Imprint of first stars era in the cosmic infrared backround fluctuations

TL;DR

This paper reports on the detection of significant cosmic infrared background fluctuations from early universe sources, suggesting they are faint, highly clustered, and originate within the first 0.7 billion years, with implications for future JWST observations.

Contribution

It provides new evidence of early universe populations contributing to CIB fluctuations, highlighting their faintness, clustering, and potential observability with JWST.

Findings

Significant CIB fluctuations persist after removing faint galaxies.

Sources are faint, with fluxes below a few nJy.

Sources are located within the first 0.7 Gyr of the universe.

Abstract

We present the latest results on CIB fluctuations from early epochs from deep Spitzer data. The results show the existence of significant CIB fluctuations at the IRAC wavelengths (3.6 to 8 mic) which remain after removing galaxies down to very faint levels. These fluctuations must arise from populations with a significant clustering component, but only low levels of the shot noise. There are no correlations between the source-subtracted IRAC maps and the corresponding fields observed with the HST ACS at optical wavelengths. Taken together, these data imply that 1) the sources producing the CIB fluctuations are individually faint with S_\nu< a few nJy at 3.6 and 4.5 mic; 2) have different clustering pattern than the more recent galaxy populations; 3) are located within the first 0.7 Gyr (unless these fluctuations can somehow be produced by - so far unobserved - local galaxies of extremely low luminosity and with the unusual for local populations clustering pattern), 4) produce contribution to the net CIB flux of at least 1-2 nW/m^2/sr at 3.6 and 4.5 mic and must have mass-to-light ratio significantly below the present-day populations, and 5) they have angular density of ~ a few per arcsec^2 and are in the confusion of the present day instruments, but can be individually observable with JWST.