New simulations provide clues to galaxies' mass

A new set of simulations have revealed that the energy released by individual stars within galaxies can have a substantial effect on where matter is located in the universe.

The Feedback in Realistic Environments, or FIRE, project is the culmination of a multiyear, multiuniversity effort that-for the first time-simulates the evolution of galaxies from shortly after the Big Bang through today.

The first simulation to factor in the realistic effects of stars on their galaxies, FIRE results suggest that the radiation from stars is powerful enough to push matter out of galaxies.

Philip Hopkins, assistant professor of theoretical astrophysics at the California Institute of Technology (Caltech) and lead author of a paper resulting from the project., said people have guessed for a long time that the 'missing physics' in these models was what they call feedback from stars.

He said when stars form, they should have a dramatic impact on the galaxies in which they arise, through the radiation they emit, the winds they blow off of their surfaces, and their explosions as supernovae.

A zoomed-in view of evolving stars within galaxies allows the researchers to see the radiation from stars and supernova explosions blowing large amounts of material out of those galaxies.

When they calculate the amount of matter lost from the galaxies during these events that feedback from stars in the simulation accurately accounts for the low masses that have been actually observed in real galaxies.

But once stars push this matter out of the galaxy, where does it go is a question, which the researchers hope to answer by combining their simulations with new observations in the coming months.