Modeling the Marked Spectrum of Matter and Biased Tracers in Real- and Redshift-Space

TL;DR

This paper develops a one-loop perturbation theory model for the marked density power spectrum of matter and biased tracers in real- and redshift-space, improving accuracy over linear theory and enabling better cosmological constraints.

Contribution

It introduces an improved one-loop Effective Field Theory model for the marked power spectrum, including a reorganization for large-scale accuracy and considerations for massive neutrinos.

Findings

One-loop EFT improves accuracy to ~5% at z=1 in real-space.

Redshift-space accuracy is ~10%, with bias coefficients aiding improvements.

A low-k correction yields sub-percent accuracy on large scales.

Abstract

We present the one-loop perturbation theory for the power spectrum of the marked density field of matter and biased tracers in real- and redshift-space. The statistic has been shown to yield impressive constraints on cosmological parameters; to exploit this, we require an accurate and computationally inexpensive theoretical model. Comparison with $N$-body simulations demonstrates that linear theory fails on all scales, but inclusion of one-loop Effective Field Theory terms gives a substantial improvement, with $\sim 5\%$ accuracy at $z = 1$. The expansion is less convergent in redshift-space (achieving $\sim 10\%$ accuracy), but there are significant improvements for biased tracers due to the freedom in the bias coefficients. The large-scale theory contains non-negligible contributions from all perturbative orders; we suggest a reorganization of the theory that contains all terms relevant on large-scales, discussing both its explicit form at one-loop and structure at infinite-loop. This motivates a low-$k$ correction term, leading to a model that is sub-percent accurate on large scales, albeit with the inclusion of two (three) free coefficients in real- (redshift-)space. We further consider the effects of massive neutrinos, showing that beyond-EdS corrections to the perturbative kernels are negligible in practice. It remains to see whether the purported gains in cosmological parameters remain valid for biased tracers and can be captured by the theoretical model.