Effects of the cosmic infrared background on delayed high-energy emission from gamma-ray bursts

Regenerated high-energy emissions from gamma-ray bursts are studied in detail. If the intrinsic primary spectrum extends to the TeV range, these very high energy photons will be absorbed by the cosmic infrared background (CIB). The high-energy electron-positron pairs thus created mainly upscatter cosmic microwave background (CMB) photons, and secondary photons are generated in the GeV-TeV range. These secondary delayed photons may be observed in the near future and would be useful as a consistency check on the intrinsic primary spectrum. In this paper, we focus on the effects of the CIB on the delayed secondary emission. In particular, we show that not only are upscattered CMB photons important but also upscattered CIB photons, especially for low-redshift bursts. These also provide additional information about the CIB, whose photon density has not definitively been determined so far.