Measuring growth index in a Universe with sterile neutrinos

Zhang, Jingfei; Li, Yunhe; Zhang, Xin

doi:10.1016/j.physletb.2014.10.044

Cited by 26 publications

(23 citation statements)

References 74 publications

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“…The presence of massive neutrinos in cosmological models is useful to investigate the accuracy and robustness of a given scenario. The cosmological effects of light sterile neutrinos are investigated in different contexts [43][44][45][46][47][48] In this paper, we are motivated to investigate a coupled DE scenario, where vacuum energy interacts with DM, by considering neutrinos scheme with sum of the active neutrino masses ( m ν ) and the effective number of rel-ativistic degrees of freedom (N eff ) as free quantities. In addition, we consider the models with one non-standard neutrino (sterile neutrino) beyond the three species predicted by the standard model, the so-called (3 + 1) models.…”

Section: Introductionmentioning

confidence: 99%

Echo of interactions in the dark sector

2017

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We investigate the observational constraints on an interacting vacuum energy scenario with two different neutrino schemes (with and without a sterile neutrino) using the most recent data from CMB temperature and polarization anisotropy, baryon acoustic oscillations (BAO), type Ia supernovae from JLA sample and structure growth inferred from cluster counts. We find that inclusion of the galaxy clusters data with the minimal data combination CMB + BAO + JLA suggests an interaction in the dark sector, implying the decay of dark matter particles into dark energy, since the constraints obtained by including the galaxy clusters data yield a non-null and negative coupling parameter between the dark components at 99% confidence level. We deduce that the current tensions on the parameters H0 and σ8 can be alleviated within the framework of the interacting as well as non-interacting vacuum energy models with sterile neutrinos.PACS numbers: 95.35.+d; 95.36.+x; 14.60.Pq; 98.80.Es

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Section: Introductionmentioning

confidence: 99%

Echo of interactions in the dark sector

2017

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“…For other relevant studies of sterile neutrinos, see, e.g., Refs. [20][21][22][23][24][25][26][27][28][29][30]. Thus, to relieve the tensions in cosmological observations, a natural choice is to consider the model with light sterile neutrinos.…”

Section: Introductionmentioning

confidence: 99%

A search for sterile neutrinos with the latest cosmological observations

Lü

Zhang

2017

Eur. Phys. J. C

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We report the result of a search for sterile neutrinos with the latest cosmological observations. Both cases of massless and massive sterile neutrinos are considered in the CDM cosmology. The cosmological observations used in this work include the Planck 2015 temperature and polarization data, the baryon acoustic oscillation data, the Hubble constant direct measurement data, the Planck SunyaevZeldovich cluster counts data, the Planck lensing data, and the cosmic shear data. We find that the current observational data give a hint of the existence of massless sterile neutrino (as dark radiation) at the 1.44σ level, and the consideration of an extra massless sterile neutrino can indeed relieve the tension between observations and improve the cosmological fit. For the case of massive sterile neutrino, the observations give a rather tight upper limit on the mass, which implies that actually a massless sterile neutrino is more favored. Our result is consistent with the recent result of neutrino oscillation experiment done by the Daya Bay and MINOS collaborations, as well as the recent result of cosmic ray experiment done by the IceCube collaboration.

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“…Many works tried to probe or disprove these possible deviations from the standard ΛCDM model (see, e.g., Refs. [65][66][67][68][69]). Particularly, in recent Planck 2015 results, the Planck Collaboration specifically discussed this topic in Ref.…”

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confidence: 99%

Testing models of vacuum energy interacting with cold dark matter

Zhang

2016

Phys. Rev. D

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We test the models of vacuum energy interacting with cold dark matter and try to probe the possible deviation from the ΛCDM model using current observations. We focus on two specific models, Q = 3βHρΛ and Q = 3βHρc. The data combinations come from the Planck 2013 data, the baryon acoustic oscillations measurements, the type-Ia supernovae data, the Hubble constant measurement, the redshift space distortions data and the galaxy weak lensing data. For the Q = 3βHρc model, we find that it can be tightly constrained by all the data combinations, while for the Q = 3βHρΛ model, there still exist significant degeneracies between parameters. The tightest constraints for the coupling constant are β = −0.026 +0.036 −0.053 (for Q = 3βHρΛ) and β = −0.00045 ± 0.00069 (for Q = 3βHρc) at the 1σ level. For all the fit results, we find that the null interaction β = 0 is always consistent with data. Our work completes the discussion on the interacting dark energy model in the recent Planck 2015 papers. Considering this work together with the Planck 2015 results, it is believed that there is no evidence for the models beyond the standard ΛCDM model from the point of view of possible interaction.Modern cosmology encounters a great puzzle in explaining the late-time cosmic acceleration, as a universe with barotropic or pressureless fluids, evolving according to the laws of general relativity, cannot fit the observational data [1, 2]. This puzzle is phenomenologically solved by introducing a new component with negative pressure, generally called dark energy. However, the fundamental nature of dark energy is still unknown. At present, a cosmological constant Λ with equation of state w = −1 is the simplest candidate of dark energy, which, however, is plagued with the so-called fine-tuning problem and coincidence problem [3,4]. These theoretical problems provide cosmologists with the motivation to consider some complex theories for explaining the cosmic acceleration, such as the dynamical dark energy models or the modified gravity (MG) theories. In particular, in order to solve the coincidence problem, cosmologists have widely investigated the interacting dark energy (IDE) scenario , where dark energy directly interacts with dark matter by exchanging energy and momentum.Regardless of the theoretical problems of Λ, the Λ cold dark matter (ΛCDM) model is still the most competitive cosmological model and is now even taken as a prototype of the standard model in cosmology, as it can excellently fit most of the current data with the least free parameters [63]. Nevertheless, other complex models mentioned above are also not excluded by the observations. Given this fact, we still need to continuously test the validity of the ΛCDM model. Undoubtedly, any deviation from it, if confirmed by observations, would be a major breakthrough in cosmology. In fact, some degree of tension between different observations has been reported for the ΛCDM model since the Planck 2013 results were published [64]. This tension has attracted much interest * Correspon...

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Measuring growth index in a Universe with sterile neutrinos

Cited by 26 publications

References 74 publications

Echo of interactions in the dark sector

Echo of interactions in the dark sector

A search for sterile neutrinos with the latest cosmological observations

Testing models of vacuum energy interacting with cold dark matter

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