The Resolved Near-Infrared Extragalactic Background

TL;DR

This paper provides updated measurements of the near-infrared extragalactic background light from resolved galaxies, combining deep observations and literature data to improve estimates and compare with other methods.

Contribution

It presents new ultradeep Ks-band galaxy counts and combines multiple data sources to refine the NIR EBL estimates, aligning them better with gamma-ray and direct measurements.

Findings

NIR EBL in J, H, Ks bands measured as 11.7, 11.5, and 10.0 nW m-2 sr-1 respectively.

New ultradeep Ks-band counts from 22 hours of Subaru MOIRCS observations.

Resolved galaxy light is isotropic within uncertainties, consistent with large-scale isotropy.

Abstract

We present a current best estimate of the integrated near-infrared (NIR) extragalactic background light (EBL) attributable to resolved galaxies in J, H, and Ks. Our results in units of nW m-2 sr-1 are 11.7+5.6 -2.6 in J, 11.5+4.5 -1.5 in H and 10.0+2.8 -0.8 in Ks. We derive these new limits by combining our deep wide-field NIR photometry from five widely separated fields with other studies from the literature to create a galaxy counts sample that is highly complete and has good counting statistics out to JHKs ~ 27-28. As part of this effort we present new ultradeep Ks-band galaxy counts from 22 hours of observations with the Multi Object Infrared Camera and Spectrograph (MOIRCS) instrument on the Subaru Telescope. We use this MOIRCS Ks-band mosaic to estimate the total missing flux from sources beyond our detection limits. Our new limits to the NIR EBL are in basic agreement with, but 10 - 20% higher than previous estimates, bringing them into better agreement with estimates of the total NIR EBL (resolved + unresolved sources) obtained from TeV gamma-ray opacity measurements and recent direct measurements of the total NIR EBL. We examine field to field variations in our photometry to show that the integrated light from galaxies is isotropic to within uncertainties, consistent with the expected large-scale isotropy of the EBL. Our data also allow for a robust estimate of the NIR light from Galactic stars, which we find to be 14.7 +/- 2.4 in J, 10.1 +/- 1.9 in H and 7.6 +/- 1.8 in Ks in units of nW m-2 sr-1.