Search Publications
A Catalog of Transient X-Ray Sources in M31
Williams, Benjamin F.; Garcia, Michael R.; Naik, S. +1 more
From 1999 October to 2002 August, 45 transient X-ray sources were detected in M31 by Chandra and XMM-Newton. We have performed spectral analysis of all XMM-Newton and Chandra ACIS detections of these sources, as well as flux measurements of Chandra HRC detections. The result is absorption-corrected X-ray light curves for these sources covering thi…
X-Ray Absorption and an X-Ray Jet in the Radio-loud Broad Absorption-line Quasar PG 1004+130
Brandt, W. N.; Garmire, G. P.; Gallagher, S. C. +4 more
We investigate the X-ray properties of PG 1004+130, a radio-loud broad absorption-line (BAL) quasar with a hybrid FR I/II radio morphology. This optically bright, low-redshift quasar was undetected by Einstein, marking it as anomalously X-ray weak relative to other radio-loud quasars. The 22.2 ks XMM-Newton and 41.6 ks Chandra observations present…
The Transparency of Solar Coronal Active Regions
Schmelz, J. T.; Brickhouse, N. S.
Resonance scattering has often been invoked to explain the disagreement between the observed and predicted line ratios of Fe XVII λ15.01 to Fe XVII λ15.26 (the ``3C/3D'' ratio). In this process photons of λ15.01, with its much higher oscillator strength, are preferentially scattered out of the line of sight, thus reducing the observed line ratio. …
Multithermal Analysis of a SOHO/CDS Coronal Loop
Schmelz, J. T.; Martens, P. C. H.
The observations from 1998 April 20 taken with the Coronal Diagnostics Spectrometer (CDS) on the Solar and Heliospheric Observatory (SOHO) of a coronal loop on the limb have shown that the plasma was multithermal along each line of sight investigated, both before and after background subtraction. The latter result relied on emission measure (EM) l…
A Hard X-Ray View of Scorpius X-1 with INTEGRAL: Nonthermal Emission?
Frontera, F.; Goldoni, P.; Stella, L. +12 more
We present here simultaneous INTEGRAL/RXTE observations of Sco X-1 and in particular a study of the hard X-ray emission of the source and its correlation with the position in the Z track of the X-ray color-color diagram. We find that the hard X-ray (above about 30 keV) emission of Sco X-1 is dominated by a power-law component with a photon index o…
Optical Structure and Proper-Motion Age of the Oxygen-rich Supernova Remnant 1E 0102-7219 in the Small Magellanic Cloud
Finkelstein, Steven L.; Ebbets, Dennis C.; Leitherer, Claus +12 more
We present new optical emission-line images of the young SNR 1E 0102-7219 in the SMC obtained with the ACS on HST. This object is a member of the oxygen-rich class of SNRs showing strong oxygen, neon, and other metal-line emissions in its optical and X-ray spectra, and an absence of hydrogen and helium. The progenitor of 1E 0102-7219 may have been…
The Low-Redshift Lyα Forest toward PKS 0405-123
Tripp, Todd M.; Jenkins, Edward B.; Davé, Romeel +5 more
We present results for Lyα forest and metal absorbers from ~7 km s-1 resolution Space Telescope Imaging Spectrograph data for QSO PKS 0405-123 (z=0.574). We analyze strong and weak samples of Lyα forest lines, containing 60 absorbers with column density logNHI>=13.3 over 0.002<z<0.423 and 44 with logNHI>…
Solar Neutron Events of 2003 October-November
Lopate, C.; Kudela, K.; Watanabe, K. +14 more
During the period when the Sun was intensely active in 2003 October-November, two remarkable solar neutron events were observed by the ground-based neutron monitors. On 2003 October 28, in association with an X17.2 large flare, solar neutrons were detected with high statistical significance (6.4 σ) by the neutron monitor at Tsumeb, Namibia. On 200…
A Burst and Simultaneous Short-Term Pulsed Flux Enhancement from the Magnetar Candidate 1E 1048.1-5937
Kaspi, Victoria M.; Woods, Peter M.; Gavriil, Fotis P.
We report on the 2004 June 29 X-ray burst detected from the direction of the AXP 1E 1048.1-5937 using the RXTE. We find a simultaneous increase of ~3.5 times the quiescent value in the 2-10 keV pulsed flux of 1E 1048.1-5937 during the tail of the burst, which identifies the AXP as the burst's origin. The burst was overall very similar to the two o…
Rotational Broadening of Atomic Spectral Features from Neutron Stars
Chang, Philip; Bildsten, Lars; Morsink, Sharon +1 more
The discovery of the first gravitationally redshifted spectral line from a neutron star (NS) by Cottam et al. has triggered theoretical studies of the physics of atomic line formation in NS atmospheres. Chang et al. showed that the hydrogenic Fe Hα line formed above the photosphere of a bursting NS is intrinsically broad. We now include rotational…