Characterizing Radio Continuum Emission from Low-redshift Lyman Continuum Leakers

Arizona State University, Scottsdale AZ

Investigators

Abstract

The reionization of the Universe is a cosmological event driven by young galaxies that resulted in the ionization of 99.99% of the hydrogen in the intergalactic medium (IGM) by a redshift of ~6. Identifying the population of galaxies responsible for reionization has been very difficult, because ionizing flux from these galaxies is absorbed in the neutral IGM. The team will address this by studying galaxies at lower redshift that resemble those at z > 6 (Lyman Continuum Emitters, LCEs). The team will also create two 40-minute planetarium shows as part of the department’s outreach program. The shows will be hosted at the Marston Planetarium at Arizona State University. They will incorporate these shows into the K–12 field trip program that brings in 10,000 middle-school students from the Phoenix metropolitan region every year. The team obtained 221 hours of VLA observations to perform the first radio continuum (RC) study of a statistical sample of 80 confirmed LCEs with well-measured escape fractions. RC is a powerful dust-independent tracer generated by thermal (free-free) and non-thermal (synchrotron) processes. However, it depends on the number of free electrons and the magnetic field. Therefore, RC complements UV or optical traces and adds a new dimension for testing feedback models. The new RC data, when combined with ancillary data from other wavelengths, will yield constraints on theoretical models and physical conditions, e.g., age of the stellar population, radiation pressure-driven feedback, stellar winds, supernova feedback, etc., that results in the leakage of ionizing flux from these systems. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.