Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session E2: Supernovae, Supernova Remnants, and Other Galactic Sources |
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Sponsoring Units: DAP Chair: Terri Brandt, NASA Room: Holiday 1 |
Saturday, April 11, 2015 3:30PM - 3:42PM |
E2.00001: The First Fermi-LAT Supernova Remnant Catalog T. J. Brandt The Fermi Gamma-ray Space Telescope's Large Area Telescope (Fermi-LAT) has shed new light on many types of Galactic objects, including many individual Supernova Remnants (SNRs). The spectral detection of hadronic gamma-ray emission from two SNRs, suggesting acceleration of cosmic ray (CR) protons, is an example of individual studies providing clues to characteristics that may be common to all SNRs. To uniformly determine SNR properties, we have developed the first systematic survey of SNRs from 1 to 100 GeV. From the 279 known radio SNRs, we found more than 100 GeV candidates, 31 of which are likely and 14 of which are marginally counterparts. These candidates span a wide range of multiwavelength properties, providing a critical context for complementary, in depth individual studies. Modeling this multiwavelength data demonstrates the need for improvements to previously sufficient, simple models describing the GeV and radio emission from hadronic and leptonic particle populations in these objects. Together with the $>$240 upper limits on GeV emission at the radio position and extension, our results also enable us to indirectly constrain SNRs' aggregate ability to accelerate CRs, and with direct measurements, will additionally enable a better understanding of CR origins. [Preview Abstract] |
Saturday, April 11, 2015 3:42PM - 3:54PM |
E2.00002: Searching for the highest energy gamma rays from Nova V339 Del with Fermi-LAT and MAGIC Elizabeth Hays The detection of gamma-ray emission from several classical novae by the Fermi Large Area Telescope suggests that these thermonuclear explosions in our Galaxy routinely accelerate particles to high energy. Although the observation of shocked material associated with the ejecta provides feasibility for gamma-ray production, the mechanism driving the acceleration is not yet well understood and the maximum energy attained, speculated to be up to a TeV, is not known. Coordinated observations of LAT-detected novae conducted by very-high-energy telescopes offer a chance to probe the energies reached in these explosive and relatively nearby events. I will present the results of joint studies between the Fermi-LAT and MAGIC, covering in particular the extended outburst detected by LAT from Nova V339 Del in 2013. [Preview Abstract] |
Saturday, April 11, 2015 3:54PM - 4:06PM |
E2.00003: Towards Multimessenger Pulsar Astronomy: A Search for Periodic Gravitational Waves from Fermi-LAT Unassociated Sources in LIGO S6 Data J.R. Sanders Gravitational waves from rotating neutron stars are interesting sources for advanced ground-based gravitational wave detectors. Observations of these signals have the potential to advance many ongoing problems in pulsar astronomy, including the discovery of radio-quiet pulsars. I discuss ongoing work on a fully coherent directed search for continuous gravitational waves in LIGO S6 data, targeting a subset of unassociated sources from the Fermi 2FGL catalog selected by spectral characteristics and high galactic latitude. This search demonstrates a framework for using gravitational wave searches of unidentified gamma-ray objects, including sources with coarse position uncertainty, to detect new pulsars in our galaxy. [Preview Abstract] |
Saturday, April 11, 2015 4:06PM - 4:18PM |
E2.00004: Observing Gamma-Ray Sources along the Galactic Plane with HAWC Hugo Ayala The High Altitude Water Cherenkov (HAWC) observatory is located in Sierra Negra, Mexico at 4100 m above sea level and will be inaugurated in March 2015. It is an array of 300 water Cherenkov detectors each containing 4 photomultiplier tubes that detect the Cherenkov light in the water produced by the secondary particles from extensive air showers. The design allows to measure high-energy gamma rays in the energy range of 100 GeV to 100 TeV. Science of the partial array has already started in 2013. Preliminary gamma-ray sky maps have been produced. The strongest features of these maps are located on the galactic plane as expected. Some event excesses are collocated with known TeVCat source while there are also previously undetected features. I will present preliminary results of the analysis of gamma-ray sources along the galactic plane. [Preview Abstract] |
Saturday, April 11, 2015 4:18PM - 4:30PM |
