Search Publications
The Relationship Between X-Ray Radiance and Magnetic Flux
Johns-Krull, Christopher M.; Pevtsov, Alexei A.; Longcope, Dana W. +4 more
We use soft X-ray and magnetic field observations of the Sun (quiet Sun, X-ray bright points, active regions, and integrated solar disk) and active stars (dwarf and pre-main-sequence) to study the relationship between total unsigned magnetic flux, Φ, and X-ray spectral radiance, LX. We find that Φ and LX exhibit a very nearly…
The Rest-Frame Optical Luminosity Density, Color, and Stellar Mass Density of the Universe from z = 0 to z = 3
van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo +11 more
We present the evolution of the rest-frame optical luminosity density jrestλ, the integrated rest-frame optical color, and the stellar mass density, ρ*, for a sample of Ks band-selected galaxies in the Hubble Deep Field-South (HDF-S). We derived jrestλ in the rest-frame U, B, and V …
Measuring Distances and Probing the Unresolved Stellar Populations of Galaxies Using Infrared Surface Brightness Fluctuations
Ajhar, Edward A.; Rieke, Marcia J.; Tonry, John L. +5 more
To empirically calibrate the IR surface brightness fluctuation (SBF) distance scale and probe the properties of unresolved stellar populations, we measured fluctuations in 65 galaxies using NICMOS on the Hubble Space Telescope. The early-type galaxies in this sample include elliptical and S0 galaxies and spiral bulges in a variety of environments.…
Completion of a Survey and Detailed Study of Double-peaked Emission Lines in Radio-loud Active Galactic Nuclei
Eracleous, Michael; Halpern, Jules P.
We report the completion of a survey of radio-loud active galactic nuclei (AGNs) begun in an earlier paper with the main goal of finding and studying broad, double-peaked Balmer lines. We present Hα spectra of 13 more broad-lined objects, including three with double-peaked Hα profiles. The final sample includes 106 radio-loud AGNs. In our final ce…
Discovery of X-Ray Quasi-periodic Oscillations from an Ultraluminous X-Ray Source in M82: Evidence against Beaming
Mushotzky, Richard F.; Strohmayer, Tod E.
We report the discovery with the European Photon Imaging Camera CCDs on board XMM-Newton of a 54 mHz quasi-periodic oscillation (QPO) in the greater than 2 keV X-ray flux from an ultraluminous X-ray source (ULX) in the starburst galaxy M82. This is the first detection of a QPO in the X-ray flux from an extragalactic ULX and confirms that the sourc…
On the Interaction between Convection and Magnetic Fields
Cattaneo, Fausto; Emonet, Thierry; Weiss, Nigel
Turbulent convection in the solar photosphere can act as a small-scale dynamo, maintaining a disordered magnetic field that is locally intense. On the other hand, convection is inhibited in the presence of a strong, externally imposed magnetic field, as for instance, in a sunspot. Large-scale, three-dimensional, numerical experiments on highly non…
A Wide-Field Hubble Space Telescope Study of the Cluster Cl 0024+1654 at z=0.4. II. The Cluster Mass Distribution
Smith, Graham P.; Treu, Tommaso; Smail, Ian +6 more
We present a comprehensive lensing analysis of the rich cluster Cl 0024+1654 (z=0.395) based on panoramic sparse-sampled imaging conducted with the WFPC2 and STIS cameras on board the Hubble Space Telescope. By comparing higher fidelity signals in the limited STIS data with the wider field data available from WFPC2, we demonstrate an ability to de…
Dynamical and Physical Properties of a Post-Coronal Mass Ejection Current Sheet
Lin, Jun; Raymond, John C.; Li, Jing +3 more
In the eruptive process of the Kopp-Pneuman type, the closed magnetic field is stretched by the eruption so much that it is usually believed to be ``open'' to infinity. Formation of the current sheet in such a configuration makes it possible for the energy in the coronal magnetic field to quickly convert into thermal and kinetic energies and cause…
Direct Detection of a Coronal Mass Ejection-Associated Shock in Large Angle and Spectrometric Coronagraph Experiment White-Light Images
Wu, S. T.; Howard, R. A.; Vourlidas, A. +2 more
The Large Angle and Spectrometric Coronagraph Experiment (LASCO) C2 and C3 coronagraphs recorded a unique coronal mass ejection (CME) on 1999 April 2. The event did not have the typical three-part CME structure and involved a small-filament eruption without any visible overlying streamer ejecta. The event exhibited an unusually clear signature of …
The Structure and Dynamics of Luminous and Dark Matter in the Early-Type Lens Galaxy of 0047-281 at z = 0.485
Treu, Tommaso; Koopmans, Léon V. E.
We have measured the kinematic profile of the early-type (E/S0) lens galaxy in the system 0047-281 (z=0.485) with the Echelle Spectrograph and Imager (ESI) on the W. M. Keck II Telescope, as part of the Lenses Structure and Dynamics (LSD) Survey. The central velocity dispersion is σ=229+/-15 km s-1, and the dispersion profile is nearly …