Lecture 6:Gamma-Ray Bursts

Light extinction:Infrared background

Multiwavelength Cosmic Background

(z = 0.54)

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.

MAGIC Collaboration, Albert et al. Science 2008;320:1752-1754Published 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.

Spectral energy distributions of 3C279 at the epochs of MAGIC observations: Feb 2006, Jan 2007, Jan-Feb 2009

2007

2009

2006

Fermi-LAT

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

High-z QSO spectra (Becker et al. 2001)

The Intergalactic mediumAbsorbs radiation:

Lyman alpha forestAnd Lyman continuumIn high redshift quasars:intervening absorption byClouds of neutral hydrogen

Balmer limit

Paschen limit

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

Typical spectrum of starburst at z = 2.036 with GRB hostOverimposed (red)

Lyman limit

Balmer limit