# An Exceptional Very High Energy Gamma-Ray Flare of PKS 2155-304

@article{Aharonian2007AnEV,
title={An Exceptional Very High Energy Gamma-Ray Flare of PKS 2155-304},
author={Felix Aharonian and et al.},
journal={The Astrophysical Journal},
year={2007},
volume={664}
}
• Published 6 June 2007
• Physics
• The Astrophysical Journal
The high-frequency peaked BL Lac PKS 2155-304 at redshift z = 0.116 is a well-known VHE (>100 GeV) γ-ray emitter. Since 2002 its VHE flux has been monitored using the H.E.S.S. stereoscopic array of imaging atmospheric Cerenkov telescopes in Namibia. During the 2006 July dark period, the average VHE flux was measured to be more than 10 times typical values observed from the object. This article focuses solely on an extreme γ-ray outburst detected in the early hours of 2006 July 28 (MJD 53,944…
285 Citations

## Figures and Tables from this paper

Fermi LAT detection of extraordinary variability in the gamma-ray emission of the blazar PKS 1510-089
• Physics
• 2013
We have reanalyzed the giant outburst of the blazar PKS 1510-089 (z=0.36) that occurred on 2011 October-November. The gamma-ray flux in the 0.1-100 GeV energy range exceeded the value of 10^-5
Variable Very High Energy γ-Ray Emission from Markarian 501
• Physics
• 2007
The blazar Markarian 501 (Mrk 501) was observed at energies above 0.10 TeV with the MAGIC telescope from May through July 2005. The high sensitivity of the instrument enabled the determination of the
A fast, very-high-energy γ-ray flare from BL Lacertae during a period of multi-wavelength activity in June 2015
• Physics
Astronomy & Astrophysics
• 2019
The mechanisms producing fast variability of the γ-ray emission in active galactic nuclei (AGNs) are under debate. The MAGIC telescopes detected a fast, very-high-energy (VHE, E  >  100 GeV) γ-ray
A model for delayed emission in a very-high energy gamma-ray flare in Markarian 501
• Physics
• 2008
Context. Recently, the MAGIC collaboration reported evidence for a delay in the arrival times of photons of different energies during a γ-ray flare from the blazar Markarian 501 on 2005 July 9. Aims.
$\gamma$-ray Flux and Spectral Variability of Blazar Ton 599 during Its 2021 Flare
• Physics
• 2021
Blazars are known to emit exceptionally variable non-thermal emission over the wide range (from radio to γ-rays) of electromagnetic spectrum. We present here the results of our γ-ray flux and
SIMULTANEOUS OBSERVATIONS OF PKS 2155–304 WITH HESS, FERMI , RXTE , AND ATOM: SPECTRAL ENERGY DISTRIBUTIONS AND VARIABILITY IN A LOW STATE
• Physics
• 2009
We report on the first simultaneous observations that cover the optical, X-ray, and high energy gamma-ray bands of the BL Lac object PKS 2155-304. The gamma-ray bands were observed for 11 days,
Energetic constraints on a rapid gamma-ray flare in PKS 1222+216
• Physics
• 2012
We study theoretical implications of a rapid very high energy (VHE) flare detected by MAGIC in the flat spectrum radio quasar PKS 1222+216. The minimum distance from the jet origin at which this
Simultaneous observations of the blazar PKS 2155−304 from ultra-violet to TeV energies
• Physics
• 2019
The results of the first ever contemporaneous multi-wavelength observation campaign on the BL Lac object PKS2155-304 involving Swift, NuSTAR, Fermi-LAT and H.E.S.S. are reported. The use of these
Synoptic studies of 17 blazars detected in very high-energy γ-rays
Since 2002, the number of detected blazars at γ-ray energies above 100 GeV has more than doubled. I study 17 blazars currently known to emit E > 100 GeV γ-rays. Their intrinsic energy spectra are
The mid-2016 flaring activity of the flat spectrum radio quasar PKS 2023-07
• Physics
Astronomy & Astrophysics
• 2018
Context. Flat spectrum radio quasars (FSRQs) can suffer strong absorption above E = 25∕(1 + z) GeV, due to gamma–gamma interaction if the emitting region is at sub-parsec scale from the super-massive

## References

SHOWING 1-10 OF 24 REFERENCES
H.E.S.S. Observations of PKS 2155-304
• Physics
• 2004
The suggested presence of features in the energy spectrum may be intrinsic to the emission from the blazar, or an indication of absorption of TeV gamma rays by the extragalactic infrared background light.
Variable Very High Energy γ-Ray Emission from Markarian 501
• Physics
• 2007
The blazar Markarian 501 (Mrk 501) was observed at energies above 0.10 TeV with the MAGIC telescope from May through July 2005. The high sensitivity of the instrument enabled the determination of the
Multi-wavelength observations of PKS 2155-304 with HESS
• Physics
• 2005
The energy outputs in the 2–10 keV and in the VHE γ-ray range are found to be similar, with the X-rays and the optical fluxes at a level comparable to some of the lowest historical measurements, indicating that PKS 2155−304 was in a low or quiescent state during the observations.
A Rapid X-ray Flare from Markarian 501.
• Physics
The Astrophysical journal
• 2000
X-ray observations of the BL Lacertae object Mrk 501 that were taken with the Rossi X-Ray Timing Explorer in 1998 May as part of a multiwavelength campaign show a very rapid flare in which the 2-10 keV flux increased by approximately 60% in less than 200 s and the shift in the energy at which the spectral power peaks is among the most rapid shifts seen from this object.
Rapid X-Ray Variability of the BL Lacertae Object PKS 2155–304
• Physics
• 1999
We present a detailed power-density spectrum and cross-correlation analysis of the X-ray light curves of the BL Lac object PKS 2155-304, observed with BeppoSAX in 1997 (SAX97) and 1996 (SAX96), aimed
X-Ray Flares from Markarian 501
• Physics
• 2005
Motivated by the recent discovery of a hierarchical X-ray flaring phenomenon in Mrk 421, we conducted a systematic search for X-ray flares from Mrk 501, another well-known TeV blazar, by making use
Extremely rapid bursts of TeV photons from the active galaxy Markarian 421
• Physics
Nature
• 1996
DISCRETE astronomical sources of photons in the TeV energy range are believed to be associated with regions in the relativistic outflow of particles and radiation from compact objects, such as
A study of BL lacertae-type objects with EXOSAT. I, Flux correlations, luminosity variability, and spectral variability
• Physics
• 1990
Results are presented on a systematic analysis of more than 200 X-ray observations on 36 BL Lac objects, obtained from the Exosat archive, providing further strong evidence that the population of
XMM-NEWTON VIEW OF PKS 2155-304: CHARACTERIZING THE X-RAY VARIABILITY PROPERTIES WITH EPIC pn
• Physics
• 2005
Starting from XMM-Newton EPIC pn data, we present the X-ray variability characteristics of PKS 2155-304 using a simple analysis of the excess variance, sigma(2)(XS), and of the fractional rms
Background modelling in very-high-energy gamma-ray astronomy
• Physics
• 2006
Ground based Cherenkov telescope systems measure astrophysical {gamma}-ray emission against a background of cosmic-ray induced air showers. The subtraction of this background is a major challenge for