Testing the performance of image deconvolution for crowded field photometry of Cepheid stars

Abstract

The systematic errors in the distance-ladder measurement of the Hubble constant (H0) have been under close scrutiny in recent years. In this work, we test a method not previously applied in this context, image deconvolution with STARRED, to examine the effects of crowding on photometry and, consequently, on the distance-ladder measurement of H0. Using simulations of crowded fields from HST images of NGC 4258, we assessed the possible bias over a range of signalto-noise ratios. The point spread function used in the simulations was extracted from another HST field, NGC 136. Ten thousand injections were performed for each crowding regime with the recovered amplitudes showing small relative errors compared with the injected amplitudes, even in low signalto-noise regimes. Our results suggest that this method is effectively unbiased within tested regimes, which could be a substantial improvement in constraining possible Cepheid photometry systematic errors.