Cosmological imprints of frozen-in light sterile neutrinos

Roland, Samuel B.; Shakya, Bibhushan

doi:10.1088/1475-7516/2017/05/027

Cited by 25 publications

(23 citation statements)

References 82 publications

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“…[277,352,353] and [17,18], where the authors considered decays and annihilations of the inflaton field or a generic scalar s as a production mechanism for sterile neutrinos, respectively. More recent studies have considered similar scenarios where the scalar s either decays into sterile neutrinos while in equilibrium [271,280,283,285,306,340,[354][355][356][357][358][359][360][361][362][363], or where it first undergoes a freeze-in itself [271, 279, 281-285, 330, 354, 358, 361, 362]. Recently, sterile neutrinos undergoing or related to freeze-in have also been studied in supersymmetric models [272,278,361,364].…”

Section: Sterile Neutrinosmentioning

confidence: 99%

The dawn of FIMP Dark Matter: A review of models and constraints

Bernal

Heikinheimo

Tenkanen

et al. 2017

Int. J. Mod. Phys. A

510

504

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Abstract. We present an overview of scenarios where the observed Dark Matter (DM) abundance consists of Feebly Interacting Massive Particles (FIMPs), produced non-thermally by the so-called freeze-in mechanism. In contrast to the usual freeze-out scenario, frozen-in FIMP DM interacts very weakly with the particles in the visible sector and never attained thermal equilibrium with the baryon-photon fluid in the early Universe. Instead of being determined by its annihilation strength, the DM abundance depends on the decay and annihilation strengths of particles in equilibrium with the baryon-photon fluid, as well as couplings in the DM sector. This makes frozen-in DM very difficult but not impossible to test. In this review, we present the freeze-in mechanism and its variations considered in the literature (dark freeze-out and reannihilation), compare them to the standard DM freeze-out scenario, discuss several aspects of model building, and pay particular attention to observational properties and general testability of such feebly interacting DM.

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Section: Sterile Neutrinosmentioning

confidence: 99%

The dawn of FIMP Dark Matter: A review of models and constraints

Bernal

Heikinheimo

Tenkanen

et al. 2017

Int. J. Mod. Phys. A

510

504

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show abstract

“…It is also known that the phase space distribution affects the warmness of DM. The non-thermal phase space distributions (especially of sterile neutrino) are calculated in the literature [27][28][29][30][31][32][33]. The resultant linear matter power spectra, on the other hand, are presented only in limited cases [34][35][36], although a direct comparison of the spectra between the non-thermal and conventional WDM models provide a more robust way to convert the Ly-α or also other lower bound on the conventional WDM mass into that on the mass of non-thermal WDM [37].…”

Section: Acknowledgments 30mentioning

confidence: 99%

Light axinos from freeze-in: production processes, phase space distributions, and Ly-α forest constraints

Bae

Kamada

Liew

et al. 2018

J. Cosmol. Astropart. Phys.

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We consider the freeze-in production of 7 keV axino dark matter (DM) in the supersymmetric Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model in light of the 3.5 keV line excess.The warmness of such 7 keV DM produced from the thermal bath, in general, appears in tension with Ly-α forest data, although a direct comparison is not straightforward. This is because the Ly-α forest constraints are usually reported on the mass of the conventional warm dark matter (WDM), where large entropy production is implicitly assumed to occur in the thermal bath after WDM particles decouple. The phase space distribution of freeze-in axino DM varies depending on production processes and axino DM may alleviate the tension with the tight Ly-α forest constraint. By solving the Boltzmann equation, we first obtain the resultant phase space distribution of axinos produced by 2-body decay, 3-body decay, and 2-to-2 scattering respectively. The reduced collision term and resultant phase space distribution are useful for studying other freeze-in scenarios as well. We then calculate the resultant linear matter power spectra for such axino DM and directly compare them with the linear matter power spectra for the conventional WDM. In order to demonstrate realistic axino DM production, we consider benchmark points with Higgsino next-to-light supersymmetric particle (NLSP) and wino NLSP. In the case of Higgsino NLSP, the phase space distribution of axinos is colder than that in the conventional WDM case, so the most stringent Ly-α forest constraint can be evaded with mild entropy production from saxion decay inherent in the supersymmetric DFSZ axion model.

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“…( 17). In this model the fermion N is a phenomenologically interesting candidate for cold DM [30,31]. We are interested especially in the keV-mass range, where the non-equilibrium dynamics can be relevant [10,11], and the resulting nonthermal momentum distribution of DM may affect the formation of large scale structures.…”

Section: Second Benchmark Model: Singlet Scalar and Fermion Extensionmentioning

confidence: 99%

Momentum distributions of cosmic relics: Improved analysis

Ala-Mattinen,

Heikinheimo,

Kainulainen

et al. 2022

Preprint

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We present a framework for solving a coupled set of momentum-dependent Boltzmann equations for the phase space distribution of cosmic relic particles, without resorting to approximations of assuming kinetic equilibrium or neglecting back scattering or elastic interactions. Our framework is amendable to precision numerical computations. To test it, we consider two benchmark models where the momentum-dependence of dark matter distribution function is potentially important: a real singlet scalar extension near the Higgs resonance, and a sterile neutrino dark matter model with a singlet scalar mediator. The singlet scalar example shows that even near sharp resonances the kinetic equilibrium holds well enough to justify the use of integrated momentum-independent Boltzmann equation in preliminary parameter scans. However, the integrated method may underestimate the relic density by up to 40% in extreme cases. In the sterile neutrino dark matter model we studied how the inclusion of previously ignored elastic interactions and processes with initial state sterile neutrinos could affect the non-thermal nature of their resulting distributions. Here the effects turned out to be negligible, proving the robustness of the earlier predictions.

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Cosmological imprints of frozen-in light sterile neutrinos

Cited by 25 publications

References 82 publications

The dawn of FIMP Dark Matter: A review of models and constraints

The dawn of FIMP Dark Matter: A review of models and constraints

Light axinos from freeze-in: production processes, phase space distributions, and Ly-α forest constraints

Momentum distributions of cosmic relics: Improved analysis

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