2023/02/28 by Richard I. Anderson, Anderson, Richard I.
Physics and Astronomy · Engineering · #Astronomy and Astrophysical Research #Astronomical Observations and Instrumentation #Scientific Research and Discoveries
paper · pdf · doi:10.48550/arxiv.2302.14379
The extragalactic distance scale is perhaps the most important application of stellar distance indicators. Among these, classical Cepheids are high-accuracy standard candles that support a 1.4% measurement of Hubble's constant, H0. The accuracy of Cepheid distances is thus directly relevant for understanding the implications of the Hubble tension, the >5σ discord among direct, late-Universe H0 measurements and H0 values inferred from the early Universe observations assuming ΛCDM cosmology. This invited review aims to provide an accessible overview of the state of the art distance ladder that has established the Hubble tension, with a focus on Cepheids, their absolute calibration using trigonometric parallaxes from the ESA mission Gaia, and other Cepheid-related systematics. New observational facilities such as JWST and upcoming large surveys will provide exciting avenues to further improve distance estimates based on Cepheids.