Kavli Affiliate: Lina Necib
| First 5 Authors: Francisco J. Mercado, Jorge Moreno, Robert Feldmann, Marckie Zeender, Jose A. Benavides Blanco
| Summary:
We utilize the cosmological volume simulation, FIREbox, to investigate how a
galaxy’s environment influences its size and dark matter content. Our study
focuses on approximately 1,200 galaxies (886 central and 332 satellite halos)
in the low-mass regime, with stellar masses between $10^6$ to $10^9$
$M_{odot}$. We analyze the size-mass relation ($r_{50} – M_{star}$), inner
dark matter mass-stellar mass ($M^{50}_{rm DM} – M_{star}$) relation, and the
halo mass-stellar mass ($M_{rm halo} – M_{star}$) relation. At fixed stellar
mass, we find the galaxies experiencing stronger tidal influences, indicated by
higher Perturbation Indices (PI $>$ 1) are generally larger and have lower
masses relative to their counterparts with lower Perturbation Indices (PI $<$
1). Applying a Random Forest regression model, we show that both the
environment (PI) and halo mass ($M_{rm halo}$) are significant predictors of a
galaxy’s relative size and dark matter content. Notably, because $M_{rm halo}$
is also strongly affected by the environment, our findings indicate that
environmental conditions not only influence galactic sizes and relative inner
dark matter content directly, but also indirectly through their impact on halo
mass. Our results highlight a critical interplay between environmental factors
and halo mass in shaping galaxy properties, affirming the environment as a
fundamental driver in galaxy formation and evolution.
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