TY  - JOUR
A1  - Shukla, A.
A1  - Mannheim, K.
T1  - Gamma-ray flares from relativistic magnetic reconnection in the jet of the quasar 3C 279
JF  - Nature Communications
N2  - Spinning black holes in the centres of galaxies can release powerful magnetised jets. When the jets are observed at angles of less than a few degrees to the line-of-sight, they are called blazars, showing variable non-thermal emission across the electromagnetic spectrum from radio waves to gamma rays. It is commonly believed that shock waves are responsible for this dissipation of jet energy. Here we show that gamma-ray observations of the blazar 3C 279 with the space-borne telescope Fermi-LAT reveal a characteristic peak-in-peak variability pattern on time scales of minutes expected if the particle acceleration is instead due to relativistic magnetic reconnection. The absence of gamma-ray pair attenuation shows that particle acceleration takes place at a distance of ten thousand gravitational radii from the black hole where the fluid dynamical kink instability drives plasma turbulence.
KW  - kink instability
KW  - energy
KW  - radiation
KW  - blazars
KW  - variability
KW  - absorption
KW  - telescope
KW  - shocks
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-231328
VL  - 11
ER  - 
TY  - JOUR
A1  - Schleicher, Bernd
A1  - Arbet-Engels, Axel
A1  - Baack, Dominik
A1  - Balbo, Matteo
A1  - Biland, Adrian
A1  - Blank, Michael
A1  - Bretz, Thomas
A1  - Bruegge, Kai
A1  - Bulinski, Michael
A1  - Buss, Jens
A1  - Doerr, Manuel
A1  - Dorner, Daniela
A1  - Elsaesser, Dominik
A1  - Grischagin, Sergej
A1  - Hildebrand, Dorothee
A1  - Linhoff, Lena
A1  - Mannheim, Karl
A1  - Mueller, Sebastian Achim
A1  - Neise, Dominik
A1  - Neronov, Andrii
A1  - Noethe, Maximilian
A1  - Paravac, Aleksander
A1  - Rhode, Wolfgang
A1  - Schulz, Florian
A1  - Sedlaczek, Kevin
A1  - Shukla, Amit
A1  - Sliusar, Vitalii
A1  - Willert, Elan
A1  - Walter, Roland
T1  - Fractional Variability—A Tool to Study Blazar Variability
JF  - Galaxies
N2  - Active Galactic Nuclei emit radiation over the whole electromagnetic spectrum up to TeV energies. Blazars are one subtype with their jets pointing towards the observer. One of their typical features is extreme variability on timescales, from minutes to years. The fractional variability is an often used parameter for investigating the degree of variability of a light curve. Different detection methods and sensitivities of the instruments result in differently binned data and light curves with gaps. As they can influence the physics interpretation of the broadband variability, the effects of these differences on the fractional variability need to be studied. In this paper, we study the systematic effects of completeness in time coverage and the sampling rate. Using public data from instruments monitoring blazars in various energy ranges, we study the variability of the bright TeV blazars Mrk 421 and Mrk 501 over the electromagnetic spectrum, taking into account the systematic effects, and compare our findings with previous results. Especially in the TeV range, the fractional variability is higher than in previous studies, which can be explained by the much longer (seven years compared to few weeks) and more complete data sample.
KW  - blazars
KW  - variability
KW  - fractional variability
KW  - active galactic nuclei
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-197348
SN  - 2075-4434
VL  - 7
IS  - 2
ER  -