Dark Matter in the Central Region of NGC 3256

TL;DR

This study reveals a significant amount of dark matter in the central region of NGC 3256, challenging the applicability of MOND models due to the high acceleration environment.

Contribution

First detailed investigation of central dark matter distribution in NGC 3256 using ALMA and 2MASS data, highlighting potential limitations of MOND.

Findings

Detection of $4.84 imes 10^{10} M_{\u00d7} in dark matter

Dark matter likely has a cuspy profile

Challenges to MOND applicability in high acceleration regions

Abstract

We investigated the central mass distribution of the luminous infrared galaxy NGC 3256 at a distance of 35 Mpc by using CO(1-0) observations of the Atacama Large Millimeter and sub-millimeter Array (ALMA) and near-IR data of the Two Micron Sky Survey (2MASS). We found that there is a huge amount of invisible dynamical mass ($4.84 \times 10^{10} M_{\odot}$) in the central region of the galaxy. The invisible mass is likely caused by some dark matter, which might have a cuspy dark matter profile. We note that this dark matter is difficult to explain with the conventional Modified Newtonian Dynamics (MOND) model, which is only applicable at a low acceleration regime, whereas the acceleration at the central region of the galaxy is relatively strong. Therefore, this discovery might pose a challenge to the conventional MOND models.