An upper limit on the stochastic gravitational-wave background of cosmological origin

Abstract

A stochastic background of gravitational waves is expected to arise from a superposition of a large number of unresolved gravitational-wave sources of astrophysical and cosmological origin. It should carry unique signatures from the earliest epochs in the evolution of the Universe, inaccessible to standard astrophysical observations(1). Direct measurements of the amplitude of this background are therefore of fundamental importance for understanding the evolution of the Universe when it was younger than one minute. Here we report limits on the amplitude of the stochastic gravitational-wave background using the data from a two-year science run of the Laser Interferometer Gravitational-wave Observatory(2) (LIGO). Our result constrains the energy density of the stochastic gravitational-wave background normalized by the critical energy density of the Universe, in the frequency band around 100 Hz, to be <6.9 X 10(-6) at 95% confidence. The data rule out models of early Universe evolution with relatively large equation-of-state parameter(3), as well as cosmic (super) string models with relatively small string tension(4) that are favoured in some string theory models(5). This search for the stochastic background improves on the indirect limits from Big Bang nucleosynthesis(1,6) and cosmic microwave background(7) at 100Hz

Measurement and subtraction of Schumann resonances at gravitational-wave interferometers

“…A SGWB from compact binary coalescences is potentially detectable by the time second-generation detectors reach design sensitivity [3]. Backgrounds from pulsars, magnetars, core-collapse supernovae, and various physical processes in the early universe are all possible as well [4][5][6], but their expected amplitudes are not as well constrained as the expected background due to compact binary coalescences. The potential for the contamination of searches for a SGWB is strong due to potential correlated environmental noise between detectors [5,[7][8][9][10][11], which would result in a systematic error in the searches.…”

Directional Limits on Persistent Gravitational Waves Using LIGO S5 Science Data

“…S5 saw milestones including limits on GWs from the Crab pulsar surpassing those inferred from the Crab's spindown [11], as well as limits on the isotropic SGWB surpassing indirect limits from big bang nucleosynthesis and the cosmic microwave background [12]. This work builds on [12,13].…”

The Transition from Pre-Octonionic to Octonionic Gravity and How It May Be Pertinent to a Re-Do of the HUP for Metric Tensors

“…It would be interesting and perhaps useful to compare this with the predictions given by Abbot [56]a s well as the revising the issue which is brought up by reference [57]. Keep in mind as well that there has been recent confirmation by Abbot [58] as to the existence of gravitational waves, which further extends what was brought up by Abbot, et al…”

“…of the LIGO observational team, which is in terms of black hole binaries, which further confirms the solutions of the issues, brought up by Abbot in [56] as well as also room to explore the insights brought up by Corda in [59] which await further investigation.…”