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Published November 2022 | public
Journal Article

Probing anisotropies of the Stochastic Gravitational Wave Background with LISA

Abstract

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 characterized 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 ∼ 10³ 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.

Additional Information

It is a pleasure to thank Valerie Domcke, Juan Garcia-Bellido and Sabino Matarrese for useful discussions. We acknowledge the LISA Publication and Presentation committee, in particular Sharan Banagiri for carefully reading and useful comments on the draft. N.B. and D.B. acknowledge partial financial support by ASI Grant No. 2016-24-H.0. R.C. is supported in part by U.S. Department of Energy Award No. DE-SC0010386. CRC acknowledges support under a UKRI Consolidated Grant ST/T000791/1. V.DL. and A.Rio. are supported by the Swiss National Science Foundation (SNSF), project The Non-Gaussian Universe and Cosmological Symmetries, project number: 200020-178787. M.F. would like to acknowledge support from the "Atracción de Talento" CAM grant 2019-T1/TIC15784. DGF (ORCID 0000-0002-4005-8915) is supported by a Ramón y Cajal contract with ref. RYC-2017-23493, by the project PROMETEO/2021/083 from Generalitat Valenciana, and by the project PID2020-113644GB-I00 from Ministerio de Ciencia e Innovación. G.F. acknowledges financial support provided under the European Union's H2020 ERC, Starting Grant agreement no. DarkGRA-757480 and under the MIUR PRIN programme, and support from the Amaldi Research Center funded by the MIUR program "Dipartimento di Eccellenza" (CUP: B81I18001170001). M.Pe. is supported by Istituto Nazionale di Fisica Nucleare (INFN) through the Theoretical Astroparticle Physics (TAsP) and the Inflation, Dark Matter and the Large-Scale Structure of the Universe (InDark) project. The work of M.Pi. was supported by STFC grants ST/P000762/1 and ST/T000791/1. M.Pi. acknowledges support by the European Union's Horizon 2020 Research Council grant 724659 MassiveCosmo ERC-2016-COG. A.Ric. acknowledges funding from Italian Ministry of Education, University and Research (MIUR) through the "Dipartimenti di eccellenza" project Science of the Universe. M.S. is supported in part by the Science and Technology Facility Council (STFC), United Kingdom, under the research grant ST/P000258/1. The work of LS is partially supported by the US-NSF grants PHY-1520292 and PHY-1820675. G.T. is partially supported by the STFC grant ST/T000813/1. S.C. acknowledges support from the Belgian Francqui Foundation through a Francqui Start-up Grant.

Additional details

Created:
August 22, 2023
Modified:
October 24, 2023