Gravitational-Wave Background Sky Maps from Advanced LIGO O1 Data

摘要

We integrate the publicly available O1 LIGO time-domain data to obtain maximum-likelihood constraints on the gravitational-wave background (GWB) arising from stochastic, persistent signals. Our method produces sky maps of the strain intensity I as a function of direction on the sky at a reference frequency fo. The data are integrated assuming a set of fixed power-law spectra for the signal. The maps provide upper limits on the amplitude of the GWB density Omega(GW)(f(0)) and any anisotropy around the background. We find 95% confidence upper limits of Omega(GW) 4.8 x 10(-7) at f(0) = 50 Hz with similar constraints on a dipole modulation for the inspiral-dominated stochastic background case.