Galaxy mergers can create spirals, perhaps?

[ollypenrice]

I've 'grown up' in astronomy with the idea that merging spirals produce ellipticals but I heard something to the contrary on the French radio the other day. This gives a quick over-view of some new ALMA results in English.   http://www.eso.org/public/news/eso1429/

Anecdotally, by the way, I'd say that the serious French radio channels have far more astronomy than we hear on the Beeb.

Olly

[JulianO]

It depends a lot on how much gas is involved in the collision. Dry mergers (galaxies with little gas) almost always seem to produce ellipticals. "Wet" mergers in contrast can produce spiral like or lenticular depending exactly on the interaction of the gas and if it ends up swirling around and making new stars.

[ollypenrice]

Thanks, that's helped my understanding. ALMA has been tracing the gas, as it seems.

Olly

[symesie04]

Interesting stuff. But just a question on that, if the school of thought up till recently had been that galaxy mergers only resulted in ellipticals wouldnt that mean that today we shouldnt see any spirals, as most if not all of the spirals we see will have gone through at least one major merger in their history?

[JulianO]

Major mergers don't happen very often, well they do in galaxy clusters, but less so out in the field. 

Its an ongoing area of research, so ideas are still somewhat fluid.