Defines a sample of ~1300 SDSS quasars as Local Red Dots matching LRD photometric colors at z~0.4-0.8, with a V-shaped subset showing Balmer absorption and [NeV] emission, and SEDs modeled as reddened AGN plus host galaxy that match LRD stacks.
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Holes in the BH$^\star$? AGN signatures in the FUV spectrum of a black-hole dominated Little Red Dot at $z=7.04$
16 Pith papers cite this work. Polarity classification is still indexing.
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Pith papers citing it
abstract
It has been suggested that "Little Red Dots" (LRDs) might be accreting black holes enshrouded by dense gas in a nearly closed geometry, which completely covers the central black hole, leading to an atmosphere-like structure known as the "black-hole star" ($\rm BH^\star$). We test this scenario by analysing new JWST spectroscopy in the far ultraviolet (FUV, rest-frame) of the prototypical LRD Abell2744-QSO1, at $z=7.04$. We found the presence of broad Ly$\alpha$ emission with an FWHM of $\sim 1000$ km/s, and detections of OI, CIV, and/or FeII emission lines. The NIRCam imaging and NIRSpec slit images indicate that the low-velocity component ($v\lesssim 200$ km/s) of Ly$\alpha$ is likely spatially extended, but the high-velocity component ($v\gtrsim 200$ km/s) of Ly$\alpha$ remains unresolved. Based on the multi-component kinematics and flux of Ly$\alpha$ relative to Balmer lines, we conclude that the observed line profile is unlikely to be broadened by subsequent resonant scattering through the interstellar medium. This suggests that the high-velocity component of Ly$\alpha$ originates in the broad-line region, although resonant scattering in the dense gas likely makes Ly$\alpha$ broader than H$\alpha$ as observed. The nebular features of this LRD indicate that there is at least one relatively optically thin direction where Ly$\alpha$ can escape from the broad-line region (BLR). We also found indications that photons from the BLR are powering fluorescence of FeII and OI on a larger physical scale. The FUV features thus challenge the fully-covered geometry interpretation and suggest that there are "holes" in the $\rm BH^\star$, or the absorbing medium is simply clumpy.
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Lyα observations of Little Red Dots show luminosities and equivalent widths like normal star-forming galaxies but lower Lyα/Hα ratios and extended asymmetric emission, supporting a two-component model with host-scale gas.
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 lower limit of 7.5e-10 cMpc^-3.
LRDs are reinterpreted as intermediate-mass super-Eddington systems with wind-driven pseudo-photospheres that explain their spectra and imply engine masses below 10^5 solar masses rather than overmassive black holes.
LRDs are interpreted as high-inclination hyper-Eddington accreting SMBHs analogous to SS 433, with V-shaped SEDs, X-ray weakness, and Balmer breaks emerging from disk self-shielding geometry.
LBDs are interpreted as lower-column analogues of LRDs in a gas-cocooned AGN sequence, with predicted spectral features including Balmer jumps and X-ray weakness.
New stack-based strong-line calibrations from ~1500 spectra yield mass-metallicity relations at z=1-10 with decreasing metallicity toward higher redshift and no slope change, plus 50 EMPG candidates at 1-4% solar metallicity showing large scatter and opposite sSFR trends.
Analysis of ~100 JWST LRDs finds redder, compact UV emission with Fe II/Mg II ~8-10 and correlations suggesting central red continuum (β_UV~0) beyond host galaxy contribution.
A theoretical model of a magnetized black hole envelope is developed to explain the broad emission lines and X-ray faintness observed in little red dots using co-rotating plasma clumps and limited X-ray sources.
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.
Narrow-line diagnostics on ~20 LRDs indicate that stellar photoionization alone cannot explain the observed ratios in many objects, implying anisotropic ionizing radiation from complex gas geometry.
JWST data on LRDs and LBDs show AGN-like excitation, strong Lyα with broad components, and X-ray weakness, implying clumpy or equatorial geometries around growing black holes rather than complete gas envelopes.
Quasi-star models using Cloudy radiative transfer reproduce the UV-NIR continuum shape, Balmer break, and hydrogen line luminosities in some LRDs when combined with host galaxy emission, but fail to account for broad helium lines and hot dust without added components.
Red supergiant collisions with massive gaseous envelopes around SMBHs in LRDs can produce detectable transients at rates up to ~0.3 yr^{-1} per LRD for compact clusters of size ≲10 pc.
Little red dots are the dust-reddened, high-inclination counterparts of little blue dots under a super-Eddington unification model, with luminosity-dependent fractions peaking near 20% and obscured systems showing systematically higher black hole masses due to selection.
