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Your search keyword '"Chael, A."' showing total 506 results
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506 results on '"Chael, A."'

501. Probing sub-GeV dark matter-baryon scattering with cosmological observables.

Author

Weishuang Linda Xu, Dvorkin, Cora, and Chael, Andrew

Subjects
*PHYSICS periodicals, *BARYONS, *SCATTERING (Physics)
Abstract

We derive new limits on the elastic scattering cross section between baryons and dark matter using cosmic microwave background data from the Planck satellite and measurements of the Lyman-alpha forest flux power spectrum from the Sloan Digital Sky Survey. Our analysis addresses generic cross sections of the form σ ∝ vn, where v is the dark matter-baryon relative velocity, allowing for constraints on the cross section independent of specific particle physics models. We include high-ℓ polarization data from Planck in our analysis, improving over previous constraints. We apply a more careful treatment of dark matter thermal evolution than previously done, allowing us to extend our constraints down to dark matter masses of ~MeV. We show in this work that cosmological probes are complementary to current direct detection and astrophysical searches. [ABSTRACT FROM AUTHOR]

Published
2018
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503. Reliability and Validity of the International Physical Activity Questionnaire for Assessing Walking.

Author

van der Ploeg, Hidde P., Tudor-Locke, Catrine, Marshall, Alison L., Craig, Cora, Hagstromer, Marla, Sjöström, M/chael, and Bauman, Adrian

Subjects
*QUESTIONNAIRES, *HUMAN locomotion, *PHYSICAL fitness, *WALKING, *METHODOLOGY
Abstract

The article provides information on the International Physical Activity Questionnaire (IPAQ). It examines the validity and reliability issues of the questionnaire and cites its relevance in evaluating public health through walking exercise. It notes the methodological approaches as well as tools used in the walking assessment. The results of the questionnaire are also highlighted.

Published
2010
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506. Gravitational Test beyond the First Post-Newtonian Order with the Shadow of the M87 Black Hole.

Author

Psaltis D, Medeiros L, Christian P, Özel F, Akiyama K, Alberdi A, Alef W, Asada K, Azulay R, Ball D, Baloković M, Barrett J, Bintley D, Blackburn L, Boland W, Bower GC, Bremer M, Brinkerink CD, Brissenden R, Britzen S, Broguiere D, Bronzwaer T, Byun DY, Carlstrom JE, Chael A, Chan CK, Chatterjee S, Chatterjee K, Chen MT, Chen Y, Cho I, Conway JE, Cordes JM, Crew GB, Cui Y, Davelaar J, De Laurentis M, Deane R, Dempsey J, Desvignes G, Dexter J, Eatough RP, Falcke H, Fish VL, Fomalont E, Fraga-Encinas R, Friberg P, Fromm CM, Gammie CF, García R, Gentaz O, Goddi C, Gómez JL, Gu M, Gurwell M, Hada K, Hesper R, Ho LC, Ho P, Honma M, Huang CL, Huang L, Hughes DH, Inoue M, Issaoun S, James DJ, Jannuzi BT, Janssen M, Jiang W, Jimenez-Rosales A, Johnson MD, Jorstad S, Jung T, Karami M, Karuppusamy R, Kawashima T, Keating GK, Kettenis M, Kim JY, Kim J, Kim J, Kino M, Koay JY, Koch PM, Koyama S, Kramer M, Kramer C, Krichbaum TP, Kuo CY, Lauer TR, Lee SS, Li YR, Li Z, Lindqvist M, Lico R, Liu J, Liu K, Liuzzo E, Lo WP, Lobanov AP, Lonsdale C, Lu RS, Mao J, Markoff S, Marrone DP, Marscher AP, Martí-Vidal I, Matsushita S, Mizuno Y, Mizuno I, Moran JM, Moriyama K, Moscibrodzka M, Müller C, Musoke G, Mus Mejías A, Nagai H, Nagar NM, Narayan R, Narayanan G, Natarajan I, Neri R, Noutsos A, Okino H, Olivares H, Oyama T, Palumbo DCM, Park J, Patel N, Pen UL, Piétu V, Plambeck R, PopStefanija A, Prather B, Preciado-López JA, Ramakrishnan V, Rao R, Rawlings MG, Raymond AW, Ripperda B, Roelofs F, Rogers A, Ros E, Rose M, Roshanineshat A, Rottmann H, Roy AL, Ruszczyk C, Ryan BR, Rygl KLJ, Sánchez S, Sánchez-Arguelles D, Sasada M, Savolainen T, Schloerb FP, Schuster KF, Shao L, Shen Z, Small D, Sohn BW, SooHoo J, Tazaki F, Tilanus RPJ, Titus M, Torne P, Trent T, Traianou E, Trippe S, van Bemmel I, van Langevelde HJ, van Rossum DR, Wagner J, Wardle J, Ward-Thompson D, Weintroub J, Wex N, Wharton R, Wielgus M, Wong GN, Wu Q, Yoon D, Young A, Young K, Younsi Z, Yuan F, Yuan YF, and Zhao SS

Abstract

The 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements. We use numerical calculations of regular, parametric, non-Kerr metrics to identify the common characteristic among these different parametrizations that control the predicted shadow size. We show that the shadow-size measurements place significant constraints on deviation parameters that control the second post-Newtonian and higher orders of each metric and are, therefore, inaccessible to weak-field tests. The new constraints are complementary to those imposed by observations of gravitational waves from stellar-mass sources.

Published
2020
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