We forecast the benefits induced by adding the bispectrum anisotropic signal to the standard , two- and three-point , clustering statistics analysis .
In particular , we forecast cosmological parameter constraints including the bispectrum higher multipoles terms together with the galaxy power spectrum ( monopole plus quadrupole ) and isotropic bispectrum ( monopole ) data vectors .
To do so , an analytical covariance matrix model is presented .
This template is carefully calibrated on well-known terms of a numerical covariance matrix estimated from a set of simulated galaxy catalogues .
After testing the calibration using the power spectrum and isotropic bispectrum measurements from the same set of simulations , we extend the covariance modelling to the galaxy bispectrum higher multipoles .
Using this covariance matrix we proceed to perform cosmological parameter inference using a suitably generated mock data vector .
Including the bispectrum mutipoles up to the hexadecapole , yields 1-D 68 \% credible regions for the set of parameters ( b _ { 1 } ,b _ { 2 } ,f, \sigma _ { 8 } ,f _ { \mathrm { NL } } , \alpha _ { \perp } , \alpha _ { \parallel } ) tighter by a factor of 30 \% on average for k _ { \mathrm { max } } = 0.09 h /Mpc , significantly reducing at the same time the degeneracies present in the posterior distribution .