Constraints on cosmic hemispherical power anomalies from quasars
Abstract
Recent analyses of the cosmic microwave background (CMB) maps from the WMAP satellite have uncovered evidence for a hemispherical power anomaly, i.e. a dipole modulation of the CMB power spectrum at large angular scales with an amplitude of ±14 percent. Erickcek et al have put forward an inflationary model to explain this anomaly. Their scenario is a variation on the curvaton scenario in which the curvaton possesses a large-scale spatial gradient that modulates the amplitude of CMB fluctuations. We show that this scenario would also lead to a spatial gradient in the amplitude of perturbations σ8, and hence to a dipole asymmetry in any highly biased tracer of the underlying density field. Using the high-redshift quasars from the Sloan Digital Sky Survey, we find an upper limit on such a gradient of |∇σ8|/σ8 < 0.027r_(lss)^(−1) (99% posterior probability), where r_(lss) is the comoving distance to the last-scattering surface. This rules out the simplest version of the curvaton spatial gradient scenario.
Additional Information
© 2009 IOP Publishing Ltd and SISSA. Received July 17, 2009. Accepted August 27, 2009. Published September 8, 2009. CH wishes to thank Y Shen for providing his quasar sample and associated mask files. CH also wishes to thank A Erickcek, M Kamionkowski, and Y Shen for their useful comments on the paper. CH is supported by the US Department of Energy under contract DE-FG03-02-ER40701, the National Science Foundation under contract AST-0807337, and the Alfred P Sloan Foundation. Funding for the Sloan Digital Sky Survey (SDSS) and SDSS-II has been provided by the Alfred P Sloan Foundation, the Participating Institutions, the National Science Foundation, the US Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, and the Max Planck Society, and the Higher Education Funding Council for England. The SDSS Web site is http://www.sdss.org/. The SDSS is managed by the Astrophysical Research Consortium (ARC) for the Participating Institutions. The Participating Institutions are the American Museum of Natural History, Astrophysical Institute Potsdam, University of Basel, University of Cambridge, Case Western Reserve University, The University of Chicago, Drexel University, Fermilab, the Institute for Advanced Study, the Japan Participation Group, The Johns Hopkins University, the Joint Institute for Nuclear Astrophysics, the Kavli Institute for Particle Astrophysics and Cosmology, the Korean Scientist Group, the Chinese Academy of Sciences (LAMOST), Los Alamos National Laboratory, the Max-Planck-Institute for Astronomy (MPIA), the Max-Planck-Institute for Astrophysics (MPA), New Mexico State University, Ohio State University, University of Pittsburgh, University of Portsmouth, Princeton University, the United States Naval Observatory, and the University of Washington.Attached Files
Submitted - 0907.0703
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- Eprint ID
- 16534
- Resolver ID
- CaltechAUTHORS:20091102-093731579
Related works
- Describes
- http://arxiv.org/abs/0907.0703 (URL)
Funding
- Department of Energy (DOE)
- DE-FG03-02-ER40701
- NSF
- AST-0807337
- Alfred P. Sloan Foundation
- Participating Institutions
- NASA
- Japanese Monbukagakusho
- Max Planck Society
- Higher Education Funding Council for England
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2009-11-02Created from EPrint's datestamp field
- Updated
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2022-07-12Created from EPrint's last_modified field
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