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@article{2418981, author = {Ananna, Tonima Tasnim and Bogdan, Akos and Kovács, Orsolya Eszter and Natarajan, Priyamvada and Hickox, Ryan C.}, article_number = {1}, doi = {http://dx.doi.org/10.3847/2041-8213/ad5669}, keywords = {Active galactic nuclei; James Webb Space Telescope; X-ray active galactic nuclei; Supermassive black holes}, language = {eng}, issn = {2041-8205}, journal = {Astrophysical Journal Letters}, title = {X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes?}, url = {https://iopscience.iop.org/article/10.3847/2041-8213/ad5669}, volume = {969}, year = {2024} }
TY - JOUR ID - 2418981 AU - Ananna, Tonima Tasnim - Bogdan, Akos - Kovács, Orsolya Eszter - Natarajan, Priyamvada - Hickox, Ryan C. PY - 2024 TI - X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes? JF - Astrophysical Journal Letters VL - 969 IS - 1 SP - 1-10 EP - 1-10 PB - IOP Publishing Ltd SN - 20418205 KW - Active galactic nuclei KW - James Webb Space Telescope KW - X-ray active galactic nuclei KW - Supermassive black holes UR - https://iopscience.iop.org/article/10.3847/2041-8213/ad5669 N2 - 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. ER -
ANANNA, Tonima Tasnim, Akos BOGDAN, Orsolya Eszter KOVÁCS, Priyamvada NATARAJAN and Ryan C. HICKOX. X-Ray View of Little Red Dots: Do They Host Supermassive Black Holes? \textit{Astrophysical Journal Letters}. IOP Publishing Ltd, 2024, vol.~969, No~1, p.~1-10. ISSN~2041-8205. Available from: https://dx.doi.org/10.3847/2041-8213/ad5669.
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