The Araucaria Project. Infrared Tip of the Red Giant Branch Distances to Five Dwarf Galaxies in the Local Group

TL;DR

This study uses near-infrared photometry of the Tip of the Red Giant Branch to accurately measure distances to five dwarf galaxies in the Local Group, confirming consistency with Cepheid-based distances and refining distance measurement techniques.

Contribution

It provides new near-infrared TRGB distance measurements for five Local Group dwarf galaxies, demonstrating their agreement with Cepheid distances and assessing systematic uncertainties.

Findings

Distances have 4% statistical error and 5-8% systematic uncertainty.

Near-infrared TRGB distances agree within 5% with Cepheid distances.

No significant offset between old and young stellar population distance indicators.

Abstract

We have obtained accurate near-infrared photometry of the Tip of the Red Giant Branches in the Local Group galaxies Sculptor, NGC 6822, NGC 3109, IC 1613 and WLM. We have used the derived TRGB magnitudes together with the absolute magnitude calibration of the near-infrared TRGB magnitude of Valenti, Ferraro and Origlia to determine the distances of these five galaxies. The statis- tical errors in the distance moduli are typically 4%. The systematic uncertain- ties are dominated by the knowledge of the mean metallicities of the red giant branches, and are in the range of 5-8%. We observe a slight (2%) systematic difference between the distances derived from the J and K bands, respectively, which is within the 1 {\sigma} errors of the distances. We compare the new distances derived in this paper with other recent distance determinations for our target galaxies and find excellent agreement. In particular, the near-infrared TRGB distances to the four dwarf irregular galaxies in the sample agree to better than 5% in each case with their Cepheid distances obtained from infrared photome- try, indicating that there is no appreciable systematic offset between these two fundamental techniques using old and young stellar populations, respectively.