Discovery of Local Analogs to JWST's Little Red Dots

TL;DR

This study identifies local low-redshift galaxies with properties similar to high-redshift JWST-detected 'Little Red Dots', providing insights into galaxy and black hole evolution.

Contribution

The paper discovers local analogs to high-redshift LRDs among Green pea galaxies hosting broad-line AGNs, revealing their similarities in spectral energy distributions and black hole properties.

Findings

7 GPs with V-shaped SEDs are likely local LRD analogs.

Most BLGPs host over-massive black holes exceeding local relations.

V-shaped BLGPs share ionization and metallicity properties with LRDs.

Abstract

Recently, the James Webb Space Telescope (JWST) has revealed a new class of high redshift (high-$z$, $z>4$) compact galaxies which are red in the rest-frame optical and blue in the rest-frame UV as V-shaped spectral energy distributions (SEDs), referred to as "Little Red Dots" (LRDs). It is very likely that LRDs host obscured broad-line active galactic nuclei (AGNs). In the meanwhile, Green pea galaxies (GPs), which are compact dwarf galaxies at low redshift, share various similar properties with high redshift star-forming galaxies. Here we aim to find the connection between the LRDs and GPs hosting broad-line AGNs (BLGPs). With a sample of 19 BLGPs obtained from our previous work, we further identify 7 GPs with V-shaped rest-frame UV-to-optical SEDs that are likely local analogs to LRDs. These V-shaped BLGPs exhibit faint UV absolute magnitudes and sub-Eddington rates similar to those of LRDs. Three of them occupy a similar region as LRDs in the BPT diagram, suggesting they have similar ionization conditions and gas-phase metallicities to LRDs. These similarities suggest that V-shaped BLGPs can be taken as local analogs of high-redshift LRDs. In addition, most (16/19) BLGPs, including 6 V-shaped BLGPs, host over-massive black holes above the local $M_{\rm BH}$-$M_{*}$ relation, making it the first sample of galaxies hosting over-massive black holes at $z<0.4$. These findings will help us learn more about the formation and co-evolution of early galaxies and black holes.