Bulletin of the American Physical Society
88th Annual Meeting of the Southeastern Section of the APS
Volume 66, Number 16
Thursday–Saturday, November 18–20, 2021; University Center Club, Florida State University, Tallahassee, Florida
Session S02: Multimessenger Astrophysics and Cataclysmic Events III |
Hide Abstracts |
Chair: Kent Yagi, University of Virginia Room: Pensacola |
Saturday, November 20, 2021 11:00AM - 11:30AM |
S02.00001: Synthesis of intermediate mass elements in massive stars Invited Speaker: Jeffrey Blackmon Understanding the origins of elements between iron and tin is challenging due to the large number of astrophysical sites that contribute. The weak s process that occurs during carbon burning in massive stars is a main contributor, but the abundances produced are very sensitive to neutron capture cross sections. New measurements of cross sections on stable zinc and germanium isotopes were conducted using the Detector for Advanced Neutron Capture Experiments. Measurements up to 1 MeV neutron energy allow the energy dependence of the Maxwellian-averaged cross sections to be accurately determined. Results will be presented with implications for our understanding of the origins of intermediate mass isotopes. [Preview Abstract] |
Saturday, November 20, 2021 11:30AM - 11:45AM |
S02.00002: 3D PIC Simulations for Relativistic Jets with a Toroidal Magnetic Field Kenichi Nishikawa We have investigated the evolution of relativistic jets self-consistently with Particle-in-Cell simulations. An important key issue is how a toroidal magnetic field affects the evolution of an e$^{\pm \, }$and an e$^{-}$-p$+$ jet, how kinetic instabilities such as the Weibel instability (WI), the mushroom instability (MI) and the kinetic Kelvin-Helmholtz instability (kKHI) are excited, and how such instabilities contribute to particle acceleration. We present that WI, MI and kKHI excited at the linear stage, generate a quasi-steady \textunderscore \textunderscore -component of electric field which accelerates and decelerates electrons. In this talk, we use a new jet injection scheme where an electric current is self-consistently generated at the jet orifice by the jet particles. We inject both e$^{\pm \, }$and and e$^{-}$-p$^{+}$ jets with a toroidal magnetic field (with a top-hat jet density profile) and for a sufficiently long time in order to examine the non-linear effects of the jet evolution. We find that different jet compositions present different strongly excited instability modes. The magnetic field in the non-linear stage generated by different instabilities becomes dissipated and reorganized into a new topology. The 3D magnetic field topology indicates possible reconnection sites and the accelerated particles are significantly accelerated in the non-linear stage by the dissipation of the magnetic field and/or reconnection. This study will shed further light on the nature of astrophysical relativistic magnetized jet phenomena. [Preview Abstract] |
Saturday, November 20, 2021 11:45AM - 12:00PM |
S02.00003: Neutron Stars in Scalar-Tensor Theories: Analytic Scalar Charges and Universal Relations Michael Stepniczka, Kent Yagi Neutron stars are ideal astrophysical sources to probe general relativity due to their large compactnesses and strong gravitational fields. For example, binary pulsar and gravitational wave observations have placed stringent bounds on certain scalar-tensor theories in which a massless scalar field is coupled to the metric through matter. A remarkable phenomenon of neutron stars in such scalar-tensor theories is spontaneous scalarization, where a normalized scalar charge remains order unity even if the matter-scalar coupling vanishes asymptotically far from the neutron star. On the other hand, certain quasi-universal relations have been found for global quantities of neutron stars (such as the moment of inertia and quadrupole moment) that are insensitive to the underlying equations of state. While most works on scalarization of neutron stars focus on numerical analysis, we derive accurate scalar charges \textit{analytically}, providing ready-to-use expressions for scalar charges in massless scalar-tensor theories. We also find a new quasi-universal relation in these theories between the scalar charge and stellar binding energy (related to stellar compactness) and give mathematical support for this relation. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700