REVIEW 26 cited by
Little Red Dots at an Inflection Point: Ubiquitous "V-Shaped" Turnover Consistently Occurs at the Balmer Limit
Not yet reviewed by Pith; the record is open.
This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.
SPECIMEN: schema-true, not a live event
T0 review · schema-true
One-sentence machine reading of the paper's core claim.
pith:XXXXXXXX · record.json · timestamp
abstract
Among the most puzzling early discoveries of JWST are "Little Red Dots" -- compact red sources that host broad Balmer emission lines and, in many cases, exhibit a "V shaped" change in slope in the rest-optical. The physical properties of Little Red Dots currently have order-of-magnitude uncertainties, because models to explain the continuum of these sources differ immensely. Here, we leverage the complete selection of red sources in the RUBIES program, supplemented with public PRISM spectra, to study the origin of this "V shape". By fitting a broken power law with a flexible inflection point, we find that a large fraction (20/44, nearly all spatially unresolved) of extremely red H$\alpha$ emitters at $2<z<6$ exhibit a strong change in slope, and that all strong inflections appear associated with the Balmer limit ($0.3645$ $\mu$m). Using a simple model of a reddened AGN with an unobscured scattered light component, we demonstrate that the observed "V shape" in Little Red Dots is unlikely to occur at any specific wavelength if the entire continuum is dominated by light from a power law AGN continuum. In contrast, models with an intrinsic feature at the Balmer limit, such as those that are dominated by evolved stellar populations in the rest-UV-to-optical, can produce the observed spectral shapes, provided that a reddened component picks up sufficiently redward of the break. While no model can comfortably explain the full Little Red Dot spectral energy distribution, the common inflection location suggests that it is most likely a single component that consistently dominates the rest-UV-to-optical in Little Red Dots, and that this component is associated with $T\sim10^4$ K hydrogen due to the clear preference for a break at H$_\infty$.
Forward citations
Cited by 26 Pith papers
-
Misaligned or chaotic? A strong break of axial symmetry in the local LRD J1025 revealed with VLT/FORS2 spectropolarimetry
The local Little Red Dot J1025 shows a 48° polarisation-angle offset between continuum and broad H-alpha, requiring broken axial symmetry.
-
(LRDs)$^2$: The Low-ReDshift Little Red Dots Survey. II. DESI DR1 Sample
The survey identifies 27 low-redshift LRDs with compact morphology, V-shaped continua, broad Balmer lines with extreme decrements, and ubiquitous outflows, matching high-z counterparts and yielding a number density lo...
-
There and back again? Neutral outflows in z~3.5 quiescent galaxies
Neutral outflows detected in 57% of z~3.5 quiescent galaxies via NaI D, with mass rates that can suppress star formation but suggest short-timescale recycling instead of permanent quenching.
-
(Re)solving the Complex Multiscale Morphology and V-shaped Spectral Energy Distribution of a Newly Discovered Strongly Lensed Little Red Dot in A383
Lensed LRD A383-LRD1 resolves into blue and red components ~300 pc apart whose combined light produces the canonical V-shaped SED.
-
What you see is what you get: empirically measured bolometric luminosities of Little Red Dots
Directly integrating the observed spectra of two Little Red Dots shows the bolometric luminosity is dominated by rest-frame optical light, lowering implied black hole masses to about 10^5 to 10^7 solar masses.
-
ATLAS. II. Extremely High Incidence of Balmer Line Absorption with Predominant Blueshifts in LRDs: Statistical Insights through Comparison with Type 1 AGNs
Balmer-line absorption occurs in ~35% (14/40) of JWST little-red-dot AGNs, roughly 850x the rate in SDSS type-1 AGNs, with mostly slow blueshifted absorber velocities.
-
Outflows in the Early Universe: Neutral gas Absorption in Galaxies at z > 3 from low-resolution JWST Spectroscopy
Excess Na I D absorption, interpreted as neutral-gas outflows, is detected in 20 of 811 galaxies at z>3 and rises steeply with stellar mass and quiescence.
-
An (in)complete NIRSpec census of Balmer absorption in Type 1 AGN -- radiation-driven outflows in little red dots, quasars and variable stars
About 44% of little red dots have hydrogen-alpha absorption from outflowing gas, implying radiatively driven outflows rather than static atmospheres.
-
JWST's Little Red Dots as collapsed Supermassive Dark Stars
Supermassive dark stars powered by dark matter annihilation can collapse into quasi-stars whose envelopes expand and cool to match the observed properties of many JWST Little Red Dots while bypassing the restrictive c...
