CWRU PAT Coffee Agenda

Tuesdays 10:30 - 11:30 | Fridays 11:30 - 12:30

+2 BICEP / Keck XIII: Improved Constraints on Primordial Gravitational Waves using Planck, WMAP, and BICEP/Keck Observations through the 2018 Observing Season.

gds6 +1 oxg34 +1

+1 Accurate relativistic observables from post-processing light cone catalogues.

bump   cjc5 +1

+1 Minimal theory of massive gravity and constraints on the graviton mass.

oxg34 +1

+1 Mapping Spatially Varying Additive Biases in Cosmic Shear Data.

ixz6 +1

Showing votes from 2021-10-01 12:30 to 2021-10-05 11:30 | Next meeting is Friday Sep 19th, 11:30 am.

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astro-ph.CO

  • Accurate relativistic observables from post-processing light cone catalogues.- [PDF] - [Article]

    Chi Tian, Matthew F. Carney, James B. Mertens, Glenn Starkman
     

    We introduce and study a new scheme to construct relativistic observables from post-processing light cone data. This construction is based on a novel approach, LC-Metric, which takes general light cone or snapshot output generated by arbitrary N-body simulations or emulations and solves the linearized Einstein equations to determine the spacetime metric on the light cone. We find that this scheme is able to determine the metric to high precision, and subsequently generate accurate mock cosmological observations sensitive to effects such as post-Born lensing and nonlinear ISW contributions. By comparing to conventional methods in quantifying those general relativistic effects, we show that this scheme is able to accurately construct the lensing convergence signal. We also find the accuracy of this method in quantifying the ISW effects in the highly nonlinear regime outperforms conventional methods by an order of magnitude. This scheme opens a new path for exploring and modeling higher-order and nonlinear general relativistic contributions to cosmological observables, including mock observations of gravitational lensing and the moving lens and Rees-Sciama effects.

  • Minimal theory of massive gravity and constraints on the graviton mass.- [PDF] - [Article]

    Antonio De Felice, Shinji Mukohyama, Masroor C. Pookkillath
     

    The Minimal theory of Massive Gravity (MTMG) is endowed non-linearly with only two tensor modes in the gravity sector which acquire a non-zero mass. On a homogeneous and isotropic background the theory is known to possess two branches: the self-accelerating branch with a phenomenology in cosmology which, except for the mass of the tensor modes, exactly matches the one of $\Lambda$CDM; and the normal branch which instead shows deviation from General Relativity in terms of both background and linear perturbations dynamics. For the latter branch we study using several early and late times data sets the constraints on today's value of the graviton mass $\mu_{0}$, finding that $(\mu_{0}/H_{0})^{2}=0.119_{-0.098}^{+0.12}$ at $68\%$ CL, which in turn gives an upper bound at $95\%$ CL as $\mu_{0}<8.4\times10^{-34}$ eV. This corresponds to the strongest bound on the mass of the graviton for the normal branch of MTMG.

  • Mapping Spatially Varying Additive Biases in Cosmic Shear Data.- [PDF] - [Article]

    T. D. Kitching, A. C. Deshpande, P. L. Taylor
     

    In this paper we address the challenge of extracting maps of spatially varying unknown additive biases from cosmic shear data. This is done by exploiting the isotropy of the cosmic shear field, and the anisotropy of a typical additive bias field, using an autocorrelation discrepancy map. We test this approach using simulations and find that the autocorrelation discrepancy map produces spatially varying features that are indicative of the additive bias field both in amplitude and spatial variation. We then apply this to the Dark Energy Survey Year 1 data, and find evidence for spatially varying additive biases of at most 0.002 on large scales. The method can be used to empirically inform modelling of the spatially varying additive bias field in any cosmological parameter inference, and can act as a validation test for cosmic shear surveys.

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