The edges of galaxies in the Fornax Cluster: Fifty percent smaller and denser compared to the field. (arXiv:2311.10144v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chamba_N/0/1/0/all/0/1">Nushkia Chamba</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hayes_M/0/1/0/all/0/1">Matthew Hayes</a>, The <a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_LSST_Dark_Energy_Science/0/1/0/all/0/1">LSST Dark Energy Science Collaboration</a>
Physically motivated measurements are crucial for understanding galaxy growth
and the role of the environment on their evolution. In particular, the growth
of galaxies as measured by their size or radial extent provides an empirical
approach for addressing this issue. However, the established definitions of
galaxy size used for nearly a century are ill-suited for these studies because
of a previously ignored bias. The conventionally-measured radii consistently
miss the diffuse, outer extensions of stellar emission which harbour key
signatures of galaxy growth, including star formation and gas accretion or
removal. This issue is addressed by examining low surface brightness
truncations or galaxy “edges” as a physically motivated tracer of size based on
star formation thresholds. Our total sample consists of $sim900$ galaxies with
stellar masses ranging from $10^5 M_{odot} < M_{star} < 10^{11} M_{odot}$.
This sample of nearby cluster, group satellite and nearly isolated field
galaxies was compiled using multi-band imaging from the Fornax Deep Survey,
deep IAC Stripe 82 and Dark Energy Camera Legacy Surveys. Across the full mass
range studied, we find that compared to the field, the edges of galaxies in the
Fornax Cluster are located at 50% smaller radii and the average stellar surface
density at the edges are two times higher. These results are consistent with
the rapid removal of loosely bound neutral hydrogen (HI) in hot, crowded
environments which truncates galaxies outside-in earlier, preventing the
formation of more extended sizes and lower density edges. In fact, we find that
galaxies with lower HI fractions have edges with higher stellar surface
density. Our results highlight the importance of deep imaging surveys to study
the low surface brightness imprints of the large scale structure and
environment on galaxy evolution.
Physically motivated measurements are crucial for understanding galaxy growth
and the role of the environment on their evolution. In particular, the growth
of galaxies as measured by their size or radial extent provides an empirical
approach for addressing this issue. However, the established definitions of
galaxy size used for nearly a century are ill-suited for these studies because
of a previously ignored bias. The conventionally-measured radii consistently
miss the diffuse, outer extensions of stellar emission which harbour key
signatures of galaxy growth, including star formation and gas accretion or
removal. This issue is addressed by examining low surface brightness
truncations or galaxy “edges” as a physically motivated tracer of size based on
star formation thresholds. Our total sample consists of $sim900$ galaxies with
stellar masses ranging from $10^5 M_{odot} < M_{star} < 10^{11} M_{odot}$.
This sample of nearby cluster, group satellite and nearly isolated field
galaxies was compiled using multi-band imaging from the Fornax Deep Survey,
deep IAC Stripe 82 and Dark Energy Camera Legacy Surveys. Across the full mass
range studied, we find that compared to the field, the edges of galaxies in the
Fornax Cluster are located at 50% smaller radii and the average stellar surface
density at the edges are two times higher. These results are consistent with
the rapid removal of loosely bound neutral hydrogen (HI) in hot, crowded
environments which truncates galaxies outside-in earlier, preventing the
formation of more extended sizes and lower density edges. In fact, we find that
galaxies with lower HI fractions have edges with higher stellar surface
density. Our results highlight the importance of deep imaging surveys to study
the low surface brightness imprints of the large scale structure and
environment on galaxy evolution.
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