Local Analogs of Little Red Dots: Clues to the X-ray Weakness
Abstract
A major question about JWST's little red dots (LRDs) at z∼4−8 is the origin of their apparent X-ray weakness. Even deep Chandra stacks yield only tentative detections or broad-band limits and cannot distinguish among super-Eddington accretion, intrinsic X-ray weakness, and Compton-thick (CT) obscuration. Local analogs offer a powerful complementary route. At z∼0.3, similarly luminous sources require ∼103−4 less exposure for comparable signal-to-noise, suffer less source confusion, and directly probe the diagnostic rest-frame soft X-rays. Here we present a pilot Einstein Probe/FXT study of six "local little red dots" (LLRDs), V-shaped broad-line green pea galaxies selected as low-redshift counterparts of LRDs. These sources show X-ray diversity: "X-normal" LLRDs resemble type 1 AGNs in X-ray luminosity and optical variability, whereas the "X-weak" stack lies ∼0.5−0.7 dex below standard unobscured-quasar scaling relations while remaining compatible with the representative LRD stack and 95% of published individual limits. The X-weak LLRDs also lack detected optical variability and have redder optical continua than X-normal LLRDs, making their V-shaped SEDs closer to those of high-redshift LRDs. The detection of the X-weak stack at ∼3.3σ with the soft-X-ray-sensitive EP-FXT provides rest-frame ∼2−3 keV constraints difficult to reconcile with a typical unobscured super-Eddington model or a local-AGN-like CT geometry examined here, although modified variants remain possible. The simplest alternative is a mildly X-ray-weak corona (Δαox∼−0.1 to −0.2) with Compton-thin absorption (NH∼1022−23 cm−2), consistent with the independent Balmer decrement/break diagnostics. Together with growing samples of local LRD analogs, our results offer a practical path for testing the physical nature of LRD X-ray weakness.
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BibTeX
@misc{chen2026local,
title = {{Local Analogs of Little Red Dots: Clues to the X-ray Weakness}},
author = {Shi-Jiang Chen and Jun-Xian Wang and Zhen-Ya Zheng and Ruqiu Lin and Luis C. Ho and Zhen-Yi Cai and Chang-Hao Chen and Zsofi Igo and Jia-Lai Kang and Ruancun Li and Teng Liu and Wenke Ren and Zhen-Bo Su},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.32430},
eprint = {2610.32430},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.32430},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Local Analogs of Little Red Dots: Clues to the X-ray Weakness
AU - Shi-Jiang Chen
AU - Jun-Xian Wang
AU - Zhen-Ya Zheng
AU - Ruqiu Lin
AU - Luis C. Ho
AU - Zhen-Yi Cai
AU - Chang-Hao Chen
AU - Zsofi Igo
AU - Jia-Lai Kang
AU - Ruancun Li
AU - Teng Liu
AU - Wenke Ren
AU - Zhen-Bo Su
PY - 2026
DA - 2026/10/23
PB - arXiv
DO - 10.48550/arxiv.2610.32430
UR - https://arxiv.org/abs/2610.32430
AB - A major question about JWST's little red dots (LRDs) at z∼4−8 is the origin of their apparent X-ray weakness. Even deep Chandra stacks yield only tentative detections or broad-band limits and cannot distinguish among super-Eddington accretion, intrinsic X-ray weakness, and Compton-thick (CT) obscuration. Local analogs offer a powerful complementary route. At z∼0.3, similarly luminous sources require ∼10^3−4 less exposure for comparable signal-to-noise, suffer less source confusion, and directly probe the diagnostic rest-frame soft X-rays. Here we present a pilot Einstein Probe/FXT study of six "local little red dots" (LLRDs), V-shaped broad-line green pea galaxies selected as low-redshift counterparts of LRDs. These sources show X-ray diversity: "X-normal" LLRDs resemble type 1 AGNs in X-ray luminosity and optical variability, whereas the "X-weak" stack lies ∼0.5−0.7 dex below standard unobscured-quasar scaling relations while remaining compatible with the representative LRD stack and 95% of published individual limits. The X-weak LLRDs also lack detected optical variability and have redder optical continua than X-normal LLRDs, making their V-shaped SEDs closer to those of high-redshift LRDs. The detection of the X-weak stack at ∼3.3σ with the soft-X-ray-sensitive EP-FXT provides rest-frame ∼2−3 keV constraints difficult to reconcile with a typical unobscured super-Eddington model or a local-AGN-like CT geometry examined here, although modified variants remain possible. The simplest alternative is a mildly X-ray-weak corona (Δα_ox∼−0.1 to −0.2) with Compton-thin absorption (N_H∼10^22−23 cm^−2), consistent with the independent Balmer decrement/break diagnostics. Together with growing samples of local LRD analogs, our results offer a practical path for testing the physical nature of LRD X-ray weakness.
ER -