Towards optimal and robust $f_{\rm NL}$ constraints with multi-tracer analyses
Abstract
We discuss the potential of the multi-tracer technique to improve observational constraints of the local primordial non-Gaussianity (PNG) parameter from the galaxy power spectrum. For two galaxy samples and , the constraining power is , where and are the linear and PNG galaxy bias parameters. We show this allows for significantly improved constraints compared to the traditional expectation based on naive universality-like relations where . Using IllustrisTNG galaxy simulation data, we find that different equal galaxy number splits of the full sample lead to different , and thus have different constraining power. Of all of the strategies explored, splitting by color is the most promising, more than doubling the significance of detecting . Importantly, since these are constraints on and not , they do not require priors on the relation. For direct constraints on , we show that multi-tracer constraints can be significantly more robust than single-tracer to misspecifications and uncertainties; this relaxes the precision and accuracy requirements for priors. Our results present new opportunities to improve our chances to detect and robustly constrain , and strongly motivate galaxy formation simulation campaigns to calibrate the relation.
Keywords
Cite
@article{arxiv.2302.09066,
title = {Towards optimal and robust $f_{\rm NL}$ constraints with multi-tracer analyses},
author = {Alexandre Barreira and Elisabeth Krause},
journal= {arXiv preprint arXiv:2302.09066},
year = {2023}
}
Comments
9 pages, 4 figures, 1 table. Comments welcomed! v2 matches version published in JCAP