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Open AccessArticle

Long-Term Multi-Band and Polarimetric View of Mkn 421: Motivations for an Integrated Open-Data Platform for Blazar Optical Polarimetry

Centro Brasileiro de Pesquisas Fisicas (CBPF), Rua Dr. Xavier Sigaud 150, Rio de Janeiro RJ 22610-010, Brazil
Agenzia Spaziale Italiana (ASDC), Via del Politecnico snc, 00133 Rome, Italy
ICRANet-Armenia, Marshall Baghramian Avenue 24a, Yerevan 0019, Armenia
Universit di Roma “La Sapienza” (ICRANet), P.le Aldo Moro 5, 00185 Rome, Italy
Author to whom correspondence should be addressed.
Galaxies 2017, 5(4), 90;
Received: 18 September 2017 / Revised: 7 November 2017 / Accepted: 27 November 2017 / Published: 30 November 2017
(This article belongs to the Special Issue Polarised Emission from Astrophysical Jets)
In this work, by making use of the large software and database resources made available through online facilities such as the ASI Science Data Center (ASDC), we present a novel approach to the modelling of blazar emission whereby the multi-epoch SED for Mkn 421 is modelled considering, in a self-consistent way, the temporal lags between bands (both in short and long-timescales). These are obtained via a detailed cross-correlation analysis, spanning data from radio to VHE gamma-rays from 2008 to 2015. In addition to that, long-term optical polarisation data is used to aid and complement our physical interpretation of the state and evolution of the source. Blazar studies constitute a clear example that astrophysics is becoming increasingly dominated by “big data”. Specific questions, such as the interpretation of polarimetric information—namely the evolution of the polarisation degree (PD) and specially the polarisation angle (PA) of a source—are very sensitive to the density of data coverage. Improving data accessibility and integration, in order to respond to these necessities, is thus extremely important and has a potentially large impact for blazar science. For this reason, we present also the project to create an open-access database for optical polarimetry, aiming to circumvent the issues raised above, by integrating long-term optical polarisation information on a number sources from several observatories and data providers in a consistent way. The platform, to be launched by the end of 2017 is built as part of the Brazilian Science Data Center (BSDC), a project hosted at CBPF, in Rio de Janeiro, and developed with the support of the Italian Space Agency (ASI) and ICRANet. The BSDC is Virtual Observatory-compliant and is built in line with “Open Universe”, a global space science open-data initiative to be launched in November under the auspices of the United Nations. View Full-Text
Keywords: blazars; optical polarimetry; SED modelling; astronomical databases blazars; optical polarimetry; SED modelling; astronomical databases
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Barres de Almeida, U.; Fraga, B.M.O.; Giommi, P.; Sahakyan, N.; Gasparyan, S.; Brandt, C.H. Long-Term Multi-Band and Polarimetric View of Mkn 421: Motivations for an Integrated Open-Data Platform for Blazar Optical Polarimetry. Galaxies 2017, 5, 90.

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