Where is all the non-dark matter hiding?
DOI: 10.1063/PT.5.024014
Science : Astrophysicists know that 83% of the matter in the universe is dark matter—invisible stuff as yet undetected. The other 17% is detectable " baryonic matter ,” the atoms and ions that make up stars, planets, dust, and gas.To astronomers’ surprise, the ratio of baryonic matter to dark matter seems to vary from galaxy to galaxy like the ratio of chocolate chips to dough in different batches of home-baked cookies.Now, a team led by Stacy McGaugh at the University of Maryland, College Park, has determined that the proportion varies by scale: The largest galaxies have the highest percentage of baryonic matter, although not quite 17%; whereas the smallest galaxies have less than 1%.
