Deep Imaging Meets Motion: Complementing Stream Photometry Through Planetary Nebula Kinematics

TL;DR

This paper demonstrates that planetary nebulae can effectively trace galaxy dynamics in outskirts, providing a cost-effective alternative to deep imaging and integral field unit observations.

Contribution

It introduces a simulation-based framework showing PNe as reliable tracers for galaxy outskirts dynamics, complementing deep imaging data.

Findings

PNe in the brightest 1.5 mag of their luminosity function recover stellar dynamics.

Combining PNe measurements with low-surface-brightness imaging enhances gravitational potential constraints.

PNe serve as an efficient alternative to expensive deep IFU observations.

Abstract

The combination of deep imaging data and kinematic measurements in galaxy outskirts promises to reveal extensive insights into the structure and history of individual galaxies. From a census of tidal features around galaxies from the Magneticum simulation, we disentangle the dynamics for a selected stellar stream from the underlying halo by identifying the stream progenitor galaxy. While these dynamics are challenging to measure observationally, we show that they are effectively obtained through planetary nebulae (PNe) as tracers, which we model in the simulation using the PN framework PICS (PNe In Cosmological Simulations). We find that the PNe in the brightest 1.5 mag of their luminosity function are sufficient to recover the underlying stellar dynamics of the massive stream. We thereby establish PNe as an attractive alternative to expensive deep IFU observations, where combining low-surface-brightness observations and PN dynamical measurements will enhance our ability to constrain the gravitational potential of galaxies.