Search Publications
Solar wind interaction with the Earth's magnetosphere: the role of reconnection in the presence of a large scale sheared flow
Califano, F.; Pegoraro, F.; Faganello, M. +1 more
The Earth's magnetosphere and solar wind environment is a laboratory of excellence for the study of the physics of collisionless magnetic reconnection. At low latitude magnetopause, magnetic reconnection develops as a secondary instability due to the stretching of magnetic field lines advected by large scale Kelvin-Helmholtz vortices. In particula…
Quasiperiodic oscillations in the light curve of GRB 080319B
Dranevich, V. A.; Dmitriyev, P. B.; Gnedin, Yu. N.
A modified spectral analysis technique is used to study the temporal structure of the emission from the γ-ray burst GRB 080319B detected in three space missions, Swift/BAT, Wind/KONUS, and Integral/SPI ACS. The energy range of the γ rays detected in these experiments covers 15-10000 keV. The time resolution for the first two of these experiments w…
Magnetospheric convection from Cluster EDI measurements compared with the ground-based ionospheric convection model IZMEM
Haaland, S. E.; Förster, M.; Gromova, L. I. +3 more
Cluster/EDI electron drift observations above the Northern and Southern polar cap areas for more than seven and a half years (2001-2008) have been used to derive a statistical model of the high-latitude electric potential distribution for summer conditions. Based on potential pattern for different orientations of the interplanetary magnetic field …
Lifetimes of High-Degree p Modes in the Quiet and Active Sun
Hill, F.; Kholikov, S.; Burtseva, O. +1 more
We study variations of the lifetimes of high-ℓ solar p modes in the quiet and active Sun with the solar activity cycle. The lifetimes in the degree range ℓ=300 - 600 and ν=2.5 - 4.5 mHz were computed from SOHO/MDI data in an area including active regions and quiet Sun using the time - distance technique. We applied our analysis to the data in four…
A Galaxy Merger Scenario for the NGC 1550 Galaxy from Metal Distributions in the X-Ray Emitting Plasma
Fukazawa, Yasushi; Makishima, Kazuo; Nakazawa, Kazuhiro +4 more
The elliptical galaxy NGC 1550 at a redshift of z = 0.01239, identified with an extended X-ray source RX J0419+0225, was observed with XMM-Newton for 31 ks. From the X-ray data and archival near-IR data of Two Micron All Sky survey, we derive the profiles of components constituting the NGC 1550 system: the gas mass, total mass, metal mass, and gal…
The QSO HE 0450-2958: Scantily Dressed or Heavily Robed? A Normal Quasar as Part of an Unusual ULIRG
Wisotzki, Lutz; Pantin, Eric; Lagage, Pierre-Olivier +5 more
The luminous z = 0.286 quasar HE 0450-2958 is interacting with a companion galaxy at 6.5 kpc distance and the whole system radiates in the infrared (IR) at the level of an ultraluminous infrared galaxy (ULIRG). A so far undetected host galaxy triggered the hypothesis of a mostly "naked" black hole (BH) ejected from the companion by three-body inte…
Multiwavelength Study of the Bright X-Ray Source Population in the Interacting Galaxies NGC 5774/NGC 5775
Gandhi, Poshak; Ghosh, Kajal K.; Gutiérrez, Carlos M. +3 more
A few nearby interacting galaxies are known that host elevated numbers of ultraluminous X-ray sources. Here we report the results of a multiwavelength study of the X-ray source population in the field of the interacting pair of galaxies NGC 5774/5775. A total of 49 discrete sources are detected, including 12 ultraluminous X-ray source candidates w…
Radial and latitudinal gradients of anomalous cosmic ray oxygen in the inner heliosphere
Mewaldt, R. A.; Cummings, A. C.; Marsden, R. G. +2 more
We use data from the Ulysses, Advanced Composition Explorer, and Solar Terrestrial Relations Observatory spacecraft to determine the radial and latitudinal gradients of anomalous cosmic ray oxygen in two energy ranges from 4.5-15.6 MeV/nuc in the inner heliosphere for the first time during an A<0 part of the solar cycle. Using measurements from…
Maximum-likelihood detection of sources among Poissonian noise
Stewart, I. M.
A maximum likelihood (ML) technique for detecting compact sources in images of the X-ray sky is examined. Such images, in the relatively low exposure regime accessible to present X-ray observatories, exhibit Poissonian noise at background flux levels. A variety of source detection methods are compared via Monte Carlo, and the ML detection method i…
Evidence for condensed-phase methane enhancement over Xanadu on Titan
Barnes, J. W.; de Pater, I.; Hartung, M. +1 more
We present evidence for condensed-phase methane precipitation near Xanadu using nine nights of observations from the SINFONI integral-field spectrograph at the Very Large Telescope and imaging analysis with empirical surface subtraction. Radiative transfer models are used to support the imaging technique by simulating the spectrometer datacubes an…