Study reveals composition of dark matter present in dark galaxies

A study by International School for Advanced Studies (SISSA) has provided information about the composition of dark matter in the dark galaxies and has also found out pieces of evidence of interaction between dark matter and luminous matter.

Chiara di Paolo, Astrophysicist from the institution, said, "We have found that disc galaxies can be represented by a universal relationship. In particular, in this study, we analysed the so-called Low-Surface-Brightness galaxies, a particular type of galaxy with a rotating disc called this way because they have a low-density brightness."

Paolo along with other astrophysicists Paolo Salucci and Adnan Erkurt led the study which was published in the monthly notices of Royal Astronomical Society.

The researchers conducted the study by analysing the rotating speed of stars and gases that compose the low-surface-brightness (LSB) galaxies through the universal rotation curve (URC) method.

"This method has shown that all disc, spiral, dwarf and now also the LSB galaxies can be represented by a universal relationship. This means that we are able to express an ordered trend through a formula which, keeping account of very few parameters, describes how dark matter and luminous matter are distributed," said Salucci.

The study revealed further surprising and unexpected results.

"We have discovered relationships of scale between the properties of the stellar disc and those of the dark matter halo, for example, a relationship between the dimensions of the stellar discs and the dimensions of the internal region with a constant density of the dark matter halo," said Chiara Di Paolo.

This result, when combined with certain specific features of LSB galaxies, suggest that in addition to the gravitational interaction, another direct interaction is present between the two types of matter that form galaxies.