# Radio continuum emission from local analogs of high-z faint LAEs: Blueberry galaxies

## TL;DR

This study investigates the radio emission properties of blueberry galaxies, young starburst analogs of high-redshift faint LAEs, revealing suppressed radio-based SFRs, high magnetic fields, and insights into cosmic ray escape and magnetic field amplification.

## Contribution

It provides the first detailed radio continuum analysis of blueberry galaxies, highlighting their unique magnetic and cosmic ray properties compared to typical star-forming galaxies.

## Key findings

- Radio-based SFR is suppressed by a factor of ~3.4
- Median non-thermal fraction is ~0.49, lower than normal galaxies
- Inferred magnetic field strength is ~27 μG, higher than in evolved systems

## Abstract

We present a radio continuum study of a population of extremely young and starburst galaxies, termed as blueberries at ${\sim}$ 1 GHz using the upgraded Giant Metrewave Radio Telescope (uGMRT). We find that their radio-based star formation rate (SFR) is suppressed by a factor of ${\sim}$ 3.4 compared to the SFR based on optical emission lines. This might be due to (i) the young ages of these galaxies as a result of which a stable equilibrium via feedback from supernovae has not yet been established (ii) escape of cosmic ray electrons via diffusion or galactic scale outflows. The estimated non-thermal fraction in these galaxies has a median value of ${\sim}$0.49, which is relatively lower than that in normal star-forming galaxies at such low frequencies. Their inferred equipartition magnetic field has a median value of 27 ${\mu}$G, which is higher than those in more evolved systems like spiral galaxies. Such high magnetic fields suggest that small-scale dynamo rather than large-scale dynamo mechanisms might be playing a major role in amplifying magnetic fields in these galaxies.