Signatures of reionization feedback in the near-infrared background

Abstract

The reionization of the intergalactic medium at redshifts z ≳ 6 is expected to have a lasting impact on galaxies residing in low-mass dark matter haloes. Unable to accrete or retain gas photo-heated to temperatures T ≳ 104 K, the star formation histories of faint galaxies in the early Universe are expected to decline as they exhaust their gas supply, and so give rise to a ‘turn-over’ at the faint-end of the galaxy luminosity function. In this work, we explore the possibility of constraining this reionization feedback with measurements of the cosmic near-infrared background (NIRB), which traces the rest-optical and ultraviolet emission of high redshift galaxies. We find that the contrast between passively-aging, low-mass galaxies quenched by reionization and bluer, actively star-forming galaxies unaffected by reionization, manifests as a scale- and colour-dependent signature in the NIRB at a level comparable to the sensitivity of NASA’s upcoming SPHEREx mission. Whereas models with pure mass suppression largely affect the signal at wavelengths ≲ 2μm, ∼5 per cent-level differences in the background persist out to ≃ 5μm for reionization feedback models on ≃ 20′ scales. Finally, the power spectra of intensity ratio maps exhibit larger ∼ tens of per-cent variations, and may thus be a promising target for future analyses.

LIMFAST. I. A Seminumerical Tool for Line Intensity Mapping

“…Meanwhile, it should also be considered as an optimistic case for the formation of Pop II stars, since their formation in low-mass (but still above this limit) systems may be regulated by radiative feedback due to reionization (Yue et al 2014(Yue et al , 2018; although, the most recent constraints on the UVLF faint-end slope from deep lensed galaxies have yet to show the presence of a turnover (Bouwens et al 2022). Moreover, while so far only kinetic feedback from supernova explosions are considered in LIMFAST, we note that reionization feedback can also leave detectable imprints on intensity mapping signals (see, e.g., Mirocha et al 2022).…”

LIMFAST. II. Line Intensity Mapping as a Probe of High-redshift Galaxy Formation

“…Cross-correlating the kSZ signal derived from the simulated ionization and velocity fields with line tracers of galaxies provides the redshift information missing in kSZ measurements. Similar ideas can be applied to other types broadband, 2D data sets such as the CMB lensing and the cosmic near-IR background, through the large-scale fluctuations of which rich information about the population of ionizing sources may be extracted (Helgason et al 2016;Sun et al 2021b;Maniyar et al 2022;Mirocha et al 2022). Furthermore, as demonstrated already in the low-z universe, 3D Lyα forest tomography serves as a promising probe of the large-scale distribution of the neutral IGM (Lee et al 2018;Newman et al 2020), which can be ideally suited for studying the late stages of the reionization process by itself or in combination with LIM data sets (Qin et al 2021a).…”