Search Publications
Cosmological implications of baryon acoustic oscillation measurements
Pâris, Isabelle; Petitjean, Patrick; Aubourg, Éric +93 more
We derive constraints on cosmological parameters and tests of dark energy models from the combination of baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) data and a recent reanalysis of Type Ia supernova (SN) data. In particular, we take advantage of high-precision BAO measurements from galaxy clustering and th…
A search for ultralight axions using precision cosmological data
Hlozek, Renée; Grin, Daniel; Marsh, David J. E. +1 more
Ultralight axions (ULAs) with masses in the range 1 0-33 eV ≤ma≤1 0-20 eV are motivated by string theory and might contribute to either the dark-matter or dark-energy densities of the Universe. ULAs could suppress the growth of structure on small scales, lead to an altered integrated Sachs-Wolfe effect on cosmic mi…
Bounds on very low reheating scenarios after Planck
Lattanzi, M.; de Salas, P. F.; Miele, G. +3 more
We consider the case of very low reheating scenarios [TRH∼O (MeV ) ] with a better calculation of the production of the relic neutrino background (with three-flavor oscillations). At 95% confidence level, a lower bound on the reheating temperature TRH>4.1 MeV is obtained from big bang nucleosynthesis, while TRH&…
Planck data reconsidered
Spergel, David N.; Hložek, Renée; Flauger, Raphael
The tension between the best fit parameters derived by the Planck team and a number of other astronomical measurements suggests either systematics in the astronomical measurements, systematics in the Planck data, the need for new physics, or a combination thereof. We reanalyze the Planck data and find that the 217 GHz ×217 GHz detector set spectru…
Tension between the power spectrum of density perturbations measured on large and small scales
Battye, Richard A.; Moss, Adam; Charnock, Tom
There is a tension between measurements of the amplitude of the power spectrum of density perturbations inferred using the cosmic microwave background (CMB) and directly measured by large-scale structure (LSS) on smaller scales. We show that this tension exists, and is robust, for a range of LSS indicators including clusters, lensing and redshift …
BBN and the CMB constrain neutrino coupled light WIMPs
Nollett, Kenneth M.; Steigman, Gary
In the presence of a light weakly interacting massive particle (WIMP) with mass mχ≲30 MeV , there are degeneracies among the nature of the WIMP (fermion or boson), its couplings to the standard model particles (to electrons, positrons, and photons, or only to neutrinos), its mass mχ, and the number of equivalent (additional) …
New constraints on f(R) gravity from clusters of galaxies
Kelly, Patrick L.; Allen, Steven W.; Rapetti, David +6 more
The abundance of massive galaxy clusters is a powerful probe of departures from general relativity (GR) on cosmic scales. Despite current stringent constraints placed by stellar and galactic tests, on larger scales alternative theories of gravity such as f(R) can still work as effective theories. Here we present constraints on two popular models o…
Reconciling Planck results with low redshift astronomical measurements
Berezhiani, Zurab; Dolgov, A. D.; Tkachev, I. I.
We show that emerging tension between the direct astronomical measurements at low redshifts and cosmological parameters deduced from the Planck measurements of the cosmic microwave background anisotropies can be alleviated if the dark matter consists of two fractions, the stable part being dominant with a smaller unstable fraction. The latter cons…
POLARBEAR constraints on cosmic birefringence and primordial magnetic fields
Chapman, Scott; Sherwin, Blake D.; Errard, Josquin +84 more
We constrain anisotropic cosmic birefringence using four-point correlations of even-parity E -mode and odd-parity B -mode polarization in the cosmic microwave background measurements made by the POLARization of the Background Radiation (POLARBEAR) experiment in its first season of observations. We find that the anisotropic cosmic birefringence sig…
Beyond six parameters: Extending Λ CDM
Di Valentino, Eleonora; Melchiorri, Alessandro; Silk, Joseph
Cosmological constraints are usually derived under the assumption of a six-parameter Λ CDM theoretical framework or simple one-parameter extensions. In this paper we present, for the first time, cosmological constraints in a significantly extended scenario, varying up to 12 cosmological parameters simultaneously, including the sum of neutrino mass…