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Energy Distribution of Individual Quasars from Far-Ultraviolet to X-Rays. I. Intrinsic Ultraviolet Hardness and Dust Opacities
Nicastro, Fabrizio; Krongold, Yair; Humphrey, Andrew +4 more
Using Chandra and HST archival data, we have studied the individual SED of 11 quasars at redshifts 0.3<z<1.8. All UV spectra show a spectral break around 1100 Å. Five X-ray spectra showed the presence of a ``soft excess,'' and seven spectra showed an intrinsic absorption. We found that for most quasars a simple extrapolation of the far-UV po…
Magnetic Cycles in the Sun: Modeling the Changes in Radius, Luminosity, and p-Mode Frequencies
Mullan, D. J.; Townsend, R. H. D.; MacDonald, J.
We report on the results obtained with a stellar evolution code in which cyclic magnetic fields are imposed in the convection zone of a 1.0 Msolar star. Magnetic effects are incorporated in two ways: (1) the field pressure and energy density are included in the equations of hydrostatic equilibrium and conservation of energy; and (2) the…
Spatially Resolved X-Ray Spectra of NGC 4258
Yang, Y.; Li, B.; Reynolds, C. S. +1 more
We report a spatially resolved, X-ray spectral analysis of NGC 4258 using archival Chandra and XMM-Newton observations. The XMM-Newton spectrum of the nuclear region is well described by two power-law components, a soft (0.57 keV) thermal component and an Fe Kα line with EW=40+/-33 eV. The properties of the second, weaker power-law component are s…
The effect of dust on Tremaine-Weinberg measurements
Gerssen, Joris; Debattista, Victor P.
We investigate the effect of dust on the observed rotation rate of a stellar bar. The only direct way to measure this quantity relies on the Tremaine & Weinberg (TW) method which requires that the tracer satisfies the continuity equation. Thus, it has been applied largely to early-type barred galaxies. We show using numerical simulations of ba…
Low surface brightness galaxies around the HDF-S. II. Distances and volume densities
Bomans, D. J.; Dettmar, R. -J.; Haberzettl, L.
Aims:With this study we aim at the spectroscopic verification of a photometrically selected sample of Low Surface Brightness (LSB) galaxy candidates in a field around the Hubble Deep Field-South (HDF-S). The sample helps to extend the parameter space for LSB galaxies to lower central surface brightnesses and to provide better estimates on the volu…
Morphology of the magnetic field near Titan: Hybrid model study of the Cassini T9 flyby
Kallio, E.; Janhunen, P.; Bertucci, C. +4 more
We study the deformation and morphology of the magnetic field near Titan by a three-dimensional numerical quasi-neutral hybrid model (HYB-Titan). We analyze two runs, one in which the sub-rotating plasma consists of oxygen (O+) ions and protons (H+) and another with only protons. We find that both cases result in the generati…
An Infrared Study of the Large-Scale Jet in Quasar PKS 1136-135
Cheung, C. C.; Takahashi, Tadayuki; Van Duyne, Jeffrey +6 more
We present Spitzer IRAC imaging of the large-scale jet in the quasar PKS 1136-135 at wavelengths of 3.6 and 5.8 µm, combined with previous VLA, HST, and Chandra observations. We clearly detect infrared emission from the jet, resulting in the most detailed multifrequency data among the jets in lobe-dominated quasars. The spectral energy distr…
Emission-Line Spectroscopy of a Damped Lyα-absorbing Galaxy at z = 0.437
Kulkarni, Varsha P.; Chun, Mark R.; Gharanfoli, Soheila +1 more
We present Keck LRIS spectra of a candidate damped Lyα (DLA) galaxy toward the QSO 3C 196 (zem=0.871). The DLA absorption system has a redshift of zDLA=0.437, and a galaxy at 1.5" from the QSO has been identified in high-resolution imaging with WFPC2 on board the Hubble Space Telescope. We have detected emission lines of [O I…
Smoothed Particle Inference: A Kilo-Parametric Method for X-Ray Galaxy Cluster Modeling
Marshall, P. J.; Peterson, J. R.; Andersson, K.
We propose an ambitious new method that models the intracluster medium in clusters of galaxies as a set of X-ray-emitting smoothed particles of plasma. Each smoothed particle is described by a handful of parameters including temperature, location, size, and elemental abundances. Hundreds to thousands of these particles are used to construct a mode…
Cold ionospheric plasma in Titan's magnetotail
Russell, C. T.; Wei, H. Y.; Dougherty, M. K. +5 more
The interaction between Titan and the corotating Saturnian plasma forms an induced magnetosphere with an elongated Alfven-wing-style magnetotail. On 26 December 2005, the Cassini spacecraft flew through Titan's magnetotail, providing the first distant tail observation, over 5 Titan radii downstream. We examine measurements observed by the magnetom…