What velocity dispersion tells us about galaxy evolution

What velocity dispersion tells us about galaxy evolution

Astronomers at Yale investigate how the number of galaxies at fixed inferred velocity dispersion (a probe of the total gravitational potential) changes as a function of time. Their results support a picture where star-forming galaxies are somehow “quenched” and transition to the non-star-forming galaxy population, consistent with leading ideas of galaxy evolution.

Cosmic blowhard: the most distant massive quasar outflow yet

Cosmic blowhard: the most distant massive quasar outflow yet

The idea of “negative feedback” on star formation in galaxies is ubiquitous, but the debate about what causes the massive outflows we see in galaxies is far from over. Now, Maiolino et al. have found evidence of a massive quasar-driven outflow at z > 6, making it the earliest instance yet of a central black hole affecting its host galaxy on a global scale.