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Cross-correlating Planck with VST ATLAS LRGs: a new test for the ISW effect in the Southern Hemisphere

Ansarinejad, Behzad; Mackenzie, Ruari; shanks, Tom; Metcalfe, Nigel

Cross-correlating Planck with VST ATLAS LRGs: a new test for the ISW effect in the Southern Hemisphere Thumbnail


Authors

Behzad Ansarinejad

Ruari Mackenzie



Abstract

The Integrated Sachs-Wolfe (ISW) effect probes the late-time expansion history of the universe, offering direct constraints on dark energy. Here we present our measurements of the ISW signal at redshifts of z¯=0.35⁠, 0.55 and 0.68, using the cross-correlation of the Planck CMB temperature map with ∼0.5 million Luminous Red Galaxies (LRGs) selected from the VST ATLAS survey. We then combine these with previous measurements based on WMAP and similar SDSS LRG samples, providing a total sample of ∼2.1 million LRGs covering ∼12000 deg2 of sky. At z¯=0.35 and z¯=0.55 we detect the ISW signal at 1.2σ and 2.3σ (or 2.6σ combined), in agreement with the predictions of ΛCDM. We verify these results by repeating the measurements using the BOSS LOWZ and CMASS, spectroscopically confirmed LRG samples. We also detect the ISW effect in three magnitude limited ATLAS+SDSS galaxy samples extending to z ≈ 0.4 at ∼2σ per sample. However, we do not detect the ISW signal at z¯=0.68 when combining the ATLAS and SDSS results. Further tests using spectroscopically confirmed eBOSS LRGs at this redshift remain inconclusive due to the current low sky coverage of the survey. If the ISW signal is shown to be redshift dependent in a manner inconsistent with the predictions of ΛCDM, it could open the door to alternative theories such as modified gravity. It is therefore important to repeat the high redshift ISW measurement using the completed eBOSS sample, as well as deeper upcoming surveys such as DESI and LSST.

Citation

Ansarinejad, B., Mackenzie, R., shanks, T., & Metcalfe, N. (2020). Cross-correlating Planck with VST ATLAS LRGs: a new test for the ISW effect in the Southern Hemisphere. Monthly Notices of the Royal Astronomical Society, 493(4), 4830-4844. https://doi.org/10.1093/mnras/staa592

Journal Article Type Article
Acceptance Date Feb 25, 2020
Online Publication Date Feb 28, 2020
Publication Date Apr 30, 2020
Deposit Date Mar 3, 2020
Publicly Available Date Mar 3, 2020
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 493
Issue 4
Pages 4830-4844
DOI https://doi.org/10.1093/mnras/staa592
Public URL https://durham-repository.worktribe.com/output/1306681

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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