Evolution of the Sérsic Index up to z=2.5 from JWST and HST
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Martorano, Marco van der Wel, Arjen Baes, Maarten Bell, Eric F. Brammer, Gabriel Franx, Marijn Gebek, Andrea Meidt, Sharon E. Miller, Tim B. Nelson, Erica Nersesian, Angelos Price, Sedona H. van Dokkum, Pieter Whitaker, Katherine Wuyts, Stijn |
| author_facet | Martorano, Marco van der Wel, Arjen Baes, Maarten Bell, Eric F. Brammer, Gabriel Franx, Marijn Gebek, Andrea Meidt, Sharon E. Miller, Tim B. Nelson, Erica Nersesian, Angelos Price, Sedona H. van Dokkum, Pieter Whitaker, Katherine Wuyts, Stijn |
| contents | The James Webb Space Telescope (JWST) is unveiling the rest-frame near-IR structure of galaxies. We measure the evolution with redshift of the rest-frame optical and near-IR Sérsic index ($n$), and examine the dependence on stellar mass and star-formation activity across the redshift range $0.5\leq z\leq2.5$. We infer rest-frame near-IR Sérsic profiles for $\approx 15.000$ galaxies in publicly available NIRCam imaging mosaics from the COSMOS-Web and PRIMER surveys. We augment these with rest-frame optical Sérsic indices, previously measured from HST imaging mosaics. The median Sérsic index evolves slowly or not at all with redshift, except for very high-mass galaxies ($M_\star > 10^{11}~{\text{M}}_\odot$), which show an increase from $n\approx 2.5$ to $n\approx 4$ at $z<1$. High-mass galaxies have higher $n$ than lower-mass galaxies ($M_\star=10^{9.5}~{\text{M}}_\odot$) at all redshifts, with a stronger dependence in the rest-frame near-IR than in the rest-frame optical at $z>1$. This wavelength dependence is caused by star-forming galaxies that have lower optical than near-IR $n$ at z>1 (but not at z<1). Both at optical and near-IR wavelengths, star-forming galaxies have lower $n$ than quiescent galaxies, fortifying the connection between star-formation activity and radial stellar mass distribution. At $z>1$ the median near-IR $n$ varies strongly with star formation activity, but not with stellar mass. The scatter in near-IR $n$ is higher in the green valley (0.25 dex) than on the star-forming sequence and among quiescent galaxies (0.18 dex) -- this trend is not seen in the optical because dust and young stars contribute to the variety in optical light profiles. Our newly measured rest-frame near-IR radial light profiles motivate future comparisons with radial stellar mass profiles of simulated galaxies as a stringent constraint on processes that govern galaxy formation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2501_02956 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Evolution of the Sérsic Index up to z=2.5 from JWST and HST Martorano, Marco van der Wel, Arjen Baes, Maarten Bell, Eric F. Brammer, Gabriel Franx, Marijn Gebek, Andrea Meidt, Sharon E. Miller, Tim B. Nelson, Erica Nersesian, Angelos Price, Sedona H. van Dokkum, Pieter Whitaker, Katherine Wuyts, Stijn Astrophysics of Galaxies The James Webb Space Telescope (JWST) is unveiling the rest-frame near-IR structure of galaxies. We measure the evolution with redshift of the rest-frame optical and near-IR Sérsic index ($n$), and examine the dependence on stellar mass and star-formation activity across the redshift range $0.5\leq z\leq2.5$. We infer rest-frame near-IR Sérsic profiles for $\approx 15.000$ galaxies in publicly available NIRCam imaging mosaics from the COSMOS-Web and PRIMER surveys. We augment these with rest-frame optical Sérsic indices, previously measured from HST imaging mosaics. The median Sérsic index evolves slowly or not at all with redshift, except for very high-mass galaxies ($M_\star > 10^{11}~{\text{M}}_\odot$), which show an increase from $n\approx 2.5$ to $n\approx 4$ at $z<1$. High-mass galaxies have higher $n$ than lower-mass galaxies ($M_\star=10^{9.5}~{\text{M}}_\odot$) at all redshifts, with a stronger dependence in the rest-frame near-IR than in the rest-frame optical at $z>1$. This wavelength dependence is caused by star-forming galaxies that have lower optical than near-IR $n$ at z>1 (but not at z<1). Both at optical and near-IR wavelengths, star-forming galaxies have lower $n$ than quiescent galaxies, fortifying the connection between star-formation activity and radial stellar mass distribution. At $z>1$ the median near-IR $n$ varies strongly with star formation activity, but not with stellar mass. The scatter in near-IR $n$ is higher in the green valley (0.25 dex) than on the star-forming sequence and among quiescent galaxies (0.18 dex) -- this trend is not seen in the optical because dust and young stars contribute to the variety in optical light profiles. Our newly measured rest-frame near-IR radial light profiles motivate future comparisons with radial stellar mass profiles of simulated galaxies as a stringent constraint on processes that govern galaxy formation. |
| title | Evolution of the Sérsic Index up to z=2.5 from JWST and HST |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2501.02956 |