Space & Astronomy

Older galaxies had a lot less dark matter

By T.K. Randall
March 18, 2017 ·  10 comments

Why did early galaxies have less dark matter ? Image Credit: NASA/CXC/M. Weiss The study, which was led by astrophysicist Reinhard Genzel from the Max Planck Institute for Extraterrestrial Physics, saw a team of astronomers using the European Southern Observatory's Very Large Telescope in Chile to observe six large star-forming galaxies from the early universe.

Their findings suggested that dark matter was a lot less prevalent in the past than it is today.Typical galaxies formed during the current era of the universe (such as the Milky Way) have an effective radius (the bright region from which half a galaxy's light is emitted) made up of 50-80% dark matter, whereas the older galaxies appeared to be comprised of as little as 10%.

Exactly why this should be the case remains unclear, however the scientists have suggested that one reason may be due to the fact that these earlier galaxies were subjected to more continuous inflows of normal matter than later galaxies, thus resulting in a lower proportion of dark matter.

These earlier galaxies were also thought to be lot more turbulent than their recent counterparts.

Source: Scientific American | Comments (10)

Tags: Dark Matter