Search Publications
Effect of Current Sheets on the Solar Wind Magnetic Field Power Spectrum from the Ulysses Observation: From Kraichnan to Kolmogorov Scaling
Li, G.; Hu, Q.; Qin, G. +1 more
The MHD turbulence theory developed by Iroshnikov and Kraichnan predicts a k-1.5 power spectrum. Solar wind observations, however, often show a k-5/3 Kolmogorov scaling. Based on 3 years worth of Ulysses magnetic field data where over 28 000 current sheets are identified, we propose that the current sheet is the cause of the …
The bolometric output and host-galaxy properties of obscured AGN in the XMM-COSMOS survey
Treister, E.; Merloni, A.; Bolzonella, M. +15 more
We present a study of the multi-wavelength properties, from the mid-infrared to the hard X-rays, of a sample of 255 spectroscopically identified X-ray selected type-2 AGN from the XMM-COSMOS survey. Most of them are obscured and the X-ray absorbing column density is determined by either X-ray spectral analyses (for 45% of the sample), or from hard…
A critical analysis of the UV luminosity function at redshift ~7 from deep WFC3 data
Giavalisco, M.; Castellano, M.; Pentericci, L. +7 more
Context. The study of the luminosity function (LF) of Lyman break galaxies (LBGs) at z = 7 is very important for ascertaining their role in the reionization of the Universe. These galaxies can be used also to investigate in detail the processes of formation and evolution of galactic structures in the infancy of our Universe.
Aims: In this wor…
Direct detection of the Enceladus water torus with Herschel
Hartogh, P.; Lellouch, E.; Crovisier, J. +9 more
Cryovolcanic activity near the south pole of Saturn's moon Enceladus produces plumes of H2O-dominated gases and ice particles, which escape and populate a torus-shaped cloud. Using submillimeter spectroscopy with Herschel, we report the direct detection of the Enceladus water vapor torus in four rotational lines of water at 557, 987, 11…
Geoeffectiveness (Dst and Kp) of interplanetary coronal mass ejections during 1995-2009 and implications for storm forecasting
Cane, H. V.; Richardson, I. G.
We summarize the geoeffectiveness (based on the Dst and Kp indices) of the more than 300 interplanetary coronal mass ejections (ICMEs) that passed the Earth during 1996-2009, encompassing solar cycle 23. We subsequently estimate the probability that an ICME will generate geomagnetic activity that exceeds certain thresholds of Dst or Kp, including …
A Deep Chandra ACIS Study of NGC 4151. II. The Innermost Emission Line Region and Strong Evidence for Radio Jet-NLR Cloud Collision
Elvis, Martin; Zezas, Andreas; Risaliti, Guido +4 more
We have studied the X-ray emission within the inner ~150 pc radius of NGC 4151 by constructing high spatial resolution emission line images of blended O VII, O VIII, and Ne IX. These maps show extended structures that are spatially correlated with the radio outflow and optical [O III] emission. We find strong evidence for jet-gas cloud interaction…
PG 1211+143: probing high-frequency lags in a high-mass active galactic nucleus
Cappi, M.; Ponti, G.; Fabian, A. C. +4 more
We present the timing analysis of the four archived XMM-Newton observations of PG 1211+143. The source is well-known for its spectral complexity, comprising a strong soft excess and different absorption systems. Soft energy band (0.3-0.7 keV) lags are detected over all the four observations, in the frequency range ν≲ 6 × 10-4 Hz, where …
UV and IR auroral emission model for the outer planets: Jupiter and Saturn comparison
Fujimoto, Masaki; Badman, Sarah V.; Tao, Chihiro
Planetary aurora display the dynamic behavior of the plasma gas surrounding a planet. The outer planetary aurora are most often observed in the ultraviolet (UV) and the infrared (IR) wavelengths. How the emissions in these different wavelengths are connected with the background physical conditions are not yet well understood. Here we investigate t…
The unusual protoplanetary disk around the T Tauri star ET Chamaeleontis
Ménard, F.; Duchêne, G.; Dent, W. R. F. +15 more
We present new continuum and line observations, along with modelling, of the faint (6-8) Myr old T Tauri star ET Cha belonging to the η Chamaeleontis cluster. We have acquired Herschel/PACS photometric fluxes at 70 µm and 160 µm, as well as a detection of the [OI] 63 µm fine-structure line in emission, and derived upper limits fo…
Empirical Reconstruction and Numerical Modeling of the First Geoeffective Coronal Mass Ejection of Solar Cycle 24
Howard, R. A.; Rouillard, A. P.; Wood, B. E. +2 more
We analyze the kinematics and morphology of a coronal mass ejection (CME) from 2010 April 3, which was responsible for the first significant geomagnetic storm of solar cycle 24. The analysis utilizes coronagraphic and heliospheric images from the two STEREO spacecraft, and coronagraphic images from SOHO/LASCO. Using an empirical three-dimensional …