Search Publications
XMM-Newton Detection of a Transient X-ray Source in the Vicinity of V838 Monocerotis
Soker, Noam; Bond, Howard E.; Kastner, Joel H. +5 more
We report the XMM-Newton/EPIC detection in 2008 March of a luminous (LX ~ 1032-33 erg s-1), variable X-ray source in the vicinity (within ~6'') of the enigmatic star V838 Mon, which underwent a spectacular outburst in early 2002. Spectral modeling of the XMM-Newton X-ray source indicates the presence of two plasma …
Characterization of Transitions in the Solar Wind Parameters
Perri, S.; Balogh, A.
The distinction between fast and slow solar wind streams and the dynamically evolved interaction regions is reflected in the characteristic fluctuations of both the solar wind and the embedded magnetic field. High-resolution magnetic field data from the Ulysses spacecraft have been analyzed. The observations show rapid variations in the magnetic f…
Observed Core of a Gradual Solar Energetic Particle Event
Thompson, B. J.; Valtonen, E.; Kocharov, L. +2 more
Using space-borne particle and EUV detection and radio spectrograms from both ground-based and space-borne instruments, we study the first phase of the major solar energetic particle (SEP) event associated with the western solar flare and fast and wide coronal mass ejection (CME) on 2000 April 4. The SEP event being observed at the magnetic connec…
X-ray Outflows in the Swift Burst Alert Detected Seyfert 1s
Winter, Lisa M.
Previous surveys of outflows in low-redshift active galactic nuclei (AGNs) have relied on the analysis of sources selected primarily for their optical/X-ray brightness and are therefore biased. Toward determining the outflow properties of local AGNs, we detect warm absorption signatures of O VII and O VIII absorption edges in the available Suzaku/…
A Non-local Thermodynamic Equilibrium Analysis of Boron Abundances in Metal-poor Stars
Shi, Jianrong; Zhao, Gang; Tan, Kefeng
The non-local thermodynamic equilibrium (NLTE) line formation of neutral boron in the atmospheres of cool stars are investigated. Our results confirm that NLTE effects for the B I resonance lines, which are due to a combination of overionization and optical pumping effects, are most important for hot, metal-poor, and low-gravity stars; however, th…
Hubble Space Telescope Near-infrared Snapshot Survey of 3CR Radio Source Counterparts. III. Radio Galaxies and Quasars in Context
O'Dea, Christopher P.; Baum, Stefi; Chiaberge, Marco +6 more
We compare the near-infrared (NIR) H-band photometric and morphological properties of low-z (z < 0.3) 3CR radio galaxies with samples of BL Lac objects and quasar host galaxies, merger remnants, quiescent elliptical galaxies, and brightest cluster galaxies drawn from the literature. In general, the 3CR host galaxies are consistent with luminous…
Observed Scaling Relations for Strong Lensing Clusters: Consequences for Cosmology and Cluster Assembly
Natarajan, Priyamvada; Comerford, Julia M.; Moustakas, Leonidas A.
Scaling relations of observed galaxy cluster properties are useful tools for constraining cosmological parameters as well as cluster formation histories. One of the key cosmological parameters, σ8, is constrained using observed clusters of galaxies, although current estimates of σ8 from the scaling relations of dynamically re…
The Non-radial Propagation of Coronal Streamers within a Solar Cycle
Tlatov, A. G.
We have analyzed the shape of the solar corona using the data of daily observations with Mark-III/IV (1980-2008) and SOHO/LASCO-2 (1996-2009) telescopes. The angles of deviation of coronal rays from the radial direction Δθ vary cyclically, reaching the maximum deviation toward the solar equator at the minimum of the solar activity. We consider the…
Modulation Mechanism of Tev, Gev, and X-ray Emission in LS5039
Yamaguchi, M. S.; Takahara, F.
The emission mechanism of the gamma-ray binary LS5039 in TeV, GeV, and X-ray energy bands is investigated. Observed light curves in LS5039 show that TeV and GeV fluxes anticorrelate, whereas TeV and X-ray fluxes correlate. However, such correlated variations have not yet been reasonably explained at this stage. Assuming that relativistic electrons…
Q2122-444: A Naked Active Galactic Nucleus Fully Dressed
Foschini, L.; Saviane, I.; Monaco, L. +6 more
Based on previous spectral and temporal optical studies, Q2122-444 has been classified as a naked active galactic nucleus (AGN) or true type 2 AGN, that is, an AGN that genuinely lacks a broad-line region (BLR). Its optical spectrum seemed to possess only narrow forbidden emission lines that are typical of type 2 (obscured) AGNs, but the long-term…