Cosmic Reionization of Hydrogen and Helium

Cosmic Reionization of Hydrogen and Helium

Cosmic reionization is a period in the Universe history when it switched from being predominantly neutral to mostly ionized. We still haven’t quite pinned down the source(s) that caused this transition, but we have our suspicions. It could be quasars. It could be galaxies. Or could it be something else?

[Figure from universe-review.ca/F05-galaxy06.htm]

Black Holes Grow First in Mergers

Black Holes Grow First in Mergers

By measuring the black hole mass and velocity dispersion of currently merging galaxies each in various stages of a merger, the authors conclude that the growth of the central super massive black hole occurs in the early stages of each merger and outpaces any bursts of star formation or central bulge growth.

The age of cross-correlations

The age of cross-correlations

When two observations share some common information, they can be “cross-correlated” to extract it. In today’s example, we discover what the matter halos and energetic phenomena in the Universe have in common through a cross-correlation.