Search Publications
Chandra Limits on X-Ray Emission Associated with the Supermassive Black Holes in Three Giant Elliptical Galaxies
Angelini, Lorella; Loewenstein, Michael; Mushotzky, Richard F. +2 more
Elliptical galaxy nuclei are the sites of the largest black holes known but typically show little or no nuclear activity. We investigate this extreme quiescence using Chandra X-Ray Observatory observations of the giant elliptical galaxies NGC 1399, NGC 4472, and NGC 4636. The unique Chandra imaging power enables us to place upper limits of 7.3, 15…
Dynamical Friction in DE Globular Cluster Systems
Ferguson, Henry C.; Mack, Jennifer; Stiavelli, Massimo +3 more
The dynamical friction timescale for globular clusters to sink to the center of a dwarf elliptical galaxy (dE) is significantly less than a Hubble time if the halos have King-model or isothermal profiles and the globular clusters formed with the same radial density profile as the underlying stellar population. We examine the summed radial distribu…
High-Resolution X-Ray and Ultraviolet Spectroscopy of the Complex Intrinsic Absorption in NGC 4051 with Chandra and the Hubble Space Telescope
Brandt, W. N.; Kaspi, Shai; Elvis, Martin +6 more
We present the results from simultaneous observations of the narrow-line Seyfert 1 galaxy NGC 4051 with the Chandra High Energy Transmission Grating Spectrometer and the Hubble Space Telescope Space Telescope Imaging Spectrograph. The X-ray grating spectrum reveals absorption and emission lines from hydrogen-like and helium-like ions of O, Ne, Mg,…
The Gaseous Extent of Galaxies and the Origin of Lyα Absorption Systems. V. Optical and Near-Infrared Photometry of Lyα-absorbing Galaxies at z<1
Chen, Hsiao-Wen; Lanzetta, Kenneth M.; Webb, John K. +1 more
We present results of a program to obtain and analyze HST WFPC2 images and ground-based images of galaxies identified in an imaging and spectroscopic survey of faint galaxies in fields of HST spectroscopic target QSOs. Considering a sample of physically correlated galaxy and absorber pairs with galaxy-absorber cross-correlation amplitude ξga<…
Evidence for a Supermassive Black Hole in the S0 Galaxy NGC 3245
Filippenko, Alexei V.; Ho, Luis C.; Rix, Hans-Walter +3 more
The S0 galaxy NGC 3245 contains a circumnuclear disk of ionized gas and dust with a radius of 1.1" (110 pc), making it an ideal target for dynamical studies with the Hubble Space Telescope (HST). We have obtained spectra of the nuclear disk with the Space Telescope Imaging Spectrograph, using a 0.2" wide slit at five parallel positions. Measuremen…
The Diversity of High- and Intermediate-Velocity Clouds: Complex C versus IV Arch
Richter, Philipp; Tripp, Todd M.; Jenkins, Edward B. +5 more
We present Far Ultraviolet Spectroscopic Explorer (FUSE) and Space Telescope Imaging Spectrograph (STIS) observations of interstellar ultraviolet absorption lines in the Galactic high-velocity cloud Complex C and the Intermediate-Velocity Arch (IV Arch) in the direction of the quasar PG 1259+593 (l=120.6d, b=+58.1d). Absorption lines from C II, N …
Hemispheric Helicity Trend for Solar Cycle 23
Pevtsov, Alexei A.; Canfield, Richard C.; Latushko, Sergei M.
Applying the same methods we used in solar cycle 22, we study active region vector magnetograms, full-disk X-ray images, and full-disk line-of-sight magnetograms to derive the helicity of solar magnetic fields in the first 4 years of solar cycle 23. We find that these three data sets all exhibit the same two key tendencies-significant scatter and …
The Variable Diffuse Continuum Emission of Broad-Line Clouds
Goad, Michael R.; Korista, Kirk T.
We investigate the wavelength-dependent intensity and reverberation properties of the UV-optical diffuse continuum emission expected from broad emission line gas. The ``locally optimally emitting clouds'' picture is adopted, with the cloud distribution functions in gas density and distance from the ionizing source determined by a fit to the mean U…
The Importance of Einstein Rings
Keeton, C. R.; Kochanek, C. S.; McLeod, B. A.
We develop a theory of Einstein rings and demonstrate it using the infrared Einstein ring images of the quasar host galaxies observed in PG 1115+080, B1608+656, and B1938+666. The shape of an Einstein ring accurately and independently determines the shape of the lens potential and the shape of the lensed host galaxy. We find that the host galaxies…
Broadband Observations of the Afterglow of GRB 000926: Observing the Effect of Inverse Compton Scattering
Piro, L.; Frontera, F.; Price, P. A. +23 more
GRB 000926 has one of the best-studied afterglows to date, with multiple X-ray observations, as well as extensive multifrequency optical and radio coverage. Broadband afterglow observations, spanning from X-ray to radio frequencies, provide a probe of the density structure of the circumburst medium, as well as of the ejecta energetics, geometry, a…