half-mass and half-light radii, r _mass / r _light , varies significantly as a function of stellar mass and redshift, complicating the interpretation of the ubiquitous r _light − M _* relation. To investigate, in this study we construct the light...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acbc74 |
| _version_ | 1797701918226644992 |
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| author | Tim B. Miller Pieter van Dokkum Lamiya Mowla |
| author_facet | Tim B. Miller Pieter van Dokkum Lamiya Mowla |
| author_sort | Tim B. Miller |
| collection | DOAJ |
| description | Recent studies have indicated that the ratio between half-mass and half-light radii, r _mass / r _light , varies significantly as a function of stellar mass and redshift, complicating the interpretation of the ubiquitous r _light − M _* relation. To investigate, in this study we construct the light and color profiles of ∼3000 galaxies at 1 < z < 2 with $\mathrm{log}{M}_{* }/{M}_{\odot }\gt 10.25$ using imcascade , a Bayesian implementation of the Multi-Gaussian Expansion (MGE) technique. imcascade flexibly represents galaxy profiles using a series of Gaussians, free of any a priori parameterization. We find that both star-forming and quiescent galaxies have, on average, negative color gradients. For star-forming galaxies, we find steeper gradients that evolve with redshift and correlate with dust content. Using the color gradients as a proxy for gradients in the M / L ratio, we measure half-mass radii for our sample of galaxies. There is significant scatter in individual r _mass / r _light ratios, which is correlated with variation in the color gradients. We find that the median r _mass / r _light ratio evolves from 0.75 at z = 2 to 0.5 at z = 1, consistent with previous results. We characterize the r _mass − M _* relation, and we find that it has a shallower slope and shows less redshift evolution than the r _light − M _* relation. This applies both to star-forming and quiescent galaxies. We discuss some of the implications of using r _mass instead of r _light , including an investigation of the size−inclination bias and a comparison to numerical simulations. |
| first_indexed | 2024-03-12T04:42:34Z |
| format | Article |
| id | doaj.art-0afdf98fd36047d28765b989c0a95fd3 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:42:34Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-0afdf98fd36047d28765b989c0a95fd32023-09-03T09:30:42ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01945215510.3847/1538-4357/acbc74Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted SizesTim B. Miller0https://orcid.org/0000-0001-8367-6265Pieter van Dokkum1https://orcid.org/0000-0002-8282-9888Lamiya Mowla2https://orcid.org/0000-0002-8530-9765Department of Astronomy, Yale University , 52 Hillhouse Ave., New Haven, CT, 06511, USA ; tim.miller@yale.eduDepartment of Astronomy, Yale University , 52 Hillhouse Ave., New Haven, CT, 06511, USA ; tim.miller@yale.eduDunlap Institute for Astronomy and Astrophysics, University of Toronto , 50 St George Street, Toronto ON, M5S 3H4, CanadaRecent studies have indicated that the ratio between half-mass and half-light radii, r _mass / r _light , varies significantly as a function of stellar mass and redshift, complicating the interpretation of the ubiquitous r _light − M _* relation. To investigate, in this study we construct the light and color profiles of ∼3000 galaxies at 1 < z < 2 with $\mathrm{log}{M}_{* }/{M}_{\odot }\gt 10.25$ using imcascade , a Bayesian implementation of the Multi-Gaussian Expansion (MGE) technique. imcascade flexibly represents galaxy profiles using a series of Gaussians, free of any a priori parameterization. We find that both star-forming and quiescent galaxies have, on average, negative color gradients. For star-forming galaxies, we find steeper gradients that evolve with redshift and correlate with dust content. Using the color gradients as a proxy for gradients in the M / L ratio, we measure half-mass radii for our sample of galaxies. There is significant scatter in individual r _mass / r _light ratios, which is correlated with variation in the color gradients. We find that the median r _mass / r _light ratio evolves from 0.75 at z = 2 to 0.5 at z = 1, consistent with previous results. We characterize the r _mass − M _* relation, and we find that it has a shallower slope and shows less redshift evolution than the r _light − M _* relation. This applies both to star-forming and quiescent galaxies. We discuss some of the implications of using r _mass instead of r _light , including an investigation of the size−inclination bias and a comparison to numerical simulations.https://doi.org/10.3847/1538-4357/acbc74Galaxy structureGalaxy radiiHigh-redshift galaxies |
| spellingShingle | Tim B. Miller Pieter van Dokkum Lamiya Mowla Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes The Astrophysical Journal Galaxy structure Galaxy radii High-redshift galaxies |
| title | Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes |
| title_full | Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes |
| title_fullStr | Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes |
| title_full_unstemmed | Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes |
| title_short | Color Gradients and Half-mass Radii of Galaxies Out to z = 2 in the CANDELS/3D-HST Fields: Further Evidence for Important Differences in the Evolution of Mass-weighted and Light-weighted Sizes |
| title_sort | color gradients and half mass radii of galaxies out to z 2 in the candels 3d hst fields further evidence for important differences in the evolution of mass weighted and light weighted sizes |
| topic | Galaxy structure Galaxy radii High-redshift galaxies |
| url | https://doi.org/10.3847/1538-4357/acbc74 |
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