Probing parity-odd bispectra with anisotropies of GW V modes

Abstract

It is well known that non-trivial squeezed tensor bispectra can lead to anisotropies in the inflationary stochastic gravitational wave (GW) background, providing us with an alternative and complementary window to primordial non-Gaussianities (NGs) with respect to the CMB. Previous works have highlighted the detection prospects of parity-even tensor NGs via the GW I-mode anisotropies. In this work we extend this by analysing for the first time the additional information carried by GW V-mode anisotropies due to squeezed NGs. We show that GW V modes allow us to probe parity-odd squeezed 〈 tts 〉 and 〈 ttt 〉 bispectra. These bispectra break parity at the non-linear level and can be introduced by allowing alternative symmetry breaking patterns during inflation, like those comprised in solid inflation. Considering a BBO-like experiment, we find that a non-zero detection of squeezed 〈 tts 〉 parity-odd bispectra in the V modes dipole is possible without requiring any short-scale enhancement of the GW power spectrum amplitude over the constraints set by the CMB. We also briefly discuss the role of V-CMB cross-correlations. Our work can be extended in several directions and motivates a systematic search for polarized GW anisotropies in the next generations of GW experiments.

Primordial gravitational waves in non-minimally coupled chromo-natural inflation

“…On the other hand, the SU(2) case, for example, comes with linearly sourced tensor modes; in non-Abelian configurations the tensor sector is indeed the most affected by the coupling to gauge fields. The chiral nature of the GW signal can be tested, depending on the size and the position of the peak, at CMB scales 2 via BT , BE correlations [29,[43][44][45] and by laser interferometers [46][47][48][49]. Given their the intriguing phenomenology, several aspects of axion-gauge fields models have been explored…”

New universal property of cosmological gravitational wave anisotropies

“…The origin of GW anisotropies of cosmological nature can be manifold. It may, for example, be inherent to the SGWB production mechanism [13][14][15][16][17][18][19][20][21]. GW anisotropies in the early universe have also been studied in the context of GWs from phase transitions [22][23][24][25][26] and cosmic strings [13,14] as well as preheating [27,28] (see [29] for a recent comprehensive review).…”

Boltzmann equations for astrophysical Stochastic Gravitational Wave Backgrounds scattering off of massive objects

“…[17]) and polarisation (e.g. [18,19]) of the latter would reveal the details of different physical processes in the inflationary era. The study of the SGWB intensity [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] has been performed so far with approaches similar to those used for the Cosmic Microwave Background (CMB): its evolution is described by a phase-space distribution function obeying 1 https://www.ligo.caltech.edu/.…”