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Main Authors: Magi, Matteo, Yoo, Jaiyul
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2401.15143
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author Magi, Matteo
Yoo, Jaiyul
author_facet Magi, Matteo
Yoo, Jaiyul
contents Cosmological probes constructed in large-scale surveys are independent of the underlying theory of gravity, and their relativistic descriptions are indeed applicable to any theory of gravity. It was shown that the presence of fluctuations with wavelength much larger than the characteristic scales of the surveys has no impact on cosmological probes, if the matter content is adiabatic and the Einstein equations are used. In this paper we study the sensitivity of cosmological probes to infrared fluctuations in Horndeski theory. We find that the extra degree of freedom in the Horndeski scalar field can induce sensitivity to infrared fluctuations in the cosmological probes, even when the matter components are adiabatic on large scales. A generalized adiabatic condition including the extra dof, in contrast, guarantees that cosmological probes are devoid of infrared sensitivity, and this solution corresponds to the adiabatic modes à la Weinberg in Horndeski theory, which can be removed by a coordinate transformation in the infrared limit. We discuss the implications of our findings and the connections to the initial conditions.
format Preprint
id arxiv_https___arxiv_org_abs_2401_15143
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Infrared Sensitivity of Cosmological Probes in Horndeski Theory
Magi, Matteo
Yoo, Jaiyul
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
Cosmological probes constructed in large-scale surveys are independent of the underlying theory of gravity, and their relativistic descriptions are indeed applicable to any theory of gravity. It was shown that the presence of fluctuations with wavelength much larger than the characteristic scales of the surveys has no impact on cosmological probes, if the matter content is adiabatic and the Einstein equations are used. In this paper we study the sensitivity of cosmological probes to infrared fluctuations in Horndeski theory. We find that the extra degree of freedom in the Horndeski scalar field can induce sensitivity to infrared fluctuations in the cosmological probes, even when the matter components are adiabatic on large scales. A generalized adiabatic condition including the extra dof, in contrast, guarantees that cosmological probes are devoid of infrared sensitivity, and this solution corresponds to the adiabatic modes à la Weinberg in Horndeski theory, which can be removed by a coordinate transformation in the infrared limit. We discuss the implications of our findings and the connections to the initial conditions.
title Infrared Sensitivity of Cosmological Probes in Horndeski Theory
topic Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
url https://arxiv.org/abs/2401.15143