Integral Field Spectroscopy: a disruptive innovation for observations of Planetary Nebulae and the PNLF

Abstract: A quarter of a century has passed since the observing technique of integral field spectroscopy (IFS) was first applied to planetary nebulae (PNe). Progress after the early experiments was relatively slow, mainly because of the limited field-of-view (FoV) of first generation instruments.With the advent of MUSE at the ESO Very Large Telescope, this situation has changed. MUSE is a wide field-of-view, high angular resolution, one-octave spanning optical integral field spectrograph with high throughput. Its major science mission has enabled an unprecedented sensitive search for Ly{\alpha} emitting galaxies at redshift up to z=6.5. This unique property can be utilized for faint objects at low redshift as well. It has been demonstrated that MUSE is an ideal instrument to detect and measure extragalactic PNe with high photometric accuracy down to very faint magnitudes out to distances of 30 Mpc, even within high surface brightness regions of their host galaxies. When coupled with a differential emission line filtering (DELF) technique, MUSE becomes far superior to conventional narrow-band imaging, and therefore MUSE is ideal for accurate Planetary Nebula Luminosity Function (PNLF) distance determinations. MUSE enables the PNLF to become a competitive tool for an independent measure of the Hubble constant, and stellar population studies of the host galaxies that present a sufficiently large number of PNe.