I implemented a bunch of routines to calculate cosmological

distances. I was motivated to do this 1) because I wanted to

generate a volume limited set of random redshifts, so I needed

a formula for the volume element and 2) I wanted some routines

that worked for more general cosmologies; I only had flat universe

code. Still don't have evolving dark energy code, but I'll write

that when I need it.

So I started from the bottom up and wrote an integration routine

to calculate the comoving distance, then all the steps needed to get

to the angular diameter distance (see Hogg astro-ph/9905116, which

mostly comes from Peebles 1993 book).

One thing I noted about that paper: I believe there is no

need to go to equation 19, which is not general. Because

you can calculate Dc, the comoving distance, between two different

redshifts, call it Dc_12, then you can implement the difference of two

DM's (comoving transverse distance) simply by using the Dc_12 in

formula 16. This will also work in any curvature and so is

general. I tested that it works for the cases where equation 19 holds

(curvature >= 0).

Now that I have this stuff going I'm generating 48 sets of 500,000

randoms from z=0.04 to 0.35. I'll set them running through the lensing

code in the background. I don't need these at the

moment since the randoms I have cover the redshift range for maxBCG,

but it will be good to have them for the future.

Corrected Lensing Profiles

Yesterday I finished to code to match the histograms of redshift, so

today I was able to do the random point corrections to the maxBCG

lensing profiles. These look OK, but there are some worrying features

in the profiles. The features are similar to what I saw in the LRG profiles.

Tomorrow I will do the jackknifing so we can do some more meaningful

analysis. I will also do sub-sampling in the "paper" versions of the

catalog. These are the clusters which will be published in Ben's catalog

paper. Essentially it is an Ngals cut and a redshift cut.

Erin

## 2 comments:

I hope you implemented those routines in Python! But anyway, you might be right about the equations; let's discuss this one off-blog. I need to update those damned notes some day...

Nope, IDL. But I did them

as IDL objects, so they will

transfer easily to Python. The

problem is that all my lensing

stuff is in IDL so I probably

won't start doing everything

in Python until I first rewrite

my lensing stuff in Python: after

I publish the cluster paper.

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