Reinhard Genzel Director, Max-Planck-Institut für extraterrestrische Physik Garching bei München, Germany
March 15, 2017
VLT observations of distant galaxies suggest they were dominated by normal matter
We see normal matter as brightly shining stars, glowing gas and clouds of dust. But the more elusive dark matterdoes not emit, absorb or reflect light and can only be observed via its gravitational effects. The presence of dark matter can explain why the outer parts of nearby spiral galaxies rotate more quickly than would be expected if only the normal matter that we can see directly were present .
What they found was intriguing: unlike spiral galaxies in the modern Universe, the outer regions of these distant galaxies seem to be rotating more slowly than regions closer to the core — suggesting there is less dark matter present than expected .