Constraining Inflation with Little Red Dots
Abstract
Primordial non-Gaussianity is a direct probe of the physics of inflation. The tightest bounds still come from the cosmic microwave background, but large-scale structure is rapidly catching up: its intrinsically three-dimensional maps contain far more modes, provided the tracer combines large volume, high redshift, strong bias and sufficient number density. The Little Red Dots (LRDs) discovered by JWST plausibly offer all four. Inspired by recent work on BAO measurements using LRDs we forecast the joint galaxy power spectrum and bispectrum of a 14,000 deg2 LRD spectroscopic survey over 4<z<9, marginalising over $32$ nuisance parameters and including the non-Gaussian bispectrum covariance. We find σ(fNLloc)=0.32, σ(fNLequil)=32 and σ(fNLorth)=10, improving on Planck by factors of $16$, $1.5$ and $2.3$. The local bound lies a factor of three below the σ(fNLloc)≃1 threshold that separates broad classes of single- and multi-field inflation. LRD clustering therefore has the potential to become an important probe of inflation, and makes a strong case for future wide-field near- to mid-infrared spectroscopy.
Related
- Connecting the Dots: Prospects for Detecting Multi-Source Inflation through Scale-Dependent and Stochastic Bias of Little Red Dots
- A critical evaluation of the physical nature of the little red dots
- Massive black holes seeded by dark matter: Implications for little red dots and gravitational wave signatures
- Paschen jumps in little red dots: Evidence of nebular continua
- The UV Side of Little Red Dots: Red, Compact, and Iron-Enhanced Rest-UV Emission with a Strong Downturn around Lyα
BibTeX
@misc{karagiannis2026constraining,
title = {{Constraining Inflation with Little Red Dots}},
author = {Dionysios Karagiannis and P. Daniel Meerburg},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.26553},
eprint = {2609.26553},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.26553},
}
RIS
TY - UNPB
TI - Constraining Inflation with Little Red Dots
AU - Dionysios Karagiannis
AU - P. Daniel Meerburg
PY - 2026
DA - 2026/09/22
PB - arXiv
DO - 10.48550/arxiv.2609.26553
UR - https://arxiv.org/abs/2609.26553
AB - Primordial non-Gaussianity is a direct probe of the physics of inflation. The tightest bounds still come from the cosmic microwave background, but large-scale structure is rapidly catching up: its intrinsically three-dimensional maps contain far more modes, provided the tracer combines large volume, high redshift, strong bias and sufficient number density. The Little Red Dots (LRDs) discovered by JWST plausibly offer all four. Inspired by recent work on BAO measurements using LRDs we forecast the joint galaxy power spectrum and bispectrum of a 14,000 deg^2 LRD spectroscopic survey over 4<z<9, marginalising over $32$ nuisance parameters and including the non-Gaussian bispectrum covariance. We find σ(f_NL^loc)=0.32, σ(f_NL^equil)=32 and σ(f_NL^orth)=10, improving on Planck by factors of $16$, $1.5$ and $2.3$. The local bound lies a factor of three below the σ(f_NL^loc)≃1 threshold that separates broad classes of single- and multi-field inflation. LRD clustering therefore has the potential to become an important probe of inflation, and makes a strong case for future wide-field near- to mid-infrared spectroscopy.
ER -