Lecture 6: Gamma-Ray Bursts Light extinction: Infrared background

Multiwavelength Cosmic Background

Extragalactic infrared background effect on blazar spectrum

Light curves. MAGIC (top) and optical R-band data (bottom) obtained for 3C 279 from February to March 2006. The long-term baseline for the optical flux is at 3 mJy. Light curves. MAGIC (top) and optical R-band data (bottom) obtained for 3C 279 from February to March 2006. The long-term baseline for the optical flux is at 3 mJy. MAGIC Collaboration, Albert et al. Science 2008;320:1752-1754 Published by AAAS

Spectrum of 3C 279 measured by MAGIC. Spectrum of 3C 279 measured by MAGIC. The gray area includes the combined statistical (1σ) and systematic errors, and underlines the marginal significance of detections at high energy. The dotted line shows compatibility of the measured spectrum with a power law of photon index α = 4.1. The blue and red triangles are measurements corrected on the basis of the two models for EBL density. Spectrum of 3C 279 measured by MAGIC. The gray area includes the combined statistical (1σ) and systematic errors, and underlines the marginal significance of detections at high energy. The dotted line shows compatibility of the measured spectrum with a power law of photon index α = 4.1. The blue and red triangles are measurements corrected on the basis of the two models for EBL density, discussed in the text.

Spectral energy distributions of 3C279 at the epochs of MAGIC observations: Feb 2006, Jan 2007, Jan-Feb 2009 Fermi-LAT 2007 2006 2009 Aleksic et al. 2011, arXiv:1101.2522

Stecker et al. 1992, ApJ, 390, L49

AGN scheme

AGN scheme with various photon fields and geometrical structures

The Intergalactic medium Absorbs radiation: Lyman alpha forest High-z QSO spectra (Becker et al. 2001) The Intergalactic medium Absorbs radiation: Lyman alpha forest And Lyman continuum In high redshift quasars: intervening absorption by Clouds of neutral hydrogen

Typical spectrum of starburst galaxy at z = 0.835 with GRB host overimposed (red dots) Paschen limit Balmer limit

Typical spectrum of starburst at z = 2.036 with GRB host Overimposed (red) Balmer limit Lyman limit