Mass models from high-resolution HI data of the dwarf galaxy NGC 1560

TL;DR

This study uses high-resolution HI data to analyze the rotation curve of dwarf galaxy NGC 1560, confirming a distinctive wiggle and evaluating different mass models, including dark matter halos and MOND.

Contribution

It provides higher resolution HI observations and a detailed mass modeling analysis, including the first verification of the wiggle feature with improved data.

Findings

Confirmed the presence of a rotation curve wiggle.

Found better fits with MOND and Burkert halo than NFW.

Revealed slight velocity differences in the inner region.

Abstract

We present HI observations performed at the GMRT of the nearby dwarf galaxy NGC 1560. This Sd galaxy is well-known for a distinct "wiggle" in its rotation curve. Our new observations have twice the resolution of the previously published HI data. We derived the rotation curve by taking projection effects into account, and we verified the derived kinematics by creating model datacubes. This new rotation curve is similar to the previously published one: we confirm the presence of a clear wiggle. The main differences are in the innermost ~100 arcsec of the rotation curve, where we find slightly (<~ 5 km/s) higher velocities. Mass modelling of the rotation curve results in good fits using the core-dominated Burkert halo (which however does not reproduce the wiggle), bad fits using the a Navarro, Frenk & White halo, and good fits using MOND (Modified Newtonian Dynamics), which also reproduces the wiggle.