Search Publications
Spacetime Foam: From Entropy and Holography to Infinite Statistics and Nonlocality
Ng, Y. Jack
Due to quantum fluctuations, spacetime is foamy on small scales. The degree of foaminess is found to be consistent with holography, a principle prefigured in the physics of black hole entropy. It has bearing on the ultimate accuracies of clocks and measurements and the physics of quantum computation. Consistent with existing archived data on activ…
Review on the solar spectral variability in the EUV for space weather purposes
Auchère, F.; Kretzschmar, M.; Dudok de Wit, T. +4 more
The solar XUV-EUV flux is the main energy source in the terrestrial diurnal thermosphere: it produces ionization, dissociation, excitation and heating. Accurate knowledge of this flux is of prime importance for space weather. We first list the space weather applications that require nowcasting and forecasting of the solar XUV-EUV flux. We then rev…
A Time-Variable X-Ray Echo: Indications of a Past Flare of the Galactic-Center Black Hole
Koyama, Katsuji; Matsumoto, Hironori; Tsuru, Takeshi Go +1 more
A time-variability study of the neutral iron line flux at 6.40keV in the Sgr B2 region from data of Suzaku and Chandra is presented. The highly ionized iron line at 6.68keV is due to Galactic Center Diffuse X-rays, and is thus time invariable. By comparing the 6.68keV and 6.40keV line fluxes, we found that the 6.40keV flux from the Sgr B2 complex …
Cassini detection of water-group pick-up ions in the Enceladus torus
Thomsen, M. F.; Wilson, R. J.; Tokar, R. L. +8 more
This study reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group pick-up ions within the proposed Enceladus torus, a radially narrow toroidal region surrounding Saturn that contains a high density of water-group neutrals. This torus is produced by the icy plumes observed near the south pole of Enceladus. The i…
The overall configuration of the interplanetary magnetic field upstream of Saturn as revealed by Cassini observations
Dougherty, M. K.; Jackman, C. M.; Forsyth, R. J.
The Cassini spacecraft approached Saturn during the declining phase of the solar cycle, at a time when the heliosphere was highly structured by compressions and rarefactions associated with corotating interaction regions (CIRs). We examine in detail the hourly averaged interplanetary magnetic field (IMF) data prior to Saturn Orbit Insertion and du…
Deep Spectroscopy of Systematically Surveyed Extended Lyα Sources at z ~ 3-5
Ouchi, Masami; Shimasaku, Kazuhiro; Ueda, Yoshihiro +4 more
Spatially extended Lyα sources that are faint and/or compact in continuum are candidates for extremely young (lesssim107 yr) galaxies at high redshifts. We present medium-resolution (R ~ 2000) VLT/VIMOS spectroscopy of 18 such extended Lyα sources found in our previous study at z ~ 3-5. The deep spectroscopy showed that all 18 objects h…
Hard X-Ray Emission of the Microquasar GRO J1655-40 during the Rise of Its 2005 Outburst
Joinet, A.; Kalemci, E.; Senziani, F.
We present an analysis of the high-energy emission of the Galactic black hole GRO J1655-40 at the beginning of its 2005 outburst. The data from 458 ks of INTEGRAL observations, spread over 4 weeks, are analyzed, along with the existing simultaneous RXTE and Swift data. The high-energy data allow us to detect the presence of a high-energy cutoff an…
On the Origin of Bimodal Horizontal Branches in Massive Globular Clusters: The Case of NGC 6388 and NGC 6441
Joo, Seok-Joo; Han, Sang-Il; Ree, Chang H. +3 more
Despite the efforts of the past decade, the origin of the bimodal horizontal branch (HB) found in some globular clusters (GCs) remains a conundrum. Inspired by the discovery of multiple stellar populations in the most massive Galactic GC, ω Centauri, we investigate the possibility that two distinct populations may coexist and are responsible for t…
The 12C/ 13C isotopic ratio in Titan hydrocarbons from Cassini/CIRS infrared spectra
Irwin, P. G. J.; Teanby, N. A.; de Kok, R. +9 more
We have analyzed infrared spectra of Titan recorded by the Cassini Composite Infrared Spectrometer (CIRS) to measure the isotopic ratio 12C/ 13C in each of three chemical species in Titan's stratosphere: CH 4, C 2H 2 and C 2H 6. This is the first measurement of 12
Observation and Modeling of Coronal "Moss" With the EUV Imaging Spectrometer on Hinode
Winebarger, Amy R.; Warren, Harry P.; Doschek, George A. +2 more
Observations of transition region emission in solar active regions represent a powerful tool for determining the properties of hot coronal loops. We present the analysis of new observations of active region moss taken with the Extreme Ultraviolet Imaging Spectrometer (EIS) on the Hinode satellite. EIS observations of a density sensitive Fe XII lin…