Search Publications
Supermagnetosonic Jets behind a Collisionless Quasiparallel Shock
Vainio, R.; Vaivads, A.; Lucek, E. A. +7 more
The downstream region of a collisionless quasiparallel shock is structured containing bulk flows with high kinetic energy density from a previously unidentified source. We present Cluster multispacecraft measurements of this type of supermagnetosonic jet as well as of a weak secondary shock front within the sheath, that allow us to propose the fol…
The Sloan Digital Sky Survey/XMM-Newton Quasar Survey: Correlation Between X-Ray Spectral Slope and Eddington Ratio
Elvis, M.; Risaliti, G.; Young, M.
We present a correlation between the 2-10 keV spectral slope Γ X and the Eddington ratio L/L EDD in a sample of ~400 Sloan Digital Sky Survey (SDSS) quasars with available hard X-ray spectra from XMM-Newton serendipitous observations. We find that the Γ X -L/L EDD correlation is strongest in objects wit…
Alfvén Waves and Their Roles in the Dynamics of the Earth's Magnetotail: A Review
Keiling, Andreas
The Earth’s magnetotail is an extremely complex system which—energized by the solar wind—displays many phenomena, and Alfvén waves are essential to its dynamics. While Alfvén waves were first predicted in the early 1940’s and ample observations were later made with rockets and low-altitude satellites, observational evidence of Alfvén waves in diff…
Multi-wavelength study of XMMU J2235.3-2557: the most massive galaxy cluster at z > 1
Böhringer, H.; Demarco, R.; Lidman, C. +14 more
Context: The galaxy cluster XMMU J2235.3-2557 (hereafter XMM2235), spectroscopically confirmed at z = 1.39, is one of the most distant X-ray selected galaxy clusters. It has been at the center of a multi-wavelength observing campaign with ground and space facilities.
Aims: We characterize the galaxy populations of passive members, the thermody…
Evolution of dipolarization in the near-Earth current sheet induced by Earthward rapid flux transport
Dandouras, I.; André, M.; Klecker, B. +7 more
We report on the evolution of dipolarization and associated disturbances of the near-Earth current sheet during a substorm on 27 October 2007, based upon Cluster multi-point, multi-scale observations of the night-side plasma sheet at X~-10 RE. Three dipolarization events were observed accompanied by activations on ground magnetograms at…
Mixed Populations in Globular Clusters: Et Tu, 47 Tuc?
Anderson, J.; Bedin, L. R.; King, I. R. +2 more
We exploit the large number of archival Hubble Space Telescope images of 47 Tuc to examine its subgiant branch (SGB) and main sequence (MS) for signs of multiple populations. In the cluster core, we find that the cluster's SGB exhibits a clear spread in luminosity, with at least two distinct components: a brighter one with a spread that is real bu…
Mineralogy of Juventae Chasma: Sulfates in the light-toned mounds, mafic minerals in the bedrock, and hydrated silica and hydroxylated ferric sulfate on the plateau
Murchie, Scott L.; Mustard, John F.; Brown, Adrian J. +10 more
Juventae Chasma contains four light-toned sulfate-bearing mounds (denoted here as A-D from west to east) inside the trough, mafic outcrops at the base of the mounds and in the wall rock, and light-toned layered deposits of opal and ferric sulfates on the plateau. Hyperspectral visible/near-infrared Compact Reconnaissance Imaging Spectrometer for M…
Solar Surface Magnetism and Irradiance on Time Scales from Days to the 11-Year Cycle
Solanki, S. K.; Schmutz, W.; Haberreiter, M. +9 more
The uninterrupted measurement of the total solar irradiance during the last three solar cycles and an increasing amount of solar spectral irradiance measurements as well as solar imaging observations (magnetograms and photometric data) have stimulated the development of models attributing irradiance variations to solar surface magnetism. Here we r…
A brief review of “solar flare effects” on the ionosphere
Lakhina, G. S.; Tsurutani, B. T.; Verkhoglyadova, O. P. +3 more
The study of solar flare effects (SFEs) on the ionosphere is having a renaissance. The development of GPS ground and satellite data for scientific use has opened up new means for high time resolution research on SFEs. At present, without continuous flare photon spectra (X rays, EUV, UV, and visible) monitoring instrumentation, the best way to mode…
The Black Hole Mass-Bulge Luminosity Relationship for Active Galactic Nuclei From Reverberation Mapping and Hubble Space Telescope Imaging
Peterson, Bradley M.; Pogge, Richard W.; Vestergaard, Marianne +1 more
We investigate the relationship between black hole mass and bulge luminosity for active galactic nuclei (AGNs) with reverberation-based black hole mass measurements and bulge luminosities from two-dimensional decompositions of Hubble Space Telescope host galaxy images. We find that the slope of the relationship for AGNs is 0.76-0.85 with an uncert…