Search Publications
A Multiphase Suzaku Study of X-rays from τ Sco
Donati, J. -F.; Oskinova, L. M.; Ignace, R. +5 more
We obtained relatively high signal-to-noise X-ray spectral data of the early massive star τ Sco (B0.2V) with the Suzaku X-ray Imaging Spectrometer (XIS) instrument. This source displays several unusual features that motivated our study: (1) redshifted absorption in UV P Cygni lines to approximately +250 km s-1 suggestive of infalling ga…
New Solar Telescope Observations of Magnetic Reconnection Occurring in the Chromosphere of the Quiet Sun
Chae, Jongchul; Goode, P. R.; Ahn, K. +5 more
Magnetic reconnection is a process in which field-line connectivity changes in a magnetized plasma. On the solar surface, it often occurs with the cancellation of two magnetic fragments of opposite polarity. Using the 1.6 m New Solar Telescope, we observed the morphology and dynamics of plasma visible in the Hα line, which is associated with a can…
A Novel Approach in Constraining Electron Spectra in Blazar Jets: The Case of Markarian 421
Takahashi, Tadayuki; Tanaka, Takaaki; Kataoka, Jun +7 more
We report results from the observations of the well-studied TeV blazar Mrk 421 with the Swift and the Suzaku satellites in 2008 December. During the observation, Mrk 421 was found in a relatively low activity state, with the corresponding 2-10 keV flux of 3 × 10-10 erg s-1 cm-2. For the purpose of robustly constrai…
Suzaku Observations of the Black Hole H1743-322 in Outburst
Yamaoka, K.; Takahashi, H.; Fabian, A. C. +5 more
We observed the Galactic black hole candidate H1743-322 with Suzaku for approximately 32 ks, while the source was in a low/hard state during its 2008 outburst. We collected and analyzed the data with the HXD/PIN, HXD/GSO, and XIS cameras spanning the energy range 0.7-200 keV. Fits to the spectra with simple models fail to detect narrow Fe XXV and …
Field and Globular Cluster Low-mass X-ray Binaries in NGC 4278
Zezas, A.; Gallagher, J.; King, A. R. +12 more
We report a detailed spectral analysis of the population of low-mass X-ray binaries (LMXBs) detected in the elliptical galaxy NGC 4278 with Chandra. Seven luminous sources were studied individually, four in globular clusters (GCs) and three in the stellar field. The range of (0.3-8 keV) L X for these sources is ~(3-8) × 1038 …
Galaxy Clusters at z >= 1: Gas Constraints from the Sunyaev-Zel'dovich Array
Andreon, S.; Carlstrom, J. E.; Leitch, E. M. +20 more
We present gas constraints from Sunyaev-Zel'dovich (SZ) effect measurements in a sample of 11 X-ray and infrared (IR) selected galaxy clusters at z>=1, using data from the Sunyaev-Zel'dovich Array (SZA). The cylindrically integrated Compton-y parameter, Y, is calculated by fitting the data to a two-parameter gas pressure profile. Where possible…
Long-duration Low-frequency Type III Bursts and Solar Energetic Particle Events
Gopalswamy, Nat; Mäkelä, Pertti
We analyzed the coronal mass ejections (CMEs), flares, and type II radio bursts associated with a set of three complex, long-duration, low-frequency (<14 MHz) type III bursts from active region 10588 in 2004 April. The durations were measured at 1 and 14 MHz using data from Wind/WAVES and were well above the threshold value (>15 minutes) nor…
The Advection of Supergranules by the Sun's Axisymmetric Flows
Williams, Peter E.; Hathaway, David H.; Cuntz, Manfred +1 more
We show that the motions of supergranules are consistent with a model in which they are simply advected by the axisymmetric flows in the Sun's surface shear layer. We produce a 10 day series of simulated Doppler images at a 15 minute cadence that reproduces most spatial and temporal characteristics seen in the SOHO/MDI Doppler data. Our simulated …
The X-ray Properties of the Optically Brightest Mini-Bal Quasars from the Sloan Digital Sky Survey
Brandt, W. N.; Schneider, Donald P.; Garmire, Gordon P. +4 more
We have compiled a sample of 14 of the optically brightest radio-quiet quasars (mi <= 17.5 and z >= 1.9) in the Sloan Digital Sky Survey Data Release 5 quasar catalog that have C IV mini-broad absorption lines (mini-BALs) present in their spectra. X-ray data for 12 of the objects were obtained via a Chandra snapshot survey using A…
The First Detection of [O IV] from an Ultraluminous X-Ray Source with Spitzer. I. Observational Results for Holmberg II ULX
Kallman, T. R.; Weaver, K. A.; Berghea, C. T. +1 more
We present the first Spitzer Infrared Spectrograph observations of the [O IV] 25.89 µm emission line detected from the ultraluminous X-ray source (ULX) in Holmberg II. This line is a well-established signature of high excitation, usually associated with active galactic nucleus (AGN). Its detection suggests that the ULX has a strong impact on…