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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. 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 haloes with mass ≲ 108.5 M⊙, 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 ∼10 per cent higher star formation and ∼30 per cent higher cold gas content. Going forwards, 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.
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Weighing in Dwarf Galaxies
Telescopes such as the Rubin Observatory and Euclid Space telescopes find more and more low mass galaxies as time passes by. However, the link between small dwarf galaxy light and star mass is currently unclear. We recently found out that there are clear differences between stellar mass depending on star formation history (SFH), according to an article published by Mithi A. C. de los Reyes. This is shown in artificial data and we can show this using real observed data. Therefore, using the Galaxy And Mass Assembly (GAMA) survey, we will compare mass estimates for small dwarf galaxies with the utilization of four different methods. We seek to find out if these methods agree. Or do they not agree? What happens when a galaxy is so small it only has a few million suns of stars inside? Are there stars missing? Using jupyter notebooks and python, we can compare the GAMA data and make plots and comparisons to answer these questions.
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- Award ID(s):
- 2319428
- PAR ID:
- 10645130
- Publisher / Repository:
- volume 245 of American Astronomical Society Meeting Abstracts, 359.10, January 2025
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
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