J 2024

X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes?

ANANNA, Tonima Tasnim, Akos BOGDAN, Orsolya Eszter KOVÁCS, Priyamvada NATARAJAN, Ryan C. HICKOX et. al.

Basic information

Original name

X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes?

Authors

ANANNA, Tonima Tasnim, Akos BOGDAN, Orsolya Eszter KOVÁCS (348 Hungary, belonging to the institution), Priyamvada NATARAJAN and Ryan C. HICKOX

Edition

Astrophysical Journal Letters, IOP Publishing Ltd, 2024, 2041-8205

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10308 Astronomy

Country of publisher

United Kingdom of Great Britain and Northern Ireland

Confidentiality degree

není předmětem státního či obchodního tajemství

References:

URL

Impact factor

Impact factor: 7.900 in 2022

Organization unit

Faculty of Science

DOI

http://dx.doi.org/10.3847/2041-8213/ad5669

UT WoS

001260083600001

Keywords in English

Active galactic nuclei; James Webb Space Telescope; X-ray active galactic nuclei; Supermassive black holes

Tags

rivok

Tags

International impact, Reviewed
Změněno: 18/7/2024 09:43, Mgr. Marie Šípková, DiS.

Abstract

V originále

The discovery of Little Red Dots (LRDs)—a population of compact, high-redshift, dust-reddened galaxies—is one of the most surprising results from JWST. However, the nature of LRDs is still debated: does the near-infrared emission originate from accreting supermassive black holes (SMBHs), or intense star formation? In this work, we utilize ultra-deep Chandra observations and study LRDs residing behind the lensing galaxy cluster, A2744. We probe the X-ray emission from individual galaxies but find that they remain undetected and provide SMBH mass upper limits of ≲(1.5–16) × 106M⊙ assuming Eddington limited accretion. To increase the signal-to-noise ratios, we conduct a stacking analysis of the full sample with a total lensed exposure time of ≈87 Ms. We also bin the galaxies based on their stellar mass, lensing magnification, and detected broad-line Hα emission. For the LRDs exhibiting broad-line Hα emission, there is a hint of a stacked signal (∼2.6σ), corresponding to an SMBH mass of ∼3.2 × 106M⊙. Assuming unobscured, Eddington-limited accretion, this black hole (BH) mass is at least 1.5 orders of magnitude lower than that inferred from virial mass estimates using JWST spectra. Given galaxy-dominated stellar mass estimates, our results imply that LRDs do not host overmassive SMBHs and/or accrete at a few percent of their Eddington limit. However, alternative stellar mass estimates may still support that LRDs host overmassive BHs. The significant discrepancy between the JWST and Chandra data hints that the scaling relations used to infer the SMBH mass from the Hα line and virial relations may not be applicable for high-redshift LRDs.

Links

GX21-13491X, research and development project
Name: Zkoumání žhavého vesmíru a porozumění kosmické zpětné vazbě (Acronym: EHU)
Investor: Czech Science Foundation
Displayed: 10/11/2024 13:47