Kavli Affiliate: Risa H. Wechsler
| First 5 Authors: Erin Kado-Fong, Erin Kado-Fong, , ,
| Summary:
Recent efforts have extended our view of the number and properties of
satellite galaxies beyond the Local Group firmly down to $rm M_starsim 10^6
M_odot$. A similarly complete view of the field dwarf population has lagged
behind. Using the background galaxies sample from the Satellites Around
Galactic Analogs (SAGA) Survey at $z<0.05$, we take inventory of the dwarf
population down to $rm M_star sim 5times10^6 M_odot$ using three metrics:
the stellar mass function (SMF) as function of environment, the stellar-to-halo
mass relation (SHMR) of dwarf galaxies inferred via abundance matching, and the
quenched fraction of highly isolated dwarfs. We find that the low-mass SMF
shape shows minimal environmental dependence, with the field dwarf SMF
described by a low-mass power-law index of $alpha_1=-1.44pm0.09$ down to $rm
M_star sim 5times10^6 M_odot$, and that the quenched fraction of isolated
dwarfs drops monotonically to $f_q sim 10^-3$ at $rm M_star sim rm
10^8.5 M_odot$. Though slightly steeper than estimates from HI kinematic
measures, our inferred SHMR agrees with literature measurements of satellite
systems, consistent with minimal environmental dependence of the SHMR in the
probed mass range. Finally, although most contemporary cosmological simulations
against which we compare accurately predict the sagalocal SHMR, we find that
big-box cosmological simulations largely over-predict isolated galaxy quenched
fractions via a turnaround in $f_q(rm M_star)$ at $rm 10^8lesssim
M_star/M_odotlesssim 10^9$, underscoring the complexities in disentangling
the drivers of galaxy formation and the need for systematic multidimensional
observations of the dwarf population across environments.
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