Friday, June 30, 2006

velocity dispersions

Still trying to figure out exactly why turning fixing a value for galaxy clutser velocity dispersions has a different effect than letting it float and finding a the best-fit minimum value. Puzzling. Very puzzling.

Shanks (Durham) gave Observers' Lunch today on "Lensing and the CMB". Although I've always liked his maverik style and the questioning of fundamental idioms - e.g. is the search for the dark matter particle like the search for the neutrino (successful) or the EM ether (unsuccessful but then leading to SR)?? - I have trouble with the current lensing model than desperatly struggles to reproduce the CMB power spectrum. Fully admitting that there could be a number of different things going on with respects to foregrounds (SZ effect and
the like) which have to be brought under better control.

In non-astronomy news, Germany play Argentina today in Berlin for a place in the World Cup Semi-final. Does it really seem a week ago?

Tuesday, June 27, 2006

We're Back!

Dear Loyal Readers,

Well, I'm back from Munchen and Berlin (sans baggage*) and having had an awesome time with the Brazillian samba beats, Tunisian horns and Bavarian spaceships it has been back down to earth with a bump. Which is a kinda weird thing considering the objects we're studying.

Not much has happened over the last couple of days. I've finally begun to decipher da Angela's distortion chi-squared code and have left a couple of things running overnight. We'll finally see how much difference the Hamilton and LS estimators *really* have...

Also helped Shanks on a piece for the AAO Newsletter bout our run in March. Curiously, they want it in Word format (WFT!!!) which has proved the most hassle.

Thursday, June 15, 2006

Hawaii 5 0

Dear all,

Once again v. sorry for the lack of posts of late, and indeed this will be the last one for at least a week.

Good news is that the redshift-space distortions paper is basically done, well at least my first version of it, and if pigs fly and Jose's code is okay overnight, we should be sending it collaboration wide presently. Hurray!

Two pretty decent talks this week Ellis (Caltech), Baldry (Liverpool John Moors) which I'd love to go into more details but that'll have to wait.

And AstroGrid workshop today. Had quite a good laugh but am still struggling even as we speak to get the workflows doing a simple simple task.

Anyway, have fun over the next week or so and speak later!


Monday, June 12, 2006

ARGH!!!! (Part 2)

ARGH!!! Just when I thought I was one step, one graph and \subsection{} away from completing the redshift-space distortion paper, I discover I've forgot to reset xi_sigma_pi_LS and I have correlation functions that are multiples of each other. Fook!

Anyway, it's so close now and the end of this week has to be a pretty hard deadline to get this done by - don't stand so close to me!!

Oooo, and Ellis (Caltech) is speaking tomorrow. Really looking forward to that and if Shanks (Durham) gets going - now that's a real Royal Rumble!!

In other news, I finally took home Mullaney's (Durham) home smoked bacon. Gonna go well with me eggs tomorrow!!

Thursday, June 08, 2006

ARGH!! (Part 1)

What is the co-moving distance of a galaxy with redshift z=0.3410 given Omega_M = 0.3 and Omega_Lambda=0.7 in a flat Universe???? Is it 939.45, 940.3 or 940.93 h^-1 Mpc???

Anyway, whatever it is, this has severly annoyed me today as just when I thought I was putting the final touches to all my graphs, there seems to be a slight issue with co-moving distances and co-ordinate transform. However, I really don't think (and really do hope) that this will have much, if any bearing on the final redshift-space measurements.

In other news, the DES is coming!! Both the CTIO and VISTA versions. Castander (IEEC, Barcelona) gave a comprehenisve seminar on the subject this lunchtime - but will this be competitive on the timescales we're talking about??

P.S. The network started having real problems last night and this post didn't published until this morning.

Wednesday, June 07, 2006

Royal Rumble

In an attempt to satisfy a regular readers request for more Middleton (Durham) related stories, here is a paper from astro-ph yesterday relating to the spin of GRS1915+105. McClintock et al. (astro-ph/0606076) claim a much higher value for the dimensionless spin parameter (a > 0.98) than Middelton et al. (astro-ph/0601540).
However, I have it on very good authority that the Middleton group are "not convinced" and this reporter thinks a Battle Royale is on the cards....

In related, non-astronomy news, Middleton has agreed to an "Erg-off" with Shone (Durham).
Gentlemen, start your engines!!

Tuesday, June 06, 2006


Everything else is on hold until I get this paper DONE. There are a lot of tweaks I can still do but really have to push now to get it past Shanks.

Sunday, June 04, 2006


Dear Loyal Readers,

Many apologies are due to the last week of non-posts. Sorry. Slightly ironically this is because I had a pretty productive week analysing my jackknife samples which ended up with a Omega_m-beta plot from Jose late on Friday evening. To summarise, at the moment a simple least squares fit to wp(sigma) and xi(r) I think favour a single power-law more (r_0 = 7.2+0.8-0.7, gamma = 1.78+0.14-0.10) but a double-power law cant be ruled out. Jose's first esimations from fitting the redshift-space distortions suggest Omega_M = 0.2, beta=0.5, velocity dispersion 400 km/s.

Other highlights of the week were another good Wednesday seminar from Ferguson (Edinburgh) talking about what we can learn by looking at very local galaxies (in this case M31 and M33) and if you see tidal stream features (M31 you do, M33 you dont).

Also, I gave a Observers' Lunch talk on Hopkins, Richards and Hernquist (astro-ph/0605678) "An Observational Determination of the Bolometric Quasar Luminosity Function" which makes some very strong but credible claims about quasar and black hole properties such as "birthrate" number and space density evolution, M* break-mass and "downsizing".