2026-06-28T10:22:21Zhttps://docta.ucm.es/rest/oai/request
oai:docta.ucm.es:20.500.14352/84302024-09-05T17:37:24Zcom_20.500.14352_14col_20.500.14352_15
Docta Complutense author Baquero Larriva, Orlando Andrés author Barrio Uña, Juan Abel author Contreras González, José Luis author Fonseca González, María Victoria author Hoang, Kim Dinh author López Moya, Marcos author Miener, Tjark author Miranda Pantoja, José Miguel author Morcuende, D. author Peñil Del Campo, Pablo author Saha, Lab 2023-06-17T09:13:35Z 2023-06-17T09:13:35Z 2021-06 0035-8711 10.1093/mnras/staa3727 https://hdl.handle.net/20.500.14352/8430 https://doi.org/10.1093/mnras/staa3727 https://academic.oup.com/mnras/ 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 Metsahovi, 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 x 10(-12) ph cm(-2) s(-1)) and in the 2-10 keV (X-ray) band (F2-10 keV < 3.6 x 10(-11) 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) gamma-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 43(-6)(+9) 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. eng Multiwavelength variability and correlation studies of Mrk 421 during historically low X-ray and gamma-ray activity in 2015-2016 journal article URL https://docta.ucm.es/bitstreams/35c0eaa3-4df3-4106-9ae3-8e394b5c9f79/download File MD5 9080a5e95ed2d8537a3264c3219c1b24 4642531 application/pdf MirandaJM146preprint.pdf URL https://docta.ucm.es/bitstreams/8759786e-b40e-46c9-afb3-8665fcd3794f/download File MD5 3d926a263c0dd235db29fb60ad689cb7 204333 text/plain MirandaJM146preprint.pdf.txt