Calibrating the Tip of the Red Giant Branch and measuring Magellanic Cloud distances to 2% exclusively with Gaia

Abstract

We have calibrated the Tip of the Red Giant Branch (TRGB) using our recent catalog of homogeneous, high-accuracy Globular Cluster (GC) distances. The GC distances were determined by a global joint fit to optical period-Wesenheit relations of their member RR Lyrae stars and type-II Cepheids, anchored by trigonometric parallaxes; all data taken from the ESA Gaia mission's (early) third data release (GDR3). Using I-band measurements in 48 GCs from P. Stetson's database, we determined $M_{I,0}=-3.948_{-0.034}^{+0.037}$ mag (1.6% in distance). Calibrating the TRGB using Gaia's homogeneous, space-based RP photometry of 53 GCs, we found $M_{RP,0}=-3.807_{-0.035}^{+0.041}$ mag (1.8%). The stated uncertainties include statistical and systematic effects, including the correlated nature of the GC distances. The robustness of our calibrations is demonstrated via tests against small-number statistics and analysis choices. Specifically, we found no significant metallicity effect for our sample of old, low-metallicity GCs. We measured $\sim 2\%$ distances to the Large (LMC) and Small Magellanic Clouds (SMC), $18.447_{-0.042}^{+0.036}$ mag ($48.9\pm 0.9$ kpc) and $18.898_{-0.054}^{+0.049}$ mag ($60.2\pm 1.4$ kpc), respectively, using a single well calibrated photometric system: RP (spectro-)photometry from GDR3. Our new TRGB distances, whose absolute scale derives from Gaia parallaxes, are fully independent of the well-known detached eclipsing binary (DEB) distances and agree with them to within the uncertainties. Combining our new TRGB and existing DEB distances, we illustrate how additional constraints may be incorporated in the Local Distance Network and obtain $H_0=73.52\pm 0.80$ km/s/Mpc. Expected improvements due to the upcoming fourth Gaia data release are discussed.

Submitted. 4 pages plus appendix. Comments welcome!

References in corpus (24)

• The Gaia mission
• Gaia Data Release 3: Summary of the content and survey properties
• Gaia Early Data Release 3: The astrometric solution
• Gaia Early Data Release 3: Parallax bias versus magnitude, colour, and position
• Gaia Early Data Release 3: Photometric content and validation
• A distance to the Large Magellanic Cloud that is precise to one per cent
• Gaia EDR3 view on Galactic globular clusters
• Accurate distances to Galactic globular clusters through a combination of Gaia EDR3, HST and literature data
• An Improved Distance to NGC 4258 and its Implications for the Hubble Constant
• A distance determination to the Small Magellanic Cloud with an accuracy of better than 2 percent based on late-type eclipsing binary stars
• Gaia Data Release 3: External calibration of BP/RP low-resolution spectroscopic data
• OGLE-ing the Magellanic System: Optical Reddening Maps of the Large and Small Magellanic Cloud from Red Clump Stars
• Homogeneous photometry VII. Globular clusters in the Gaia era
• The Parallax of Omega Centauri Measured from Gaia EDR3 and a Direct, Geometric Calibration of the Tip of the Red Giant Branch and the Hubble Constant
• The Extragalactic Distance Database: The Color-Magnitude Diagrams and Tip of the Red Giant Branch Distances Catalog
• Gaia DR3: Specific processing and validation of all-sky RR Lyrae and Cepheid stars -- The Cepheid sample
• Sharpening the Tip of the Red Giant Branch
• Validation of the accuracy and precision of Gaia EDR3 parallaxes with globular clusters
• The Hubble Space Telescope Survey of M31 Satellite Galaxies I. RR Lyrae-based Distances and Refined 3D Geometric Structure
• The Local Distance Network: a community consensus report on the measurement of the Hubble constant at 1% precision
• A Gaia Data Release 3 View on the Tip of the Red Giant Branch Luminosity
• Calibrating and standardizing the Tip of the Red Giant Branch in the Small Magellanic Cloud using small-amplitude red giants
• A joint 1% calibration of the RR Lyrae & type-II Cepheid Leavitt laws yields homogeneous distances to 93 Galactic globular clusters
• Automated Identification of the Tip of the Red Giant Branch in Globular Clusters with Gaia Data