| Title: |
BlackTHUNDER strikes twice: Balmer-line absorption in an overmassive Little Red Dot at z = 7.04 |
| Authors: |
D’Eugenio, Francesco; Maiolino, Roberto; Perna, Michele; Übler, Hannah; Ji, Xihan; McClymont, William; Koudmani, Sophie; Sijacki, Debora; Juodžbalis, Ignas; Scholtz, Jan; Bennett, Jake S; Bunker, Andrew J; Carniani, Stefano; Charlot, Stéphane; Cresci, Giovanni; Curtis-Lake, Emma; Dalla Bontà, Elena; Inayoshi, Kohei; Jones, Gareth C; Lyu, Jianwei; Marconi, Alessandro; Mazzolari, Giovanni; Nelson, Erica J; Parlanti, Eleonora; Robertson, Brant E; Schneider, Raffaella; Simmonds, Charlotte; Tacchella, Sandro; Venturi, Giacomo; Willott, Chris; Witstok, Joris; Witten, Callum |
| Publisher Information: |
Oxford University Press (OUP) |
| Publication Year: |
2026 |
| Collection: |
University of Central Lancashire: CLOK - Central Lancashire Online Knowledge |
| Subject Terms: |
F500 - Astronomy |
| Description: |
JWST has revealed a population of ‘Little Red Dots’ (LRDs): compact, red objects at redshifts z = 2–9 with ‘v’-shaped spectral energy distributions, broad permitted lines, and, often, hydrogen Balmer absorption. We use NIRSpec/IFS data from the BlackTHUNDER survey to study the H α line in the LRD Abell2744-QSO1 at z = 7.04, which is a confirmed AGN due to time-variable equivalent width (EW) in its broad emission lines. The H α spectral profile is non-Gaussian, requiring at least two Gaussian components. We also detect a narrow-line Gaussian component, and strong H α absorption (EW relative to the continuum $\sim 22_{+12}^{-7}\mathring{\rm A}$), confirming a connection between the strong Balmer break and line absorption. The absorber is at rest with respect to broad H α, suggesting that the gas cannot be interpreted as an inflow or outflow, forming instead a long-lived structure. Its velocity dispersion is $\sigma _abs = 110^{+20}_{-10}$ km s−1, consistent with the value inferred from the analysis of the Balmer break. Based on H α, we infer a black hole mass of log (M•/M⊙) = 7.2, smaller but close to the previous estimates based on H β. The Eddington ratio is 0.09. Combining the high signal-to-noise ratio of the narrow H α line with the spectral resolution R = 3, 700 of the G395H grating, we infer a narrow-line intrinsic dispersion $\sigma _\mathrm{n}=22_{-6}^{+5}$ km s−1, which places a stringent constraint on the black-hole-to-dynamical-mass ratio of this system to be M•/Mdyn = 0.15–1.2, confirming the overmassive nature of the black hole and potentially leaving little room for a host galaxy. |
| Document Type: |
article in journal/newspaper |
| File Description: |
application/pdf |
| Language: |
English |
| ISSN: |
0035-8711 |
| Relation: |
https://knowledge.lancashire.ac.uk/id/eprint/58588/1/58588%20D%27Eugenio%20et%20al.%20VOR.pdf; D’Eugenio, Francesco, Maiolino, Roberto, Perna, Michele, Übler, Hannah, Ji, Xihan orcid iconorcid:0000-0002-1660-9502 , McClymont, William orcid iconorcid:0009-0009-5565-3790 , Koudmani, Sophie orcid iconorcid:0000-0002-1528-5091 , Sijacki, Debora, Juodžbalis, Ignas et al (2026) BlackTHUNDER strikes twice: Balmer-line absorption in an overmassive Little Red Dot at z = 7.04. Monthly Notices of the Royal Astronomical Society, 547 (4). stag401. ISSN 0035-8711 |
| DOI: |
10.1093/mnras/stag401 |
| Availability: |
https://knowledge.lancashire.ac.uk/id/eprint/58588/; https://doi.org/10.1093/mnras/stag401; https://knowledge.lancashire.ac.uk/id/eprint/58588/1/58588%20D%27Eugenio%20et%20al.%20VOR.pdf |
| Rights: |
cc_by_4 |
| Accession Number: |
edsbas.A7E74780 |
| Database: |
BASE |