Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetry
Francesco D'Eugenio, Gabriele Pezzulli, Roberto Maiolino, Alessandro Marconi, Xihan Ji, Cristina Ramos Almeida, Andrea Ferrara, Piero Madau, Xiaojing Lin, José A. Acosta-Pulido, Fuyan Bian, Matilde Brazzini, Zheng Cai, Stefano Carniani, Xiaohui Fan, Ignas Juodžbalis, Robert G. Pascalau, Jan Scholtz, Charlotte Simmonds, Fengwu Sun, Sandro Tacchella
astro-ph.GA
Submitted: 2026-07-30
Comments: 21 pages, 12 figures. Submitted to MNRAS, comments welcome
Project page: http://basebe.obspm.fr
License: http://creativecommons.org/licenses/by/4.0/
The gist: Little Red Dots (LRDs) are compact active galactic nuclei (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth.
Terminology
Abstract
Little Red Dots (LRDs) are compact active galactic nuclei (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth. We present VLT/FORS2 optical linear spectropolarimetry of the closest known LRD, SDSS J102530.29+140207.3, at z=0.1. In total light, we detect spatially extended narrow-H alpha emission, probably tracing the host galaxy. We measure a nearly grey continuum polarisation p cont=1.53 plus or minus0.04 (rand.) plus or minus 0.20(syst.) per cent, while broad H alpha is less polarised, p H alpha=0.58-0.84 per cent. We rule out polarisation by Milky Way dust and dilution by an unpolarised line. The polarised continuum with a depolarised line resembles local Seyfert-1 nuclei and favours a single dominant source over multi-source explanations. After Stokes-continuum subtraction, broad H alpha shows no blue-to-red swing, but there is a significant (48 plus or minus 4) continuum-to-line offset in polarisation angle. This implies a break of axial symmetry inside this object, posing interesting geometrical challenges to all existing LRD models and frameworks. We discuss different possible origins of this symmetry break and possible paths to discriminate between them with future observations.
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- The $M_{\rm BH}-M_{*}$ Relationship at $3<z<7$: Big Black Holes in Little Red Dots
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- Discovery of Multiply Ionized Iron Emission Powered by an Active Galactic Nucleus in a z~7 Little Red Dot
- The GlimmIr: Spectroscopic Variability in a z~7 LRD Indicates Rapid Changes in Both the Narrow and Broad Line Regions
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- Wings of little dots: Exponential broad lines from a stratified BLR
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- A "Black Hole Star" Reveals the Remarkable Gas-Enshrouded Hearts of the Little Red Dots
- Little Red Dots as Intermediate Mass, Super-Eddington Engines: Insights from Type IIn Supernovae and The 1837-1856 Great Eruption of eta Carinae
- Small hosts, big appetites: unveiling rapid and early low-mass black hole growth in cosmological zoom-in simulations of dwarf galaxies
- The Little Red Dots Are Direct Collapse Black Holes
- Little Red Dots: One Photometric Tag Concealing Diverse Spectroscopic Flavors of Massive Star Formation and Black Hole Activity
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