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
Radiogalaxy IC 310
(80 Mpc)
TeV emitting region is
~100 Schwarzschild radii
Blazar-like behavior
Aleksic et
al., MAGIC
Collab. 2014
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
Multiwavelength Cosmic Background
Stecker et al. 1992, ApJ, 390, L49
Infrared intergalactic background
Albert et al. 2008
3C 279 (z = 0.54)
MAGIC (top) and optical Rban (bottom) light curves of
the FSRQ 3C 279 (z = 0.54)
from February to March
2006. 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:
S3 0218+35, z = 0.944
PKS1441+25, z = 0.939
MAGIC Collaboration, Albert et al. Science 2008;320:1752-1754
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
Albert et al. 2008
Light curves
TeV blazar Mkn421 (z = 0.031),
Campaign of April 1998
Spectral energy distribution
Maraschi et al. 1999
Multiwavelength observations of
Mkn421 (z = 0.031) in
2008 May 24 - Jun 23
Donnarumma et al. 2009
Multi-wavelength campaign on the blazar Mkn421 (2009 Jan 19 - Jun 1)
Abdo et al. 2011
Mkn501 (z = 0.034)
May – Jul 2005
Tavecchio et al. 2001
Albert et al. 2007
Blazar
PKS2155-304
Observed with
HESS
Atmospheric
Cerenkov
Telescope
Aharonian et al. 2009
Days
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
Albert et al. 2008
What is the observational evidence that blazars and
GRBs are highly relativistic sources with strong
special relativity aberration effects?
1) Large luminosities
2) Non-thermal spectra
3) superluminal motions (blazars, but also micro-QSO)
4) Gamma-ray transparency
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).
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
Elihu Boldt
The Extreme Universe: Some Views From Here
Closing lecture, 3rd INTEGRAL Workshop:
The Extreme Universe, Taormina, September 14-18 1998
Astrophysical Letters & Communications Vol. 37, 1999
arXiv:astro-ph/9902040
Reviews on TeV Astronomy:
http://tevcat.uchicago.edu/reviews.html