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Abstract |
The existence of magnetic fields is ubiquitous on astrophysical (e.g., planets and
stars) as well as on cosmological scales (galaxies and galaxy clusters). Low-
frequency radio observations are revealing an increasing number of diffuse radio
sources in galaxy clusters visible through their synchrotron emission. Recently,
the diffuse synchrotron radio emission was also detected in the region connecting
the pairs of galaxy clusters which is an indirect probe of magnetisation of the
Universe on filamentary scales. On the other hand, a search for extended gamma-
ray emission from distant blazars provides an intriguing possibility of detecting
very weak magnetic fields in cosmic voids. This poses an exciting avenue for
studying the generation mechanisms and evolution of observed large-scale magnetic
fields. In this talk, I will review few observational effects of magnetic fields
helping us to explore the magnetized Universe on cosmological scales; I will
briefly discuss the astrophysical and primordial scenarios for explaining the
observed magnetization of the Universe, including the motivation for studying the
primordial magnetic fields (PMFs; the seed fields generated in the early
Universe). Finally, I will present our results on the evolution of PMFs during
large scale structure formation (in connection with previous work for the
radiation dominated epoch). We use cosmological magnetohydrodynamical (MHD) code
ENZO to evolve inflation-generated magnetic fields which might have unlimited
correlation length scale and causally, phase-transition generated magnetic fields
characterized by the correlation length having an upper limit equal to the Hubble
length scale. We study how these seed magnetic fields evolve during structure
formation and what can be the observable traces of such fields. Our findings
include the distinctive evolution of different seed fields retaining the
information of magnetic initial conditions on the largest scales of the Universe.
We compare simulated Faraday rotation measures from different seeding scenarios
with recent observational data and give future prospects in the search of the
origin of cosmic, large scale correlated magnetic fields. |
