Constraints on the Optical Depth of Galaxy Groups and Clusters
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Flender-2017-Constraints on the Optical Depth.pdf
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Author(s)
Flender, Samuel
Nagai, Daisuke
McDonald, Michael A.
Date Issued
March 2017
Journal
Astrophysical Journal
Publisher
IOP Publishing
Citation
Flender, Samuel; Nagai, Daisuke and McDonald, Michael. “Constraints on the Optical Depth of Galaxy Groups and Clusters.” The Astrophysical Journal 837, no. 2 (March 2017): 124 © 2017 The American Astronomical Society
Version
Final published version
Abstract
Future data from galaxy redshift surveys, combined with high-resolutions maps of the cosmic microwave background, will enable measurements of the pairwise kinematic Sunyaev–Zel'dovich (kSZ) signal with unprecedented statistical significance. This signal probes the matter-velocity correlation function, scaled by the average optical depth (τ) of the galaxy groups and clusters in the sample, and is thus of fundamental importance for cosmology. However, in order to translate pairwise kSZ measurements into cosmological constraints, external constraints on τ are necessary. In this work, we present a new model for the intracluster medium, which takes into account star formation, feedback, non-thermal pressure, and gas cooling. Our semi-analytic model is computationally efficient and can reproduce results of recent hydrodynamical simulations of galaxy cluster formation. We calibrate the free parameters in the model using recent X-ray measurements of gas density profiles of clusters, and gas masses of groups and clusters. Our observationally calibrated model predicts the average τ₅₀₀ (i.e., the integrated τ within a disk of size R ₅₀₀) to better than 6% modeling uncertainty (at 95% confidence level). If the remaining uncertainties associated with other astrophysical uncertainties and X-ray selection effects can be better understood, our model for the optical depth should break the degeneracy between optical depth and cluster velocity in the analysis of future pairwise kSZ measurements and improve cosmological constraints with the combination of upcoming galaxy and CMB surveys, including the nature of dark energy, modified gravity, and neutrino mass.
MIT Department
MIT Kavli Institute for Astrophysics and Space Research
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Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use.
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DOI of Published Version
https://doi.org/10.3847/1538-4357/aa60bf
