Improved limits on short-wavelength gravitational waves from the cosmic microwave background

Details Improved limits on short-wavelength gravitational waves from the cosmic microwave background Improved limits on short-wavelength gravitational waves from the cosmic microwave background

2012-03-19

arxiv.org/abs/1203.4232v1

Astronomy and Astrophysics

Astrophysics

Cosmology and Extragalactic Astrophysics

5 pages, 3 figures

Scientific paper

The cosmic microwave background (CMB) is affected by the total radiation density around the time of decoupling. At that epoch, neutrinos comprised a significant fraction of the radiative energy, but there could also be a contribution from primordial gravitational waves with frequencies greater than ~ 10^-15 Hz. If this cosmological gravitational wave background (CGWB) were produced under adiabatic initial conditions, its effects on the CMB and matter power spectrum would mimic massless non-interacting neutrinos. However, with homogenous initial conditions, as one might expect from certain models of inflation, pre big-bang models, phase transitions and other scenarios, the effect on the CMB would be distinct. We present updated observational bounds for both initial conditions using the latest CMB data at small scales from the South Pole Telescope (SPT) in combination with Wilkinson Microwave Anisotropy Probe (WMAP), current measurements of the baryon acoustic oscillations, and the Hubble parameter. With the inclusion of the data from SPT the adiabatic bound on the CGWB density is improved by a factor of 1.7 to 10^6 Omega_gw < 8.7 at the 95% confidence level (C.L.), with weak evidence in favor of an additional radiation component consistent with previous analyses. The constraint can be converted into an upper limit on the tension of horizon-sized cosmic strings that could generate this gravitational wave component, with Gmu < 2 10^-7 at 95% C.L., for string tension Gmu. The homogeneous bound improves by a factor of 3.5 to 10^6 Omega_gw < 1.0 at 95% C.L., with no evidence for such a component from current data.

Affiliated with

Also associated with

No associations

Rating

Improved limits on short-wavelength gravitational waves from the cosmic microwave background 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 Improved limits on short-wavelength gravitational waves from the cosmic microwave background, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Improved limits on short-wavelength gravitational waves from the cosmic microwave background will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-493016