Past Events

  • Astronomy seminar: "Using the environment to infer supernova progenitor properties"

    David Rittenhouse Laboratory, A6

    Lluis Galbany, University of Pittsburgh

    Integral Field Spectroscopy (IFS) applied to supernova (SN) environmental studies have shown the potential of this technique to directly characterize the galactic environmental parameters at SN locations, compare them to those at different locations of the galaxy, and put constraints on progenitor stars for different SN types. In this talk, I will summarize current efforts from the PISCO compilation, Hi-KIDS, MaNGA, and the AMUSING surveys, that have put together more than 500 SN hosts observed with IFS, and give details about published results from these datasets. 

  • Special Seminar: "This Is Not A Diversity Talk" - POSTPONED MAKE UP DATE TBD

    David Rittenhouse Laboratory, A8

    John A. Johnson, The Harvard-Smithsonian Center for Astrophysics

    The American discourse on the various disparities present in society generally, and academia specifically, focuses primarily on observations of the state of a given situation---e.g. a lack of diversity---rather than on the actions that lead to such a state. This approach is just as dissatisfying and ultimately ineffectual as observing that certain stars are "bright," rather than describing any of the physical principles that lead to the observed properties of a star.

  • Astronomy seminar: "Measurements of Degree-Scale B-mode Polarization with the BICEP/Keck Experiments at South Pole"

    David Rittehouse Laboratory, A6

    Benjamin Racine, Harvard-Smithsonian Center for Astrophysics

    The BICEP and Keck experiments, located at the South Pole, are currently observing the polarized microwave sky at the degree scale using refractive telescopes. They are searching for a signature of primordial gravitational waves in the so-called B modes of the cosmic microwave background (CMB), parametrized with the tensor-to-scalar ratio r. In this talk I will introduce our latest analysis which includes BICEP2 and Keck array data up to the end of 2015.

  • Astronomy seminar: "TBA"

    David Rittenhouse Laboratory, A6

    Barth Netterfield, University of Toronto

  • Astronomy seminar: "The Hunt for Exomoons"

    David Rittenhouse Laboratory, A6

    David Kipping, Columbia University

    Since astronomers first started detecting exoplanets, interest in possible exomoons soon followed. Moons could be habitable worlds in their own right but also influence the habitability of planets they orbit. Besides from habitability, discovering moons would provide rich insights into the formation and evolution of planetary systems, potentially revealing the banality/uniqueness of our own solar system’s architecture.

  • Astronomy seminar: "Reverse Engineering the local Universe"

    David Rittenhouse Laboratory

    Edoardo Carlesi, IAP Potsdam

    Constrained simulations (CS) provide a powerful alternative approach to the random-phase Initial Conditions (ICs) cosmological simulations. In this method, galaxy peculiar velocity measurements are used to reconstruct the matter density field and generate a set of ICs whose final outcome closely matches the observed Universe. Hence, while the results obtained with the standard techniques can be compared to the data in a statistical sense only, in a CS we can exploit the constraining potential of the high-precision near-field observations by means of a direct comparison. 

  • Astronomy seminar: "Stellar Forensics with the Most Powerful Explosions in the Universe"

    David Rittenhouse Laboratory, A6

    Maryam Modjaz, New York University

    Supernovae (SNe) and Long-duration Gamma-ray Bursts (GRBs) are exploding stars and constitute the most powerful explosions in the universe. Since they are visible over large cosmological distances, release elements heavier than Helium, and leave behind extreme remnants such as black holes, they are fascinating objects, as well as crucial tools for many areas of astrophysics, including cosmology.

  • Astronomy seminar: "Two instruments to start the new decade: HERA for 21cm cosmology and SPARCS to Monitor M-Dwarf flares affecting exoplanets"

    David Rittenhouse Laboratory, A6

    Daniel Jacobs, Arizona State University

    Two new kinds of instruments are coming of age at the end of this decade: low frequency radio telescopes and cubesats, both being used to probe questions of our cosmic origin and the nature of exoplanets. The redshifted 21 cm hydrogen line is a unique probe of the early universe. A recent putative detection by EDGES, of a larger than expected signal, raises more questions. The Hydrogen Epoch of Reionization Array (HERA) is designed to answer these questions by providing high significance detection of fluctuations in the redshift range 6 to 20.

  • 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)