A Supermagnified Little Red Dot with a Resolved Host
Abstract
Little red dots (LRDs) are an intriguing new class of sources in the early universe discovered by the James Webb Space Telescope (JWST) characterized by V-shaped spectra and extremely compact sizes. Their underlying mechanisms still remain the subject of ongoing debate. We present JWST observations of a gravitationally lensed LRD nicknamed "Best Friend" at zspec = 8.297±0.002. Its high magnification factor of μ= 36+8−12 makes it the highest magnified LRD reported to date and unveils both the resolved structure of its host and a central engine less than 7 pc in size. The spectrum of the central engine, in which broad lines are not detected, possibly owing to the limited S/N and spectral resolution, is better interpreted as black hole activity rather than a dense star cluster. The latter cannot be fully excluded, but if true, the resulting lower limit on stellar density would be >1.25+0.4−0.3·106 M⊙/pc2, which is around 2 orders of magnitude higher than stellar densities of typical clusters at high-z. By performing a spatially resolved analysis of NIRCam photometry and NIRSpec/PRISM spectroscopy, we find that the host stellar mass is log(M⋆/M⊙) = 7.3+0.2−0.8. Best Friend demonstrates the power of lensing to reveal the morphologies of LRDs.
Related
- Broad-band host measurements of little red dots and similar compact nuclei require source-conditioned polychromatic PSFs
- Little Red Dot − Host Galaxy = Black Hole Star: A Gas-Enshrouded Heart at the Center of Every Little Red Dot
- Host Galaxy UV Emission and Dust Reddening in Little Red Dots
- Lyα in Compact Broad-Line Emitters, Including Little Red Dots, Is More Closely Linked to the Host Galaxy than to the Broad-Line Nucleus
- Little red dots host black hole stars: a unified family of gas-reddened AGN revealed by JWST /NIRSpec spectroscopy
BibTeX
@misc{judez2026supermagnified,
title = {{A Supermagnified Little Red Dot with a Resolved Host}},
author = {Jon Judež and Roberta Tripodi and Nicholas S. Martis and Maruša Bradač and Rosa M. Mérida and Chris J. Willott and Guillaume Desprez and Vesna Pirc Jevšenak and Yoshihisa Asada and Gregor Rihtaršič and Lilan Yang and Roberto Abraham and Gabriel B. Brammer and Viicente Estrada-Carpenter and Jasleen Matharu and Lamiya A. Mowla and Adam Muzzin and Gaël Noirot and Ghassan T. E. Sarrouh and Marcin Sawicki and Sunna Withers and Jacqueline Antwi-Danso and Giordano Felicioni and Anishya Harshan and Vladan Markov and Maya Merchant and Visal Sok},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.00202},
eprint = {2611.00202},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.00202},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - A Supermagnified Little Red Dot with a Resolved Host
AU - Jon Judež
AU - Roberta Tripodi
AU - Nicholas S. Martis
AU - Maruša Bradač
AU - Rosa M. Mérida
AU - Chris J. Willott
AU - Guillaume Desprez
AU - Vesna Pirc Jevšenak
AU - Yoshihisa Asada
AU - Gregor Rihtaršič
AU - Lilan Yang
AU - Roberto Abraham
AU - Gabriel B. Brammer
AU - Viicente Estrada-Carpenter
AU - Jasleen Matharu
AU - Lamiya A. Mowla
AU - Adam Muzzin
AU - Gaël Noirot
AU - Ghassan T. E. Sarrouh
AU - Marcin Sawicki
AU - Sunna Withers
AU - Jacqueline Antwi-Danso
AU - Giordano Felicioni
AU - Anishya Harshan
AU - Vladan Markov
AU - Maya Merchant
AU - Visal Sok
PY - 2026
DA - 2026/11/01
PB - arXiv
DO - 10.48550/arxiv.2611.00202
UR - https://arxiv.org/abs/2611.00202
AB - Little red dots (LRDs) are an intriguing new class of sources in the early universe discovered by the James Webb Space Telescope (JWST) characterized by V-shaped spectra and extremely compact sizes. Their underlying mechanisms still remain the subject of ongoing debate. We present JWST observations of a gravitationally lensed LRD nicknamed "Best Friend" at z_spec = 8.297±0.002. Its high magnification factor of μ= 36^+8_−12 makes it the highest magnified LRD reported to date and unveils both the resolved structure of its host and a central engine less than 7 pc in size. The spectrum of the central engine, in which broad lines are not detected, possibly owing to the limited S/N and spectral resolution, is better interpreted as black hole activity rather than a dense star cluster. The latter cannot be fully excluded, but if true, the resulting lower limit on stellar density would be >1.25^+0.4_−0.3·10^6 M_⊙/pc^2, which is around 2 orders of magnitude higher than stellar densities of typical clusters at high-z. By performing a spatially resolved analysis of NIRCam photometry and NIRSpec/PRISM spectroscopy, we find that the host stellar mass is log(M_⋆/M_⊙) = 7.3^+0.2_−0.8. Best Friend demonstrates the power of lensing to reveal the morphologies of LRDs.
ER -