Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session H12: Astrophysical Neutrinos |
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Sponsoring Units: DAP Chair: John Matthews, University of Utah Room: 250DE |
Sunday, April 17, 2016 8:30AM - 8:42AM |
H12.00001: A Study of Spatially-Coincident IceCube Neutrinos and Fermi Gamma-Ray Sources Hannah Seymour, Reshmi Mukherjee, Michael Shaevitz, Marcos Santander The IceCube neutrino telescope has detected very-high-energy neutrino events with energies between several hundred TeV to a few PeV beginning inside the detector. These events are unlikely to have originated in the atmosphere, and are suspected to come from astrophysical sources, the likes of which can also be observed in gamma rays by the Fermi Gamma-Ray Space Telescope. We present an analysis of archival GeV gamma-ray data collected with the Large Area Telescope onboard the Fermi satellite to search for gamma-ray sources spatially coincident with the locations of high-enery muon neutrinos detected by IceCube. The combined detection of gamma rays and neutrinos from an astrophysical source will allow us to identify cosmic-ray acceleration sites. [Preview Abstract] |
Sunday, April 17, 2016 8:42AM - 8:54AM |
H12.00002: High Energy Atmospheric Neutrino Fluxes From a Realistic Primary Spectrum Felipe Campos Penha, Hans Dembinski, Thomas K. Gaisser, Serap Tilav Atmospheric neutrino fluxes depend on the energy spectrum of primary nucleons entering the top of the atmosphere. Before the advent of \textsl{AMANDA} and the \textsl{IceCube Neutrino Observatory}, measurements of the neutrino fluxes were generally below $\sim1\,\mathrm{TeV}$, a regime in which a simple energy power law sufficed to describe the primary spectrum. Now, \textsl{IceCube}'s muon neutrino data extends beyond $1\,\mathrm{PeV}$, including a combination of neutrinos from astrophysical sources with background from atmospheric neutrinos. At such high energies, the steepening at the knee of the primary spectrum must be accounted for. Here, we describe a semi-analytical approach for calculating the atmospheric differential neutrino fluxes at high energies. The input is a realistic primary spectrum consisting of 4 populations with distinct energy cutoffs, each with up to 7 representative nuclei, where the parameters were extracted from a global fit {[}\textsl{T. K. Gaisser, T. Stanev, and S. Tilav (2013)}{]}. We show the effect of each component on the atmospheric neutrino spectra, above $10\,\mathrm{TeV}$. The resulting features follow directly from recent air shower measurements included in the fit. [Preview Abstract] |
Sunday, April 17, 2016 8:54AM - 9:06AM |
H12.00003: A new method to constrain flavor ratio of astrophysical neutrinos Shirley Li, Mauricio Bustamante, John Beacom We are entering a new era of neutrino astronomy with the recent IceCube discovery of high-energy astrophysical neutrinos. Important questions, such as what their sources are, arise with these events. The flavor composition of these neutrinos has been identified as a rich observable, containing information about the production processes and neutrino properties. So far, only $\nu_\mu$ charged current interactions can be uniquely identified in IceCube. We propose new methods that can help identify $\nu_\tau$ events. Our method could significantly enhance the IceCube flavor measurement sensitivity, making it possible to tell if new physics is required to explain the flavor composition. [Preview Abstract] |
Sunday, April 17, 2016 9:06AM - 9:18AM |
H12.00004: The matter-neutrino resonance around thick disks Michael Deaton We are studying neutrino flavor transformations in typical neutron star merger environments. Here a dominance of $\bar{\nu}_e$ over $\nu_e$ fluxes introduces transformation behaviors qualitatively different from those seen in supernovae. Discovered in thin disk models, the matter neutrino resonance (MNR) may behave differently around thick disks, or not appear at all. I'll present what we have learned about the MNR using a phenomenological model motivated by hydrodynamical simulations of post-merger disks. [Preview Abstract] |
Sunday, April 17, 2016 9:18AM - 9:30AM |
H12.00005: Abstract Withdrawn
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Sunday, April 17, 2016 9:30AM - 9:42AM |
