Dark matter exists in the inner parts of our galaxy

The image displays rotation curve tracers used in the study, placed over a photograph of the disc of the Milky Way, used to measure the rotation speed of the galaxy. The tracers are colour-coded in blue or red according to their relative motion with respect to the Sun.

A study published in Nature Physics has found for the first time direct observational proof of dark matter at the heart of our galaxy.

The researchers, headed by Dr. Miguel Pato of Technische Universitaet Muenchen in Germany, compiled a number of previously published measurements of the movement and rotation of gas and stars in the Milky Way. They then compared the measured rotation speeds with a model that predicts what the speed should be if there was only luminous matter (i.e. stars and cosmic gas or dust) in the galaxy.

The results showed that the observed rotation did not fit the predicted model, leading researchers to conclude that the rotation cannot be explained unless large quantities of dark matter existed in the Milky Way.

According to the research team, “throughout the Universe, the evidence for dark matter is compelling in dwarfs, spiral galaxies, galaxy clusters as well as at cosmological scales.” However, until now “it has been historically difficult to pin down the dark matter contribution to the total mass density in the Milky Way, particularly in the innermost regions of the Galaxy and in the solar neighbourhood.”

The method used by the researchers will allow to measure the distribution of dark matter in our Galaxy with unprecedented precision in future astronomical observations.

"This will permit to refine the understanding of the structure and evolution of our Galaxy. And it will trigger more robust predictions for the many experiments worldwide that search for dark matter particles," says Pato.

  1. http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys3237.html
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