@Article{PalitRaulCorr:2018:NuSiIo,
               author = "Palit, Sourav and Raulin, Jean-Pierre and Correia, 
                         Em{\'{\i}}lia",
          affiliation = "{Universidade Presbiteriana Mackenzie} and {Universidade 
                         Presbiteriana Mackenzie} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)}",
                title = "Lower ionospheric plasma-chemical evolution and VLF signal 
                         modulation by a series of SGR x-ray bursts: numerical simulation 
                         with an ion-chemistry model",
              journal = "Journal of Geophysical Research: Space Physics",
                 year = "2018",
               volume = "123",
               number = "9",
                pages = "7930--7942",
                month = "Sept.",
             keywords = "ionosphere, SGR, X-ray, VLF, Monte Carlo, ion chemistry.",
             abstract = "The X-ray and gamma ray radiation from astrophysical transient 
                         sources, like X-ray bursts from soft gamma repeaters (SGRs) and 
                         gamma ray bursts (GRBs), can affect the plasma properties of the 
                         lower ionosphere and middle atmosphere. Multiple very low 
                         frequency (VLF) receivers in South America, with an unprecedented 
                         high time resolution of 20 ms, detected one such series of bursts 
                         from SGR J1550-5418 on 22 January 2009. Due to lack of other 
                         suitable means of observation corresponding to the lower part of 
                         Earth's ionosphere (similar to 60-100 km), the VLF detection and 
                         analysis of transient ionizing events (mostly of solar origin) has 
                         emerged as an excellent method to investigate various chemical and 
                         plasma characteristics at these heights. Extragalactic events, 
                         like SGR bursts and GRBs, with sharp modulation in their radiation 
                         time profile and very high energy photon abundances provide most 
                         unique opportunities of such studies with the possibility of 
                         extending even lower heights in the atmosphere. Here, for the 
                         first time, an extensive computer model, consisting of the 
                         combination of Monte Carlo ionization rate computation, a one 
                         dimensional atmospheric chemistry module, and VLF waveguide mode 
                         calculation, for the reconstruction of VLF signal modulation 
                         produced by SGR X-ray burst starting from the observed spectrum 
                         and lightcurve of the event is presented. We gain some valuable 
                         insight on the nature of chemical and dynamic evolution over the 
                         entire height range of the atmosphere examined from the 
                         exercise.",
                  doi = "10.1029/2018JA025773",
                  url = "http://dx.doi.org/10.1029/2018JA025773",
                 issn = "2169-9402",
             language = "en",
           targetfile = "palit_lower.pdf",
        urlaccessdate = "27 abr. 2024"
}