Cosmic Infrared Background from Population III Stars and Its Effect on Spectra of High- z Gamma-Ray Bursts

We discuss the contribution of Population III stars to the near-IR (NIR)cosmic infrared background (CIB) and its effect on spectra of high-$z$high-energy gamma-ray bursts (GRBs). It is shown that if Population III weremassive stars, the claimed NIR CIB excess will be reproduced if only ~ 4+/-2%of all baryons went through these stars. Regardless of the precise value of theNIR CIB produced by them, they would leave enough photons to provide a largeoptical depth for high-energy photons from high-z GRBs. Observations of suchGRBs are expected following the planned launch of NASA's GLAST mission. Thepresence or absence of such damping in the spectra of high-$z$ GRBs will thenprovide important information on the emissions from the Population III. Thelocation of this cutoff may also serve as an indicator of the GRB's redshift.Comment: Ap.J.Letters, in press. Revision includes discussion of CIB and low-z blazars. Some typos corrected and minor error in Fig.2 correcte