5 papers
Converging on the Cepheid Metallicity Dependence: Implications of Non-Standard Gaia Parallax Recalibration on Distance Measures
Louise Breuval, Gagandeep S. Anand, Richard I. Anderson +20
By comparing Cepheid brightnesses with geometric distance measures including Gaia EDR3 parallaxes, most recent analyses conclude metal-rich Cepheids are brighter, quantified as $γ…
The Perfect Host: JWST Cepheid Observations in a Background-Free SN Ia Host Confirm No Bias in Hubble-Constant Measurements
Adam G. Riess, Siyang Li, Gagandeep S. Anand +8
Cycle 1 JWST observations of Cepheids in SN Ia hosts resolved their red-giant-dominated NIR backgrounds, sharply reducing crowding and showing that photometric bias in lower-resolu…
Tip of the Red Giant Branch Distances with JWST. II. I-band Measurements in a Sample of Hosts of 10 SN Ia Match HST Cepheids
Siyang Li, Gagandeep S. Anand, Adam G. Riess +7
The Hubble Tension, a >5 sigma discrepancy between direct and indirect measurements of the Hubble constant (H0), has persisted for a decade and motivated intense scrutiny of the pa…
The Hubble constant anchor galaxy NGC 4258: metallicity and distance from blue supergiants
Rolf-Peter Kudritzki, Miguel A. Urbaneja, Fabio Bresolin +5
A quantitative spectroscopic study of blue supergiant stars in the Hubble constant anchor galaxy NGC 4258 is presented. The non-LTE analysis of Keck I telescope LRIS spectra yields…
JWST Validates HST Distance Measurements: Selection of Supernova Subsample Explains Differences in JWST Estimates of Local H0
Adam G. Riess, Dan Scolnic, Gagandeep S. Anand +16
JWST provides new opportunities to cross-check the HST Cepheid/SNeIa distance ladder, which yields the most precise local measure of H0. We analyze early JWST subsamples (~1/4 of t…