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Date
2021-03Type
- Journal Article
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Cited 6 times in
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Cited 10 times in
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Abstract
Context. The origin of the γ-ray emission of the blazar Mrk 421 is still a matter of debate.
Aims. We used 5.5 years of unbiased observing campaign data, obtained using the FACT telescope and the Fermi-LAT detector at TeV and GeV energies, the longest and densest so far, together with contemporaneous multi-wavelength observations, to characterise the variability of Mrk 421 and to constrain the underlying physical mechanisms.
Methods. We studied and correlated light curves obtained by ten different instruments and found two significant results.
Results. The TeV and X-ray light curves are very well correlated with a lag of < 0.6 days. The GeV and radio (15 Ghz band) light curves are widely and strongly correlated. Variations of the GeV light curve lead those in the radio.
Conclusions. Lepto-hadronic and purely hadronic models in the frame of shock acceleration predict proton acceleration or cooling timescales that are ruled out by the short variability timescales and delays observed in Mrk 421. Instead the observations match the predictions of leptonic models. © ESO 2021 Show more
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publishedExternal links
Journal / series
Astronomy & AstrophysicsVolume
Pages / Article No.
Publisher
EDP SciencesSubject
astroparticle physics; radiation mechanisms: non-thermal; BL Lacertae objects: individual: Mrk 421; radiative transferOrganisational unit
08823 - Biland, Adrian (Tit.-Prof.)
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Show all metadata
Citations
Cited 6 times in
Web of Science
Cited 10 times in
Scopus
ETH Bibliography
yes
Altmetrics