PDA

View Full Version : The Cosmological Parameters 2005


marcus
Jan9-06, 08:46 PM
this just came out

http://arxiv.org/abs/astro-ph/0601168

it is an update, as of year-end 2005, of the best estimates of the values of the main cosmological parameters

like the Hubble parameter
and the dark energy density (or cosm. const.)
and the Omega number which is used to indicate how close to being spatially flat the universe is.

AFAIK there are no surprises here, the Hubble parameter is still 73 km/s per Megaparsec, and so on. but here it is if you want an up-to-date reference on the basic numbers

EL
Jan10-06, 05:33 AM
Nice review!

Looking forward to see what the new data from WMAP will tell us. Rumours say they will be released any day (as if we havn't heard that before...:rolleyes:).

Garth
Jan10-06, 11:37 AM
Interestingly, there still seems to be debate over the accepted value of Hubble's constant.

That paper gives the LCDM-WMAP fitted value of
H0 = 73 ± 3 km/sec/Mpsc whereas Tammann's paper The Ups and Downs of the Hubble Constant (http://arxiv.org/abs/astro-ph/0512584) gives the value:A proposed solution is summarized here. The conclusion is that H0 = 63.2 +/- 1.3 (random) +/- 5.3 (systematic) on all scales. The expansion age becomes then (with Omegam = 0.3, OmegaLambda = 0.7) 15.1 Gyr
The two values are almost consistent if we take the extreme limit on the lower error bar for the 'WMAP' value (70) and the extreme limit on the upper error bar for the 'Tammann' value (69.8), but one wonders if the age of 'precision cosmology' is not so precise after all.

Garth

Chronos
Jan11-06, 02:08 AM
I cast aside Tamman's paper with predudice. He appears to ignore a great deal of good observational evidence.