-
Quenching of X-ray emission in little red dots by both Compton-thick gas and high accretion rates
X-ray non-detection of little red dots requires both Compton-thick gas columns (~1e25 cm^-2) and intrinsically weak X-ray emission with bolometric correction k_bol,X ≳ 30.
-
Light, heavy, primordial: exploring the diversity of black hole seeding and growth mechanisms in the JWST era
Primordial black holes and heavy astrophysical seeds with super-Eddington accretion reproduce JWST-observed black hole masses, stellar masses, and low metallicities at z~7-10, while light seeds with Eddington-limited ...
-
Ultrahigh-energy cosmogenic neutrino emissions in the high-redshift universe
If Little Red Dots accelerate protons to ~10 EeV, their interactions with the high-redshift CMB produce a ~50 PeV cosmogenic neutrino bump consistent with IceCube.
-
The Two Orbital, Interacting Hatano-Nelson Model
In the two-orbital interacting Hatano-Nelson model, phase diagrams show regimes of purely real spectra controlled by interaction strength, non-Hermiticity, and interchain hopping, with links to skin modes and qualitat...
-
Paschen Jumps in Little Red Dots: Evidence for Nebular Continua
Paschen jumps in Little Red Dots indicate their continua originate from free-bound recombination emission in low-temperature nebular gas rather than thermalized or AGN components.
-
Connecting the Dots: UV-Bright Companions of Little Red Dots as Lyman-Werner Sources Enabling Direct Collapse Black Hole Formation
UV-bright companions to Little Red Dots provide Lyman-Werner fluxes of J21 ~ 10^2.5-10^5 that can suppress H2 cooling and enable direct collapse to massive black holes.
-
VENUS: When Red meets Blue -- A multiply imaged Little Red Dot with an apparent blue companion behind the galaxy cluster Abell 383
JWST resolves A383-LRD1 into a compact red Little Red Dot candidate and a blue companion at z≈6, magnified ~9–16× by cluster lensing.
-
Spectral Uniformity of Little Red Dots: A Natural Outcome of Coevolving Seed Black Holes and Nascent Starbursts
Coevolving super-Eddington black holes and nuclear starbursts in high-redshift halos naturally generate the V-shaped UV-to-optical spectra and weak high-energy emission of little red dots.
-
Do Little Red Dots Vary?
Super-Eddington accretion models can explain why little red dots show almost no variability, whereas standard sub-Eddington AGN variability models predict changes that should already have been seen.
-
Investigating Little Red Dots with UV Excess: Are They the High-Redshift Siblings of Blue Hot DOGs?
Little Red Dots are not the high-redshift relatives of Blue-excess Hot DOGs; they have less dust obscuration, little hot dust, and likely a different power source.
-
Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). XXIV. 54 New Quasars and Candidate Obscured Quasars at $5.71 \le z \le 7.02$
Spectroscopic follow-up of the completed HSC-SSP survey yields 43 new quasars, 11 candidate obscured quasars, and 29 galaxies at z 5.71 to 7.02.
-
A "Black Hole Star" Reveals the Remarkable Gas-Enshrouded Hearts of the Little Red Dots
A source 660 million years after the Big Bang is interpreted as a black hole star with a dust-free dense gas atmosphere, implying Little Red Dots have black hole masses overestimated by orders of magnitude.
-
Quenching of X-ray emission in little red dots by both Compton-thick gas and high accretion rates
LRDs require Compton-thick gas at moderate metallicity plus high accretion rates producing weak X-rays to explain their non-detection, implying they are not chemically pristine.
-
Ultrahigh-energy cosmogenic neutrino emissions in the high-redshift universe
High-redshift AGN emitting UHE protons up to 10^19 eV generate a 50 PeV cosmogenic neutrino bump consistent with IceCube data from their JWST-measured average properties without fine-tuning.
-
The Two Orbital, Interacting Hatano-Nelson Model
Phase diagrams for a purely real spectrum are obtained in the two-particle sector of a two-chain interacting Hatano–Nelson–Hubbard model, with winding-number and Lindblad checks of boundary and open-system behavior.
-
Evidence of violation of Case B recombination in Little Red Dots
In one of seven Little Red Dots, the broad Hδ/Hα ratio is more than 5σ below the Case B prediction, signalling a breakdown of standard recombination in very dense gas.
-
The BlueDOG at Cosmic Noon: A Possible Analog to Little Red Dots?
A z=2.6 hyperluminous dust-obscured galaxy with an LRD-like SED hosts a ~10^10.2 Msun black hole, while the origin of its blue UV excess is left ambiguous.
Discussion (0). Sign in to comment.