Constraints on primordial non-Gaussianity using multitracer technique for skew spectrum

TL;DR

This paper demonstrates that combining the skew spectrum with the multitracer technique significantly improves constraints on primordial non-Gaussianity by reducing cosmic variance, using simulations to validate the approach.

Contribution

It extends the skew spectrum method to multitracer analysis, showing enhanced constraints on local primordial non-Gaussianity in large-scale structure surveys.

Findings

Multitracer approach reduces cosmic variance noise.

Errors on $f_{NL}^{loc}$ decreased by 73%.

Skew spectrum combined with multitracer improves non-Gaussianity constraints.

Abstract

Extracting the bispectrum information from the large scale structure observations is challenging due to the complex models and the computational costs to measure the signal and its covariance. Recently, the skew spectrum was proposed to access parts of the bispectrum information with a more effective way and has been confirmed it can provide complementary information to that enclosed in the power spectrum measurements. In this work, we generalize the theory to apply the multitracer technique and explore its ability to constrain the local type primordial non-Gaussianity. Using the spectra and their covariance estimated from $N$-body simulations, we find the multitracer approach is effective to reduce the cosmic variance noise. The $1\sigma$ marginalized errors for $b_1^2A_s, n_s$ and $f_{\rm NL}^{\rm loc}$ are reduced by 50\%, 52\% and 73\% comparing with the results using only power spectrum obtained from a single tracer. It indicate that both the skew spectrum and the multitracer technique are useful to constrain the primordial non-Gaussianity with the forthcoming wide-field galaxy surveys.