Past Events

  • Astronomy seminar: "Cosmological Seed Magnetic Field from Inflation"

    David Rittenhouse Laboratory, A6

    Bharat Ratra, Kansas State University

    A cosmological magnetic field of nG strength on Mpc length scales could be the seed magnetic field needed to explain observed few microG large-scale galactic magnetic fields. I first briefly review the observational and theoretical motivations for such a seed field, two galactic magnetic field amplification models, and some non-inflationary seed field generation scenarios. I then discuss an inflation magnetic field generation model. I conclude by mentioning possible extensions of this model as well as potentially observable consequences.

  • Astro Seminar: **POSTPONED UNTIL THE FALL**

    David Rittenhouse Laboratory, A4

    David Kipping (Columbia)

  • Astro Seminar: “Information from Cosmological Data”

    David Rittenhouse Laboratory, A4

    Ben Wandelt (CCA/Paris)

  • Astro Seminar: (TBA)

    David Rittenhouse Laboratory, A4


  • Astro Seminar: "Dark Matter Clustering in the Dissipationless Limit"

    David Rittenhouse Laboratory, A4

    Michael Joyce (Sorbonne Université, Paris)

    An accurate description and understanding of matter clustering in the strongly non-linear regime, even neglecting baryonic physics, remains a problem which is relevant to cosmology and of fundamental interest. My talk will be structured around three questions about it: (1) How well do current simulations resolve this clustering? (2) Is the so-called "stable clustering" approximation a relevant one? (3) Are there really "universal" properties of non-linear clustering?

  • Astro Seminar: "Moving Mesh Astrophysics"

    David Rittenhouse Laboratory, A4

    Paul Duffel (UC Berkeley)

    Novel methods in recent years have been developed for numerically solving the hydrodynamical and MHD equations relevant to all kinds of astrophysical flows.  I will first (briefly) present one such computational technique, where the numerical grid follows the MHD flow using a "moving mesh".  I will then present some astrophysical scenarios for which I have applied this method, including planet formation and high-energy transients such as supernovae and gamma ray bursts.

  • Astro Seminar:"Probing Galaxy Formation with Modern Cosmological Simulations"

    David Rittenhouse Laboratory, A4

    Paul Torrey (MIT)

    Cosmological simulations are among the most powerful tools available to probe the non-linear regime of cosmic structure formation.  They also provide a clear test-bed for understanding the impact that hydrodynamics and feedback processes have on the evolution of galaxies.  I will present an overview of modern galaxy formation simulations that couple a novel moving mesh computational method with explicit baryon feedback prescriptions.

  • Astro Seminar: "The Milky Way's Dust in Three Dimensions"

    David Rittenhouse Laboratory, A4

    Edward Schlafly (Lawrence Berkeley National Laboratory)

    Most observations of the Milky Way's gas and dust are limited to two dimensions; their angular distribution is precisely measured, but their distribution in distance is much more uncertain.  Large surveys of stars can be used to resolve this uncertainty.  Because light from stars is absorbed and scattered by intervening material before observation on earth, the Galaxy's stars can be used as a dense network of lighthouses to illuminate the structure and properties of the Milky Way's interstellar medium.

  • **CANCELLED** Astro Seminar: (TBA)

    David Rittenhouse Laboratory, A4


  • **CANCELLED** Astro Seminar: "The Twisted Universe: The Cosmic Quest to Reveal Which End is Up"

    David Rittenhouse Laboratory, A4

    Brian Keating (UCSD)

    The cosmic microwave background (CMB) has spectacularly advanced our understanding of the origin, composition, and evolution of our universe. Yet there is still much to glean from this, the oldest light in the universe. Powerful telescopes are plying the skies in a quest to discover new physics. This talk concentrates on measurements by cutting-edge CMB telescopes which offer a glimpse into an exhilarating, and largely unexplored branch of astrophysics: the search for unique signatures in the polarization of the CMB.