11:00 am–12:00 pm ERC 401
Title: Using Mira Variables for Cosmological Distance Measurements
Abstract: The present-day expansion rate of the universe, known as the Hubble Constant, is one of the few directly measurable cosmological parameters. In recent years, the persistent disagreement between the value of the Hubble Constant obtained from direct distance-ladder measurements to nearby galaxies and the value inferred from observations of the Cosmic Microwave Background (CMB), assuming a standard Lambda-CDM cosmological model, has become one of the strongest indications of new physics. While the most precise distance ladder currently uses Cepheids, independent measurements of distances made with other standard candles can serve as a cross-check for systematics in distance measurements, helping to either solidify or resolve the tension.
One such alternative precision distance indicator and calibrator of Type Ia supernovae (SNe) is Mira variables – highly evolved, asymptotic giant branch stars – which are astrophysically distinct from the more commonly used Cepheids or the Tip of the Red Giant Branch (TRGB). In addition to being highly luminous and ubiquitous, Miras can be detected and characterized using only near-infrared and infrared observations, which is particularly advantageous in the era of the JWST and the Roman. In my talk, I will discuss the current progress in the development of the Mira distance ladder and its Hubble Constant measurements, with a focus on recent HST and JWST observations of Mira variables in M101, the nearest recent host galaxy of a Type Ia supernova.
Zoom: https://uchicago.zoom.us/j/96477534182?pwd=ypU41Y4kOxRWO3cSRImezBYtv75UGH.1
