Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session X09: Supernovae and Tidal Disruption EventsOn Demand
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Sponsoring Units: DAP Room: Roosevelt 4 |
Tuesday, April 21, 2020 10:45AM - 10:57AM On Demand |
X09.00001: Improving Cosmology Measurements with Type Ia Supernova Spectral Time Series Greg Aldering Type Ia supernovae (SNe Ia) continue to be a leading probe for cosmology - able to measure the dark energy equation of state, growth of structure, and the Hubble constant. A limitation to their accuracy is that the standardization methods are empirical, with residual unexplained dispersion that leaves open the door for differences in dust extinction or progenitor properties that can be confused with cosmology parameters. The seriousness of this issue is illustrated by the correlations with SN host galaxy properties that remain after the application of current standardization methods. The sample of spectrophotometric time series of nearby SNe Ia obtained by the Nearby Supernova Factory has proven able to address a number of these issues. We will present new cosmology constraints based on this dataset, and discuss several new insights and results that can make SNe Ia an even more powerful probe. In particular, we find that the unexplained dispersion can be cut in half, and that the residual correlations of SN luminosity with host galaxy properties are greatly reduced, by locating SNe Ia in a 3D non-linear space. We also demonstrate the ability to obtain excellent flux calibration (to 0.5 percent RMS). These insights will be invaluable for on-going and upcoming SN cosmology surveys. [Preview Abstract] |
Tuesday, April 21, 2020 10:57AM - 11:09AM |
X09.00002: CSP-II SE-SNe spectroscopy in the NIR Melissa Shahbandeh, Eric Hsiao, Peter Hoeflich, Chris Ashall I will present a sample of 109 near-infrared (NIR) spectra of 40 Stripped Envelope Core Collapse Supernovae (SESNe), obtained by the Carnegie Supernova Project II (CSP-II). This diverse dataset constitutes the largest NIR sample of SESNe. NIR spectroscopy provides a unique probe for SN physics with several advantages over observations in the optical. Specifically, the H I and C I lines are stronger and more isolated in the NIR. This advantage combined with our large sample allows us to investigate long-standing issues. For example, are SNe Ic truly stripped of their helium or are their helium shells not being sufficiently excited by gamma-rays? We found that all subclasses show a strong profile at 1.05 micron. By using different constraints including velocity and line strength of this feature for selected SNe within the sample, we show that the 1.05 micron feature is most probably carbon in Type Ic SNe. This result indicates that in SNe Ic there is no significant amount of helium shell present. We also detect CO in 8 SNe within the sample, which appears as early as 50 days. CO is an effective cooler and can help us understand the dust production in SESNe. [Preview Abstract] |
Tuesday, April 21, 2020 11:09AM - 11:21AM Not Participating |
X09.00003: Proto-neutron star convection in 3D supernova simulations Hiroki Nagakura, Adam Burrows, David Radice, David Vartanyan It has been suggested that the envelope of proto-neutron star (PNS) is convectively unstable during the development of core-collapse supernova (CCSN) explosion. The PNS convection appears from the early post bounce phase and persists for a long time (\textgreater 1s) whether the shock wave is revived or not - thus it would be a generic feature in all massive stellar death including a case with black hole formation. This could also affect the neutrino - gravitational wave signals, magnetic field amplification in PNS and explosion mechanism of CCSN. However, we know little about the physics of PNS convection since detailed analyses with 3D CCSN models are required to build a comprehensive understanding of the complex dynamics: it has not been done thus far. In this talk I will present a result of our systematic study of PNS convection in 3D CCSN simulations and then discuss the basic characteristics and diversity of PNS convection. [Preview Abstract] |
Tuesday, April 21, 2020 11:21AM - 11:33AM Not Participating |
