From: Mike Gladders (gladders@ociw.edu)
Date: Tue Jan 24 2006 - 14:02:10 PST
I agree with Peter on this. Given the relative densities we are seeing of
possible elliptical hosts (see the fig I just sent around), the fact that
we don't see 15-20 x the # of Ia in clusters vs the field in these fields
actually argues the the Ia rate in clusters is lower (which also,
reassuringly, implies they are nice and quiescent...). Saying otherwise
ventures into possibly dangerous territory which may unnecessarily open us
up to unwarranted criticism...
It may also be worth noting, in the space that we don't have, that the
presence of the ICM is probably more effective at preventing further gas
cooling and SF cluster ellipticals vs the field (the gas starvation
/strangulation scenario for turning cluster galaxies red...).
m
On Tue, 24 Jan 2006, prme wrote:
> I think this is dangerous terrain: Mark Sullivan's poster on SNe rates
> vs. host properties talks about two opos of Ia's, one associated
> with active SF galaxies, the other with quiescent E's. The dust free
> Ia's are more likely to be those associated with the quiescent
> progenitors, whereas the interaction enhanced rates are likely
> associated with SF and dust. Dust in E's is also associated with
> optical emission, and emission is associated with radio loud galaxies
> as has been said. I think we should *not* claim that we expect
> a higher SNIa rate in cluster E's than field E's because
> a) I think this is not the case
> b) it may lead to questions about the dust-free claim, which is
> fundamental to the proposal.
>
> Peter Eisenhardt
>
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