Bulletin of the American Physical Society
2017 Annual Meeting of the APS Mid-Atlantic Section
Volume 62, Number 19
Friday–Sunday, November 3–5, 2017; Newark, New Jersey
Session J5: Astro III: High Energy |
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Chair: David Spergel, Princeton / CCA at Flatiron Room: Atrium, Campus Center, NJIT |
Saturday, November 4, 2017 4:15PM - 4:51PM |
J5.00001: The Physics of Pulsar Magnetospheres Invited Speaker: Anatoly Spitkovsky Pulsars are rotating magnetized neutron stars that emit repeating pulses of radiation spanning all of the electromagnetic spectrum. 50 years after their discovery, more than 2000 pulsars are known, and they have been used as sensitive astronomical probes of diverse phenomena including the properties of interstellar medium and the predictions of general theory of relativity. Despite great observational successes, our theoretical understanding of how pulsar magnetospheres work and shine is woefully incomplete. Pulsars bring together aspects of classical and quantum electrodynamics, coupled with strongly magnetized plasma physics in curved rotating spacetimes of a massive compact object. The nonlinear interplay of these effects makes it a very difficult but rewarding problem to study. I will review the status and progress of pulsar magnetospheric modeling in various approximations, including force-free and relativistic magnetohydrodynamics, culminating with recent developments of fully kinetic simulations of pulsar magnetospheres. These simulations allow us to find the shape of the magnetosphere and the location and physics of particle acceleration regions, constraining the origin of high energy emission. The pulsar magnetosphere is a prototype for other strongly magnetized astrophysical objects, and I will discuss how the lessons from pulsar modeling can be useful in understanding the physics of black hole jets and in predicting electromagnetic counterparts to gravitational wave sources. [Preview Abstract] |
Saturday, November 4, 2017 4:51PM - 5:03PM |
J5.00002: Systematic Effects in the Measurement of Large Scale Anisotropies Lindsey Diehl, Miguel Mostafa The High Altitude Water Cherenkov (HAWC) Observatory detects cosmic rays and gamma rays in the multi-TeV energy range. An unexpected (and still unexplained) large scale anisotropy is observed in the spatial distribution of the arrival directions of cosmic rays at these very high energies. I studied the arrival directions of both cosmic rays and gamma rays detected with the HAWC Observatory as a function of their energy. This study will help with the understanding of systematic and detector effects on the measurement of the large scale anisotropy. [Preview Abstract] |
Saturday, November 4, 2017 5:03PM - 5:15PM |
J5.00003: Modeling the Distribution of Arrival Directions of Ultra-High-Energy Cosmic Rays with Physically Motivated Functions Aaron Kandel, Miguel Mostafa The study of ultra-high-energy cosmic rays (UHECR) comprises a significant area of inquiry in modern astrophysics research. While hypotheses regarding the origin of UHECR exist, their sources are still unknown. Ongoing research uses the distribution of arrival directions to validate or refute the different source(s) hypotheses. The goal of this project is to model the distribution of the arrival directions of the observed cosmic rays using a function that accounts for the shower-producing interactions of the particles with the atmosphere. Using data from the Pierre Auger Observatory, the applicability of the proposed function is evaluated through a statistical analysis. This development allows new research to apply a two-parameter function when evaluating and simulating the distributions of arrival directions of UHECR. [Preview Abstract] |
Saturday, November 4, 2017 5:15PM - 5:27PM |
J5.00004: Integrating Luminescent Concentrators into HAWC Brian Carvajal, Segev BenZvi The High-Altitude Water Cherenkov (HAWC) observatory measures high energy cosmic and gamma rays using Photomultiplier Tubes (PMTs) inside large water tanks. To reduce the cost of future water-Cherenkov observatories, we investigate methods of light collection to reduce the number of PMTs while maintaining the same level of sensitivity. A luminescent concentrator offers the possibility of collecting and directing light towards the detector at very low cost. We have designed and tested a prototype luminescent concentrator using Kuraray wavelength-shifting fibers. We report on the optical gain of the fiber concentrator measured in the laboratory. [Preview Abstract] |
Saturday, November 4, 2017 5:27PM - 5:39PM |
J5.00005: The Interplay of Opacities and Rotation in Promoting the Explosion Core-Collapse Supernovae David Vartanyan, Adam Burrows, David Radice For over five decades, the mechanism of explosion in core-collapse supernovae has been a central unsolved problem in astrophysics, challenging both our computational capabilities and our understanding of relevant physics. Current simulations often produce explosions, but they are at times underenergetic. The neutrino mechanism, wherein a fraction of emitted neutrinos is absorbed in the mantle of the star to reignite the stalled shock, remains the dominant model for reviving explosions in massive stars undergoing core collapse. We present here a diverse suite of 2D axisymmetric simulations produced by FORNAX, a highly parallelizable multidimensional supernova simulation code . We explore the effects of various corrections, including the many-body correction, to neutrino-matter opacities and the possible role of rotation in promoting explosion amongst various core-collapse progenitors. [Preview Abstract] |
Saturday, November 4, 2017 5:39PM - 6:15PM |
J5.00006: Asymmetric Planetary Nebulae as a Context for the Physics of Accretion, Outflows, and Binary Interactions Invited Speaker: Eric Blackman Accretion and outflows from astrophysical disks have long been studied both for the unifying or distinguishing physics in different contexts, and used in constructing phenomenological scenarios to explain observations of specific systems. I will first highlight some recent unifying lessons and fundamental grand challenges for accretion disk theory, and in particular regarding the role of magnetic fields and large scale transport. I will then describe how asymmetries seen in the end states of stellar evolution more likely involve accretion and binaries than previously thought. In the context of low mass stars, I will discuss some dramatic constraints on the outflow power and associated accretion rates required of these systems. This dovetails into progress in our ongoing efforts to understand broader questions of the orbital and accretion evolution of a giant star interacting with low mass companions or planets, the accretion rates incurred, and their ultimate fate in a common envelope. [Preview Abstract] |
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