Search Publications
Discovery of an Unusual Optical Transient with the Hubble Space Telescope
Huang, X.; Lidman, C.; Amanullah, R. +27 more
We present observations of SCP 06F6, an unusual optical transient discovered during the Hubble Space Telescope Cluster Supernova Survey. The transient brightened over a period of ~100 days, reached a peak magnitude of ~ 21.0 in both i 775 and z 850, and then declined over a similar timescale. There is no host galaxy or progen…
Disk-Jet Connection in the Radio Galaxy 3C 120
Peterson, Bradley W.; McHardy, Ian M.; Gaskell, C. Martin +33 more
We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 120 between 2002 and 2007 at X-ray (2-10 keV), optical (R and V bands), and radio (14.5 and 37 GHz) wave bands, as well as imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the 5 yr of observation, significant dips in the X-ray light curve are foll…
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…