Probing Intra-Halo Light with Galaxy Stacking in CIBER Images

TL;DR

This study uses stacking analysis of CIBER images to directly measure intra-halo light around galaxies at intermediate redshifts, revealing that a significant fraction of galaxy light resides in extended outskirts, impacting our understanding of cosmic background light.

Contribution

First direct measurement of intra-halo light around $L_*$ galaxies at $z\, ext{~0.2-0.5}$ using CIBER stacking, linking IHL to large-scale background fluctuations.

Findings

Approximately 50% of galaxy light is in outskirts beyond 10 kpc.

Detected non-linear one-halo clustering consistent with simulations.

IHL significantly contributes to the near-infrared extragalactic background.

Abstract

We study the stellar halos of $0.2\lesssim z \lesssim 0.5$ galaxies with stellar masses spanning $M_*\sim 10^{10.5}$ to $10^{12}M_\odot$ (approximately $L_*$ galaxies at this redshift) using imaging data from the Cosmic Infrared Background Experiment (CIBER). A previous CIBER fluctuation analysis suggested that intra-halo light (IHL) contributes a significant portion of the near-infrared extragalactic background light (EBL), the integrated emission from all sources throughout cosmic history. In this work, we carry out a stacking analysis with a sample of $\sim$30,000 Sloan Digital Sky Survey (SDSS) photometric galaxies from CIBER images in two near-infrared bands (1.1 and 1.8 $\mu$m) to directly probe the IHL associated with these galaxies. We stack galaxies in five sub-samples split by brightness, and detect an extended galaxy profile, beyond the instrument point spread function (PSF), derived by stacking stars. We jointly fit a model for the inherent galaxy light profile, plus large-scale one- and two-halo clustering to measure the extended galaxy IHL. We detect non-linear one-halo clustering in the 1.8 $\mu$m band, at a level consistent with numerical simulations. Our results on the galaxy profile suggest that $\sim 50\%$ of the total galaxy light budget in our galaxy sample resides in the outskirts of the galaxies at $r > 10$ kpc. We describe this extended emission as IHL and and are able to study how this fraction evolves with cosmic time. These results are new in the near-infrared wavelength at the $L_*$ mass scale, and suggest that IHL has a significant contribution to the integrated galactic light, and to the amplitude of large-scale background fluctuations.