Synthetic Cepheid Period-Luminosity & Period-Color Relations in Spitzer's IRAC Bands

TL;DR

This paper develops synthetic period-luminosity and period-color relations for Cepheids in Spitzer's IRAC bands using pulsation models with varying compositions, aiding future Hubble constant measurements.

Contribution

It introduces new synthetic P-L and P-C relations based on stellar pulsation models with different helium and metallicity levels, compared to empirical data.

Findings

Synthetic relations match empirical data within uncertainties

Metallicity and helium variations affect the P-L and P-C relations

Empirical relations are refined using latest infrared surface brightness distances

Abstract

The mid-infrared period-luminosity (P-L) relation for Cepheids will be important in the JWST era, as it holds the promise of deriving the Hubble constant within 2% accuracy. We present the synthetic P-L and period-color (P-C) relations, derived from a series of stellar pulsation models with varying helium and metallicity abundance, in the Spitzer IRAC bands. Selected synthetic P-L and P-C relations were compared to the empirical relations derived from Galactic and Large Magellanic Cloud Cepheids. We also present the empirical P-L relations based on the latest distance measurements using infrared surface brightness techniques.