Toward Precision Cosmology with Improved PNLF Distances Using VLT-MUSEI. Methodology and Tests

The [O iii] lambda 5007 planetary nebula luminosity function (PNLF) is an established distance indicator that has been used for more than 30 yr to measure the distances of galaxies out to similar to 15 Mpc. With the advent of the Multi-Unit Spectroscopic Explorer on the Very Large Telescope (MUSE) as an efficient wide-field integral-field spectrograph, the PNLF method is due for a renaissance, as the spatial and spectral information contained in the instrument's data cubes provides many advantages over classical narrowband imaging. Here we use archival MUSE data to explore the potential of a novel differential emission-line filter (DELF) technique to produce spectrophotometry that is more accurate and more sensitive than other methods. We show that DELF analyses are superior to classical techniques in high surface brightness regions of galaxies, and we validate the method both through simulations and via the analysis of data from two early-type galaxies (NGC 1380 and NGC 474) and one late-type spiral (NGC 628). We demonstrate that with adaptive optics support or under excellent seeing conditions, the technique is capable of producing precision (less than or similar to 0.05 mag) [O iii] photometry out to distances of 40 Mpc while providing discrimination between planetary nebulae and other emission-line objects such as H ii regions, supernova remnants, and background galaxies. These capabilities enable us to use MUSE to measure precise PNLF distances beyond the reach of Cepheids and the tip of the red giant branch method and become an additional tool for constraining the local value of the Hubble constant.

Automated summary

This study explores the potential of the DELF technique using archival MUSE data, demonstrating its superiority in high surface brightness regions of galaxies and validating its effectiveness through data analysis of early-type and late-type spiral galaxies. The technique is capable of producing precise [O iii] photometry out to distances of 40 Mpc under excellent observing conditions, while also discriminating between different emission-line objects. These capabilities make MUSE a valuable tool for measuring PNLF distances beyond traditional methods and constraining the local value of the Hubble constant.