Search Publications
Dark Energy Survey year 1 results: Constraints on extended cosmological models from galaxy clustering and weak lensing
Bechtol, K.; Smith, M.; Nichol, R. C. +112 more
We present constraints on extensions of the minimal cosmological models dominated by dark matter and dark energy, Λ CDM and w CDM , by using a combined analysis of galaxy clustering and weak gravitational lensing from the first-year data of the Dark Energy Survey (DES Y1) in combination with external data. We consider four extensions of the minima…
Primordial black holes from inflation with nonminimal derivative coupling
Wu, Puxun; Yu, Hongwei; Fu, Chengjie
We propose a novel enhancement mechanism of the curvature perturbations in the nonminimal derivative coupling inflation model with a coupling parameter related to the inflaton field. By considering a special form of the coupling parameter as a function of the inflaton, a period of ultra-slow-roll inflation can be realized due to the gravitationall…
Refinement of the standard halo model for dark matter searches in light of the Gaia Sausage
Evans, N. Wyn; McCabe, Christopher; O'Hare, Ciaran A. J.
Predicting signals in experiments to directly detect dark matter (DM) requires a form for the local DM velocity distribution. Hitherto, the standard halo model (SHM), in which velocities are isotropic and follow a truncated Gaussian law, has performed this job. New data, however, suggest that a substantial fraction of our stellar halo lies in a st…
New constraints on sterile neutrino dark matter from NuSTAR M31 observations
Wik, Daniel R.; Krivonos, Roman; Beacom, John F. +4 more
We use a combined 1.2 Ms of NuSTAR observations of M31 to search for x-ray lines from sterile neutrino dark matter decay. For the first time in a NuSTAR analysis, we consistently take into account the signal contribution from both the focused and unfocused fields of view. We also reduce the modeling systematic uncertainty by performing spectral fi…
Constraints on a Bianchi type I spacetime extension of the standard Λ CDM model
Kumar, Suresh; Akarsu, Özgür; Sharma, Shivani +1 more
We consider the simplest anisotropic generalization, as a correction, to the standard Λ CDM model, by replacing the spatially flat Robertson-Walker metric by the Bianchi type-I metric, which brings in a new term Ωσ 0a-6 (mimicking the stiff fluid) in the average expansion rate H (a ) of the Universe. From Hubble and Pantheon …
Cosmological constraints on neutrino self-interactions with a light mediator
Lattanzi, Massimiliano; Natoli, Paolo; Forastieri, Francesco
If active neutrinos undergo nonstandard ("secret") interactions (NS ν Is ), the cosmological evolution of the neutrino fluid might be altered, leaving an imprint in cosmological observables. We use the latest publicly available CMB data from Planck to constrain NS ν Is inducing ν -ν scattering, under the assumption that the mediator ϕ of the secre…
Cosmological constraints on post-Newtonian parameters in effectively massless scalar-tensor theories of gravity
Rossi, Massimo; Ballardini, Mario; Braglia, Matteo +4 more
We study the cosmological constraints on the variation of Newton's constant and on post-Newtonian parameters for simple models of the scalar-tensor theory of gravity beyond the extended Jordan-Brans-Dicke theory. We restrict ourselves to an effectively massless scalar field with a potential V ∝F2, where F (σ )=Npl2…
Primordial gravitational waves and the H0-tension problem
Benetti, Micol; Graef, Leila L.; Alcaniz, Jailson S.
We analyze the H0-tension problem in the context of models of the early universe that predict a blue tilted spectrum of primordial gravitational waves (GWs), which is a positive value of the tensor tilt nT. By considering the GW's contribution, NeffGW, to the effective number of relativistic degrees of f…
LISA Pathfinder platform stability and drag-free performance
Mendes, L.; Russano, G.; Lloro, I. +76 more
The science operations of the LISA Pathfinder mission have demonstrated the feasibility of sub-femto-g free fall of macroscopic test masses necessary to build a gravitational wave observatory in space such as LISA. While the main focus of interest, i.e., the optical axis or the x -axis, has been extensively studied, it is also of great importance …
M I C R O S C O P E limits on the strength of a new force with comparisons to gravity and electromagnetism
Fayet, Pierre
Extremely weak new forces could lead to apparent violations of the equivalence principle. The MICROSCOPE experiment implies that the relative strength of a new long-range force, compared with gravity, is constrained to |α¯ g|<3.2 ×10-11 , 2.3 ×10-13 , 2.2 ×10-13 , 6.7 ×10-13 , and 1.5 ×10