Gravitational Wave Background Sky Maps from Advanced LIGO O1 Data

Abstract

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 $f_0$. The data is integrated assuming a set of fixed power-law spectra for the signal. The maps provide upper limits on the amplitude of the GWB density ${\Omega }_{\mathrm{GW}}(f_0)$ and any anisotropy around the background. We find 95\% confidence upper limits of ${\Omega }_{\mathrm{GW}}<4.8\times 10^{-7}$ at $f_0=50$ Hz with similar constraints on a dipole modulation for the inspiral-dominated stochastic background case.

5 pages, 3 figures, 3 tables