1. Lecture 5
Multi-wavelength cosmic background
And TeV emission suppression
Cross-section for pair production in
Photon-photon collisions
TeV and multi-wavelength spectra of
blazars

2. Radiogalaxy IC 310
(80 Mpc)
TeV emitting region is ~100 Schwarzschild radii
Blazar-like behavior
Aleksic et al., MAGIC Collab. 2014

3. Starburst galaxy NGC 253 (3 Mpc) Gamma-ray emission from starbursts
Is due to hadronic interactions
With dense interstellar matter:
“calorimetry” of cosmic rays
Lacki et al. 2011
Abramowski et al. 2012

4. Multiwavelength Cosmic Background

5. Stecker et al. 1992, ApJ, 390, L49

6. Infrared intergalactic background
Albert et al. 2008

7. 3C 279 (z = 0.54)
MAGIC (top) and optical R-ban (bottom) light curves of the FSRQ 3C 279 (z = 0.54) from February to March The long-term baseline for the optical flux is at 3 mJy.
Until recently, 3C279 was the most distant TeV emitter with spectroscopically measured redshift.
Announced in 2014 and 2015:
S , z = 0.944
PKS , z = 0.939
Light curves. MAGIC (top) and optical R-band data (bottom) obtained for 3C 279 from February to March The long-term baseline for the optical flux is at 3 mJy.
MAGIC Collaboration, Albert et al. Science 2008;320:

8. 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.
z = 0.54
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.
Albert et al. 2008

9. Spectral energy distribution
Light curves
TeV blazar Mkn421 (z = 0.031),
Campaign of April 1998
Spectral energy distribution
Maraschi et al. 1999

10. Multiwavelength observations of Mkn421 (z = 0.031) in
2008 May 24 - Jun 23
Donnarumma et al. 2009

11. Multi-wavelength campaign on the blazar Mkn421 (2009 Jan 19 - Jun 1)
Abdo et al. 2011

12. Mkn501 (z = 0.034) Tavecchio et al. 2001 Albert et al. 2007
May – Jul 2005
Tavecchio et al. 2001
Albert et al. 2007

13. Blazar PKS2155-304 Observed with HESS Atmospheric Cerenkov Telescope
Aharonian et al. 2009
Days
Days

14. 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.
z = 0.54
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.
Albert et al. 2008

15. What is the observational evidence that blazars and GRBs are highly relativistic sources with strong special relativity aberration effects?
Large luminosities
Non-thermal spectra
superluminal motions (blazars, but also micro-QSO)
Gamma-ray transparency

16. Compactness Compactness arguments hold for both blazars
and GRBs (Cavallo & Rees 1978): the opacity
tau_gg is much larger than 1 for the OBSERVED
Luminosities, sizes of emitting region (i.e. variability
Times) and frequencies. If one corrects for relativistic
Aberration and replaces these quantities with the
intrinsic ones, one obtains tau_gg opacities less
Than 1 (i.e. transparent to gamma-rays). See
Compactnes argument for blazars in Maraschi et
al. (1992).
In GRBs one has fluences instead of fluxes. See Cavallo
& Rees (1978).

17. C.M. Urry & P. Padovani 1995
Unified Schemes for Radio-Loud Active Galactic Nuclei
PASP, 107, 803
G.B. Rybicki & A.P. Lightman 1979
Radiation Processes in Astrophysics
G. Cavallo & M. J. Rees 1978
A qualitative study of cosmic fireballs and gamma-ray bursts
MNRAS, 183, 359
L. Maraschi, G. Ghisellini, & A. Celotti 1992
A jet model for the gamma-ray emitting blazar 3C279
ApJ, 397, L5
I.F. Mirabel & L.F. Rodriguez 1999
Sources of Relativistic Jets in the Galaxy
Annual Review of Astronomy & Astrophysics 37, 409

18. Reviews on TeV Astronomy:
Elihu Boldt
The Extreme Universe: Some Views From Here
Closing lecture, 3rd INTEGRAL Workshop:
The Extreme Universe, Taormina, September
Astrophysical Letters & Communications Vol. 37, 1999
arXiv:astro-ph/
Reviews on TeV Astronomy: