Event DetailsEvent Dates: Friday, December 4, 2015 - 12:00pmSeminar Location: JILA 10th Floor - Foothills RoomSpeaker Name(s): Tina KahniashiliSpeaker Affiliation(s): Carnegie Mellon University Seminar Type/SubjectScientific Seminar Type: Astrophysics Lunch SeminarEvent Details & Abstract: Observations show that galaxies have magnetic fields with a component that is coherent over a large fraction of the galaxy with field strengths of order microGauss. These fields are supposed to be the result of amplification of an initial weak seed magnetic field of unknown nature. A recent study, based on the correlation of Faraday rotation measures and MgII absorption lines (which trace halos of galaxies) indicates that coherent microGauss-strength magnetic fields were already in place in normal galaxies (like the Milky Way) when the Universe was less than half its present age. This places strong constraints both on the strength of the initial magnetic seed field and the timescale required for amplification. Understanding the origin and evolution of these fields is one of the challenging questions of modern astrophysics. In this talk I will address the primordial magnetogenesis scenario, and discuss how does a seed field evolve during the evolution of the universe, including during phase transitions and the formation of cosmic structure. I will address observational signatures of primordial magnetic fields, such as the effects on cosmic microwave background radiation, the large scale structure, big-bang nucleosythesis, etc.