SCALES. I. Bridging Lensed Clump - Giant Clump Scales in Lensed Galaxies at z=1−4
Abstract
Dense star-forming regions in z>1 galaxies, often termed 'clumps', have been studied across two distinct regimes of telescope resolution, each motivating interpretations in tension with the other. In the SCALES series (Star-Forming Clumps As Layered Emergent Structures), we aim to connect star-forming structures across scales, from the ∼100 pc clumps in lensed studies to the ∼kpc-scale ''giant'' clumps in unlensed surveys. In this first paper, we present a difference-of-Gaussian (DoG) decomposition that simultaneously models ≈ 50−400 pc (lensed) clumps and ∼kpc-scale component (the extended component, or EC), which would together constitute the giant clumps seen at lower resolution. Here the EC is treated as a scale-separated local background rather than a physical object, absorbing all light that is not a compact clump. Applying this to 23 moderately lensed (μ≈ 2−9) galaxies at zspec = 1−4 to evaluate clump properties (deferring ECs and giant clumps to SCALES-II), we measure a clump stellar mass function slope of 1.88 ± 0.04, consistent with the ≈2 expected for hierarchical star formation, and with that of ∼kpc-scale clumps in unlensed galaxies. We also show that empirical correlations of clump surface densities and clump-to-host mass ratio with redshift are exaggerated by redshift-dependent detection bias, so ≈ 50−400 pc clumps are largely co-similar across our range (z = 1−4). Finally, combining clump mass, size and age estimates with literature gas-dispersion measurements at similar scales, we argue that ∼100 pc clumps are themselves composed of star-cluster-like sub-components at much smaller scales.
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BibTeX
@misc{kalita2026scales,
title = {{SCALES. I. Bridging Lensed Clump - Giant Clump Scales in Lensed Galaxies at $z=1-4$}},
author = {Boris S. Kalita and Adélaïde Claeyssens and Luis C. Ho and Miroslava Dessauges-Zavadsky and Natascha M. Förster Schreiber and Emanuele Daddi and John D. Silverman and Naval Kishor Bhadari and Changhao Chen and Fangzhou Jiang and Ke Wang and Jinning Liang and Alvaro Segovia Otero and Jinyi Shangguan},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03866},
eprint = {2610.03866},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03866},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - SCALES. I. Bridging Lensed Clump - Giant Clump Scales in Lensed Galaxies at z=1−4
AU - Boris S. Kalita
AU - Adélaïde Claeyssens
AU - Luis C. Ho
AU - Miroslava Dessauges-Zavadsky
AU - Natascha M. Förster Schreiber
AU - Emanuele Daddi
AU - John D. Silverman
AU - Naval Kishor Bhadari
AU - Changhao Chen
AU - Fangzhou Jiang
AU - Ke Wang
AU - Jinning Liang
AU - Alvaro Segovia Otero
AU - Jinyi Shangguan
PY - 2026
DA - 2026/10/29
PB - arXiv
DO - 10.48550/arxiv.2610.03866
UR - https://arxiv.org/abs/2610.03866
AB - Dense star-forming regions in z>1 galaxies, often termed 'clumps', have been studied across two distinct regimes of telescope resolution, each motivating interpretations in tension with the other. In the SCALES series (Star-Forming Clumps As Layered Emergent Structures), we aim to connect star-forming structures across scales, from the ∼100 pc clumps in lensed studies to the ∼kpc-scale ''giant'' clumps in unlensed surveys. In this first paper, we present a difference-of-Gaussian (DoG) decomposition that simultaneously models ≈ 50−400 pc (lensed) clumps and ∼kpc-scale component (the extended component, or EC), which would together constitute the giant clumps seen at lower resolution. Here the EC is treated as a scale-separated local background rather than a physical object, absorbing all light that is not a compact clump. Applying this to 23 moderately lensed (μ≈ 2−9) galaxies at z_spec = 1−4 to evaluate clump properties (deferring ECs and giant clumps to SCALES-II), we measure a clump stellar mass function slope of 1.88 ± 0.04, consistent with the ≈2 expected for hierarchical star formation, and with that of ∼kpc-scale clumps in unlensed galaxies. We also show that empirical correlations of clump surface densities and clump-to-host mass ratio with redshift are exaggerated by redshift-dependent detection bias, so ≈ 50−400 pc clumps are largely co-similar across our range (z = 1−4). Finally, combining clump mass, size and age estimates with literature gas-dispersion measurements at similar scales, we argue that ∼100 pc clumps are themselves composed of star-cluster-like sub-components at much smaller scales.
ER -