Ultra-Diffuse Galaxies as Extreme Star-forming Environments II: Star Formation and Pressure Balance in HI-Rich UDGs
arXiv:2209.05500 · doi:10.3847/1538-4357/ac9673
Abstract
In addition to occupying the extreme, diffuse tail of the dwarf galaxy population, Ultra-Diffuse Galaxies (UDGs) are themselves a key laboratory in which to study star formation in extreme low-density environments. In the second paper of this series, we compare the spatially resolved star formation activity of 22 HI-selected UDGs and 21 "normal" dwarf galaxies within 120 Mpc to predictions within the pressure-regulated, feedback-modulated (PRFM) theory of star formation. To do so, we employ a joint SED fitting method that allows us to estimate star formation rate and stellar mass surface density from UV-optical imaging. We find that the PRFM framework extends successfully to the UDG regime - although the UDGs in our sample show unusually low star formation rate surface densities given their HI content, this low star formation efficiency can be naturally explained by the diffuse structure of the UDGs. In fact, when cast in the PRFM framework, the relationship between midplane pressure and star formation in the UDG sample is in good agreement not only with the "normal" dwarf reference sample, but also with measurements from more massive galaxies. Our results suggest that despite their low star formation efficiencies, the HI-rich UDGs need not be forming stars in an exotic manner. We also find that the UDGs are likely H-poor compared even to the overall dwarf population.
Accepted to ApJ, 22 pages, 11 figures
References in corpus (20)
- The NumPy array: a structure for efficient numerical computation
- The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
- UV Star Formation Rates in the Local Universe
- astroquery: An Astronomical Web-Querying Package in Python
- Forty-Seven Milky Way-Sized, Extremely Diffuse Galaxies in the Coma Cluster
- NIHAO XI: Formation of Ultra-Diffuse Galaxies by outflows
- Superbubbles in the Multiphase ISM and the Loading of Galactic Winds
- Still Missing Dark Matter: KCWI High-Resolution Stellar Kinematics of NGC1052-DF2
- Revisiting the Integrated Star Formation Law. Paper I: Non-Starbursting Galaxies
- Mutual influence of supernovae and molecular clouds
- Robust HI kinematics of gas-rich ultra-diffuse galaxies: hints of a weak-feedback formation scenario
- Pressure-Regulated, Feedback-Modulated Star Formation In Disk Galaxies
- Cosmic ray feedback from supernovae in dwarf galaxies
- Thermal Pressure in the Cold Neutral Medium of Nearby Galaxies
- EDGE-CALIFA survey: Self-regulation of Star formation at kpc scales
- Galaxy And Mass Assembly (GAMA): The inferred mass--metallicity relation from z=0 to 3.5 via forensic SED fitting
- The Intrinsic Shapes of Low Surface Brightness Galaxies: a Discriminant of LSBG Formation Mechanisms
- The Molecular Clouds Fueling a 1/5 Solar Metallicity Starburst
- IR SED and Dust Masses of Sub-solar Metallicity Galaxies at z~2.3
- The molecular gas resolved by ALMA in the low-metallicity dwarf merging galaxy Haro 11