A Systematic Assessment of Total Stellar Mass Measurements with Spatially Resolved Photometry and Medium Bands at 1 < z < 9: The Impact of Mass-to-Light Variations and Outshining
Abstract
JWST NIRCam spatially resolved photometry enables studies of galaxies' stellar populations and stellar masses on sub-kpc scales. We use JWST (CANUCS, Technicolor, JUMPS) and HST data, covering wide- and medium-band UV-IR filters to study the stellar mass bias between spatially resolved and integrated photometry of ∼3000 galaxies at 1 <zphot< 9. The 2D parameter maps reveal spatial variations in stellar mass and populations, showing that integrated measurements systematically underestimate stellar masses. We find that the stellar mass bias remains small for galaxies with specific star formation rate sSFR < 10−9 yr−1, but increases for galaxies with sSFR > 10−8.5 yr−1. For these high-sSFR galaxies, the median offset reaches Δlog10 (M∗) ∼ -0.36 dex with the largest bias occurring in low-mass (M∗ ≤ 10 9.5 M⊙) galaxies. These results are consistent with the outshining of older populations by recent star formation. High-sSFR galaxies also show spatial variations in their mass-to-light ratios (M∗/LV): the stellar mass bias decreases with σ[log10(M∗/LV)] for galaxies with 10−8 ≤ sSFR[yr−1] < 10−9, with the strongest trend for 10−7 ≤ sSFR[yr−1] < 10−8, quantified by the Spearman correlation coefficient ρS=−0.37. While medium bands are important for constraining stellar masses from integrated photometry, spatially resolved photometry reduces the impact of their absence, with dispersion offsets of Δlog10 (M∗) = 0.33 dex for integrated photometry but 0.15 dex for resolved photometry when only wide-bands are included.
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BibTeX
@misc{jagga2026systematic,
title = {{A Systematic Assessment of Total Stellar Mass Measurements with Spatially Resolved Photometry and Medium Bands at 1 < z < 9: The Impact of Mass-to-Light Variations and Outshining}},
author = {Naadiyah Jagga and Adam Muzzin and Visal Sok and Vivian Yun Yan Tan and Ghassan Sarrouh and Kartheik Iyer and Yoshihisa Asada and Chris J. Willott and Maruša Bradač and Nicholas S. Martis and Gaël Noirot and Gregor Rihtaršič and Marcin Sawicki and Sunna Withers and Jacqueline Antwi-Danso and Samantha C Berek and Danilo Marchesini and Maya Merchant and Katherine Myers},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.35996},
eprint = {2609.35996},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.35996},
}
RIS
TY - UNPB
TI - A Systematic Assessment of Total Stellar Mass Measurements with Spatially Resolved Photometry and Medium Bands at 1 < z < 9: The Impact of Mass-to-Light Variations and Outshining
AU - Naadiyah Jagga
AU - Adam Muzzin
AU - Visal Sok
AU - Vivian Yun Yan Tan
AU - Ghassan Sarrouh
AU - Kartheik Iyer
AU - Yoshihisa Asada
AU - Chris J. Willott
AU - Maruša Bradač
AU - Nicholas S. Martis
AU - Gaël Noirot
AU - Gregor Rihtaršič
AU - Marcin Sawicki
AU - Sunna Withers
AU - Jacqueline Antwi-Danso
AU - Samantha C Berek
AU - Danilo Marchesini
AU - Maya Merchant
AU - Katherine Myers
PY - 2026
DA - 2026/10/05
PB - arXiv
DO - 10.48550/arxiv.2609.35996
UR - https://arxiv.org/abs/2609.35996
AB - JWST NIRCam spatially resolved photometry enables studies of galaxies' stellar populations and stellar masses on sub-kpc scales. We use JWST (CANUCS, Technicolor, JUMPS) and HST data, covering wide- and medium-band UV-IR filters to study the stellar mass bias between spatially resolved and integrated photometry of ∼3000 galaxies at 1 <z_phot< 9. The 2D parameter maps reveal spatial variations in stellar mass and populations, showing that integrated measurements systematically underestimate stellar masses. We find that the stellar mass bias remains small for galaxies with specific star formation rate sSFR < 10^−9 yr^−1, but increases for galaxies with sSFR > 10^−8.5 yr^−1. For these high-sSFR galaxies, the median offset reaches Δlog_10 (M_∗) ∼ -0.36 dex with the largest bias occurring in low-mass (M_∗ ≤ 10^ 9.5 M_⊙) galaxies. These results are consistent with the outshining of older populations by recent star formation. High-sSFR galaxies also show spatial variations in their mass-to-light ratios (M_∗/L_V): the stellar mass bias decreases with σ[log_10(M_∗/L_V)] for galaxies with 10^−8 ≤ sSFR[yr^−1] < 10^−9, with the strongest trend for 10^−7 ≤ sSFR[yr^−1] < 10^−8, quantified by the Spearman correlation coefficient ρ_S=−0.37. While medium bands are important for constraining stellar masses from integrated photometry, spatially resolved photometry reduces the impact of their absence, with dispersion offsets of Δlog_10 (M_∗) = 0.33 dex for integrated photometry but 0.15 dex for resolved photometry when only wide-bands are included.
ER -