Work

Testing the Stellar Feedback-driven Breathing Mode in Low-mass Galaxies with Gas Kinematics

Year: 2026

Type: article

Abstract: Hydrodynamic simulations have proposed that stellar feedback and bursty star formation can produce dark matter cores in low-mass galaxies. A key prediction is that feedback-driven gas outflow and inflow cycles can lead to “breathing modes” (rapid fluctuations in the global gravitational potential), which drive correlated variations in galaxy size, kinematics, and star formation rate (SFR). In this paper, we test the dynamical effects of feedback-driven breathing modes using a sample of 103 star-forming low-mass galaxies with stellar masses between 7.9 < log M * / M ⊙ < 9.6 and 0.02 < z < 0.19. We measure ionized gas velocity dispersions from H α emission lines and compare them to mock observations from the FIRE-2 simulations. We compare gas velocity dispersions ( σ gas ), stellar masses, and specific star formation rates (sSFRs). We find a positive correlation between gas velocity dispersion residuals at fixed stellar masses (Δ σ gas ) and sSFR in both data and simulations. However, the relation is tighter in FIRE-2 compared to the data. FIRE-2 produces more low-sSFR galaxies compared to our observational sample; however, the sSFR distributions agree after limiting both samples to a minimum sSFR. A deeper and more complete photometric sample further indicates that observed low-mass galaxies could span the full range of sSFR predicted in the FIRE-2 simulations. Our results support the existence of short-timescale dynamical effects driven by gas outflow and inflow cycles in low-mass galaxies and motivate additional tests of the breathing mode.

Source: The Astrophysical Journal

DOI: 10.3847/1538-4357/aea28f