Calcium Triplet Absorption is Common around Little Red Dots

arXiv:2609.25349 · astro-ph.GA · Submitted 2026-09-21 · Read on arXiv

astro-ph.GA

Submitted: 2026-09-21

Updated: 2026-09-21

Comments: 14 pages, 4 figures, comments very welcome

License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/

Terminology

• Metallicity — 18× in this paper · explained in 3 episodes
• AGN — 8× in this paper · explained in 1 episode
• Little Red Dots — 5× in this paper · explained in 2 episodes
• Degeneracy — 3× in this paper · explained in 3 episodes
• Abundance — 2× in this paper · explained in 1 episode
• Clustering — 2× in this paper · explained in 2 episodes
• Little Red Dots (LRDs) — 2× in this paper · explained in 3 episodes
• Trace — 2× in this paper · explained in 2 episodes
• Velocity Dispersion — 1× in this paper · explained in 2 episodes

Sources

• A GLIMPSE of the 99%: a census of the faintest galaxies during the epoch of reionization and its implications for galaxy formation models
• Little Red Dots As Late-stage Quasi-stars
• ABCD: The Nuclear Structure of the Little Red Dots Revealted through Absorption, Break, Continuum, and Decrement
• A PANORAMIC of UV-optical morphologies of "Little Red Dots": Two groups of LRDs distinguished by UV half-light radius
• Little Red Dots host Black Hole Stars: A unified family of gas-reddened AGN revealed by JWST/NIRSpec spectroscopy
• Irony at z=6.68: a bright AGN with forbidden Fe emission and multi-component Balmer absorption
• VENUS: When Red meets Blue -- A multiply imaged Little Red Dot with an apparent blue companion behind the galaxy cluster Abell 383
• RUBIES: A Spectroscopic Census of Little Red Dots; All V-Shaped Point Sources Have Broad Lines
• BlackTHUNDER -- A non-stellar Balmer break in a black hole-dominated little red dot at $z=7.04$
• JADES -- The Rosetta Stone of JWST-discovered AGN: deciphering the intriguing nature of early AGN
• An (in)complete NIRSpec census of Balmer absorption in Type 1 AGN -- radiation-driven outflows in little red dots, quasars and variable stars
• Black Hole Envelopes in Little Red Dots
• The Deepest GLIMPSE of a Dense Gas Cocoon Enshrouding a Little Red Dot
• An unambiguous AGN and a Balmer break in an Ultraluminous Little Red Dot at z=4.47 from Ultradeep UNCOVER and All the Little Things Spectroscopy
• The Discovery of Little Red Dots in the Local Universe: Signatures of Cool Gas Envelopes
• The Large-scale Environments of Low-luminosity AGNs at $3.9 < z < 6$ and Implications for Their Host Dark Matter Halos from a Complete NIRCam Grism Redshift Survey
• The Balmer Break and Optical Continuum of Little Red Dots from Super-Eddington Accretion
• Synthetic Spectral Library of Optically Thick Atmospheres for Little Red Dots
• Little Red Dots as Obscured Little Blue Dots: A Super-Eddington Unification Model
• Non-LTE atmosphere models of very luminous sources and their applicability to Little Red Dots, quasi-stars, and similar objects

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• Constraining reionization-era Ly alpha escape with JELS-MUSE: a highly complete H alpha-selected sample at z about6.1
• Deriving volume density profiles of filaments from observed surface densities
• Little Red Dots and Supermassive Black Hole Seed Formation in Ultralight Dark Matter Halos
• MEGATRON: how the first stars can create an iron metallicity plateau in the smallest dwarf galaxies