Weekly archive
LRDigestWeekly digests of little red dots and JWST-selected AGN papers, with curated reading notes and archive pages.
654 indexed papers · 430 research notes
Radiative-transfer models and three illustrative spectra support a hypothesis that little blue dots are lower-column, gas-cocooned AGN related to little red dots. Balmer-jump offsets are suggestive, but population-level fitting and discriminating tests remain outstanding.
Across roughly 100 JWST-selected LRDs, rest-UV emission is redder and about four times more compact than matched star-forming galaxies. Stacked spectral trends and high Fe II/Mg II favor a substantial compact central component, although its physical origin remains model-dependent.
In 14 JWST LRD spectra, four show >3σ Paschen-continuum breaks, including one 12σ case. The authors interpret these slope changes as hydrogen free-bound emission, favouring low-temperature, minimally reddened nebular continua over fully thermalised continua.
JWST imaging of a z=6.027, doubly lensed Little Red Dot resolves red and blue compact components separated by about 300 pc. Their blended light can produce an LRD-like V-shaped SED, but the red component remains ambiguously stellar or AGN-powered.
Proposes Little Red Dots as “reionization factories,” where a Weyl-curvature–driven Cosmic Tide funnels intergalactic HI into colliding streams that shock, compress, and trigger rapid starbursts whose LyC reionizes hydrogen. In this picture, hot HII escapes along interstitial directions, so reionization proceeds via outflowing plasma rather than requiring extreme photon escape fractions. The model predicts a gas-dominated rest‑optical continuum—HII bremsstrahlung with a minimum‑timescale red cutoff and an IR rollover from opacity—while the UV is stellar, naturally producing strong Balmer breaks. It also anticipates narrow+broad Balmer components and slightly shifted Balmer absorption from bulk‑moving n=2 HI, with a proof‑of‑concept SED fit to J1025+1402; the scenario is explicitly speculative.
This Letter decomposes NIRCam imaging in 8 broad and 9 medium bands to isolate off-centered emission around four LRDs in Abell 2744 (UNCOVER + MegaScience). Three blobs are confirmed to be physically associated with their LRDs, with two showing medium-band excess consistent with very strong [O III] λλ4959,5007. While all three SEDs can be fit as ~10^8 Msun star-forming systems, the two [O III]-extreme cases are best explained as pure nebular emission from low-density, low-metallicity gas photoionized by the nearby LRD. Adopting LRD halo masses, the implied baryonic halo accretion rates are ~2–9 Msun/yr, suggesting growth to ~10^9 Msun by z≈4 if sustained at 10% star-formation efficiency.
Using the highest-S/N JWST/NIRSpec spectra of LRD-like broad-line sources, the authors show that Balmer-line wings are exponential and symmetric, as expected from electron scattering in a compact, Compton-thick ionized cocoon. Convolving a narrow Doppler core with this scattering kernel yields intrinsic widths of only a few hundred km/s, implying black holes of ~10^5–10^7 M⊙ accreting near the Eddington limit within light‑day–scale gas with mild outflows. Accounting for scattering lowers previous mass estimates by ~2 dex and naturally explains LRD traits, including very weak X-ray/radio via nebular reprocessing. This reframes LRDs as young, rapidly growing SMBHs rather than overmassive quasars for their hosts.