Present bounds on the relativistic energy density in the Universe from cosmological observables

Details Present bounds on the relativistic energy density in the Universe from cosmological observables Present bounds on the relativistic energy density in the Universe from cosmological observables

2006-12-06

arxiv.org/abs/astro-ph/0612150v2

JCAP 0703:006,2007

Astronomy and Astrophysics

Astrophysics

Scientific paper

10.1088/1475-7516/2007/03/006

We discuss the present bounds on the relativistic energy density in the Universe parameterized in terms of the effective number of neutrinos N using the most recent cosmological data on Cosmic Microwave Background (CMB) temperature anisotropies and polarization, Large Scale galaxy clustering from the Sloan Digital Sky Survey (SDSS) and 2dF, luminosity distances of type Ia Supernovae, Lyman-alpha absorption clouds (Ly-alpha), the Baryonic Acoustic Oscillations (BAO) detected in the Luminous Red Galaxies of the SDSS and finally, Big Bang Nucleosynthesis (BBN) predictions for 4He and Deuterium abundances. We find N= 5.2+2.7-2.2 from CMB and Large Scale Structure data, while adding Ly-alpha and BAO we obtain N= 4.6+1.6-1.5 at 95 % c.l.. These results show some tension with the standard value N=3.046 as well as with the BBN range N= 3.1+1.4-1.2 at 95 % c.l., though the discrepancy is slightly below the 2-sigma level. In general, considering a smaller set of data weakens the constraints on N. We emphasize the impact of an improved upper limit (or measurement) of the primordial value of 3He abundance in clarifying the issue of whether the value of N at early (BBN) and more recent epochs coincide.

Affiliated with

Also associated with

No associations

Rating

Present bounds on the relativistic energy density in the Universe from cosmological observables does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Present bounds on the relativistic energy density in the Universe from cosmological observables, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Present bounds on the relativistic energy density in the Universe from cosmological observables will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-451660