Search Publications
Molecular clouds as origin of the Fermi gamma-ray GeV excess
Biermann, Peter L.; de Boer, Wim; Bosse, Léo +2 more
The so-called GeV excess of the diffuse Galactic gamma-ray emission, as observed by the Fermi-LAT satellite, is studied with a spectral template fit based on energy spectra for each relevant process of gamma-ray emission. This has the advantage over "conventional" analysis because one includes the spectral knowledge of physical processes into the …
Consistency of Hitomi, XMM-Newton, and Chandra 3.5 keV data from Perseus
Conlon, Joseph P.; Day, Francesca; Jennings, Nicholas +2 more
Hitomi observations of Perseus with the Soft X-ray Spectrometer (SXS) provide a high-resolution look at the 3.5 keV feature reported by multiple groups in the Perseus cluster. The Hitomi spectrum—which involves the sum of diffuse cluster emission and the pointlike central active galactic nucleus (AGN)—does not show any excess at E ∼3.5 keV , givin…
Constraining cosmological ultralarge scale structure using numerical relativity
Peiris, Hiranya V.; Braden, Jonathan; Johnson, Matthew C. +1 more
Cosmic inflation, a period of accelerated expansion in the early universe, can give rise to large amplitude ultralarge scale inhomogeneities on distance scales comparable to or larger than the observable universe. The cosmic microwave background (CMB) anisotropy on the largest angular scales is sensitive to such inhomogeneities and can be used to …
Testing physical models for dipolar asymmetry: From temperature to k space to lensing
Contreras, D.; Zibin, J. P.
One of the most intriguing hints of a departure from the standard cosmological model is a large-scale dipolar power asymmetry in the cosmic microwave background (CMB). If not a statistical fluke, its origins must lie in the modulation of the position-space fluctuations via a physical mechanism, which requires the observation of new modes to confir…
Robust predictions for an oscillatory bispectrum in Planck 2015 data from transient reductions in the speed of sound of the inflaton
Hu, Bin; Torrado, Jesús; Achúcarro, Ana
We update the search for features in the cosmic microwave background (CMB) power spectrum due to transient reductions in the speed of sound, using Planck 2015 CMB temperature and polarization data. We enlarge the parameter space to much higher oscillatory frequencies of the feature, and define a robust prior independent of the ansatz for the reduc…
New observational limits on dark radiation in braneworld cosmology
Mathews, Grant J.; Kusakabe, Motohiko; Gangopadhyay, Mayukh Raj +1 more
A dark radiation term arises as a correction to the energy-momentum tensor in the simplest five-dimensional RS-II brane-world cosmology. In this paper we revisit the constraints on dark radiation based upon the newest results for light element nuclear reaction rates, observed light element abundances, and the power spectrum of the cosmic microwave…
Recovering a redshift-extended varying speed of light signal from galaxy surveys
Salzano, Vincenzo
We investigate a new method to recover (if any) a possible varying speed of light (VSL) signal from cosmological data. It comes as an upgrade by Salzano, Dąbrowski, and Lazkoz [Phys. Rev. Lett.114, 101304 (2015), 10.1103/PhysRevLett.114.101304; Phys. Rev. D 93, 063521 (2016), 10.1103/PhysRevD.93.063521], where it was argued that such a signal coul…
General relativistic observable for gravitational astrometry in the context of the Gaia mission and beyond
Geralico, Andrea; Lattanzi, Mario G.; Crosta, Mariateresa +1 more
With the launch of the Gaia mission, general relativity (GR) is now at the very core of astrometry. Given the high level of accuracy of the measurements, the development of a suitable relativistic model for carrying out the correct data processing and analysis has become a critical necessity; its primary goal is to have a consistent set of stellar…
Testing physical models for dipolar asymmetry with CMB polarization
Banday, A. J.; Górski, K. M.; Scott, D. +2 more
The cosmic microwave background (CMB) temperature anisotropies exhibit a large-scale dipolar power asymmetry. To determine whether this is due to a real, physical modulation or is simply a large statistical fluctuation requires the measurement of new modes. Here we forecast how well CMB polarization data from Planck and future experiments will be …
Is there another coincidence problem at the reionization epoch?
Lombriser, Lucas; Smer-Barreto, Vanessa
The cosmological coincidences between the matter and radiation energy densities at recombination as well as between the densities of matter and the cosmological constant at the present time are well known. We point out that, moreover, the third intersection between the energy densities of radiation and the cosmological constant coincides with the …