Search Publications
Detection of B-Mode Polarization at Degree Angular Scales by BICEP2
Ade, P. A. R.; Bock, J. J.; Hildebrandt, S. R. +45 more
We report results from the BICEP2 experiment, a cosmic microwave background (CMB) polarimeter specifically designed to search for the signal of inflationary gravitational waves in the B-mode power spectrum around ℓ∼80. The telescope comprised a 26 cm aperture all-cold refracting optical system equipped with a focal plane of 512 antenna coupled tra…
Unidentified Line in X-Ray Spectra of the Andromeda Galaxy and Perseus Galaxy Cluster
Boyarsky, A.; Franse, J.; Iakubovskyi, D. +1 more
We report a weak line at 3.52 ±0.02 keV in x-ray spectra of the Andromeda galaxy and the Perseus galaxy cluster observed by the metal-oxide-silicon (MOS) and p -n (PN) CCD cameras of the XMM-Newton telescope. This line is not known as an atomic line in the spectra of galaxies or clusters. It becomes stronger towards the centers of the objects; is …
Indications of a Late-Time Interaction in the Dark Sector
Melchiorri, Alessandro; Said, Najla; Salvatelli, Valentina +2 more
We show that a general late-time interaction between cold dark matter and vacuum energy is favored by current cosmological data sets. We characterize the strength of the coupling by a dimensionless parameter qV that is free to take different values in four redshift bins from the primordial epoch up to today. This interacting scenario is…
Evidence for Massive Neutrinos from Cosmic Microwave Background and Lensing Observations
Battye, Richard A.; Moss, Adam
We discuss whether massive neutrinos (either active or sterile) can reconcile some of the tensions within cosmological data that have been brought into focus by the recently released Planck data. We point out that a discrepancy is present when comparing the primary CMB and lensing measurements both from the CMB and galaxy lensing data using CFHTLe…
Neutrinos Help Reconcile Planck Measurements with the Local Universe
Hu, Wayne; Wyman, Mark; Rudd, Douglas H. +1 more
Current measurements of the low and high redshift Universe are in tension if we restrict ourselves to the standard six-parameter model of flat ΛCDM. This tension has two parts. First, the Planck satellite data suggest a higher normalization of matter perturbations than local measurements of galaxy clusters. Second, the expansion rate of the Univer…
Firehose and Mirror Instabilities in a Collisionless Shearing Plasma
Kunz, Matthew W.; Schekochihin, Alexander A.; Stone, James M.
Hybrid-kinetic numerical simulations of firehose and mirror instabilities in a collisionless plasma are performed in which pressure anisotropy is driven as the magnetic field is changed by a persistent linear shear S. For a decreasing field, it is found that mostly oblique firehose fluctuations grow at ion Larmor scales and saturate with energies …
Cosmological Constraints on Brans-Dicke Theory
Avilez, A.; Skordis, C.
We report strong cosmological constraints on the Brans-Dicke (BD) theory of gravity using cosmic microwave background data from Planck. We consider two types of models. First, the initial condition of the scalar field is fixed to give the same effective gravitational strength Geff today as the one measured on Earth, GN. In th…
Possible Evidence for Free Precession of a Strongly Magnetized Neutron Star in the Magnetar 4U 0142+61
Hiraga, J. S.; Enoto, T.; Murakami, H. +5 more
Magnetars are a special type of neutron stars, considered to have extreme dipole magnetic fields reaching ∼1011 T. The magnetar 4U 0142+61, one of the prototypes of this class, was studied in broadband x rays (0.5-70 keV) with the Suzaku observatory. In hard x rays (15-40 keV), its 8.69 sec pulsations suffered slow phase modulations by …
Evidence for Gravitational Lensing of the Cosmic Microwave Background Polarization from Cross-Correlation with the Cosmic Infrared Background
Ade, P. A. R.; Borrill, J.; Keskitalo, R. +74 more
We reconstruct the gravitational lensing convergence signal from cosmic microwave background (CMB) polarization data taken by the Polarbear experiment and cross-correlate it with cosmic infrared background maps from the Herschel satellite. From the cross spectra, we obtain evidence for gravitational lensing of the CMB polarization at a statistical…
Inflation with Whip-Shaped Suppressed Scalar Power Spectra
Starobinsky, Alexei A.; Hazra, Dhiraj Kumar; Smoot, George F. +1 more
Motivated by the idea that inflation occurs at the grand unified theory symmetry breaking scale, in this Letter we construct a new class of large field inflaton potentials where the inflaton starts with a power law potential; after an initial period of relatively fast roll that lasts until after a few e folds inside the horizon it transits to the …