Accurate fluid approximation for massive neutrinos in cosmology

Nascimento, Caio Felipe Fonseca do

doi:10.1103/physrevd.108.023505

Cited by 2 publications

(3 citation statements)

References 21 publications

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“…First, we approximated the sound speed of the neutrino fluid in terms of the velocity dispersion of the non-relativistic neutrinos [17]. It will be interesting to improve this approximation, as has been proposed in a recent study [45], and study the effects on the matter power spectrum. We also plan to extend the current study to the mildly nonlinear regime in a perturbative scheme, utilizing the linear kernels derived in this work.…”

Section: Discussionmentioning

confidence: 99%

“…This two-fluid treatment introduces a distinct free-streaming length scale, similar to the Jeans scale, into the fluid equations due to the presence of massive neutrinos. The validity of the fluid approximation including massive neutrinos has been extensively studied in [17,18], and recently in [45]. In the non-relativistic limit, the coupled fluid equations are given as follows (ignoring vorticity and nonlinear terms),…”

Section: Jcap12(2023)004mentioning

confidence: 99%

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Revisiting coupled CDM-massive neutrino perturbations in diverse cosmological backgrounds

Pal,

Samanta,

Pal

2023

J. Cosmol. Astropart. Phys.

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Massive neutrinos are well-known to cause a characteristic suppression in the growth of structures at scales below the neutrino free-streaming length. A detailed understanding of this suppression is essential in the era of precision cosmology we are entering into, enabling us to better constrain the total neutrino mass and possibly probe (beyond)-ΛCDM cosmological model(s). Instead of the usual N-body simulation or Boltzmann solver, in this article we consider a two-fluid framework at the linear scales, where the neutrino fluid perturbations are coupled to the CDM (+ baryon) fluid via gravity at redshifts of interest. Treating the neutrino mass fraction f ν as a perturbative parameter, we find solutions to the system with redshift-dependent neutrino free-streaming length in ΛCDM background via two separate approaches. The perturbative scale-dependent solution is shown to be in excellent agreement with numerical solution of the two-fluid equations valid to all orders in f ν, and also agrees with results from CLASS to a good accuracy. We further generalize the framework to incorporate different evolving dark energy backgrounds and found sub-percent level differences in the suppression, all of which lie within the observational uncertainty of BOSS-like surveys. We also present a brief discussion on the prospects of the current analysis in the context of upcoming missions.

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Section: Discussionmentioning

confidence: 99%

Section: Jcap12(2023)004mentioning

confidence: 99%

Revisiting coupled CDM-massive neutrino perturbations in diverse cosmological backgrounds

Pal,

Samanta,

Pal

2023

J. Cosmol. Astropart. Phys.

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“…In practice the transition at the free-streaming scale is rather smooth, with the neutrino species fully behaving like CDM only at scales above the neutrino horizon scale which is approximately set by the freestreaming scale when evaluated at the moment when neutrinos first became nonrelativistic and lies at much larger scales. See figure1in[54] for more details.…”

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confidence: 99%

Neutrino winds on the sky

Nascimento,

Loverde

2023

J. Cosmol. Astropart. Phys.

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We develop a first-principles formalism to compute the distortion to the relic neutrino density field caused by the peculiar motions of large-scale structures. This distortion slows halos down due to dynamical friction, causes a local anisotropy in the neutrino-CDM cross-correlation, and reduces the global cross-correlation between neutrinos and CDM. The local anisotropy in the neutrino-CDM cross-spectrum is imprinted in the three point cross-correlations of matter and galaxies, or the bispectrum in Fourier space, producing a signal peaking at squeezed triangle configurations. This bispectrum signature of neutrino masses is not limited by cosmic variance or potential inaccuracies in the modeling of complicated nonlinear and galaxy formation physics, and it is not degenerate with the optical depth to reionization. We show that future surveys have the potential to detect the distortion bispectrum.

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Accurate fluid approximation for massive neutrinos in cosmology

Cited by 2 publications

References 21 publications

Revisiting coupled CDM-massive neutrino perturbations in diverse cosmological backgrounds

Revisiting coupled CDM-massive neutrino perturbations in diverse cosmological backgrounds

Neutrino winds on the sky

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