Search Publications
How Complex is the Obscuration in Active Galactic Nuclei? New Clues from the Suzaku Monitoring of the X-Ray Absorbers in NGC 7582
Fiore, Fabrizio; Bianchi, Stefano; Piconcelli, Enrico +3 more
We present the results of a Suzaku monitoring campaign of the Seyfert 2 galaxy, NGC 7582. The source is characterized by very rapid (on timescales even lower than a day) changes of the column density of an inner absorber, together with the presence of constant components arising as reprocessing from a Compton-thick material. The best-fitting scena…
Discovery of Strong Radiative Recombination Continua from the Supernova Remnant IC 443 with Suzaku
Yamaguchi, H.; Ozawa, M.; Koyama, K. +4 more
We present the Suzaku spectroscopic study of the Galactic middle-aged supernova remnant (SNR) IC 443. The X-ray spectrum in the 1.75-6.0 keV band is described by an optically thin thermal plasma with the electron temperature of ~0.6 keV and several additional Lyman lines. We robustly detect, for the first time, strong radiative recombination conti…
Magnetic Reconnection along Quasi-separatrix Layers as a Driver of Ubiquitous Active Region Outflows
Mandrini, C. H.; van Driel-Gesztelyi, L.; Démoulin, P. +2 more
Hinode's EUV Imaging Spectrometer (EIS) has discovered ubiquitous outflows of a few to 50 km s-1 from active regions (ARs). These outflows are most prominent at the AR boundary and appear over monopolar magnetic areas. They are linked to strong non-thermal line broadening and are stronger in hotter EUV lines. The outflows persist for at…
A Large Reservoir of Ionized Gas in the Galactic Halo: Ionized Silicon in High-Velocity and Intermediate-Velocity Clouds
Shull, J. Michael; Danforth, Charles W.; Collins, Joseph A. +1 more
The low Galactic halo is enveloped by a sheath of ionized, low-metallicity gas, which can provide a substantial (1 M ⊙ yr-1) cooling inflow to replenish star formation in the disk. Using absorption spectra from the Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer toward 37 active galactic nuclei at high latit…
Suzaku Discovery of the Strong Radiative Recombination Continuum of Iron from the Supernova Remnant W49B
Yamaguchi, H.; Ozawa, M.; Koyama, K. +2 more
We present a hard X-ray spectrum of unprecedented quality of the Galactic supernova remnant (SNR) W49B obtained with the Suzaku satellite. The spectrum exhibits an unusual structure consisting of a saw-edged bump above 8 keV. This bump cannot be explained by any combination of high-temperature plasmas in ionization equilibrium. We firmly conclude …
Flux Rope Formation Preceding Coronal Mass Ejection Onset
Green, L. M.; Kliem, B.
We analyze the evolution of a sigmoidal (S-shaped) active region toward eruption, which includes a coronal mass ejection (CME) but leaves part of the filament in place. The X-ray sigmoid is found to trace out three different magnetic topologies in succession: a highly sheared arcade of coronal loops in its long-lived phase, a bald-patch separatrix…
Simultaneous Multi-Wavelength Observations of Sgr A* During 2007 April 1-11
Grosso, N.; Dowell, C. D.; Porquet, D. +18 more
We report the detection of variable emission from Sgr A* in almost all wavelength bands (i.e., centimeter, millimeter, submillimeter, near-IR, and X-rays) during a multi-wavelength observing campaign. Three new moderate flares are detected simultaneously in both near-IR and X-ray bands. The ratio of X-ray to near-IR flux in the flares is consisten…
The Distribution of Dark Matter Over Three Decades in Radius in the Lensing Cluster Abell 611
Richard, Johan; Treu, Tommaso; Marshall, Philip J. +5 more
We present a detailed analysis of the baryonic and dark matter distribution in the lensing cluster Abell 611 (z = 0.288), with the goal of determining the dark matter profile over an unprecedented range of cluster-centric distance. By combining three complementary probes of the mass distribution, weak lensing from multi-color Subaru imaging, stron…
The SLACS Survey. VIII. The Relation between Environment and Internal Structure of Early-Type Galaxies
Treu, Tommaso; Gavazzi, Raphaël; Marshall, Philip J. +5 more
We study the relation between the internal structure of early-type galaxies and their environment using 70 strong gravitational lenses from the SLACS Survey. The Sloan Digital Sky Survey (SDSS) database is used to determine two measures of overdensity of galaxies around each lens—the projected number density of galaxies inside the tenth nearest ne…
Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity
Kaaret, Philip; Yamaoka, Kazutaka; Kalemci, Emrah +3 more
Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R in) can be…