Bulletin of the American Physical Society
2016 Annual Meeting of the Far West Section
Volume 61, Number 17
Friday–Saturday, October 28–29, 2016; Davis, California
Session F1: Astrophyics |
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Chair: Patricia Sparks, Harvey Mudd College Room: Ball Room A |
Friday, October 28, 2016 2:00PM - 2:12PM |
F1.00001: CMB delensing for detecting primordial B-mode Signal Zhen Pan, Ethan Anderes, Lloyd Knox One of the major targets for next-generation CMB experiments is the detection of the primordial B-mode signal. Planning is under way for Stage-IV experiments that are projected to have instrumental noise small enough to make lensing and foregrounds the dominant source of uncertainty for estimating the tensor-to-scalar ratio $r$ from polarization maps. This makes delensing a crucial part of future CMB polarization science. In this paper we will present two likelihood methods for estimating the tensor-to-scalar ratio $r$ from CMB polarization observations. These two methods combine the benefits of a full scale likelihood approach with the tractability of the quadratic delensing technique. The first method probes high frequency primordial B-mode fluctuations via a pixel space local likelihood approximation. The second method is a pixel space, all order likelihood analysis of the low frequency (high signal-to-noise) quadratic delensed B-modes. The tractability of both methods relies on a crucial factorization of the pixel space covariance matrix of the polarization observations which allows one to compute the full likelihood profile, as a function of $r$, at the same computational cost of a single likelihood evaluation. [Preview Abstract] |
Friday, October 28, 2016 2:12PM - 2:24PM |
F1.00002: Gravitational lensing with a twist: E and B-modes in the Lynx deep field Andrew Bradshaw, James Jee, Tony Tyson In the single thin-lens approximation for gravitational lensing, correlations in the galaxy shear field can simply be described by the gradient of the projected surface mass density along the line of sight. Thus only E-modes are produced through lensing, and typically any nonzero observed B-modes (curl component of the field) are attributed to systematic errors in the observing or data analysis. However, as we show, under realistic observing conditions the shear field can have an observable B-mode. Here we present a deep, multi-band galaxy shape & photometric redshift catalog going out to a redshift of z~2 (B/V/R/i/z ~ 26th magnitude) in the Lynx field, which is rich with galaxy clusters around redshift of z~0.5. Multiple clusters in the field are detected as peaks in the E-mode map, and are subsequently cataloged and simulated. Additionally, we present and speculate on our detection of observed B-modes which are observed in multiple bandsâ€™ shape catalogs and in non-zero shape correlation functions. [Preview Abstract] |
Friday, October 28, 2016 2:24PM - 2:36PM |
F1.00003: A Model for Axions Producing Extended gamma-ray Emission from Neutron Star J0108-1431 Bijan Berenji Axions are hypothetical particles proposed to solve the strong CP problem in QCD and may constitute a significant fraction of the dark matter in the Universe. Axions are expected to be produced in neutron stars and subsequently decay, producing gamma-rays detectable by the Fermi Large Area Telescope (Fermi-LAT). Considering that light axions may travel a long range before they decay into gamma rays, neutron stars may appear as a spatially-extended source of gamma rays. We extend our previous search for gamma rays from axions, based on a point source model, to consider the neutron star as an extended source of gamma rays. present including the fundamental astrophysics and relativistic, extended gamma-ray emission from axions around neutron stars. A Monte Carlo simulation of the LAT gives us an expectation for the extended angular profile and spectrum. We predict a mean angular spread of 0.8 degrees with energies in the range 30-200 MeV. We consider projected sensitivities for mass limits on axions from J0108-1431, a neutron star at a distance of 240 pc, arange not probed by observations before.~ Based on the extended angular profile of the source, the expected sensitivity of the 95{\%} CL upper limit on the axion mass from J0108-1431 is \textgreater 10 meV. [Preview Abstract] |
Friday, October 28, 2016 2:36PM - 2:48PM |
F1.00004: Compact and extended objects from self-interacting phantom fields John Scott, Douglas Singleton, Vladimir Dzhunushaliev, Vladimir Folomeev, Arislan Makhmudov, Ainur Urazalina In this talk we discuss localized and extended objects for gravitating, self-interacting phantom fields. The phantom fields come from two scalar fields with a ``wrong sign" kinetic energy term in the Lagrangian. This study covers several solutions supported by these phantom fields: phantom balls, traversable wormholes, phantom cosmic strings, and ``phantom" domain walls. We will focus mostly on the wormhole solutions. [Preview Abstract] |
Friday, October 28, 2016 2:48PM - 3:00PM |
F1.00005: Little Conformal Symmetry Houtz Rachel, Kitran Colwell, John Terning We explore a new class of natural models which ensure the one-loop divergences in the Higgs mass are cancelled. The top-partners that cancel the top loop are new gauge bosons, and the symmetry relation that ensures the cancellation arises at an infrared fixed point. Such a cancellation mechanism can, a la Little Higgs models, push the scale of new physics that completely solves the hierarchy problem up to 5-10 TeV. When embedded in a supersymmetric model, the stop and gaugino masses provide the cutoffs for the loops, and the mechanism ensures a cancellation between the stop and gaugino mass dependence of the Higgs mass parameter. [Preview Abstract] |
Friday, October 28, 2016 3:00PM - 3:12PM |
F1.00006: Quantum Field Theory of Interacting Dark Matter/Dark Energy: Dark Monodromies Teresa Hamill, Guido D'Amico, Nemanja Kaloper We discuss how to formulate a quantum field theory of dark energy interacting with dark matter. We show that the proposals based on the assumption that dark matter is made up of heavy particles with masses which are very sensitive to the value of dark energy are strongly constrained. Quintessence-generated long range forces and radiative stability of the quintessence potential require that such dark matter and dark energy are completely decoupled. However, if dark energy and a fraction of dark matter are very light axions, they can have significant mixings which are radiatively stable and perfectly consistent with quantum field theory. Such models can naturally occur in multi-axion realizations of monodromies. The mixings yield interesting signatures which are observable and are within current cosmological limits but could be constrained further by future observations. [Preview Abstract] |
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