Search Publications
Transient and Highly Polarized Double-Peaked Hα Emission in the Seyfert 2 Nucleus of NGC 2110
Moran, Edward C.; Eracleous, Michael; Barth, Aaron J. +1 more
We have discovered an extremely broad, double-peaked Hα emission line in the polarized flux spectrum of NGC 2110, establishing that this well-studied Seyfert 2 galaxy contains a disk-like hidden broad-line region (BLR). Several properties of NGC 2110 suggest that it is an obscured twin of Arp 102B, the prototypical double-peaked emission-line acti…
Strength of Coronal Mass Ejection-driven Shocks near the Sun and Their Importance in Predicting Solar Energetic Particle Events
Wang, Yuming; Shen, Chenglong; Wang, S. +3 more
Coronal shocks are important structures, but there are no direct observations of them in solar and space physics. The strength of shocks plays a key role in shock-related phenomena, such as radio bursts and solar energetic particle (SEP) generation. This paper presents an improved method of calculating Alfvén speed and shock strength near the Sun.…
A Possible Magnetar Nature for IGR J16358-4726
Kouveliotou, C.; Walter, R.; Ubertini, P. +10 more
We present detailed spectral and timing analysis of the hard X-ray transient IGR J16358-4726 using multisatellite archival observations. A study of the source flux time history over 6 yr suggests that lower luminosity transient outbursts can be occurring in intervals of at most 1 yr. Joint spectral fits of the higher luminosity outburst using simu…
IGR J22517+2218=MG3 J225155+2217: A New Gamma-Ray Lighthouse in the Distant Universe
Gehrels, N.; Giommi, P.; Bird, A. J. +7 more
We report on the identification of a new soft gamma-ray source, namely, IGR J22517+2218, detected with INTEGRAL IBIS. The source, which has an observed 20-100 keV flux of ~4×10-11 ergs cm-2 s-1, is spatially coincident with MG3 J225155+2217, a quasar at z=3.668. The Swift XRT 0.5-10 keV continuum is flat (Γ=1.5) wi…
The High-Energy Emission of GRO J1655-40 As Revealed with INTEGRAL Spectroscopy of the 2005 Outburst
Díaz Trigo, M.; Wijnands, R.; Mas-Hesse, J. M. +10 more
We present broadband (3-500 keV) INTEGRAL X-ray spectra and X-ray/optical light curves of the luminous black hole X-ray transient and relativistic jet source GRO J1655-40. Our analysis covers four Target of Opportunity observations of the outburst that started in 2005 February. We find that the high-energy emission of GRO J1655-40 can be modeled w…
A Deep Chandra Look at the Low-LB Elliptical NGC 821: X-Ray Binaries, a Galactic Wind, and Emission at the Nucleus
Elvis, M.; Pellegrini, S.; Baldi, A. +4 more
The relatively nearby (distance = 24.1 Mpc) elliptical galaxy NGC 821, hosting a central massive black hole but inactive at all wavelengths, was observed with Chandra for a total exposure time of 230 ks in order to search for nuclear emission and gas available for accretion. Within its optical image, 41 sources were detected, with spectral propert…
First Detection of Phase-dependent Colliding Wind X-Ray Emission outside the Milky Way
Corcoran, Michael F.; Moffat, Anthony F. J.; Nazé, Yaël +1 more
After having reported the detection of X-rays emitted by the peculiar system HD 5980, we assess here the origin of this high-energy emission from additional X-ray observations obtained with XMM-Newton. This research provides the first detection of apparently periodic X-ray emission from hot gas produced by the collision of winds in an evolved mass…
A Comparative Study of Optical and Ultraviolet Effective Temperatures for DA White Dwarfs from the IUE Archive
Bergeron, P.; Lajoie, C. -P.
We present a comparative study of effective temperatures determined from the hydrogen Balmer lines and from the UV energy distribution for 140 DA white dwarfs drawn from the International Ultraviolet Explorer (IUE) archive. Our results indicate that the optical and UV temperatures of the majority of stars below Teff~40,000 K and within …
Monitoring the Variable Interstellar Absorption toward HD 219188 with Hubble Space Telescope STIS
Welty, Daniel E.
We discuss the results of continued optical and UV spectroscopic monitoring of the variable intermediate-velocity (IV) absorption at vsolar=-38 km s-1 toward HD 219188. After reaching maxima in mid-2000, the column densities of both Na I and Ca II in that IV component declined by factors >~2 by the end of 2006. Comparisons…
The Field of the TeV Source HESS J1804-216 in X-Rays and Other Wavelengths
Garmire, G. P.; Pavlov, G. G.; Kargaltsev, O.
The field of the extended TeV source HESS J1804-216 was serendipitously observed with the Chandra ACIS detector on 2005 May 4. The data reveal several X-ray sources within the bright part of HESS J1804-216. The brightest of these objects, CXOU J180432.4-214009, which has been also detected with Swift (2005 November 3) and Suzaku (2006 April 6), is…