A new study has just determined that Galaxy NGC 3256, a luminous infrared galaxy (LIRG), may contain a staggering amount of dark matter within its center. This galaxy, which can be found in the Hydra-Centaurus supercluster complex 114 million light years away from Earth, is one of the most vividly bright galaxies close to us and was created after two disk galaxies that were rich in gas merged with each other.
According to Phys.org, with dark-matter halo merging occurring so often with LIRGs, Galaxy NGC 3256 was the perfect place for astronomers to study to see if they could detect dark matter within its central region.
In the new study, Israa Abdulqasim Mohammed Ali from the University of Malaya in Kuala Lumpur, Malaysia obtained data taken from the Two Micron All Sky Survey (2MASS) and the Atacama Large Millimeter and sub-millimeter Array (ALMA) and “investigated the central mass distribution of the luminous infrared galaxy NGC 3256 at a distance of 35 Mpc by using CO(1-0) observations.”
With such a large amount of data to analyze, the team figured out what the mass distribution was for Galaxy NGC 3256 and found that there was an extremely large amount of invisible dynamical mass within the galaxy’s center which equated to 87 percent of the entirety of the galaxy’s dynamical mass. After taking into account the center’s stellar mass and molecular mass, researchers determined that dark matter is almost certainly the reason for the invisible mass.
— Phys.org (@physorg_com) October 11, 2018
“The amount of dark matter is about 4.84 ± 0.42 × 1010 solar masses, which is significantly larger than the stellar mass. It is clear that even the velocity was not circular, the dynamical mass that would be required to account for the observed velocity dispersion is still much larger than the baryonic mass, and thus the existence of a huge amount of dark matter in the central region of the galaxy is necessary.”
When it comes to dark matter lurking in the center of galaxies, this is an area that is wide open when it comes to research as there have been so few studies conducted on the subject. While astronomers acknowledge that dark matter is usually found in the outer areas of galaxies, it has never been determined that it has any importance in the central regions of these galaxies when it comes to overall mass.
Scientists involved in the new study on Galaxy NGC 3256 note that their findings may have a profound effect on modified Newtonian dynamics theory.
“What is more important is that this missing mass problem cannot be explained with the traditional MOND [modified Newtonian dynamics] theory because of strong acceleration in the central region of the galaxy. Since most of the dark matter phenomena at galactic scales can usually be explained by the MOND theory very well, this discovery thus poses a significant challenge to the traditional MOND models.”
The new study on Galaxy NGC 3256, which determined that its center may hold a large amount of dark matter, has been published in arXiv.org.