Red Spiral Galaxies in the Cosmic Noon Unveiled in the First JWST Image

TL;DR

The JWST image reveals a significant number of red spiral galaxies at cosmic noon, providing new insights into their morphology, star formation activity, and potential contamination in high-redshift galaxy surveys.

Contribution

This study is the first to unveil the detailed spiral morphology of red galaxies at $z extasciitilde2.5$ using JWST, suggesting they are a passive, dust-reddened population.

Findings

Red spiral galaxies are more common at $z extasciitilde2.5$ than in the local universe.

These galaxies likely have low star formation rates and moderate dust reddening.

Their spectral energy distribution can mimic $z>10$ galaxies, affecting high-redshift galaxy identification.

Abstract

In the first image of the James Webb Space Telescope (JWST) of SMACS J0723.3-7327, one of the most outstanding features is the emergence of a large number of red spiral galaxies, because such red spiral galaxies are only a few percent in the number fraction among nearby spiral galaxies. While these apparently red galaxies were already detected with the Spitzer Space Telescope at $\sim3-4{\rm \mu m}$, the revolutionized view from JWST's unprecedented spatial resolution has unveiled their hidden spiral morphology for the first time. Within the red spiral galaxies, we focus on the three most highly red galaxies that are very faint in the $<0.9\,{\rm \mu m}$ bands and show red colors in the $2-4\,{\rm \mu m}$ bands. Our study finds that the three extremely red spiral galaxies are likely to be in the Cosmic Noon (i.e., $1 < z < 3$) and could be consistent with passive (i.e., $\sim$ zero star-formation rates) galaxies having moderate dust reddening (i.e., $A_{\rm V}\sim1\,{\rm mag}$). These "red spiral" galaxies would be interesting, potentially new population of galaxies, as we start to see their detailed morphology using JWST, for the first time. Finally, we note that the spectral energy distribution of these red $z\sim2.5$ galaxies could mimic $z>10$ Lyman break galaxies and contaminate to $z>10$ galaxy samples, especially when they were faint and small.