NYU Arts & Science
Astrophysics and Relativity Seminars
January 23, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Marilena Loverde
Stony Brook University

Neutrinos, Quintessence and Structure Formation in the Universe

The large-scale structure of our universe (the distribution of galaxies on very large-scales for instance) contains a wealth of information about the origin, evolution, and matter content of the universe. Extracting this information relies crucially on understanding how galaxies and other biased objects trace the large-scale matter distribution. In a universe such as our own, with both cold dark matter and massive neutrinos, or in alternative cosmologies with clustered quintessence, this problem is much more complicated. I will discuss new tools that my group has developed to study gravitational evolution in cosmologies with multiple fluids, the novel signatures we have identified including a new probe of neutrino mass, and the broader implications for models of large-scale structure.


January 30, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Jennifer Barnes
Columbia University

Welcome to the multi-messenger era: a report on the first binary neutron star merger detection

On August 17th, the gravitational wave detectors LIGO and Virgo observed for the first time the signature of a binary neutron star merger. Roughly two seconds later, the Fermi satellite detected a short gamma-ray burst whose location was consistent with the position of the gravitational wave source. These signals triggered an electromagnetic follow-up campaign by dozens of groups around the world, who quickly identified an electromagnetic counterpart, which was observed over the next several weeks at energies ranging from the x-ray to the radio. These observations allowed astronomers to construct a detailed picture of an event that had previously been studied only theoretically, and to test key theories about the nature of neutron star mergers. Among these is whether mergers are the astrophysical site of r-process nucleosynthesis, which produces roughly half of elements heavier than iron. I will give an overview of the electromagnetic observations of this system, with an emphasis on the optical and infrared emission (the "kilonova") powered by the radioactive decay of elements synthesized in the merger. I will outline how recent theoretical advances allowed us to interpret kilonova observations and decode signs of heavy element production.


February 6, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Phil Armitage
University of Colorado

Tidal disruption at home and abroad

Upcoming surveys of the transient sky are expected to discover large numbers of events in which stars are tidally disrupted by supermassive black holes. Among this bounty it may be possible to identify events where the black hole is part of a binary system, providing a new route to finding close supermassive black hole binaries. I will show the results of simulations of tidal disruption by close binaries, and discuss how such events may be understood and isolated. Closer to home, I will argue that the odd properties of the first interstellar visitor to the Solar System, Oumuamua, could point to it being a fragment of a larger body tidally disrupted by a giant planet during ejection from an extrasolar planetary system.


February 13, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Ryan Foley
UC Santa Cruz

TBA (dark energy/supernovae)



February 20, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Viviana Acquaviva
City University of New York

TBA (galaxy surveys; machine learning)



February 27, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Chiara Mingarelli
Simons Center for Computational Astrophysics

TBA (supermassive black holes; gravitational waves)



March 6, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Chang Feng
Universit of Illinois - Urbana-Champaign

TBA (large-scale structure)



March 13, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)

No Astro Seminar (spring break)



March 20, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Lina Necib
Caltech

Empirical Determination of the Dark Matter Velocity Distribution

Using the hydrodynamic simulation Eris, we found that the kinematics of dark matter follows closely the kinematics of old metal poor stars, present in the Milky Way's stellar halo. We use this correspondence to obtain the first empirical measurement of the local velocity distribution of dark matter, by analyzing the Gaia data and computing the velocity distribution of metal poor stars. We find that this velocity distribution is peaked at lower velocities than the generally assumed Maxwell Boltzmann distribution, leading to a weakening of direct detection limits at dark matter masses less than 10 GeV by almost a factor of two. We also found a few kinematic outliers in the stellar data that might be hints of dark matter substructure.


March 27, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Jackie Faherty
AMNH

TBA (low-mass stars)



April 3, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Chris Hayward
Flatiron Institute

TBA (galaxy formation)



April 17, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Ilsedore Cleeves
Center for Astronomy - Harvard University

TBA (proto-planetary disks)



May 1, 2018 Tuesday 2:00 PM  +
726 Broadway, 940, CCPP Seminar
Astrophysics and Relativity Seminars (astro)


Ben Farr
University of Oregon

TBA (LIGO, neutron stars)