Maximum likelihood map making with the Laser Interferometer Space Antenna

Abstract

Given the recent advances in gravitational-wave detection technologies, the detection and characterisation of gravitational-wave backgrounds (GWBs) with the Laser Interferometer Space Antenna (LISA) is a real possibility. To assess the abilities of the LISA satellite network to reconstruct anisotropies of di↵erent angular scales and in di↵erent directions on the sky, we develop a map-maker based on an optimal quadratic estimator. The resulting maps are maximum likelihood representations of the GWB intensity on the sky integrated over a broad range of frequencies. We test the algorithm by reconstructing known input maps with di↵erent input distributions and over di↵erent frequency ranges. We find that, in an optimal scenario of well understood noise and high frequency, high SNR signals, the maximum scales LISA may probe are`max . 15. The map-maker also allows to test the directional dependence of LISA noise, providing insight on the directional sky sensitivity we may expect.

Non-Gaussian stochastic gravitational waves from phase transitions

“…Given the discussion below eq. (3.6), we see that for such values α, β, LISA sensitivity would be able to probe max 10 which is within its expected angular resolution (see [28,37] for discussions on LISA sensitivity to stochastic GWB). Still it is very challenging to probe beyond ≈ O (10) in LISA.…”

“…The prospects of GW map-making have been discussed previously in the literature, for a review see e.g. [35], along with some recent work [36,37]. For previous discussions on anisotropies and non-Gaussianity of GWB, see [38,39].…”

Probing pre-Recombination Physics by the Cross-Correlation of Stochastic Gravitational Waves and CMB Anisotropies

“…The situation is more optimistic for BBO and DECIGO for which the improvement on the errors is a bit better and can be obtained even with smaller values of A * . However, for realistic values of GW max ∼ 15 [27], the improvement in the error is never larger than ∼ 10%.…”

“…Although most of the research on the SGWB has focused on the isotropic part of the graviton two-point function, i.e., its energy density, the characterization of other SGWB observables have been studied, such as higher point graviton correlation functions [23] and their polarization [24,25] and anisotropies [26][27][28]. Furthermore, another way to maximize the information that can be extracted by GW data is by cross-correlating them with those from other cosmological observations.…”

Cross-correlating Astrophysical and Cosmological Gravitational Wave Backgrounds with the Cosmic Microwave Background

“…While the former generation mechanism is source/model-dependent, the latter is model-independent and ubiquitous for all the SGWB sources. Tools and techniques to measure anisotropic components of the SGWB have been developed in [29][30][31][32][33][34][35][36][37]. The physics that governs SGWB anisotropies (at least in the geometric optics limit) displays strong analogies with that underlying Cosmic Microwave Background (CMB) fluctuations [38][39][40][41].…”