# Subaru narrow-band imaging search for Lyman continuum from galaxies at z>3 in the GOODS-N field

## TL;DR

This study uses Subaru narrow-band imaging to search for Lyman continuum emission from galaxies at z>3 in the GOODS-N field, providing upper limits on LyC escape fractions and comparing results with another protocluster field.

## Contribution

First narrow-band imaging survey targeting LyC emission at z>3 in the GOODS-N field, establishing upper limits on escape fractions and comparing with SSA22 field results.

## Key findings

- Detected 2 star-forming galaxies and 1 AGN as LyC candidates.
- Estimated LyC escape fraction upper limit of 8%.
- Found potential higher LyC leakage frequency in SSA22 compared to GOODS-N.

## Abstract

We report results of a search for galaxies at z>3 with Lyman continuum (LyC) emission using a narrow-band filter NB359 with Subaru / Suprime-Cam in a ~800 arcmin$^2$ blank field around the GOODS-N. We use 103 star-forming galaxies (SFGs) and 8 AGNs with spectroscopic redshifts in a range between 3.06 and 3.5, and 157 photometrically selected z=3.1 Lyman $\alpha$ emitter (LAE) candidates as the targets. After removing galaxies spectroscopically confirmed to be contaminated by foreground sources, we found two SFGs and one AGN as candidate LyC emitting sources among the targets with spectroscopic redshifts. Among LAE candidates, five sources are detected in the NB359 image, and three among them may be contaminated by foreground sources. We compare the sample galaxies in the GOODS-N with those in the SSA22, where a prominent protocluster at z=3.1 is known and the LyC search using the same NB359 filter has been made. Frequency of galaxies with LyC leakage in the SSA22 field may be about two times higher than the galaxies in the GOODS-N with the sample UV magnitude range, although the numbers of LyC detections in these fields are too small to make a statistically significant conclusion. By combining the sample galaxies in these fields, we place the 3$\sigma$ upper limits of the observed LyC-to-UV flux density ratio and LyC escape fraction for galaxies at z=3.1 with absolute UV magnitude $M_{UV} < -18.8$ as ($f_{LyC}/f_{UV})_{obs} < 0.036$ and $f_{esc}^{abs}<8$\%, respectively.