Chandra Program to study Galaxy Zoo Mergers approved

Good news, everyone!

Earlier this year we submitted a proposal to use the Chandra X-ray Observatory to observe a set of merging galaxies in X-rays. The target list for Cycle 12 has just been released, and with a bit of scanning, you can find a set of targets with names like “GZ_Merger_AGN_1”. These targets are a set of beautiful merging galaxies discovered by YOU as part of Galaxy Zoo 1 and the Merger Hunt. The 12 approved targets are here:

These 12 mergers are all very pretty, but they have something else in common: they all host active galactic nuclei (AGN) – feeding supermassive black holes at their centers. X-rays are great for finding such hungry black holes, but we already know that all 12 of these mergers are AGN, so why observe them again? We’re looking for a mythical rare beast: the binary AGN!

Only a handful of these objects are known and they were discovered by chance. We believe that every massive galaxy has a supermassive black hole at its center and so when two galaxies merge, then there should be two black holes around for a while, that is, until they merge. The goal of our Chandra study of these 12 mergers is to systematically search for binary AGN in merging galaxies to work out what fraction of them feature two feeding black holes. Knowing whether such phases are common or not is important for understanding how black holes interact with galaxies in mergers and what exactly happens to them as they plunge towards the center of the new galaxies where they are doomed to merge and form a single supermassive black hole.

As usual, it may be quite a while before we get the data. The observing cycle won’t start for a while and takes about a year. Since our observations are short and we don’t have any time constraints (they’re galaxies, they don’t move!) the Chandra operators will most likely schedule our observations in between longer projects and time sensitive observations and so we won’t know when they will happen. Of course, once we do get the data, we’ll definitely update you.

Oh and you might notice some of the targets in the Merger Zoo in the near future. We’ll need your help to fully understand them….