Investigating bursty star formation and interstellar medium conditions in low-mass galaxies

Low-mass galaxies or dwarf galaxies (galaxies with stellar massM∗<10⁹ᐧ⁵.5M⊙) are the most abundant systems in the universe, and are the progenitors of present-day Milky Way-mass galaxies. Compared to massive galaxies, low-mass galaxies exhibit higher specific star formation rates (sSFR), and have shallower gravitational potential wells; therefore the effects of feedback from star formation are stronger in these systems. The feedback ensuing from an intense star formation episode can rapidly heat and expel gas from these galaxies, causing a momentary quenching of star formation. Subsequent star formation episodes are then triggered through the accretion of new gas and recycling of the expelled gas. The timescale of these recurring episodes ranges from a few to tens of millions of years (Myr). Several studies have found observational evidence of this "bursty" star formation in low-mass galaxies. Bursty star formation provides a plausible solution to the cusp/core problem within the Lambda Cold Dark Matter (LCDM) model. Observations of neutral hydrogen in low-mass galaxies show a flat central density distribution, contradicting the pure dark matter simulations, which predict a central cusp. However, simulations in small galaxies show that flat density profiles can be naturally produced through central starbursts. Bursty star formation causes the matter in the central region to expand, resulting in flatter density profiles over multiple episodes of starbursts. Bursty star formation could also quantify the scatter in scaling relations, such as that in the star-forming main sequence and the stellar mass M∗--gas-phase metallicity relation (MZR). Bursty star formation has been observed in low-mass galaxies only in the local universe. Highredshift galaxies are expected to have bursty star formation, due to a higher baryonic accretion rate. Being sensitive to feedback mechanisms, distant low-mass galaxies are therefore crucial for understanding the processes governing galaxy formation and evolution. However, they have not been studied thoroughly due to the difficulty in observing them. In this study, we examine the star formation and the physical conditions in low-mass galaxies beyond the local universe.

Name thesis:degree_name

Ph. D

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Physics

Grantor dc:publisher

University of Missouri--Columbia

Year dc:date.issued

2025

Author dc:creator

• Teppala, Teja

Advisor dc:contributor.advisor

• Guo, Yicheng

Language dc:language.iso

eng, English

DOI

https://doi.org/10.32469/10355/110292

OAI identifier oai:identifier

oai:mospace.umsystem.edu:10355/110292