Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1779605 | New Astronomy | 2006 | 11 Pages |
Abstract
Motivated by the idea that the recently detected near-infrared (1.2-4 μm) excess over the contribution of known galaxies is due to redshifted light from the first cosmic stars [MNRAS 339 (2003) 973], 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 of νIν = 2.7 nW mâ2 srâ1 at 24 μm gives a good fit for all the considered blazars.
Related Topics
Physical Sciences and Engineering
Physics and Astronomy
Astronomy and Astrophysics
Authors
M. Mapelli, R. Salvaterra, A. Ferrara,