Non-LTE wind atmosphere models computed with CMFGEN reproduce the SED and Balmer decrement of most Little Red Dots when dust-attenuated with Av ~2, while predicting Fe II, O I, and Ca lines, but struggle to produce both a genuine Balmer break and strong lines simultaneously.
citing papers explorer
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A Population of Little Red Dot-like Quasars in SDSS
Defines a sample of ~1300 SDSS quasars as Local Red Dots matching LRD photometric colors at z~0.4-0.8, with a V-shaped subset showing Balmer absorption and [NeV] emission, and SEDs modeled as reddened AGN plus host galaxy that match LRD stacks.
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Through the Veil: Ly$\alpha$ Illuminates the Host Galaxies of Little Red Dots
Lyα observations of Little Red Dots show luminosities and equivalent widths like normal star-forming galaxies but lower Lyα/Hα ratios and extended asymmetric emission, supporting a two-component model with host-scale gas.
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(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 lower limit of 7.5e-10 cMpc^-3.
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Little Red Dots as Intermediate Mass, Super-Eddington Engines: Insights from Type IIn Supernovae and The 1837-1856 Great Eruption of $\eta$ Carinae
LRDs are reinterpreted as intermediate-mass super-Eddington systems with wind-driven pseudo-photospheres that explain their spectra and imply engine masses below 10^5 solar masses rather than overmassive black holes.
-
Little Red Dots as Supermassive Analogs of SS 433
LRDs are interpreted as high-inclination hyper-Eddington accreting SMBHs analogous to SS 433, with V-shaped SEDs, X-ray weakness, and Balmer breaks emerging from disk self-shielding geometry.
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TBD LBD: The nature of `little blue dots'
LBDs are interpreted as lower-column analogues of LRDs in a gas-cocooned AGN sequence, with predicted spectral features including Balmer jumps and X-ray weakness.
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JADES: the mass-metallicity relation at $z=1-10$. New calibrations, extremely metal-poor galaxies, and chemical diversity
New stack-based strong-line calibrations from ~1500 spectra yield mass-metallicity relations at z=1-10 with decreasing metallicity toward higher redshift and no slope change, plus 50 EMPG candidates at 1-4% solar metallicity showing large scatter and opposite sSFR trends.
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The UV Side of Little Red Dots: Red, Compact, and Iron-Enhanced Rest-UV Emission with a Strong Downturn around Ly$\alpha$
Analysis of ~100 JWST LRDs finds redder, compact UV emission with Fe II/Mg II ~8-10 and correlations suggesting central red continuum (β_UV~0) beyond host galaxy contribution.
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A Magnetized Black Hole Envelope Model for Little Red Dots
A theoretical model of a magnetized black hole envelope is developed to explain the broad emission lines and X-ray faintness observed in little red dots using co-rotating plasma clumps and limited X-ray sources.
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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.
-
Constraints on the Gas Geometry Surrounding Little Red Dots through Narrow-Line Diagnostics
Narrow-line diagnostics on ~20 LRDs indicate that stellar photoionization alone cannot explain the observed ratios in many objects, implying anisotropic ionizing radiation from complex gas geometry.
-
Little Red and Blue Dots: AGN-excited narrow lines, Lyman-$\alpha$ emission, and resemblance to standard quasars
JWST data on LRDs and LBDs show AGN-like excitation, strong Lyα with broad components, and X-ray weakness, implying clumpy or equatorial geometries around growing black holes rather than complete gas envelopes.
-
The quasi-star model for Little Red Dots: potential and challenges
Quasi-star models using Cloudy radiative transfer reproduce the UV-NIR continuum shape, Balmer break, and hydrogen line luminosities in some LRDs when combined with host galaxy emission, but fail to account for broad helium lines and hot dust without added components.
-
Transient Signatures of Star-Envelope Collisions in Little Red Dots
Red supergiant collisions with massive gaseous envelopes around SMBHs in LRDs can produce detectable transients at rates up to ~0.3 yr^{-1} per LRD for compact clusters of size ≲10 pc.
-
Little red dots as obscured little blue dots: relative abundances, luminosities, and black-hole masses
Little red dots are the dust-reddened, high-inclination counterparts of little blue dots under a super-Eddington unification model, with luminosity-dependent fractions peaking near 20% and obscured systems showing systematically higher black hole masses due to selection.
-
Non-LTE atmosphere models of very luminous sources and their applicability to Little Red Dots, quasi-stars, and similar objects
Non-LTE wind atmosphere models computed with CMFGEN reproduce the SED and Balmer decrement of most Little Red Dots when dust-attenuated with Av ~2, while predicting Fe II, O I, and Ca lines, but struggle to produce both a genuine Balmer break and strong lines simultaneously.