Bulletin of the American Physical Society
Annual Meeting of the APS Four Corners Section
Volume 60, Number 11
Friday–Saturday, October 16–17, 2015; Tempe, Arizona
Session D2: Cosmology I |
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Chair: Tanmay Vachaspati, Arizona State University Room: MU230 |
Friday, October 16, 2015 1:50PM - 2:02PM |
D2.00001: \textsc{THE EFFECT OF EARLY SUPERNOVAE ON THE COSMIC MICROWAVE BACKGROUND RADIATION} Brandon Vernon, Joseph Smidt, David Neilsen The first atoms formed about 380,000 years after the big bang, making the universe largely transparent to photons. These photons from the early universe are observable today in the cosmic microwave background (CMB) radiation. The first stars that formed were the massive population iii stars, and supernovae from these first stars interacted with the cmb through the sunyaev-zel'dovish effect: high energy electrons from supernova explosions scatter with cmb photons, boosting their energy through inverse compton scattering. We are investigating the effect of early supernovae on the cmb using a halo model to predict the power spectrum of the SZ effect on the cmb. We will discuss the halo model and some preliminary results of this research. [Preview Abstract] |
Friday, October 16, 2015 2:02PM - 2:14PM |
D2.00002: A Tale of Two Timescales: Mixing, Mass Generation, and Phase Transitions in the Early Universe Jeff Kost, Keith Dienes, Brooks Thomas Light scalar fields such as axions and string moduli can play an important role in early-universe cosmology. However, many factors can significantly impact their late-time cosmological abundances. For example, in cases where the potentials for these fields are generated dynamically --- such as during cosmological mass-generating phase transitions --- the duration of the time interval required for these potentials to fully develop can have significant repercussions. Likewise, in scenarios with multiple scalars, mixing amongst the fields can also give rise to an effective timescale that modifies the resulting late-time abundances. Previous studies have focused on the effects of either the first or the second timescale in isolation. In our study, by contrast, we examine the new features that arise from the interplay between these two timescales when both mixing and time-dependent phase transitions are introduced together. As a result, we find new possibilities for early-universe phenomenology and cosmological evolution, and highlight the importance of taking into account the time dependence associated with phase transitions in cosmological settings. [Preview Abstract] |
Friday, October 16, 2015 2:14PM - 2:26PM |
D2.00003: How General are Gravitational Wave Predictions from Preheating after Inflation? Jeffrey Hyde A period of early universe inflation resolves several questions left unexplained in standard big bang cosmology, but its realization will require new ideas beyond the Standard Model of particle physics. In particular, an open question is the nature of the process known as reheating, by which the coherent state of the field responsible for inflation evolves into a thermal state of Standard Model particles. Since this involves interactions at very high energies, it is interesting to ask whether there are any observable effects that may survive until today, allowing us to study this energy scale - far above the what is accessible to colliders - empirically. Some work has predicted gravitational wave production during a brief “preheating” phase, that could in principle be observable. I’ll describe my work showing that these predictions can depend enormously on interactions of the decay products that previous studies have largely ignored. This suggests that existing predictions may not be reliably extrapolated to realistic models. On the other hand, identifying the effect of various terms is a useful first step towards finding a way to extract insight into the underlying model, should this gravitational wave spectrum be measured. [Preview Abstract] |
Friday, October 16, 2015 2:26PM - 2:38PM |
D2.00004: Gravity from the Thermodynamics of Spacetime Andrew Svesko, Maulik Parikh There is a paradigm shift underway in our understanding of gravity: Gravity might not be a fundamental force at all. The intense theoretical study of black hole thermodynamics has led to the radical idea that gravity, and perhaps spacetime itself, might be only an emergent phenomenon. That is, gravity might emerge in a macroscopic, thermodynamic limit of some underlying microscopic theory, in roughly the way that the macroscopic fluidity of water emerges from microscopic molecules of $H_{2}O$. Applying $dQ = T\delta S$, where $S$ is given by the entropy formula for a black hole, I will show how to derive the classical equations of Einstein's theory of general relativity, as well as some of its generalizations, directly from the first law of thermodynamics. This result provides evidence that the origin of gravity is thermodynamics. [Preview Abstract] |
Friday, October 16, 2015 2:38PM - 3:02PM |
D2.00005: Vacuum Solutions in Pure Quadratic Gravity Invited Speaker: Damien Easson I will present new traversable wormhole and non-singular black hole solutions in pure, scale-free, quadratic gravity. These solutions require no null energy condition violating or "exotic" matter and are supported only by the vacuum of the theory. The solutions are found when the conformal transformation required to move to the dual Einstein frame is singular. Solutions in this case are argued to arise in the strong coupling limit of General Relativity. [Preview Abstract] |
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