Bulletin of the American Physical Society
Fall 2021 Meeting of the APS New England Section
Volume 66, Number 9
Friday–Saturday, October 22–23, 2021; Virtual; Eastern Time
Session A01: Contributed Session I |
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Chair: Richard Price, MIT |
Friday, October 22, 2021 5:00PM - 5:15PM |
A01.00001: X-raying the Sub-lightyear Environment of Supermassive Black Holes Mislav Balokovic, Meg Urry, Samatha Cabral, Laura Brenneman, Tristan Weaver The innermost environment of supermassive black holes (SMBH) are often hidden from our view by the gas and dust surrounding it on larger spatial scales. They are too small in terms of angular size on the sky to resolve with nearly any modern telescope. However, the X-ray radiation produced in the immediate vicinity of the SMBH allows us to probe the larger-scale components shaped by the tenuous balance between inflows and outflows of matter. Recent studies of active galactic nuclei (AGN) in the nearby universe placed interesting constraints on the geometry of these systems using X-ray data. The percentage of sightlines to the SMBH covered by significant amounts of gas was found to non-monotonically depend on luminosity. We are further probing this relationship using self-consistent multi-epoch spectral analyses, which we will demonstrate using new X-ray data on a high-luminosity quasar and a low-luminosity AGN. In the latter case we find a uniform, nearly spherical, low-density distribution of gas on sub-lightyear scales, similar to recent results for other low-luminosity AGN. We will also show how very long baseline interferometry measurements can inform building of new X-ray spectral models for angularly unresolved signatures of the SMBH environment geometry in the X-ray band. [Preview Abstract] |
Friday, October 22, 2021 5:15PM - 5:30PM |
A01.00002: Diurnal Variation in Cosmic Rays Lindsay Yatsuhashi, Fiona Willette, Tomohiko Narita A diurnal variation is the change in the amount of cosmic rays that reach Earth throughout the day. Due to the Sun's rotation and magnetic field, we expect to see more muons during the daytime and less muons, and therefore less cosmic rays, during the nighttime. Observing muons over many days allows us to look for these diurnal variations in cosmic rays. Cosmic rays are high energy particles that move at the speed of light and create a shower of muons and electrons when colliding with atoms in Earth's atmosphere. The muons that reach Earth's surface can be detected with a telescope composed of a scintillator and a photomultiplier tube. These telescopes record the number of muons that pass through, as well as the time each muon came through, and we can observe cosmic rays by observing the muons. By observing the muons for many days, we can look for diurnal variations in cosmic rays. From our experiments, we did not find evidence of a diurnal variation in cosmic rays.~ [Preview Abstract] |
Friday, October 22, 2021 5:30PM - 6:00PM |
A01.00003: Semiclassical Trans-Series from the Perturbative Hopf-Algebraic Dyson-Schwinger Equations Max Meynig, Gerald Dunne, Michael Borinsky The seminal work of Dirk Kreimer and Alaine Connes uncovered the structure underlying Renormalization in quantum field theory. This work has enabled perturbative calculations to incredibly high orders, notably the through the Hopf-approximation of the Dyson-Schwinger equations. We study the Hopf approximation to the Dyson-Schwinger equations for a $\phi^3$ theory in six dimensions. Our main new result is to decode the perturbative Hopf formulation to find a rich nonperturbative structure. Our results have the characteristics of semi-classical series involving instanton and anti-instanton interactions but arise from a purely perturbative formalism. [Preview Abstract] |
Friday, October 22, 2021 6:00PM - 6:15PM |
A01.00004: Resurgence and the Schwinger Effect Zachary Harris, Gerald Dunne Describing quantum systems in the presence of extreme electromagnetic fields is a very hard problem, one which defines the frontiers of many areas of research from astrophysics to non-linear optics. In this talk, I will explore the strong magnetic field regime and the complementary strong electric field regime for the Schwinger effect: the creation of particle-antiparticle pairs from vacuum. One of our best tools for solving hard problems is perturbation theory, but many of the phenomena of interest in systems with strong fields or interactions are non-perturbative. Moreover, even in systems of weak fields, perturbative expansions are generically divergent. Though it seems perturbation theory is completely inapplicable to these problems, it turns out that the divergence of the weak field expansions is deeply connected to the appearance of non-perturbative phenomena. These ideas can be used to construct remarkably accurate new extrapolations from the weak field to the strong field regime. [Preview Abstract] |
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