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 black hole in a near-pristine galaxy 700 million years after the Big Bang
15 Pith papers cite this work, alongside 15 external citations. Polarity classification is still indexing.
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Pith papers citing it
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abstract
The recent discovery of a large number of massive black holes within the first two billion years after the Big Bang, as well as their peculiar properties, have been largely unexpected based on the extrapolation of the properties of luminous quasars. These findings have prompted the development of several theoretical models for the early formation and growth of black holes, which are, however, difficult to differentiate. We report the metallicity measurement around a gravitationally lensed massive black hole at redshift 7.04 (classified as a Little Red Dot), hosted in a galaxy with very low dynamical mass. The weakness of the [OIII]5007 emission line relative to the narrow H$\beta$ emission indicates extremely low metallicity, about $4\times 10^{-3}$ solar, and even more metal poor in the surrounding few 100 pc. We argue that such properties cannot be uncommon among accreting black holes around this early cosmic epoch. Explaining such a low chemical enrichment in a system that has developed a massive black hole is challenging for most theories. Models assuming heavy black hole seeds (such as Direct Collapse Black Holes) or super-Eddington accretion scenarios struggle to explain the observations, although they can potentially reproduce the observed properties in some cases. Models invoking "primordial black holes" (i.e. putative black holes formed shortly after the Big Bang) may potentially explain the low chemical enrichment associated with this black hole, although this class of models also requires further developments for proper testing.
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Direct [OIII]4364-based metallicities show that galaxies with stellar masses 10^6.7-9 solar masses at z~6-8 are 0.3-0.5 dex more metal-poor than local galaxies of the same mass, with slope 0.25 and 0.2 dex scatter.
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.
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.
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.
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.
Monte Carlo solutions of the Smoluchowski equation for PBH clusters yield finite runaway timescales and evolving mass distributions that form high-redshift SMBHs, shortened further by mass segregation.
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.
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.
Half of strong CIII] emitters at z=5-7 show secure AGN signatures, with median equivalent width rising 0.67 dex relative to z=3-4 galaxies.
Dark matter clustering, possibly via self-interaction, may help stellar-remnant black holes reach over 10^7 solar masses by z=10.
Next-generation IFU instruments could detect core scouring and tangential anisotropy from MBH binaries up to z~0.14 for ~150 pc cores and higher redshifts for larger cores, expanding searchable volume by 30-40 times including lower-mass systems.
SKAO continuum surveys will detect radio emission from JWST AGN and LRDs and distinguish between Compton-thick absorption, intrinsically weak accretion, and dense gas cocoon scenarios.
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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A Glimpse of the Low-Mass End of the Direct Mass-Metallicity Relation at $z\sim6-8$
Direct [OIII]4364-based metallicities show that galaxies with stellar masses 10^6.7-9 solar masses at z~6-8 are 0.3-0.5 dex more metal-poor than local galaxies of the same mass, with slope 0.25 and 0.2 dex scatter.
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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.
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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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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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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.
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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.
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Smoluchowski Coagulation Equation and the Evolution of Primordial Black Hole Clusters
Monte Carlo solutions of the Smoluchowski equation for PBH clusters yield finite runaway timescales and evolving mass distributions that form high-redshift SMBHs, shortened further by mass segregation.
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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.
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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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The AGN nature of strong CIII emitters in the Early Universe with JWST
Half of strong CIII] emitters at z=5-7 show secure AGN signatures, with median equivalent width rising 0.67 dex relative to z=3-4 galaxies.
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Dark Matter and the Early Formation of Supermassive Black Holes
Dark matter clustering, possibly via self-interaction, may help stellar-remnant black holes reach over 10^7 solar masses by z=10.
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Unveiling the properties of galaxy cores excavated by supermassive black hole binaries with SHARP
Next-generation IFU instruments could detect core scouring and tangential anisotropy from MBH binaries up to z~0.14 for ~150 pc cores and higher redshifts for larger cores, expanding searchable volume by 30-40 times including lower-mass systems.
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Unveil the nature of JWST-AGN and Little Red Dots with SKAO continuum surveys
SKAO continuum surveys will detect radio emission from JWST AGN and LRDs and distinguish between Compton-thick absorption, intrinsically weak accretion, and dense gas cocoon scenarios.
- Evidence for Intermediate-Mass Black Holes From Microlensing Signatures in CHIME/FRB catalog 2