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NGC 5548 in a Low-Luminosity State: Implications for the Broad-Line Region
Peterson, Bradley M.; Pogge, Richard W.; Vestergaard, Marianne +15 more
We describe results from a new ground-based monitoring campaign on NGC 5548, the best-studied reverberation-mapped AGN. We find that it was in the lowest luminosity state yet recorded during a monitoring program, namely L5100=4.7×1042 ergs s-1. We determine a rest-frame time lag between flux variations in the conti…
A study of Jupiter's aurorae with XMM-Newton
Branduardi-Raymont, G.; Soria, R.; Cravens, T. E. +6 more
We present a detailed analysis of Jupiter's X-ray (0.2-10 keV) auroral emissions as observed over two XMM-Newton revolutions in Nov. 2003 and compare it with that of an earlier observation in Apr. 2003. We discover the existence of an electron bremsstrahlung component in the aurorae, which accounts for essentially all the X-ray flux above 2 keV: i…
Prompt and Afterglow Emission Properties of Gamma-Ray Bursts with Spectroscopically Identified Supernovae
Ramirez-Ruiz, Enrico; Kouveliotou, Chryssa; Kaneko, Yuki +8 more
We present a detailed spectral analysis of the prompt and afterglow emission of four nearby long-soft gamma-ray bursts (GRBs 980425, 030329, 031203, and 060218) that were spectroscopically found to be associated with Type Ic supernovae and compare them to the general GRB population. For each event, we investigate the spectral and luminosity evolut…
High-resolution imaging of the anomalous flux ratio gravitational lens system CLASS B2045+265: dark or luminous satellites?
McKean, J. P.; Blandford, R. D.; Thompson, D. +6 more
The existence of flux ratio anomalies between fold and cusp images in galaxy-scale strong-lens systems has led to an interpretation based on the presence of a high mass fraction of cold dark matter (CDM) substructures around galaxies, as predicted by numerical N-body simulations. These substructures can cause large perturbations of the image magni…
Self-gravity wakes and radial structure of Saturn's B ring
Sremčević, M.; Colwell, J. E.; Esposito, L. W. +2 more
We analyze stellar occultations by Saturn's rings observed with the Cassini Ultraviolet Imaging Spectrograph and find large variations in the apparent normal optical depth of the B ring with viewing angle. The line-of-sight optical depth is roughly independent of the viewing angle out of the ring plane so that optical depth is independent of the p…
Source of Nitrogen Isotope Anomaly in HCN in the Atmosphere of Titan
Liang, Mao-Chang; Yung, Yuk L.; Heays, Alan N. +2 more
The 14N/15N ratio for N2 in the atmosphere of Titan was recently measured to be a factor of 2 higher than the corresponding ratio for HCN. Using a one-dimensional photochemical model with transport, we incorporate new isotopic photoabsorption and photodissociation cross sections of N2, computed quantum-m…
Proper Motions of Dwarf Spheroidal Galaxies from Hubble Space Telescope Imaging. V. Final Measurement for Fornax
Minniti, Dante; Mateo, Mario; Piatek, Slawomir +5 more
The measured proper motion of Fornax, expressed in the equatorial coordinate system, is (µα,µδ)=(47.6+/-4.6,-36.0+/-4.1) mas century-1. This proper motion is a weighted mean of four independent measurements for three distinct fields. Each measurement uses a quasi-stellar object as a reference point. Rem…
The XMM-Newton Wide-Field Survey in the COSMOS Field. IV. X-Ray Spectral Properties of Active Galactic Nuclei
Finoguenov, A.; Taniguchi, Y.; Fiore, F. +25 more
We present a detailed spectral analysis of pointlike X-ray sources in the XMM-Newton COSMOS field. Our sample of 135 sources only includes those that have more than 100 net counts in the 0.3-10 keV energy band and have been identified through optical spectroscopy. The majority of the sources are well described by a simple power-law model with eith…
Trends in effusive style at the Tharsis Montes, Mars, and implications for the development of the Tharsis province
Greeley, Ronald; Williams, David A.; Bleacher, Jacob E. +2 more
We mapped lava flows on the Tharsis Montes (Arsia Mons, Pavonis Mons, and Ascraeus Mons) using High Resolution Stereo Camera images that centrally transect each shield from north to south, covering ~20% of each shield's surface. These data were co-registered to Mars Orbiter Laser Altimeter, Thermal Emission Imaging System, and Mars Orbiter Camera …
Evidence of a Broad Relativistic Iron Line from the Neutron Star Low-Mass X-Ray Binary Serpens X-1
Strohmayer, Tod E.; Bhattacharyya, Sudip
We report on an analysis of XMM-Newton data from the neutron star low-mass X-ray binary (LMXB) Serpens X-1 (Ser X-1). Spectral analysis of EPIC PN data indicates that the previously known broad iron Kα emission line from this source has a significantly skewed structure with a moderately extended red wing. The asymmetric shape of the line is well d…