SNELLS-HD I: a first look at the stellar properties of the massive strong-lens galaxy SNL-1 with 50 pc resolution

Abstract: We present a dynamical and chemical study of the centre of a massive early-type strong-lens galaxy ESO286-G022 (SNL-1). Analysing new data obtained through the adaptive-optics-assisted Narrow-Field Mode of VLT/MUSE, we aim to measure the mass distribution and internal properties of SNL-1 at $\sim 50\ {\rm pc}$ resolution. In particular, we aim to address the tension in the reported IMF measurements of SNL-1 between strong-lens/dynamical and spectral-fitting techniques. We fit a triaxial orbital dynamical model to the measured stellar kinematics, including constraining the mass of the (resolved) central supermassive black-hole. The dynamical model is consistent with the mass-to-light ratio expected for a Kroupa-like IMF. We also employ a highly-flexible spectral-fitting technique, which instead favours a Salpeter-like IMF (low-mass slope $\alpha\approx 2.3$) over the same spatial region. To conclude, we discuss possible origins of this discrepancy, both intrinsic and technical.