H12.00006: Choked Jets and Low-Luminosity Gamma-Ray Bursts as Hidden Neutrino Sources Nicholas Senno, Kohta Murase, Peter Mészáros I will discuss choked gamma-ray burst (GRB) jets as possible sources of very high-energy (VHE) cosmic neutrinos. The jet propagation physics and radiation constraints are taken into account. We find that efficient shock acceleration of cosmic rays inside a high density stellar environment is possible for sufficiently low-powered jets and/or jets buried in an extended optically think envelope. Such conditions are favorable also for the GRB jets to become stalled. Such choked jets may explain transrelativistic SNe or low-luminosity GRBs by launching quasi-spherical shocks that breakout in the optically thick wind. Focusing on this possibility, we calculate the resulting diffuse neutrino spectra using the latest results of the local llGRB rate and luminosity function. We confirm that llGRBs can potentially give a significant contribution to the measured neutrino flux. The results are compatible with the IceCube (IC) data around 10-100 TeV without contradicting other IC limits on classical GRBs. Choked and llGRBs are dark in GeV-TeV gamma rays, and do not contribute significantly to the Fermi diffuse gamma-ray background. Precursor TeV neutrinos emerging prior to the shock breakout emission can be used as smoking gun evidence for a choked jet model for llGRBs. [Preview Abstract] |
Sunday, April 17, 2016 9:42AM - 9:54AM |
H12.00007: Propagation of neutrinos in hot and dense media samina masood We study the propagation of neutrinos in hot and dense media of stellar systems as well as in the very early universe. Our emphasis is on the study of the basic properties of neutrinos with tiny mass and their interactions with the hot and dense media. We also discuss the relevance of our results to astrophysics and cosmology. [Preview Abstract] |
Sunday, April 17, 2016 9:54AM - 10:06AM |
H12.00008: Two Dimensional Simulations of Core-Collapse Supernovae with Neutrino Transport in FLASH Evan O'Connor, Sean Couch Core-collapse supernovae are the end stage of massive star evolution and are central to many aspects of astrophysics. They are the birth site of both neutron stars and black holes and their shocks are responsible for spreading the products of stellar evolution throughout the Galaxy and regulating star formation. Despite their importance and decades of research, the precise mechanism that converts the initial implosion of the collapsing iron core to an explosion that unbinds the majority of the star is unknown. However, we know that the majority of the energy released is ultimately radiated in neutrinos and that the physics of neutrino transport and neutrino heating-among many other aspects-must be treated carefully when modelling the core-collapse supernova central engine. In this talk, I will present recent simulations of core-collapse supernovae from the FLASH hydrodynamics code. We perform two dimensional, neutrino transport simulations using several progenitors. We test the influence of general relativity by using a pseudorelativistic potential that effectively models GR. We show that the more compact protoneutron star predicted from GR increases the neutrino heating and can lead to explosions where the corresponding Newtonian simulations fail. [Preview Abstract] |
Sunday, April 17, 2016 10:06AM - 10:18AM |
H12.00009: Overview of the ANITA-III Long-duration Balloon Payload Flight and the Improvements in the ANITA-IV Scheduled Mission Viatcheslav Bugaev The high-altitude balloon-borne Antarctic Impulsive Transient Antenna mission (ANITA) was designed to detect cosmogenic neutrinos using radio impulses generated via the Askaryan effect in the Antarctic ice. ANITA is also sensitive to geomagnetic emission from ultra-high energy cosmic rays as well. ANITA-III was launched from McMurdo, Antarctica on December 17th, 2014 and flew for 23 days. We present preliminary analysis results of the data collected during this period. Preparations for the ANITA-IV campaign are underway, with the expected flight in December 2016. We provide an overview of the ANITA-IV instrument, which has significant improvements in hardware. These will reduce neutrino energy threshold by $50-60\%$ compared to ANITA-III, moving the sensitive energy range closer to the peak of the cosmogenic neutrino spectrum. [Preview Abstract] |
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