X09.00004: A Parametric Study of the SASI in 2D: Newtonian vs. GR Hydrodynamics Samuel Dunham, Eirik Endeve, Anthony Mezzacappa, Kelly Holley-Bockelmann Core-collapse supernovae involve multiple branches of physics, all of which interact with each other to produce explosions that populate the universe with elements and produce neutrinos and gravitational waves. One of these branches is hydrodynamics (HD), which is important because some HD instabilities are widely believed to play important roles in the reenergization of the stalled shock. One such instability is the standing accretion shock instability (SASI) (Blondin et al., 2003, ApJ, 548, 971), a phenomenon that is at first best understood using only HD. Using our new code, \texttt{thornado} (Endeve et al., 2019, J. Phys.: Conf. Ser. 1225 012014), we perform a new parameter study of the SASI using (1) Runge-Kutta discontinuous-Galerkin (Cockburn \& Shu, 2001, JSC, 16, 3) methods to obtain high-order accurate results and (2) general relativity (GR). We investigate and discuss growth rates and oscillation frequencies of the SASI in the linear regime and compare amongst the different models. More specifically, we focus on the differences in the evolution of the SASI when using non-relativistic vs. GRHD, and choose values of the parameters (e.g., mass of the proto-neutron star) to reflect typical conditions in the shock-revival phase, as well as to enhance the effects of GR. [Preview Abstract] |
Tuesday, April 21, 2020 11:33AM - 11:45AM Not Participating |
X09.00005: Multimessenger Asteroseismology of Core-Collapse Supernovae John Ryan Westernacher-Schneider, Evan O'Connor, Erin O'Sullivan, Irene Tamborra, Meng-Ru Wu, Sean M. Couch, Felix Malmenbeck We identify the proto-neutron star mode responsible for imprint on both gravitational waves and neutrinos in simulations using an eigenfunction matching procedure. This procedure reveals an unphysical enhancement of mode frequencies in pseudo-Newtonian simulations. We find evidence that the mechanism of imprint on neutrinos is via direct hydrodynamic modulation of the neutrinospheres. [Preview Abstract] |
Tuesday, April 21, 2020 11:45AM - 11:57AM |
X09.00006: Galactic Supernova Neutrino Detection with the NOvA Detectors Justin Vasel, Andrey Sheshukov, Alec Habig Detectors around the world are poised to measure the neutrino flux from the next galactic core-collapse supernova in unprecedented detail and to shed light on the hitherto poorly-understood dynamics involved in these explosions, and on the nature of the neutrino itself. Because complete neutrino flavor sensitivity will be critical for extracting valuable physics insights from such an observation, a diverse array of capable detectors is desirable. NOvA is a long-baseline neutrino oscillation experiment designed to measure a neutrino beam with energies narrowly-peaked around 2 GeV. For a 27 solar mass supernova at 10 kpc, several thousand MeV-scale neutrino interactions are expected to occur in NOvA’s liquid scintillator near and far detectors. Measuring these neutrinos requires overcoming several challenges: the supernova neutrino spectrum is close to detection threshold, the far detector is subject to a large cosmic muon flux, and each interaction generates a small number of depositions which can resemble electronic noise. In this talk, I present recent work in addressing these challenges to enable NOvA to make a measurement of the neutrino flux from the next galactic core-collapse supernova. [Preview Abstract] |
Tuesday, April 21, 2020 11:57AM - 12:09PM On Demand |
X09.00007: On The general characteristics of neutrino-driven outflows Payel Mukhopadhyay Neutrino signal from the next galactic supernova may carry in it imprints of the matter profile features that fall in the density range of $\sim 10^3$ g/cm$^3$. The features in question include discontinuities and small-scale fluctuations, which are caused by shocks and turbulent mixing. A well-discussed example is the shockwave expanding through the envelope of the star, which reaches the relevant densities a few seconds after the onset of the explosion. Here, however, we focus on the shocks and turbulent mixing occurring in the post-shock region, in the hot bubble created by neutrino-driven outflows from the surface of the proto-neutron star. Extending the traditional treatment of supersonic neutrino winds, we establish physical criteria for the formation of the termination shock, which depend on the parameters of the explosions, such as the neutrino luminosity, proton-neutron star radius and mass, and the postshock density. For realistic physical conditions, the system is found to be on the edge of shock formation, thus reconciling seemingly disparate numerical results in the literature and providing a sensitive probe of the inner workings of the supernova. [Preview Abstract] |
Tuesday, April 21, 2020 12:09PM - 12:21PM On Demand |
X09.00008: The CEvNS Glow of a Supernova in Large Underground Detectors Adryanna Smith Coherent elastic neutrino-nucleus scattering (CEvNS) is a neutral-current process in which a neutrino scatters off an entire nucleus, depositing a tiny recoil energy. The process has high rate but low energy deposition. It is especially interesting for supernova burst detection in that it allows measurement of properties of all flavor components of the supernova burst. This talk will discuss prospects for detection of the CEvNS component of a supernova neutrino burst in existing and future large neutrino detectors. [Preview Abstract] |
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