Abstract
Extragalactic planetary nebulae (PNe) offer a way to determine the distance to their host galaxies thanks to the nearly universal shape of the planetary nebulae luminosity function (PNLF). Accurate PNe distance measurements rely on obtaining well-sampled PNLFs and the number of observed PNe scales with the encompassed stellar mass. This means either disposing of wide-field observations or focusing on the bright central regions of galaxies. In this work we take this second approach and conduct a census of the PNe population in the central regions of galaxies in the Fornax cluster, using VLT/MUSE data for the early-type galaxies observed over the course of the Fornax3D survey. Using such integral-field spectroscopic observations to carefully separate the nebular emission from the stellar continuum, we isolated [O III] 5007 Å sources of interest, filtered out unresolved impostor sources or kinematic outliers, and present a catalogue of 1350 unique PNe sources across 21 early-type galaxies, which includes their positions, [O III] 5007 Å line magnitudes, and line-of-sight velocities. Using the PNe catalogued within each galaxy, we present independently derived distance estimates based on the fit to the entire observed PNLF observed while carefully accounting for the PNe detection incompleteness. With these individual measurements, we arrive at an average distance to the Fornax cluster itself of 19.86 ± 0.32 Mpc (μPNLF = 31.49 ± 0.04 mag). Our PNLF distance measurements agree well with previous distances based on surface brightness fluctuations, finding no significant systematic offsets between the two methods as otherwise reported in previous studies.
Highlights
Extragalactic planetary nebulae (PNe) are detectable at great distances, via their strong [O iii] 5007 Å emission, with surveys extending out as far as the Coma Cluster, ∼100 Mpc
Using the PNe catalogued within each galaxy, we present independently derived distance estimates based on the fit to the entire observed planetary nebulae luminosity function (PNLF) observed while carefully accounting for the PNe detection incompleteness
Extending the work of Spriggs et al (2020) to the full sample of early-type galaxies (ETGs) targeted by the Fornax3D survey we have presented a catalogue of 1350 unique PNe sources across 21 different objects
Summary
Extragalactic planetary nebulae (PNe) are detectable at great distances, via their strong [O iii] 5007 Å emission, with surveys extending out as far as the Coma Cluster, ∼100 Mpc,. U-strasbg.fr/viz-bin/cat/J/A+A/653/A167 where PNe were detected within the intracluster medium (Gerhard et al 2005) Their ionised [O iii] 5007 Å emission is unresolved at such distances, and when embedded within the bright stellar continuum of the galaxy only a careful modelling of the stellar continuum allows one to measure the PNe [O iii] flux. With more detailed SBF, SNIa, and other distance estimators, we see that the Fornax cluster may be further away than the initial estimates ranging between 16 Mpc and 19 Mpc. Here, we continue the detection work of S20, and carry out a census of PNe populations within the central, middle and halo regions of the remaining early-type galaxies (ETGs) of the Fornax3D (F3D) survey (Sarzi et al 2018). This was found in S20 to produce a better map in [O iii] 5007 Å emissions, which led to a greater number of PNe detected
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