Diffuse intergalactic magnetic fields and constraints for observations by CTA and ASTRI Mini-Array

• Grant number: 17/05542-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2017
• End date: October 31, 2018
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Paramita Barai
• Grantee: Stela Adduci Faria
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 16/01355-5 - High-energy astrophysics of galaxies and AGN in the cosmological context by connecting numerical simulations and observations with the CTA and ASTRI Mini-Array, AP.JP

Abstract

Primordial magnetic fields are amplified by turbulent dynamo effects, as well as by star-formation and stellar evolution processes in the InterStellar Medium of galaxies. At the same time, powerful galactic outflows are generated by energy feedback from various processes: stars, stellar evolution, and SuperNovae (SN) explosion, together with large-scale dynamical events, e.g. galaxy mergers, and tidal interactions between galaxies. In massive galaxies, energetic winds are also produced by gas accretion onto central supermassive black holes and resulting Active Galactic Nuclei (AGN) feedback. The magnetic fields in galaxy ISM are dragged out by strong galactic outflows with time, magnetically enriching the InterGalactic Medium (IGM) at larger cosmological distances. These magnetic fields permeate the turbulent IGM and may influence large scale structure formation. The magnetic fields also impact the propagation of cosmic-rays and gamma-rays produced by AGN and gamma-ray-bursts at cosmological distances. The origin of the large-scale diffuse InterGalactic Magnetic Fields (IGMFs) is not known. The IGMFs could be: generated in a primordial space filling manner, or produced locally in galaxies and further transported out efficiently by galactic outflows to fill a significant IGM volume fraction. For the second case, the contribution of SN-driven versus AGN-driven outflows in transporting out magnetic fields is also not known. The magnetic field properties are very difficult to measure directly, especially in the low-density diffuse regions of the IGM; which this project aims to shed light on. The scientific goals of this Iniciação Científica fellowship project are: - Investigate the origin of the IGMFs, by computing the contributions of galactic outflows (driven by SN versus AGN) on the advection of magnetic fields from galaxies to the IGM. - Explore the evolution of IGMFs through cosmic epochs. - Constrain the strength and the filling factor of the cosmic magnetic fields, by combining numerical simulation results with gamma-ray observations (current, and future observations done by the CTA and its precursor - the ASTRI MINI-ARRAY). This project will introduce all these stimulating concepts and theories to the undergraduate student, and teach her/him about the relevant numerical techniques to achieve the same purpose. Therefore, with this study the student will accomplish the following training goals. (1) Learn about the physical processes (SN, AGN) producing galactic outflows. (2) Introduction to the hydrodynamics and magnetohydrodynamics (MHD) numerical methodology. (3) Introduction to cosmological volume (using periodic boundary conditions) hydrodynamical simulations, which form representative volumes of the Universe. (4) Analyze and post-process the output of 3D hydrodynamics numerical code GADGET-3. (5) Interpret the numerical simulation results and compare with observations. (AU)