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243783.pdf (1.56 MB)

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2021-11

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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/219867

Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017

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https://doi.org/10.1093/mnras/staa3727

Resum

We report a characterization of the multiband flux variability and correlations of the nearby (z = 0.031) blazar Markarian 421 (Mrk 421) using data from Metsähovi, Swift, Fermi-LAT, MAGIC, FACT, and other collaborations and instruments from 2014 November till 2016 June. Mrk 421 did not show any prominent flaring activity, but exhibited periods of historically low activity above 1 TeV (F>1 TeV < 1.7 × 10−12 ph cm−2 s−1) and in the 2–10 keV (X-ray) band (F erg cm−2 s−1), during which the Swift-BAT data suggest an additional spectral component beyond the regular synchrotron emission. The highest flux variability occurs in X-rays and very high-energy (E > 0.1 TeV) γ-rays, which, despite the low activity, show a significant positive correlation with no time lag. The HRkeV and HRTeV show the harder-when-brighter trend observed in many blazars, but the trend flattens at the highest fluxes, which suggests a change in the processes dominating the blazar variability. Enlarging our data set with data from years 2007 to 2014, we measured a positive correlation between the optical and the GeV emission over a range of about 60 d centred at time lag zero, and a positive correlation between the optical/GeV and the radio emission over a range of about 60 d centred at a time lag of d. This observation is consistent with the radio-bright zone being located about 0.2 parsec downstream from the optical/GeV emission regions of the jet. The flux distributions are better described with a lognormal function in most of the energy bands probed, indicating that the variability in Mrk 421 is likely produced by a multiplicative process.

Matèries

Galàxies actives, Cosmologia, Radiació

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Active galaxies, Cosmology, Radiation

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Articles publicats en revistes (Física Quàntica i Astrofísica)
Articles publicats en revistes (Institut de Ciències del Cosmos (ICCUB))

Citació

CERRUTI, Matteo, et al. Investigation of the correlation patterns and the Compton dominance variability of Mrk 421 in 2017. Astronomy & Astrophysics. 2021. Vol. 655, num. id, pags. 36 pp. ISSN 0004-6361. [consulted: 16 of August of 2026]. Available at: https://hdl.handle.net/2445/219867

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