Polarimetry with e-ASTROGAM Space Observatory
IDPASC Portugal - PHD Programme 2017
2017 / 2018
Experimental Particle Physics | Astrophysics
Rui Curado da Silva
Universidade de Coimbra
Laboratório de Instrumentação e Física Experimental de Partículas
Polarized gamma-ray emissions over 1 MeV were never observed. The most energetic polarized emissions recorded were obtained by ESA INTEGRAL [1, 2]. By measuring the polarization angle and degree of linear polarization of the gamma-ray sources, it will be possible to obtain two additional observational parameters thereby allowing better discrimination between various models explaining the operation of emission sources. Polarimetric observations can provide important information about geometries, magnetic fields, composition and emission mechanisms in a wide variety of gamma-ray sources such as: pulsars, solar flares, active galactic nuclei, galactic black holes or gamma-ray bursts. The new e-ASTROGAM (http://eastrogam.iaps.inaf.it) space mission should provide e+/e- pair production based polarimetry in the MeV and GeV regions . This space mission was submitted to ESA M5 call for missions in 2015 and it is expected that it will be selected for Phase A (study and evaluation phase by ESA). The PI of the mission is Prof. Alessando Di Angelis of the Dipartimento di Fisica e Astronomia Galileo Galilei, Padova, Italy that is also LIP member. Mission e-ASTROGAM is a breakthrough space Observatory, with a detector composed by a Silicon tracker, a calorimeter, and an anticoincidence system, dedicated to the study of the non-thermal Universe in the energy range from 0.3 MeV to 3 GeV. It should provide unprecedented sensitivity, angular and energy resolution, combined with polarimetric capability. Thanks to its performance in the MeV-GeV domain, substantially improving its predecessors, e-ASTROGAM will open a new window on the non-thermal Universe. The selected PhD student should perform a complete study of the polarimetric potential of e-ASTROGAM main instrument, estimating the minimum detectable polarization for the most intense gamma-ray emission sources, such as the Vela, Crab and Geminga pulsars or the unpredictable GRB emissions. This study will be performed in the framework of e-ASTROGAM mission consortium within mission LIP team, which is performing research tasks for e-ASTROGAM supported by H2020 project AHEAD (Activities in the High Energy Astrophysics Domain). This research work will be performed mostly by mass model (instrument geometry and celestial source modeling) simulation using MEGAlib  dedicated program, based on GEANT4. Several instrument configurations will be tested in order to optimize e-ASTROGAM polarimetric performances. Experimental tests will be performed, in order to validate the main simulated results.  A. J. Dean et al., “Polarized gamma ray emission from the CRAB”, Science 321, 1183, 2008.  M. Forot et al., “Polarisation of the Crab pulsar and nebula as observed by the INTEGRAL/IBIS telescope”, The Astrophys. J. Lett. 688, L29, 2008.  “The e-ASTROGAM mission: Exploring the extreme Universe with gamma rays in the MeV - GeV range”, Alessandro De Angelis, (…), Rui Silva et al., Exp. Astron., 2017.  “MEGAlib – The Medium Energy Gamma-ray Astronomy Library”, Andreas Zoglauer et al., New Astronomy Reviews 50 (2006) 629–632.