New Parallaxes of Galactic Cepheids from Spatially Scanning the Hubble Space Telescope: Implications for the Hubble Constant

By A. Riess, S. Casertano, W. Yuan, Lucas Macri, Jay Anderson, J. Mackenty, J. B. Bowers, K. Clubb, A. Filippenko, David O. Jones and 1 more. 2018

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We present new measurements of the parallax of seven long-period (≥10 days) Milky Way (MW) Cepheid variables (SS CMa, XY Car, VY Car, VX Per, WZ Sgr, X Pup, and S Vul) using one-dimensional astrometric measurements from spatial scanning of Wide-Field Camera 3 on the Hubble Space Telescope (HST). The observations were obtained at ∼6 month intervals over 4 years. The distances are 1.7–3.6 kpc, with a mean precision of 45 μas (signal-to-noise ratio (S/N) ≈ 10) and a best precision of 29 μas (S/N = 14). The accuracy of the parallaxes is demonstrated through independent analyses of >100 reference stars. This raises to 10 the number of long-period Cepheids with significant parallax measurements, 8 obtained from this program. We also present high-precision mean F555W, F814W, and F160W magnitudes of these Cepheids, allowing a direct, zeropoint-independent comparison to >1800 extragalactic Cepheids in the hosts of 19 SNe Ia. This sample addresses two outstanding systematic uncertainties affecting prior comparisons of MW and extragalactic Cepheids used to calibrate the Hubble constant (H0): their dissimilarity of periods and photometric systems. Comparing the new parallaxes to their predicted values derived from reversing the distance ladder gives a ratio (or independent scale for H0) of 1.037 ± 0.036, consistent with no change and inconsistent at the 3.5σ level with a ratio of 0.91 needed to match the value predicted by Planck cosmic microwave background data in concert with ΛCDM. Using these data instead to augment the Riess et al. measurement of H0 improves the precision to 2.3%, yielding 73.48 ± 1.66 km s−1 Mpc−1, and the tension with Planck + ΛCDM increases to 3.7σ. The future combination of Gaia parallaxes and HST spatial scanning photometry of 50 MW Cepheids can support a <1% calibration of H0.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/272cd4d4e527d1867eecc404aacfbc01ff4681f8

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Citations in the corpus

Baryon acoustic oscillations from the cross-correlation of Lyα absorption and quasars in eBOSS DR14 (2019, methodology): “Nevertheless, as previously noted (Aubourg et al. 2015; Addison et al. 2018), the combination of BAO and nucleosynthsis provides a CMB-free confirmation of the tension with the distance-ladder determinations of H0 (Riess et al. 2016, 2018a,b).”
Interacting scenarios with dynamical dark energy: Observational constraints and alleviation of the H0 tension (2019, result): “…independently of the combination of datasets considered, the estimated values of the Hubble parameter H0 are greater compared to the ΛCDM-based Planck’s estimation [117] and close to the local measurements of H0 from Riess et al. 2016 [118], Riess et al. 2018 [119] and Riess et al. 2019 [113].”
Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data (2018, background): “The reported 3.7σ tension of H0 between Planck and the local measurement (Riess et al. 2018) reduces to 3.1σ by adding our cosmic shear measurement.”
Dark, cold, and noisy: constraining secluded hidden sectors with gravitational waves (2018, unknown): “In view of the current tension between the high and low redshift measurements of the Hubble parameter H0 (see [23] and references therein), this bound may be considered somewhat too strong.”
Hubble Tension: The Evidence of New Physics (2023, background): “After that, the SH0ES project, which started in 2005, also produces many H0 results [34,35,39,129].”
New physics in light of the H0 tension: An alternative view (2019, background): “more updated local measurements of H0 have become available [20, 22], which have actually worsened the H0 tension.”