# On the stellar masses of giant clumps in distant star-forming galaxies

## TL;DR

This study examines how observational limitations like resolution and sensitivity affect the inferred stellar masses of giant clumps in distant star-forming galaxies, highlighting biases and uncertainties in current measurements.

## Contribution

It demonstrates that resolution and sensitivity significantly bias clump mass estimates, complicating the determination of a characteristic clump mass scale from observations.

## Key findings

- Clump masses vary widely depending on selection method.
- Limited resolution inflates mass estimates due to clump clustering.
- Sensitivity thresholds bias the low-mass end of the distribution.

## Abstract

We analyse 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 ~10^9 Msun for clumps in the often-referenced field galaxies to ~10^7 Msun 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.