@Article{VitorianoBott:2018:UsCrEn,
               author = "Vitoriano, R. P. and Botti, Luiz Cl{\'a}udio Lima",
          affiliation = "{Universidade Presbiteriana Mackenzie} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)}",
                title = "Using cross entropy optimization to model active galactic nuclei 
                         light curves from VLBA MOJAVE Images",
              journal = "Astrophysical Journal",
                 year = "2018",
               volume = "854",
               number = "1",
                pages = "e59",
             keywords = "galaxies: active – galaxies: jets – galaxies: nuclei – methods: 
                         statistical – radio continuum: galaxies – techniques: 
                         interferometric.",
             abstract = "We present in this article a new method to derive the observed 
                         properties of outbursts in relativistic jets. We use the VLBI 
                         MOJAVE maps to obtain the light curves, based on the principle 
                         that the variability of extragalactic sources, in this case 3C 279 
                         and 4C +29.45, should appear in high resolution observations since 
                         1996 until 2016. The use of the cross entropy method (CE) can 
                         accurately determine the ranges of parameters for a sequence of 
                         outbursts based on the shock-wave model, where the decay/rise 
                         timescale ratio has a small spread and the use of a unique index 
                         1.3 generates a good fit modeled by functions of outbursts and by 
                         the model of the three stages. By the CE method, one can 
                         automatically get the start epochs as well as the occurrence of 
                         rise and decline times of the outbursts in the light curves. The 
                         values found are in agreement with the power-law distribution of 
                         energy, which shows that the cooling of electrons is a predominant 
                         process during the initial phase of the shock model evolution. The 
                         results of the decomposition show that the outbursts match the 
                         VLBI components observed in jets in addition to showing strong 
                         evidence of the peaks in the frequencies of 15.3 GHz. With this, 
                         we can model the shock waves with reference to the distance at the 
                         core of AGN to obtain the Doppler factor and the Lorentz factor.",
                  doi = "10.3847/1538-4357/aaa4f8",
                  url = "http://dx.doi.org/10.3847/1538-4357/aaa4f8",
                 issn = "0004-637X and 1538-4357",
                label = "self-archiving-INPE-MCTIC-GOV-BR",
             language = "en",
        urlaccessdate = "27 abr. 2024"
}