Tuesday, August 25 2020
18:30 - 19:30

IMSc Webinar

Magnetic Field Evolution in Galaxies and Common Envelope Evolution in Stars

Luke Chamandy

University of Rochester

Part-1: Many galaxies contain interstellar magnetic fields with energy densities comparable to those of thermal motions, turbulence, and cosmic rays. These fields are amplified from small seed fields, and then maintained, by a turbulent dynamo. Intriguingly, they can be coherent on scales of up to several kiloparsecs, much larger than the correlation scale of turbulence. I will present dynamo models that may help to explain various properties of the large-scale components of galactic magnetic fields, and discuss how such models will be extended in the near future. I will then explain how collaborators and I are combining galaxy formation models and dynamo models to understand how the magnetic fields of galaxies evolved, as a population, over the history of the Universe.
Part-2: Common envelope evolution begins when a star, usually a giant, engulfs a companion. This is followed by a rapid inspiral of the companion and core of the giant, owing to gas dynamical friction drag. Liberated orbital energy is transferred to the envelope, helping to unbind it. The progenitors of many astrophysical phenomena, including luminous red novae, certain types of planetary nebulae, and most compact object coalescences observable through gravitational waves, are believed to involve common envelope events. I will present the results of high-resolution 3D global hydrodynamical simulations of common envelope evolution, with a focus on drag force evolution, envelope unbinding, and accretion of gas onto the companion.
Comments: Google meet link: meet.google.com/snx-bnaa-sqy

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