E2.00005: Reconstructing core-collapse supernovae waveforms with advanced era interferometers Jessica McIver Among of the wide range of potentially interesting astrophysical sources for Advanced LIGO and Advanced Virgo are galactic core-collapse supernovae. Although detectable core-collapse supernovae have a low expected rate (a few per century, or less) these signals would yield a wealth of new physics in the form of many messengers. Of particular interest is the insight into the explosion mechanism driving core-collapse supernovae that can be gleaned from the reconstructed gravitational wave signal. A well-reconstructed waveform will allow us to assess the likelihood of different explosion models, perform model selection, and potentially map unexpected features to new physics.~ This talk will present a study evaluating the current performance of the reconstruction of core-collapse supernovae gravitational wave signals. We used simulated waveforms modeled after different explosion mechanisms that we first injected into fake strain data re-colored to the expected Advanced LIGO/Virgo noise curves and then reconstructed using the pipelines Coherent Waveburst 2G and BayesWave. We will discuss the impact of these results on our ability to accurately reconstruct core-collapse supernovae signals, and by extension, other potential astrophysical generators of rich, complex waveforms. [Preview Abstract] |
Saturday, April 11, 2015 4:30PM - 4:42PM |
E2.00006: Neutrino-driven turbulent convection in stalled supernova cores David Radice, Christian Ott, Ernazar Abdikamalov, Sean Couch, Roland Haas, Erik Schnetter The dynamics of neutrino-driven turbulent convection, in the quasi-steady phases of a core-collapse supernova explosion following the shock stall, is emerging as being of crucial importance in aiding, or hindering, a successful explosion. In this talk I will present some recent and ongoing numerical studies done with the goal of of a) characterizing neutrino-driven convection in a simplified setting and b) understanding finite numerical resolution effects in more realistic explosion models. [Preview Abstract] |
Saturday, April 11, 2015 4:42PM - 4:54PM |
E2.00007: The Supernova Explosion Code (SNEC) Viktoriya Giryanskaya, Christian Ott, Anthony Piro, Mathieu Renzo, Sean Couch, Drew Clausen, Justin Ellis, Luke Roberts We present the SuperNova Explosion Code (SNEC), an open-source Lagrangian code that solves for the hydrodynamics and equilibrium-diffusion radiation transport in the expanding envelopes of core-collapse supernovae (CCSNe), taking into account recombination effects and the presence of radioactive nickel. Given a model of the progenitor star and an explosion energy, the code generates the bolometric light curve, as well as the light curves in different observed wavelength bands in the blackbody approximation. Using SNEC, we present lightcurves resulting from explosions of a grid of pre-explosion stars (computed with the MESA code) whose hydrogen envelopes have been systematically stripped to different extents and at different points of their evolution. [Preview Abstract] |
Saturday, April 11, 2015 4:54PM - 5:06PM |
E2.00008: Analytic Closure Relations in M1 Neutrino Radiation Transport in Core-Collapse Supernovae Elena Murchikova, Christian D. Ott, Ernazar Abdikamalov, Evan O'Connor, John Wendell, Todd Urbatsch Neutrinos play a crucial role in core-collapse supernova explosions. They deposit energy in the region behind the stalled shock and aid its revival. Moreover, together with gravitational waves, they are the only messengers that provide us with information from the supernova core. Full neutrino transport is a 6+1 dimensional problem and efficient yet accurate approximations are necessary to include neutrino transport in simulations. One approximation that has recently become popular is the M1 radiation transport scheme, which solves equations for the first two angular moments of the transport equation and closes the expansion with an analytic closure based on values of the first two moments. The quality of the M1 approximation depends on the quality of the chosen closure relation and it is not a priori clear, which closure to chose under which circumstances. We carry out an extensive study of closure relations available in the literature and compare M1 results to full Monte Carlo transport solutions in the context of spherically-symmetric core-collapse supernovae. We consider post-core-bounce configurations at multiple different times and study the dependence of the physical closure relation (obtained with Monte Carlo) on neutrino energy, species, and the background matter. [Preview Abstract] |
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