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Cross-bispectra constraints on modified gravity theories from the Nancy Grace Roman Space Telescope and the Rubin Observatory Legacy Survey of Space and Time

Heinrich, Chen and Dorè, Olivier (2020) Cross-bispectra constraints on modified gravity theories from the Nancy Grace Roman Space Telescope and the Rubin Observatory Legacy Survey of Space and Time. Physical Review D, 102 (12). Art. No. 123549. ISSN 2470-0010. doi:10.1103/physrevd.102.123549.

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One major goal of upcoming large-scale-structure surveys is to constrain dark energy and modified gravity theories. In particular, galaxy clustering and gravitational lensing convergence are probes sensitive to modifications of general relativity. While the standard analysis for these surveys typically includes power spectra or 2-point correlation functions, it is known that the bispectrum contains additional information that could offer improved constraints on parameters when combined with the power spectra. However, the use of bispectra has been limited so far to one single probe, e.g., the lensing convergence bispectrum or the galaxy bispectrum. In this paper, we extend the formalism to explore the power of cross-bispectra between different probes, and exploit their ability to break parameter degeneracies and improve constraints. We study this on a test case of lensing convergence and galaxy density auto- and cross-bispectra, for a particular subclass of Horndeski theories parametrized by the running of the Planck mass c_M and the braiding parameter c_B. Using the 2000  deg² notional survey of the Nancy Grace Roman Space Telescope with overlapping photometry from the Rubin Observatory Legacy Survey of Space and Time, we find that a joint power spectra and bispectra analysis with three redshift bins at l_(max) = 1000 yields σ_(cM) = 1.0 and σ_(cB) = 0.3, both a factor of ∼1.2 better than the power spectra results; this would be further improved to σ_(cM) = 0.7 and σ_(cB) = 0.2 if l_(max) = 3000 is taken. Furthermore, we find that using all possible cross-bispectra between the two probes in different tomographic bins improves upon auto-bispectra results by a factor of 1.3 in σ_(cM), 1.1 in σ_(cB), and 1.3 in σ_(Ωm). We expect that similar benefits of using cross-bispectra between probes could apply to other science cases and surveys.

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URLURL TypeDescription Paper
Heinrich, Chen0000-0003-0426-1948
Dorè, Olivier0000-0001-7432-2932
Additional Information:© 2020 American Physical Society. Received 19 June 2020; accepted 10 November 2020; published 31 December 2020. We thank Masahiro Takada, Bhuvnesh Jain, Wayne Hu, Tim Eifler, Atsushi Taruya, Ben Bose, Hiroyuki Tashiro, Hayato Motohashi, Zachary Slepian, Kris Pardo, and Agnes Ferté for useful discussions. We thank the Nancy Grace Roman Space Telescope Cosmology with the High Latitude Survey Science Investigation Team for providing feedback for this work and the redshift distributions used in the forecast. C. H. especially thanks Miguel Zumalacárregui for providing private versions of hi_class and guidance on using the software; C. H. also thanks Tessa Baker for sharing her personal notes on Horndeski theories. Part of this work was done at Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. California Institute of Technology. Government sponsorship acknowledged.
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Issue or Number:12
Record Number:CaltechAUTHORS:20210210-082014191
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:107979
Deposited By: Tony Diaz
Deposited On:10 Feb 2021 17:27
Last Modified:16 Nov 2021 19:07

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