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On the Stellar Masses of Giant Clumps in Distant Star-forming Galaxies


Dessauges-Zavadsky, Miroslava; Schaerer, Daniel; Cava, Antonio; Mayer, Lucio; Tamburello, Valentina (2017). On the Stellar Masses of Giant Clumps in Distant Star-forming Galaxies. Astrophysical Journal Letters, 836(2):L22.

Abstract

We analyze stellar masses of clumps drawn from a compilation of star-forming galaxies at 1.1 < z < 3.6. Comparing clumps selected in different ways, and in lensed or blank field galaxies, we examine the effects of spatial resolution and sensitivity on the inferred stellar masses. Large differences are found, with median stellar masses ranging from $\sim {10}^{9}\,{M}_{\odot }$ for clumps in the often-referenced field galaxies to $\sim {10}^{7}\,{M}_{\odot }$ for fainter clumps selected in deep-field or lensed galaxies. We argue that the clump masses, observed in non-lensed galaxies with a limited spatial resolution of ~1 kpc, are artificially increased due to the clustering of clumps of smaller mass. Furthermore, we show that the sensitivity threshold used for the clump selection affects the inferred masses even more strongly than resolution, biasing clumps at the low-mass end. Both improved spatial resolution and sensitivity appear to shift the clump stellar mass distribution to lower masses, qualitatively in agreement with clump masses found in recent high-resolution simulations of disk fragmentation. We discuss the nature of the most massive clumps, and we conclude that it is currently not possible to properly establish a meaningful clump stellar mass distribution from observations and to infer the existence and value of a characteristic clump mass scale.

Abstract

We analyze stellar masses of clumps drawn from a compilation of star-forming galaxies at 1.1 < z < 3.6. Comparing clumps selected in different ways, and in lensed or blank field galaxies, we examine the effects of spatial resolution and sensitivity on the inferred stellar masses. Large differences are found, with median stellar masses ranging from $\sim {10}^{9}\,{M}_{\odot }$ for clumps in the often-referenced field galaxies to $\sim {10}^{7}\,{M}_{\odot }$ for fainter clumps selected in deep-field or lensed galaxies. We argue that the clump masses, observed in non-lensed galaxies with a limited spatial resolution of ~1 kpc, are artificially increased due to the clustering of clumps of smaller mass. Furthermore, we show that the sensitivity threshold used for the clump selection affects the inferred masses even more strongly than resolution, biasing clumps at the low-mass end. Both improved spatial resolution and sensitivity appear to shift the clump stellar mass distribution to lower masses, qualitatively in agreement with clump masses found in recent high-resolution simulations of disk fragmentation. We discuss the nature of the most massive clumps, and we conclude that it is currently not possible to properly establish a meaningful clump stellar mass distribution from observations and to infer the existence and value of a characteristic clump mass scale.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:2017
Deposited On:23 Feb 2018 07:16
Last Modified:03 Jul 2018 13:01
Publisher:IOP Publishing
ISSN:2041-8205
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.3847/2041-8213/aa5d52

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