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Friday, February 1st 2019

11:00 am:

Friday, February 8th 2019

11:00 am:

Friday, February 15th 2019

11:00 am:

Friday, February 22nd 2019

11:00 am:

Friday, March 1st 2019

11:00 am:

Friday, March 8th 2019

11:00 am:

Friday, March 15th 2019

11:00 am:

Friday, March 22nd 2019

11:00 am:

Friday, March 29th 2019

11:00 am:

The intrinsically multi-dimensional neutrino-driven explosion mechanism of core-collapse supernovae (CCSNe) is notoriously difficult to model self-consistently.

As a matter of either computational expediency or necessity, nuclear burning, when included at all, is traditionally constrained to a small reaction network consisting only of the (α,γ) reactions necessary in linking 4He to 56Ni.

Feedback between the evolving hydrodynamics and changing composition, and resulting energy generation, precludes the deficiencies of this simplification from being entirely resolved with post-processing calculations.

Using a much more realistic, in situ reaction network capable of accurately tracking nuclear energy generation and neutronization, we examine the nucleosynthesis in multidimensional, self-consistent, neutrino-driven supernova models.

We find differences between the in situ and post-processing approaches, indicating that such rigor in evolving the nuclear composition is needed to accurately calculate the nucleosynthesis of matter that has been ejected from the inner regions of the explosion mechanism.

This has implications for some of the most interesting nucleosynthetic processes in CCSNe, specifically α-rich and α-poor freeze-out, which produces several isotopes particularly relevant to observations (e.g.44Ti, 48Ca, and 92Mo).

Thursday, April 4th 2019

1:30 pm:

We examine the prospects for coherent spin-transformations of Majorana neutrinos (i.e., neutrino-antineutrino transformations) in a core-collapse supernova environment. We observe that, under certain conditions, resonant effects can drive substantial neutrino-antineutrino conversion, with potential implications for subsequent flavor evolution as well as the neutron-to-proton ratio (equivalently, the electron fraction) of the material in the supernova envelope. We also investigate a nonlinear feedback mechanism that arises from the coupling between the neutrino distributions and the electron fraction, potentially assisting the stabilization of the resonance.

Friday, April 12th 2019

11:00 am:

Neutrino flavor conversions are known to play a very important role in core-collapse supernova explosions. Inside a supernova, neutrino density is so large that neutrino-neutrino interactions take place, giving rise to "collective oscillations" occurring with a rate much larger than the usual MSW flavor conversions. In this talk, I would like to discuss some of the interesting aspects of these rapid flavor conversions, and the impact they can have on supernova explosions and nucleosynthesis. Finally, I will also talk about a simple way of diagnosing the presence of these instabilities in large scale numerical simulations.

Friday, April 26th 2019

11:00 am:

I will discuss new strategies to discover or constrain dark matter using neutron stars and gravitational waves.

Friday, May 3rd 2019

11:00 am:

The rapid neutron capture process (r process) is responsible for the production of half of the elements heavier than iron that we observe in the Universe. The quest to identify its actual astrophysical site is still ongoing, but there are strong indications, including the recent observation of the GW170817 electromagnetic counterpart, that make neutron star mergers (NSM) a likely candidate. Reliable estimates of nucleosynthesis yields on NSM require an accurate description of the relevant nuclear physics inputs including nuclear masses, neutron capture rates, β- and α-decay rates and, for ﬁssioning nuclei, ﬁssion rates and ﬁssion fragments distributions. Several of these quantities can be computed from a consistent theoretical framework using the energy density functional (EDF) approach.

In this talk I will revise how uncertainties in the nuclear physics properties of neutron-rich nuclei impact nucleosynthesis calculations, with a focus in the ﬁssion properties of (super)heavy nuclei. I will present a new set of ﬁssion rates obtained from microscopic nuclear many-body calculations, which are used as a nuclear input in r-process nucleosynthesis calculations in NSM. The possible formation of superheavy elements during the r-process nucleosynthesis as well as the impact on kilonova light curve, a quasithermal transient powered by freshly synthesized r-process nuclei, will be discussed. Finally, I will introduce recent developments in the estimation of ﬁssion yields and the possible extension to r-process nuclei.

Friday, May 10th 2019

11:00 am:

Friday, May 17th 2019

11:00 am:

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