Kavli Affiliate: Risa H. Wechsler
| First 5 Authors: Yasmeen Asali, Yasmeen Asali, , ,
| Summary:
We investigate how Milky Way-like environments influence the sizes and
structural properties of low-mass galaxies by comparing satellites of Milky Way
analogs from the Satellites Around Galactic Analogs (SAGA) Survey with two
control samples: an environmentally agnostic population from the SAGA
background (SAGAbg) sample and isolated galaxies from the SDSS NASA-Sloan
Atlas. All sizes and structural parameters are measured uniformly using
pysersic to ensure consistency across samples. We find the half-light sizes of
SAGA satellites are systematically larger than those of isolated galaxies, with
the magnitude of the offset ranging from 0.05 to 0.12 dex (10-24%) depending on
the comparison sample and completeness cuts. This corresponds to physical size
differences between 85-200 pc at 10^7.5 solar masses and 220-960 pc at 10^10
solar masses. This offset persists among star-forming galaxies, suggesting that
environment can influence the structure of low-mass galaxies even before it
impacts quenching. The intrinsic scatter in the size-mass relation is lower for
SAGA satellites than isolated galaxies, and the S’ersic index distributions of
satellites and isolated galaxies are similar. In comparison to star-forming
satellites, quenched SAGA satellites have a slightly shallower size-mass
relation and rounder morphologies at low-mass, suggesting that quenching is
accompanied by structural transformation and that the processes responsible
differ between low- and high-mass satellites. Our results show that
environmental processes can imprint measurable structural differences on
satellites in Milky Way-mass halos.
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