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Updated: Jun 23, 2025
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The Generation of Higher-order Laguerre-Gauss Optical Beams for High-precision Interferometry
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Time-Delay Cosmography: Measuring the Hubble Constant and Other Cosmological Parameters with Strong Gravitational
S Birrer1,2, M Millon2,3, D Sluse4
1Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 USA.
Space Science Reviews
|June 20, 2024
Summary
Time-delay cosmography uses light travel time differences in lensed images to measure cosmic distances and the Hubble constant. This method offers a precise alternative to other techniques, potentially resolving the Hubble tension.
Area of Science:
- Cosmology
- Astrophysics
- Gravitational Lensing
Background:
- Multiply lensed images of the same source exhibit time delays due to path length and gravitational potential differences.
- These time delays are a consequence of general relativity and the structure of the universe.
- Measuring these delays allows for independent calculations of cosmological parameters.
Purpose of the Study:
- To detail the methodology of time-delay cosmography.
- To review recent advances and results in the field.
- To provide an outlook for future precision measurements of the Hubble constant.
Main Methods:
- Utilizing the time delay of photons arriving from multiply lensed quasars or galaxies.
- Analyzing the path length differences and gravitational potential variations experienced by photons.
- Cross-correlating light curves of lensed images to determine time delays.
Main Results:
- Time-delay cosmography provides precise and competitive measurements of the Hubble constant ().
- The method is independent of local distance ladders and early-universe physics.
- Upcoming observations promise a 1% precision measurement of .
Conclusions:
- Time-delay cosmography is a powerful tool for measuring the Hubble constant.
- It has the potential to resolve the current 'Hubble tension'.
- Future advancements will provide increasingly accurate cosmological measurements.
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