Model-independent dark energy equation of state from unanchored baryon acoustic oscillations

Evslin, Jarah

doi:10.1016/j.dark.2016.06.001

Cited by 6 publications

(10 citation statements)

References 49 publications

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“…Fixing Ω m to its ΛCDM-Planck value, which provides a more realistic parameter region, the compatibility with a cosmological constant remains about 2σ. In this case there is a clear preference for a higher current value of the dark energy equation of state with a lower value at high redshift, consistent with the results of previous analyses [9].…”

Section: Finally Insupporting

confidence: 90%

Isolating the Lyman alpha forest BAO anomaly

Evslin

2017

J. Cosmol. Astropart. Phys.

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A 2.5-3σ discrepancy has been reported between the baryonic acoustic oscillation peak (BAO) in the Lyman α forest at z ∼ 2.34 and the best fit Planck ΛCDM cosmology. To isolate the origin of the tension, we consider unanchored BAO, in which the standard BAO ruler is not calibrated, eliminating any dependence on cosmology before redshift z ∼ 2.34. We consider BOSS BAO measurements at z ∼ 0.32, 0.57 and 2.34, using the full 2-dimensional constraints on the angular and line of sight BAO scale, as well as isotropic BAO measurements by 6dF and SDSS at z ∼ 0.106 and z ∼ 0.15. We find that the z > 0.43 data alone is in 2.9σ of tension with ΛCDM with or without the Planck best fit values of the mass fraction Ω m and the BAO scale r d H 0 , indicating that the tension arises not from the ΛCDM parameters but from the dark energy evolution itself at 0.57 < z < 2.34. This conclusion is supported when the acoustic scale measured by the CMB is included, which further increases the tension and excludes a solution with a constant dark energy equation of state. Including the low z BAO data, which is itself consistent with ΛCDM, reduces the tension to just over 2σ, however in this case a CPL parametrization of the dark energy evolution yields only a modest improvement.

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Section: Finally Insupporting

confidence: 90%

Isolating the Lyman alpha forest BAO anomaly

Evslin

2017

J. Cosmol. Astropart. Phys.

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“…It is worth mentioning that popular extensions of the base ΛCDM model such as nonzero space curvature or varying in time dark energy equation-of-state only partially ease the tension between BAO measurements and are not able to eliminate the Ly-α anomaly completely, see for example [10,11]. For this reason, such a prominent discrepancy between BAO probes at low and high redshifts still deserves a special study.…”

Section: Introductionmentioning

confidence: 99%

Dark matter component decaying after recombination: Sensitivity to baryon acoustic oscillation and redshift space distortion probes

2018

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It has been recently suggested [1] that a subdominant fraction of dark matter decaying after recombination may alleviate tension between high-redshift (CMB anisotropy) and low-redshift (Hubble constant, cluster counts) measurements. In this report, we continue our previous study [2] of the decaying dark matter (DDM) model adding all available recent baryon acoustic oscillation (BAO) and redshift space distortions (RSD) measurements. We find, that the BAO/RSD measurements generically prefer the standard ΛCDM and combined with other cosmological measurements impose an upper limit on the DDM fraction at the level of ∼ 5 %, strengthening by a factor of 1.5 limits obtained in [2] mostly from CMB data. However, the numbers vary from one analysis to other based on the same Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12 (DR12) galaxy sample. Overall, the model with a few percent DDM fraction provides a better fit to the combined cosmological data as compared to the ΛCDM: the cluster counting and direct measurements of the Hubble parameter are responsible for that. The improvement can be as large as 1.5 σ and grows to 3.3 σ when the CMB lensing power amplitude AL is introduced as a free fitting parameter.

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“…However, assuming the standard CDM cosmological model, the Planck data is in 3σ of tension with an every growing list of measurements, from Lyman α forest baryon acoustic oscillations [19] to the Hubble constant as determined by the local distance ladder [20]. While massive sterile neutrinos alone cannot eliminate these tensions [21,22], they do ease the tension by increasing the uncertainties reported by Planck [18] and they may be part of a larger solution involving dynamical dark energy [23][24][25].…”

Section: Motivationmentioning

confidence: 99%

Getting the most neutrinos out of IsoDAR

et al. 2017

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Several experimental collaborations worldwide intend to test sterile neutrino models by measuring the disappearance of antineutrinos produced via isotope decay at rest (IsoDAR). The most advanced of these proposals have very similar setups, in which a proton beam strikes a target yielding neutrons which are absorbed by a high isotopic purity 7 Li converter, yielding 8 Li whose resulting decay yields the antineutrinos. In this note, we use FLUKA and GEANT4 simulations to investigate three proposed modifications of this standard proposal. In the first, the 7 Li is replaced with 7 Li compounds including a deuterium moderator. In the second, a gap is placed between the target and the converter to reduce the neutron bounce-back. Finally, we consider cooling the converter with liquid nitrogen. We find that these modifications can increase the antineutrino yield by as much as 50%. The first also substantially reduces the quantity of high purity 7 Li which is needed.

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Model-independent dark energy equation of state from unanchored baryon acoustic oscillations

Cited by 6 publications

References 49 publications

Isolating the Lyman alpha forest BAO anomaly

Isolating the Lyman alpha forest BAO anomaly

Dark matter component decaying after recombination: Sensitivity to baryon acoustic oscillation and redshift space distortion probes

Getting the most neutrinos out of IsoDAR

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