A Lagrangian perturbation theory in the presence of massive neutrinos

Journal Article · Mon Oct 12 00:00:00 EDT 2020 · Journal of Cosmology and Astroparticle Physics

DOI:https://doi.org/10.1088/1475-7516/2020/10/034· OSTI ID:1769260

Aviles, Alejandro ^[1]; Banerjee, Arka ^[2]

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1. Consejo Nacional de Ciencia y Tecnología (México); Instituto Nacional de Investigaciones Nucleares (México)
2. Stanford Univ., CA (United States); SLAC National Accelerator Lab., Menlo Park, CA (United States)

We develop a Lagrangian Perturbation Theory (LPT) framework to study the clustering of cold dark matter (CDM) in cosmologies with massive neutrinos. We follow the trajectories of CDM particles with Lagrangian displacements fields up to third order in perturbation theory. Once the neutrinos become non-relativistic, their density fluctuations are modeled as being proportional to the CDM density fluctuations, with a scale-dependent proportionality factor. This yields a gravitational back-reaction that introduces additional scales to the linear growth function, which is accounted for in the higher order LPT kernels. Through non-linear mappings from Eulerian to Lagrangian frames, we ensure that our theory has a well behaved large scale behavior free of unwanted UV divergences, which are common when neutrino and CDM densities are not treated on an equal footing, and in resummation schemes that manifestly break Galilean invariance. We use our theory to construct correlation functions for both the underlying matter field, as well as for biased tracers using ConvolutionLPT. Redshift-space distortions effects are modeled using the Gaussian Streaming Model. When comparing our analytical results to simulated data from the Quijote¹ simulation suite, we find good accuracy down to r = 20 Mpc h ^-1 at redshift z = 0.5, for the real space and redshift space monopole particle correlation functions with no free parameters. The same accuracy is reached for the redshift space quadrupole if we additionally consider an effective field theory parameter that shifts the pairwise velocity dispersion. For modeling the correlation functions of tracers we adopt a simple Lagrangian biasing scheme with only density and curvature operators, which we find sufficient to reach down to r = 20 Mpc h ^-1 when comparing to simulated halos.

• Research Organization: SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: AC02-76SF00515
• OSTI ID: 1769260
• Journal Information: Journal of Cosmology and Astroparticle Physics, Vol. 2020, Issue 10; ISSN 1475-7516
• Publisher: Institute of Physics (IOP)
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Large Scale Structure
Massive neutrinos
Perturbation Theory