Discovery of low-redshift analogues to "Little Red Dots" in DESI: A later evolutionary stage of compact LRDs?

TL;DR

This study identifies low-redshift candidates similar to high-redshift 'Little Red Dots' using DESI data, revealing differences that suggest they may be later evolutionary stages or physically distinct systems.

Contribution

The paper presents five low-redshift analogues to high-redshift LRDs from DESI data, offering insights into their properties and evolutionary status.

Findings

Low-redshift candidates resemble high-redshift LRDs in SEDs and emission lines.

Significant differences in BPT diagram positions and stellar masses suggest different physical conditions.

Candidates may represent later evolutionary stages or systems with related properties.

Abstract

The James Webb Space Telescope (JWST) has recently discovered a population of compact, red sources at z > 4 known as "Little Red Dots" (LRDs). They are characterized by their V-shaped continuum spectra and prominent broad Balmer emission lines. As their underlying physical nature remains debated and direct study at high-redshift is challenging; therefore, we seek to identify and characterize LRD analogues in the low-redshift universe to constrain their properties and potential evolutionary pathways. We identified five candidates at z = 0.2-0.4 from the Dark Energy Spectroscopic Instrument (DESI) that exhibit spectral energy distributions (SEDs) and broad Balmer emission lines closely resembling their high-redshift counterparts. However, we find significant differences: our low-redshift sample occupies a different region on the Baldwin, Phillips \& Terlevich (BPT) diagram, and their stellar masses are significantly higher, suggesting a more substantial host galaxy contribution. These sources are not necessarily direct local analogues of high-redshift LRDs, but may represent later evolutionary stages of compact, rapidly accreting systems, or systems with related observational properties arising under different physical conditions. This sample provides a valuable laboratory for detailed follow-up studies to elucidate the nature of LRD-like phenomena.