Constraining the dark matter content of NGC 1291 using hydrodynamic gas response simulations

TL;DR

This study uses hydrodynamic gas response simulations of dust lane morphology in NGC 1291 to constrain its dark matter content and bar dynamics, finding a near-infrared M/L ratio consistent with stellar population models and a fast-rotating bar.

Contribution

It introduces a novel method of constraining dark matter and bar pattern speed using gas response simulations matched to dust lane morphology.

Findings

The M/L ratio of NGC 1291 aligns with stellar population synthesis predictions.

The galaxy's bar rotates fast, with a corotation radius ≤ 1.4 times the bar length.

Results suggest a borderline maximum disc for NGC 1291.

Abstract

We present a pilot study on the nearby massive barred galaxy NGC 1291, in which we use dynamical modelling to constrain the disc mass-to-light ratio (M/L), thus breaking the degeneracy between the baryonic and dark matter in its central regions. We use the gas, specifically the morphology of the dust lanes on the leading side of the bar, as a tracer of the underlying gravitational potential. We run a large number of hydrodynamic gas response simulations, in potentials obtained directly from near-infrared images of the galaxy, which have three free parameters: the M/L, the bar pattern speed and the height function. We explore the three-dimensional parameter space, by comparing the morphology of the shocks created in the gas response simulations with those of the observed dust lanes, and find the best-fitting models; these suggest that the M/L of NGC 1291 agrees with that predicted by stellar population synthesis models in the near-infrared ($\approx$0.6\,$M_{\odot}/L_{\odot}$), which leads to a borderline maximum disc for this galaxy. Furthermore, we find that the bar rotates fast, with a corotation radius which is $\leq$ 1.4 times the bar length.