Gamma-ray constraints on the infrared background excess

Abstract

Motivated by the idea that the recently detected near-infrared (1.2-4 micron) excess over the contribution of known galaxies is due to redshifted light from the first cosmic stars (Salvaterra & Ferrara 2003), we have used the effect caused by photon-photon absorption on gamma-ray spectra of blazars to put constraints on extragalactic background light (EBL) from the optical to the far-IR bands. Our analysis is mainly based on the blazar H 1426+428, for which we assume a power-law unabsorbed spectrum. We find that an EBL model with no excess over known galaxies in the near-infrared background (NIRB) is in agreement with all the considered blazars; however, it implies a very peculiar intrinsic spectrum for H 1426+428. Additional data on the blazars 1ES1101-232, H 2356-309 and PKS 2155-304 exclude the existence of a strong NIRB excess consistent with Kelsall's model of zodiacal light subtraction (ZL); the COBE/DIRBE measurements, after Wright's model ZL subtraction, represent a firm NIRB upper limit. The constraints on the optical EBL are weaker, due to the fact that predictions from different optical EBL models are often comparable to the experimental errors. In the mid-infrared the SPITZER measurement at 24 micron gives a good fit for all the considered blazars.

28 pages, 13 figures; revised version accepted for publication in New Astronomy

References in corpus (6)

• The 24 Micron Source Counts in Deep Spitzer Surveys
• Number Counts At 3 < lambda < 10 um From the Spitzer Space Telescope
• H.E.S.S. Observations of PKS 2155-304
• Simultaneous Constraints on the Spectrum of the Extragalactic Background Light and the Intrinsic Tev Spectra of Mrk 421, Mrk 501, and H1426+428
• Population III and the Near-Infrared Background Excess
• Is There an Imprint of Primordial Stars in the Tev Gamma-Ray Spectrum of Blazars?

Cited by in corpus (5)

• Formation of hard VHE gamma-ray spectra of blazars due to internal photon-photon absorption
• Constraints on the Cosmic Near Infrared Background Excess from NICMOS Deep Field Observations
• DIRBE Minus 2MASS: Confirming the CIRB in 40 New Regions at 2.2 and 3.5 Microns
• Probing the 3.6 Micron CIRB with Spitzer in 3 DIRBE Dark Spots
• Extragalactic Background Light: new constraints from the study of the photon-photon absorption on blazar spectra