The oldest and most luminous galaxies in the early Universe are surprisingly compact, having stellar masses similar to present-day elliptical galaxies but much smaller sizes. This suggests that massive galaxies have grown in size by a factor of about five over the past ten billion years, leading to the expectation that the stars in these galaxies have much higher velocities than those in present-day galaxies of the same mass. Here, the stellar velocity dispersion for a compact massive galaxy at redshift z = 2.186 is indeed found to be very high.
- Pieter G. van Dokkum
- Mariska Kriek
- Marijn Franx
