Galaxy mergers

How do you form a large galaxy? Does it just start out as a big galaxy or do you build it up by colliding and merging little galaxies? Numerical simulations that attempt to model large parts of the Universe seem to show that larger galaxies can be created from the mergers of dwarf galaxies in a "bottom up" approach. Of course they are just simulations, so is there evidence that that is actually happening? The short answer is yes. A nice example is in a new image just released by the Hubble Space Telescope (HST) showing a galaxy undergoing this very process of eating smaller galaxies and putting on the lightyears around its middle.

MRC 1138-262
Composite of separate exposures made by the ACS on the HST. It shows the Spiderweb Galaxy at the centre surrounded by hundreds of other galaxies. CREDIT: NASA, ESA, George Miley and Roderik Overzier (Leiden Observatory, the Netherlands)
The image shows the galaxy MRC 1138-262 - or the Spiderweb Galaxy - sitting in the centre of a large swarm of smaller galaxies, a few of which are being consumed. Of course, as we have come to discover in recent years, the centres of large galaxies tend to be the home of supermassive black holes and the Spiderweb Galaxy seems to be no different. The effects of this central "engine" can be seen by radio telescopes which show huge jets of material being flung out of the galaxy in opposite directions. It seems like a very interesting galaxy but I'm glad I don't live there.

Tags: | |
Posted in astro blog by Stuart on Thursday 12th Oct 2006 (13:31 BST) | Permalink
[an error occurred while processing this directive]
[an error occurred while processing this directive]