Search Publications
KAT-7 observations of an unbiased sample of mass-selected galaxy clusters
Brunetti, G.; Venturi, T.; Dallacasa, D. +7 more
The presence of megaparsec-scale radio haloes in galaxy clusters has already been established by many observations over the last two decades. The emerging explanation for the formation of these giant sources of diffuse synchrotron radio emission is that they trace turbulent regions in the intracluster medium, where particles are trapped and accele…
Long-Duration Gamma-Ray Burst Host Galaxies in Emission and Absorption
Fynbo, Johan P. U.; Perley, Daniel A.; Tanvir, Nial R. +2 more
The galaxy population hosting long-duration GRBs provides a means to constrain the progenitor and an opportunity to use these violent explosions to characterize the nature of the high-redshift universe. Studies of GRB host galaxies in emission reveal a population of star-forming galaxies with great diversity, spanning a wide range of masses, metal…
Unexpected spatial intensity distributions and onset timing of solar electron events observed by closely spaced STEREO spacecraft
Gómez-Herrero, R.; Dresing, N.; Heber, B. +2 more
We present multi-spacecraft observations of four solar electron events using measurements from the Solar Electron Proton Telescope (SEPT) and the Electron Proton Helium INstrument (EPHIN) on board the STEREO and SOHO spacecraft, respectively, occurring between 11 October 2013 and 1 August 2014, during the approaching superior conjunction period of…
HERUS: A CO Atlas from SPIRE Spectroscopy of Local ULIRGs
Lebouteiller, Vianney; Cormier, Diane; Pearson, Chris +10 more
We present the Herschel SPIRE Fourier Transform Spectroscopy (FTS) atlas for a complete flux-limited sample of local ultraluminous infrared galaxies (ULIRGs) as part of the HERschel Ultra Luminous InfraRed Galaxy Survey (HERUS). The data reduction is described in detail and was optimized for faint FTS sources ,with particular care being taken for …
Planck constraints on scalar-tensor cosmology and the variation of the gravitational constant
Ichiki, Kiyotomo; Sugiyama, Naoshi; Ooba, Junpei +1 more
Cosmological constraints on the scalar-tensor theory of gravity by analyzing the angular power spectrum data of the cosmic microwave background (CMB) obtained from the Planck 2015 results are presented. We consider the harmonic attractor model, in which the scalar field has a harmonic potential with curvature (β ) in the Einstein frame and the the…
Deep Morphological and Spectral Study of the SNR RCW 86 with Fermi-LAT
Troja, E.; Orlando, E.; Hill, A. B. +107 more
RCW 86 is a young supernova remnant (SNR) showing a shell-type structure at several wavelengths and is thought to be an efficient cosmic-ray (CR) accelerator. Earlier Fermi Large Area Telescope results reported the detection of γ-ray emission coincident with the position of RCW 86 but its origin (leptonic or hadronic) remained unclear due to the p…
Magnetic fields of opposite polarity in sunspot penumbrae
Franz, M.; Schmidt, W.; Solanki, S. K. +25 more
Context. A significant part of the penumbral magnetic field returns below the surface in the very deep photosphere. For lines in the visible, a large portion of this return field can only be detected indirectly by studying its imprints on strongly asymmetric and three-lobed Stokes V profiles. Infrared lines probe a narrow layer in the very deep ph…
Distance-dependent Offsets between Parallaxes for Nearby Stars and Gaia DR1 Parallaxes
Gies, Douglas R.; Henry, Todd J.; Winters, Jennifer G. +3 more
We use 612 single stars with previously published trigonometric parallaxes placing them within 25 pc to evaluate parallaxes released in Gaia’s first data release (DR1). We find that the Gaia parallaxes are, on average, 0.24 ± 0.02 mas smaller than the weighted mean trigonometric parallax values for these stars in the solar neighborhood. We also fi…
Applications for edge detection techniques using Chandra and XMM-Newton data: galaxy clusters and beyond
Fabian, A. C.; Sanders, J. S.; Walker, S. A.
The unrivalled spatial resolution of the Chandra X-ray observatory has allowed many breakthroughs to be made in high-energy astrophysics. Here we explore applications of Gaussian gradient magnitude (GGM) filtering to X-ray data, which dramatically improves the clarity of surface brightness edges in X-ray observations, and maps gradients in X-ray s…
Ion chemistry in the coma of comet 67P near perihelion
Gunell, H.; Wurz, P.; Altwegg, K. +33 more
The coma and the comet-solar wind interaction of comet 67P/Churyumov-Gerasimenko changed dramatically from the initial Rosetta spacecraft encounter in 2014 August through perihelion in 2015 August. Just before equinox (at 1.6 au from the Sun), the solar wind signal disappeared and two regions of different cometary ion characteristics were observed…