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Published on: September 11, 2019
Backreaction during inflation: a physical gauge invariant formulation.
F Finelli1, G Marozzi, G P Vacca
1INAF/IASF Bologna, Istituto di Astrofisica Spaziale e Fisica Cosmica di Bologna via Gobetti 101, I-40129 Bologna, Italy.
Physical Review Letters
|April 27, 2011
Summary
We investigate quantum backreaction from scalar fluctuations during cosmic inflation. Free-falling observers experience no backreaction under specific conditions, impacting effective Hubble rate and fluid equation of state.
Area of Science:
- Cosmology
- Quantum Field Theory
- General Relativity
Background:
- Cosmological backreaction is crucial for understanding the universe's evolution.
- Previous studies often lacked gauge invariance, limiting their applicability.
- Scalar fluctuations during inflation are a key area of research.
Purpose of the Study:
- To compute cosmological backreaction in a genuinely gauge-invariant manner.
- To analyze the impact of scalar fluctuations on spacetime dynamics during inflation.
- To identify conditions under which observers experience no scalar-induced backreaction.
Main Methods:
- Development of a novel, genuinely gauge-invariant approach.
- Utilizing effective equations to describe averaged geometry dynamics.
- Analysis within a cosmological inflationary context.
Main Results:
- A gauge-independent computation of quantum backreaction is achieved.
- The impact of long-wavelength scalar fluctuations on spacetime is quantified.
- Conditions are derived where free-falling (geodetic) observers show no scalar-induced backreaction.
Conclusions:
- The developed gauge-invariant method provides a robust framework for cosmological backreaction studies.
- Understanding observer-dependent backreaction is essential for accurate cosmological models.
- Specific conditions can render scalar-induced backreaction negligible for certain observers.
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