2019/11/21 by K. L. Larson, T. Díaz-Santos, L. Armus +15 · 1 citation
Physics and Astronomy · #astro-ph.GA
paper · pdf · doi:10.3847/1538-4357/ab5dc3
arxiv created 2019/11/21 · arxiv updated 2020/01/29
We present HST narrow-band near-infrared imaging of Paα and Paβ emission of 48 local Luminous Infrared Galaxies (LIRGs) from the Great Observatories All-Sky LIRG Survey (GOALS). These data allow us to measure the properties of 810 spatially resolved star-forming regions (59 nuclei and 751 extra-nuclear clumps), and directly compare their properties to those found in both local and high-redshift star-forming galaxies. We find that in LIRGs, the star-forming clumps have radii ranging from ∼90-900 pc and star formation rates (SFRs) of ∼1×10-3 to 10 M_\odotyr-1, with median values for extra-nuclear clumps of 170 pc and 0.03 M_\odotyr-1. The detected star-forming clumps are young, with a median stellar age of 8.7 Myrs, and a median stellar mass of 5×105 M_\odot. The SFRs span the range of those found in normal local star-forming galaxies to those found in high-redshift star-forming galaxies at \rmz=1-3. The luminosity function of the LIRG clumps has a flatter slope than found in lower-luminosity, star-forming galaxies, indicating a relative excess of luminous star-forming clumps. In order to predict the possible range of star-forming histories and gas fractions, we compare the star-forming clumps to those measured in the MassiveFIRE high-resolution cosmological simulation. The star-forming clumps in MassiveFIRE cover the same range of SFRs and sizes found in the local LIRGs and have total gas fractions that extend from 10 to 90%. If local LIRGs are similar to these simulated galaxies, we expect future observations with ALMA will find a large range of gas fractions, and corresponding star formation efficiencies, among the star-forming clumps in LIRGs.