Archive for October 19, 2016

KiDS-450: Testing extensions to the standard cosmological model [CEA]

Posted in The Universe and Stuff with tags , , , on October 19, 2016 by telescoper

Since I’ve just attended a seminar in Cardiff by Catherine Heymans on exactly this work, I couldn’t resist reblogging the arXiver entry for this paper which appeared on arXiv a couple of days ago.

The key finding is that the weak lensing analysis of KIDS data (which is mainly to the distribution of matter at low redshift) does seem to be discrepant with the predictions of the standard cosmological model established by Planck (which is sensitive mainly to high-redshift fluctuations).

Could this discrepancy be interpreted as evidence of something going on beyond the standard cosmology? Read the paper to explore some possibilities!


We test extensions to the standard cosmological model with weak gravitational lensing tomography using 450 deg$^2$ of imaging data from the Kilo Degree Survey (KiDS). In these extended cosmologies, which include massive neutrinos, nonzero curvature, evolving dark energy, modified gravity, and running of the scalar spectral index, we also examine the discordance between KiDS and cosmic microwave background measurements from Planck. The discordance between the two datasets is largely unaffected by a more conservative treatment of the lensing systematics and the removal of angular scales most sensitive to nonlinear physics. The only extended cosmology that simultaneously alleviates the discordance with Planck and is at least moderately favored by the data includes evolving dark energy with a time-dependent equation of state (in the form of the $w_0-w_a$ parameterization). In this model, the respective $S_8 = sigma_8 sqrt{Omega_{rm m}/0.3}$ constraints agree at the $1sigma$ level, and there is `substantial concordance’ between…

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Chuck Berry on a Summer’s Day

Posted in Music with tags , , , , , , , on October 19, 2016 by telescoper

I was meaning to post this yesterday about Chuck Berry to mark his 90th Birthday. I’m putting it here as a bit of an oddity but I hope you find it interesting.

Chuck Berry appeared in Bert Stern’s classic film Jazz on Summer’s Day which was filmed at the 1958 Newport Jazz Festival. He performed on that occasion with a pick-up band called the Newport All-Stars, and the number that made it into the film was Sweet Little Sixteen, a tune that he actually wrote. I find two things fascinating about this performance. One is that the “backing band” is a stellar group of Jazz legends: the drummer is the great Jo Jones (who led the lightly swinging rhythm section of the great Count Basie band of the 1930s); the trumpeter is Buck Clayton, another Basie alumnus; and the trombonist is none other than Jack Teagarden. To a Jazz fan like myself, the talents of these musicians are totally wasted: they seem somewhat bemused by Chuck Berry’s gyrations on stage as well as bored by the material. When the time comes for the improvised solos that a jazz audience demands, only the relatively unknown clarinettist Rudy Rutherford – usually a tenor saxophonist who played with a number of bands, including Count Basie’s – was prepared to stand up and be counted, his strange effort is evidently a source of great amusement to the rest of the band, but at least he got into the spirit!

The other fascinating thing is what a historical document this is. During the 1950s Jazz was beginning to lose out to Rock and Roll in the popularity stakes, hence the plan of booking Chuck Berry to boost the audience figures at the Newport Jazz Festival. The tension on stage is almost palpable and even Chuck Berry occasionally looks a bit embarrassed by the whole thing. But it’s also a wonderfully observed portrayal of the styles of the time, especially through the audience shots. I wonder what happened to the cute couple dancing to this performance?

Anyway, belated best wishes on his 90th Birthday, here’s Chuck Berry recorded live 58 years ago at the Newport Jazz Festival in 1958, singing and playing Sweet Little Sixteen.


P.S. I forgot to mention the superb photography.