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18 April 2024 |
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Roll of the Dice: A Stochastically Sampled IMF Alters the StellarContent of Simulated Dwarf Galaxies | | Elaad Applebaum
; Alyson M. Brooks
; Thomas R. Quinn
; Charlotte R. Christensen
; | | Date: |
31 Oct 2018 | | Abstract: | Cosmological simulations are reaching the resolution necessary to study
ultra-faint dwarf galaxies. Observations indicate that in small populations,
the stellar initial mass function (IMF) is not fully populated; rather, stars
are sampled in a way that can be approximated as coming from an underlying
probability density function. To ensure the accuracy of cosmological
simulations in the ultra-faint regime, we present an improved treatment of the
IMF. For the first time, we implement a self-consistent, stochastically
populated IMF in cosmological hydrodynamic simulations. We test our method
using high-resolution simulations of a Milky Way halo, run to $z=6$, yielding a
sample of nearly 100 galaxies. We also use an isolated dwarf galaxy to
investigate the resulting systematic differences in galaxy properties. We find
that a stochastic IMF in simulations makes feedback burstier, strengthening
feedback, and quenching star formation earlier in small dwarf galaxies. For
galaxies in halos with mass $lesssim10^{8.5}$ M$_odot$, a stochastic IMF
typically leads to lower stellar mass compared to a continuous IMF, sometimes
by more than an order of magnitude. We show that existing methods of ensuring
discrete supernovae incorrectly determine the mass of the star particle and its
associated feedback. This leads to overcooling of surrounding gas, with at
least ${sim}$10 per cent higher star formation and ${sim}$30 per cent higher
cold gas content. Going forward, to accurately model dwarf galaxies and compare
to observations, it will be necessary to incorporate a stochastically populated
IMF that samples the full spectrum of stellar masses. | | Source: | arXiv, 1811.0022 | | Services: | Forum | Review | PDF | Favorites | |
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