publications

On Zero Point Calibration of the Red Giant Branch Tip in the Magellanic Clouds. (arXiv)

Hoyt, T. J., Submitted June 2021 (In Review)

This comprehensive paper addresses a number of misconceptions and biases in previous measurements of the Tip of the Red Giant Branch (TRGB) made in the Magellanic Clouds. In so doing, I make the most accurate measurements of the TRGB in the Clouds to date, and resolve a recent debate in the literature over the method's zero point calibration.

The Carnegie Chicago Hubble Program X: Tip of the Red Giant Branch Distances to NGC 5643 and NGC 1404 (ADS, arXiv)

Hoyt, T. J., Beaton, R. L., Freedman, W. L., et al. (2021), ApJ, 915, 34.

New distances are determined to supernova (SN) ``calibrator'' galaxies, the crucial anchors of the SN Hubble Diagram which in turn calibrates our measurements of the Hubble constant. I presented novel analysis techniques for optimizing TRGB measurements in the outer regions of L* galaxies. Comparisons are made between the SN Ia and TRGB distances to each galaxy and the relative locations of NGC 1316 and NGC 1404 in the Fornax Cluster are explored in depth.

CCHP VIII. An Independent Determination of the Hubble Constant Based on the Tip of the Red Giant Branch (ADS, arXiv)

Freedman, W. L., Madore, B. F., Hatt, D., Hoyt, T. J., Jang, I. S., Beaton, R. L., Burns, C. R., Lee, M. G., Monson, A. J., Neeley, J. R., Phillips, M. M., Rich, J. A., Seibert, M. (2019)

Results from the first "phase" of the CCHP were presented. We determined a measurement of the Hubble constant comparable in precision to that of the Cepheid-based determinations (SH0ES, Riess et al.). We determined an H0 = 69.8 km/s/Mpc, squarely in the middle of the high-redshift and Cepheid measurements that define the "Hubble Tension."

Distances to Local Group Galaxies via Population II, Stellar Distance Indicators. I. The Sculptor Dwarf Spheroidal (ADS, arXiv)

Tran, Q. H., Hoyt, T. J., Freedman, W. L., Madore, B. F., Oakes, E., Cerny W., Hatt, D., Beaton, R. L., (2022)

Distances to Local Group Galaxies via Population II, Stellar Distance Indicators. II. The Fornax Dwarf Spheroidal (ADS, arXiv)

Oakes, E., Hoyt, T. J., Freedman, W. L., Madore, B. F., Tran, Q. H., Cerny W., Beaton, R. L., Seibert, M. (2022)

Using high dynamic range data taken with the IMACS instrument on Magellan Baade, we determined a trio of old-age distances to the Sculptor and Fornax galaxies based on RR Lyrae, the Tip of the Red Giant Branch, and the Horizontal Branch. The key step forward of these new results is the use of homogeneous photometric systems throughout, both in the calibration and application of the distance indicators to the dwarf galaxies. Because all three distances are homogeneously calibrated, they could be combined into some of the most accurate distances to these galaxies.