LRD host galaxies show average metallicity 0.08 Z_sun with narrow stable range, challenging pristine-gas formation models while ruling out typical local AGN.
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A direct black hole mass measurement in a Little Red Dot at the Epoch of Reionization
13 Pith papers cite this work. Polarity classification is still indexing.
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abstract
Recent discoveries of faint active galactic nuclei (AGN) at the redshift frontier have revealed a plethora of broad \Halpha emitters with optically red continua, named Little Red Dots (LRDs), which comprise 15-30\% of the high redshift broad line AGN population. Due to their peculiar spectral properties and X-ray weakness, modeling LRDs with standard AGN templates has proven challenging. In particular, the validity of single-epoch virial mass estimates in determining the black hole (BH) masses of LRDs has been called into question, with some models claiming that masses might be overestimated by up to 2 orders of magnitude, and other models claiming that LRDs may be entirely stellar in nature. We report the direct, dynamical BH mass measurement in a strongly lensed LRD at $z = 7.04$. The combination of lensing with deep spectroscopic data reveals a rotation curve that is inconsistent with a nuclear star cluster, yet can be well explained by Keplerian rotation around a point mass of 50 million Solar masses, consistent with virial BH mass estimates from the Balmer lines. The Keplerian rotation leaves little room for any stellar component in a host galaxy, as we conservatively infer $M_{\rm BH}/M_{*}>2$. Such a ''naked'' black hole, together with its near-pristine environment, indicates that this LRD is a massive black hole seed caught in its earliest accretion phase.
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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.
LRDs transition from underdense low-halo-mass environments at z>4 to typical galaxy conditions by z~3.5, with halo growth leading to larger sizes and SED changes that explain their disappearance at lower redshifts.
GR viscous hydro simulations of Bondi-type super-Eddington flows find that black-hole mass controls whether a photon-trapped inflow-outflow structure or a convective envelope forms, with ~10% Eddington accretion onto the black hole in both cases.
Two FRBs exhibit microlensing signatures consistent with intermediate-mass black holes of masses approximately 500-600 and 1500-2500 solar masses, interpreted as possible evidence for isolated primordial black holes comprising about 4% of dark matter.
Spectral fitting of The Cliff LRD with Bagpipes yields a BH*-like solution with a low-mass metal-poor host, moderate dust, smooth star formation history, and high BH-to-stellar mass ratio.
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 accretion are ruled out; PBHs uniquely show a decreasing black hole-to-stellar mass
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.
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.
A bias-controlled quasar sample of ~2000 objects demonstrates that the X-ray-to-UV luminosity relation remains constant from redshift 0.7 to 5.
High-resolution cosmological zoom-in simulations find that major mergers do not trigger sustained super-Eddington black hole accretion in low-mass halos when feedback is included; episodes occur only immediately after seeding or with feedback disabled.
A review summarizing recent advances in strong gravitational lensing applications and near-future prospects with the James Webb Space Telescope.
Supermassive black holes form naturally at cosmic dawn when dark matter is axions or axion-like particles with mass above 10^{-16} eV/c².
citing papers explorer
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The metallicities of little red dot host galaxies: LRDs are metal poor, but not pristine
LRD host galaxies show average metallicity 0.08 Z_sun with narrow stable range, challenging pristine-gas formation models while ruling out typical local AGN.
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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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Why Little Red Dots Disappear at z < 3: Evolution of Number Density and Halo Mass
LRDs transition from underdense low-halo-mass environments at z>4 to typical galaxy conditions by z~3.5, with halo growth leading to larger sizes and SED changes that explain their disappearance at lower redshifts.
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A formation scenario of black hole-envelope systems --viscous hydrodynamics simulation in general relativity--
GR viscous hydro simulations of Bondi-type super-Eddington flows find that black-hole mass controls whether a photon-trapped inflow-outflow structure or a convective envelope forms, with ~10% Eddington accretion onto the black hole in both cases.
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Evidence for Intermediate-Mass Black Holes From Microlensing Signatures in CHIME/FRB catalog 2
Two FRBs exhibit microlensing signatures consistent with intermediate-mass black holes of masses approximately 500-600 and 1500-2500 solar masses, interpreted as possible evidence for isolated primordial black holes comprising about 4% of dark matter.
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Testing the BH$^*$ Model: a UV-to-Optical Spectral Fitting of The Cliff
Spectral fitting of The Cliff LRD with Bagpipes yields a BH*-like solution with a low-mass metal-poor host, moderate dust, smooth star formation history, and high BH-to-stellar mass ratio.
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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 accretion are ruled out; PBHs uniquely show a decreasing black hole-to-stellar mass
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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.
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On the quenching of LRD X-ray emission 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.
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The X-ray-to-UV relation does not evolve in homogeneous quasar samples
A bias-controlled quasar sample of ~2000 objects demonstrates that the X-ray-to-UV luminosity relation remains constant from redshift 0.7 to 5.
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The role of major mergers in triggering super-Eddington accretion
High-resolution cosmological zoom-in simulations find that major mergers do not trigger sustained super-Eddington black hole accretion in low-mass halos when feedback is included; episodes occur only immediately after seeding or with feedback disabled.
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Strong Gravitational Lensing with the James Webb Space Telescope
A review summarizing recent advances in strong gravitational lensing applications and near-future prospects with the James Webb Space Telescope.
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Axions explain the formation of supermassive black holes at cosmic dawn
Supermassive black holes form naturally at cosmic dawn when dark matter is axions or axion-like particles with mass above 10^{-16} eV/c².