Université de GenèveDépartement de Physique ThéoriqueCAP Genève

Probing Anisotropies of the Stochastic Gravitational Wave Background with LISA

24. January 2022
Cite as: 
N. Bartolo et al., (2022) [arXiv:2201.08782].
We investigate the sensitivity of the Laser Interferometer Space Antenna (LISA) to the anisotropies of the Stochastic Gravitational Wave Background (SGWB). We first discuss the main astrophysical and cosmological sources of SGWB which are character- ized by anisotropies in the GW energy density, and we build a Signal-to-Noise estimator to quantify the sensitivity of LISA to different multipoles. We then perform a Fisher matrix analysis of the prospects of detectability of anisotropic features with LISA for individual multipoles, focusing on a SGWB with a power-law frequency profile. We compute the noise angular spectrum taking into account the specific scan strategy of the LISA detector. We analyze the case of the kinematic dipole and quadrupole generated by Doppler boosting an isotropic SGWB. We find that β Ω_{GW} ∼ 2 × 10^{−11} is required to observe a dipolar signal with LISA. The detector response to the quadrupole has a factor ∼ 10^{3} β relative to that of the dipole. The characterization of the anisotropies, both from a theoretical perspective and from a map-making point of view, allows us to extract information that can be used to understand the origin of the SGWB, and to discriminate among distinct superimposed SGWB sources.


Département de Physique Théorique
Université de Genève
24, quai Ernest Ansermet
1211 Genève 4
Directions & contact