Not so much
As foreseen, paperwork and late messages ...At the afternoon Steinmetz from Postdan gave us a talk (for the whole physics faculty) and after that there was a barbecue at the institute for him. The talk was held in german, what reduced my comprehencion about it, but the whole picture was there.
The question I took from it to search for an answer is about hierarchical formation. You merge 2 disk galaxies and form an spheroidal (not to use the merge 2 spirals and form an elliptical). This spheroidal creates a disk again and merge again. And so on. OK. spheroids rotate, we see dust rings and lanes as rotation signatures. Is it enough to form a disk again??? But the question is: a couple of years ago the problem to the merger model of formation of globular cluster populations were that Spirals are GCs poor (S_N ~ 0.6), while ellipticals as GCs rich (S_N ~ 3.5 up to 12 or 15 ...), and you don't create more stars in GCs than in the field. I remember seeing estimates showing that even if you used all the gas to form GCs, it wouldn't be enough (maybe an extreme comment).
How is it going?? Are "we" able to form more GCs nowadays??? Or the people just forgot my beloved GCs???????
Tomorrow life gets back to the normal!
posted by Cris Da Rocha @ 10:38 PM
5 Comments:
OK. There are a lot of questions to be answered in hierarchical models at small scales.
Regarding GCs in ellipticals. Ellipticals are old, GCs are old as well. They were formed when gas was much more abundant than today. Could it help?
The questios I have from the same talk was basically: What is the importance of mergers? What is the importance of accretion (gas and dwarfs)? and the importance of disk destruction?
Miguel V.
PS: And what about dry mergers? ;-)
About the gas abundance, of course there should be a lot of gas. The problem is the fraction of stars IN GCs and OUT of GCs formed during the merger, since the S_N is the number of clusters normalized by the galaxy brightness, you just scale the number and the S_N stays stable.
Of course also it will depend on star formation efficiency, fraction IN/OUT GCs and some other effects. But, what scares me a bit is the fact that I don't see it being considered ... (of course, there's no resolution in the simulations to that and GCs, up to now, don't have a DM halo).
About importance of mergers, accretion and disk destruction ... let me know when you find this out. Unfortunatelly, since the talk was held in German, I really could not get the whole thing and didn't feel confortable to ask about some of those issues and also about this "specific angular momentum" plot he showed. Gotta read the paper! :-)
Hi Cris--
Check out the review article that Jean and I just wrote (astro-ph/0602601), which has a reasonably up to date summary of the situation. People have started to try to use the metal-poor GCs more, since then you can avoid lots of the messiness that you were describing. The bottom line with metal-poor GCs is that you can make some of the lower-mass Es/S0s (typically in groups), but not the massive cluster Es (work mostly by Rhode & Zepf). This is a minimal constraint, which is exciting!
Hi Jay!
good to have you around here!
Actually this review is on my "to read urgently" list, but the dynamical evolution and simulations are taking too much of my time :-) I'll be reading it and checking if I get a better picture of the topic. Also check what's new in Kathy's work.
Eventhough I haven't worked with GCs for a while, they are still one of my favorite topics!
Glad to see the review paper mentioned here. I am just wondering why much of Elmegreen's work on star cluster formation were not discussed in the review.
I would appreciate your insights.
Post a Comment
<< Home