Search Publications
Modeling of the Extreme-Ultraviolet and Soft X-Ray Emission in a Solar Coronal Bright Point
Warren, Harry P.; Brooks, David H.
Previous studies have been able to reproduce both the observed intensities and the morphology of high-temperature solar plasma using steady state heating models. These models, however, have been unable to reproduce the lower temperature emission observed in active regions. Here we present results from numerical simulations of a coronal bright poin…
Secondary Photons from High-Energy Protons Accelerated in Hypernovae
Asano, Katsuaki; Mészáros, Peter
Recent observations show that hypernovae may deposit some fraction of their kinetic energy in mildly relativistic ejecta. In the dissipation process of such ejecta in a stellar wind, cosmic-ray protons can be accelerated up to ~1019 eV. We discuss the TeV to MeV gamma-ray and the X-ray photon signatures of cosmic rays accelerated in hyp…
High-Energy Properties of PKS 1830-211
Torres, Diego F.; Zhang, Shu; Wang, Jian-Min +4 more
We report an analysis of X-ray and γ-ray observations of PKS 1830-211, based on long-term campaigns carried out by INTEGRAL and COMPTEL. The INTEGRAL data currently available provide a 33 σ significance detection in the 20-100 keV band, while the COMPTEL 6 yr data provide a 5.2 σ significance detection in the 1-3 MeV energy band. In hard X-rays, I…
Line Intensity Ratios in the EIS Range Sensitive to Electron Densities in 107 K Plasmas
Landi, E.; Doschek, G. A.; Feldman, U.
Electron density variations during the rise, maximum, and decay phases of flaring plasmas at T simeq 10 MK are important quantities to be used to test flare models. To date, electron density values measured in solar flares are, with few exceptions, only lower limits. With the launch of the EUV Imaging Spectrometer (EIS) on Hinode, it has become po…
High-Resolution X-Ray Imaging of the Center of IC 342
Mak, Daisy S. Y.; Pun, Chun S. J.; Kong, Albert K. H.
We present the results of a high-resolution (θFWHM ~ 0.5'') 12 ks Chandra HRC-I observation of the starburst galaxy IC 342 taken on 2006 April 2. We identify 23 X-ray sources within the central 30' × 30' region of IC 342 and resolve the historical ultraluminous X-ray source (ULX), X3, near the nucleus into two sources, namely, C12 and C…
A Systematic Survey of H I Lyα and O VI Doublet Profiles Observed in Polar Coronal Holes at Solar Minimum
Nakagawa, Akinari
A systematic, comprehensive survey of H I Lyα and O VI doublet profiles in polar coronal holes is performed using spectroscopic observation by the SOHO Ultraviolet Coronagraph Spectrometer (UVCS) at solar minimum in 1996-1997. By decomposing coronal hole profiles into component Gaussians, we determine detailed height distributions of profile param…
Relativistic Outflows in Two Quasars in the Chandra Deep Field South
Wang, J. X.; Zheng, Z. Y.
In this paper we provide new 1 Ms Chandra ACIS spectra of two quasars in the Chandra Deep Field South (CDF-S) which had strong and extremely blueshifted X-ray emission/absorption line features in previous 1 Ms spectra, with outflowing bulk velocity v ~ 0.65-0.84c. In the new 1 Ms spectra, the relativistic blueshifted line feature is solidly confir…
XMM-Newton Observations of the Red Type 1.8 Quasar 2M1049+5837: Reflection from Cold and Warm (Ionized) Matter
Wilkes, B. J.; Pounds, K. A.; Schmidt, G. D.
Chandra observations of the type 1.8, low-redshift (z = 0.115), red (J - KS ~ 2) quasar 2MASSJ 104943+583750 (2M1049+5837) indicated an unusually hard X-ray spectrum (HR ~ 0.6), suggesting obscuration of NH ~ 4 × 1022 cm-2 and a flat Γ ~ 0.4 power-law slope. A higher signal-to-noise ratio XMM-Newton obse…
The Tilted Solar Dipole as Observed and Modeled during the 1996 Solar Minimum
Raouafi, N. -E.; Petrie, G. J. D.; Norton, A. A.
We examine the tilt of the solar magnetic dipole away from the rotational axis near the 1996 solar minimum. A persistent tilted dipole may result from an MHD instability acting on the toroidal bands in the solar interior. Nonaxisymmetric eruption of sunspots has been predicted by dynamo theory and observed in sunspot location patterns. The decay o…
Discovery and Interpretation of an X-Ray Period in the Galactic Center Source CXOGC J174536.1-285638
Muno, Michael P.; Eikenberry, Stephen S.; Bandyopadhyay, Reba M. +1 more
We present X-ray and infrared observations of the X-ray source CXOGC J174536.1-285638. Previous observations suggest that this source may be an accreting binary with a high-mass donor (HMXB) or a colliding wind binary (CWB). Based on the Chandra and XMM-Newton light curve, we have found an apparent 189 +/- 6 day periodicity with better than 99.997…