Wide-angle and relativistic effects in Fourier-space clustering statistics

Galaxy power spectrum and bispectrum signals are distorted by peculiar velocities other relativistic effects arising from a perturbed spacetime background. In addition, study of correlation functions tracers in Fourier space is often done the plane-parallel approximation under which it assumed that line-of-sight (LOS) vectors parallel. this work we show simple perturbative procedure can be employed for fast evaluation beyond (wide-angle) corrections to bispectrum. We also evolution linear matter density fluctuations context found method. For at level, compare leading order wide-angle contributions multipoles galaxy with those non-integrated integrated estimate their possible contamination on local fNL measurements few. compute presence nonlinear terms one-loop order. bispectrum, alone, even fully symmetric choices LOS, give rise imaginary, odd-parity (dipole, octupole, etc.) many cases larger than previously known ones origin. calculate these provide an estimator measuring dipole data, using LOS definition. Finally, real apparent induced unity.