Gravitational wave background from binary systems

Understand

Basic aspects of the background of gravitational waves and its mathematical characterization are reviewed.

• The spectral energy density parameter $\Omega(f)$, commonly used as a quantifier of the background, is derived for an ensemble of many identical sources emitting at different times and locations.
• For such an ensemble, $\Omega(f)$ is generalized to account for the duration of the signals and of the observation, so that one can distinguish the resolvable and unresolvable parts of the background.
• The unresolvable part, often called confusion noise or stochastic background, is made by signals that cannot be either individually identified or subtracted out of the data.