Thursday, June 15, 2006

Long time coming

Is that fact that I've been doing a lot of research
a good excuse for neglecting my research blog?

I've been very busy. Ben Koester and I have been
going back and forth trying to make the maxBCG
cluster catalog all that it can be. As usual, 95%
of the work goes into the most difficult 5%. I think
I can say this: we understand things well enough
that we know that we can basically stop working
on it (for now). We also know what data is usable.

With the new and improved catalog I've been running
the lensing code and Morad has been measuring the
number density and luminosity profiles. Morad and
Sarah both plan to write Science papers from Morad's
work. In the short term, I am most interested in extracting
the r200-Ngals relationship from the luminosity profiles.
With this we have a good size estimate within which
we can can re-measure the cluster properties. This is an
update of Sarah's original measurement of r200-ngals for
the new algorithm. The new algorithm is significantly different,
at least in concept; we will see if the r200-ngals scaling
is different.

It will be interesting to compare this r200 to the r200 we
will get from the mass profiles. We have both the mass
and luminosity profiles, so we will get mass-to-light
ratios as a function of radius. Sarah and Morad are interested
in galaxy-formation and such topics and this should provide
an excellent starting point for that as well.

I have measured the lensing around very low
luminosity galaxies using a catalog from Michael Blanton.
This should be very interesting since there are few reliable
statistical mass measurements at these luminosities. Currently
Michael basically just has the number density argument. I have
also run Chris Miller's cluster catalog through. It is an
extremely well understood catalog from spectroscopic data.
The S/N isn't great because they are few in number and nearby
in space, making their lensing strength weak. A factor of
two improvement in number is on the way with the processing
of dr4.

Finally, I completed the set of shapelet decompositions for the
DES simulations. Now I hope to push to higher redshift by
looking at the GOODS fields. The statistics are poor, but this
will possibly give us a handle on morphology evolution.


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