Detecting primordial features with LISA. Issue 7 (1st July 2022)

• Record Type: Journal Article
• Authors: Fumagalli, Jacopo; Pieroni, Mauro; Renaux-Petel, Sébastien; Witkowski, Lukas T.
• Is Part Of: Journal of cosmology and astroparticle physics. Volume 2022:Issue 7(2022)
• Publication Date: 2022-07-01
• Subjects: gravitational waves / experiments -- gravitational waves / theory -- primordial gravitational waves (theory) -- inflation; Cosmology -- Periodicals; Astrophysics -- Periodicals; 523.0105
• DOI: 10.1088/1475-7516/2022/07/020
• Languages: English
• ISSNs: 1475-7516

Abstract

Abstract: Oscillations in the frequency profile of the stochastic gravitational wave background are a characteristic prediction of small-scale features during inflation. In this paper we present a first investigation of the detection prospects of such oscillations with the upcoming space-based gravitational wave observatory LISA. As a proof of principle, we show for a selection of feature signals that the oscillations can be reconstructed with LISA, employing a method based on principal component analysis. We then perform a Fisher forecast for the parameters describing the oscillatory signal. For a sharp feature we distinguish between the contributions to the stochastic gravitational wave background induced during inflation and in the post-inflationary period, which peak at different frequencies. We find that for the latter case the amplitude of the oscillation is expected to be measurable with < 10% accuracy if the corresponding peak satisfies h 2 ΩGW ≳ 10 -12 -10 -11, while for inflationary-era gravitational waves a detection of the oscillations requires a higher peak amplitude of h 2 ΩGW, as the oscillations only appear on the UV tail of the spectrum. For a resonant feature the detection prospects with LISA are maximised if the frequency of the oscillation falls into the range ω log = 4 to 10. Our results confirm that oscillations in the frequency profile of the stochastic gravitational wave background are a worthwhile target for future detection efforts and offer a key for experimentally testing inflation at small scales.