Search Publications
Possible AGN Shock Heating in the Cool-Core Galaxy Cluster Abell 478
Finoguenov, Alexis; Mohr, Joseph J.; Sanderson, Alastair J. R.
We present a detailed X-ray study of the intracluster medium (ICM) of the nearby cool-core galaxy cluster Abell 478 (z=0.088), based on Chandra and XMM-Newton observations. Using a wavelet-smoothing hardness analysis, we derive detailed temperature maps of A478, revealing a surprising amount of temperature structure for an apparently well-relaxed …
An Unusual Spectral State of an Ultraluminous Very Soft X-Ray Source during Outburst
Kong, A. K. H.; Di Stefano, R.
We report the results of Chandra and XMM-Newton observations of a new outburst of an ultraluminous X-ray source in M101. During a Chandra monitoring observation of M101, M101 ULX-1 was found to be in outburst in 2004 December, the second outburst in 2004. The peak bolometric luminosity is about 3×1040 ergs s-1 (7×1039
A Refined Ephemeris and Phase-resolved X-Ray Spectroscopy of the Geminga Pulsar
Jackson, M. S.; Halpern, J. P.
We present a refined, phase-connected, postglitch ephemeris for the Geminga pulsar that is a good fit to all the postglitch data from EGRET, ASCA, and XMM-Newton. We also present the results of phase-resolved spectroscopy of two XMM-Newton X-ray observations of the Geminga pulsar obtained in 2002 and 2004. An investigation is made into a previousl…
Discovery of X-Ray Emission from Supernova 1970G with Chandra: Filling the Void between Supernovae and Supernova Remnants
Kuntz, K. D.; Immler, Stefan
We report the discovery of X-ray emission from SN 1970G in M101, 35 yr after its outburst, using deep X-ray imaging with the Chandra X-Ray Observatory. The Chandra ACIS spectrum shows that the emission is soft (<~2 keV) and characteristic of the reverse-shock region. The X-ray luminosity, L0.3-2=(1.1+/-0.2)×1037 ergs s
Magnetic Free Energies of Breakout Coronal Mass Ejections
Antiochos, Spiro K.; DeVore, C. Richard
A critical issue in understanding and eventually predicting coronal mass ejections (CMEs) is determining the magnetic free energy that can drive the explosive eruption. We present calculations of this free energy for the breakout CME model, which postulates that the preeruption magnetic topology is a multipolar field with a null point in the coron…
The Ages of Globular Clusters in NGC 4365 Revisited with Deep HST Observations
Vesperini, Enrico; Kundu, Arunav; Zepf, Stephen E. +6 more
We present new Hubble Space Telescope (HST) NIC3, near-infrared H-band photometry of globular clusters (GCs) around NGC 4365 and NGC 1399 in combination with archival HST WFPC2 and ACS optical data. We find that NGC 4365 has a number of globular clusters with bluer optical colors than expected for their red optical-to-near-infrared colors and an o…
The Absorption Spectrum of High-Density Stellar Ejecta in the Line of Sight to η Carinae
Gull, T. R.; Nielsen, K. E.; Bruhweiler, F. +3 more
Using the high-dispersion near-UV (NUV) mode of the Space Telescope Imaging Spectrograph (STIS) aboard the Hubble Space Telescope (HST) to observe η Carinae, we have resolved and identified over 500 sharp circumstellar absorption lines of iron-group singly ionized and neutral elements with ~20 velocity components ranging from -146 to -585 km s
A Dynamical Simulation of the Debris Disk around HD 141569A
Ford, H. C.; Infante, L.; Zheng, W. +36 more
We study the dynamical origin of the structures observed in the scattered-light images of the resolved debris disk around HD 141569A. The disk has two conspicuous spiral rings and two large-scale spiral arms. We explore the roles of radiation pressure from the central star, gas drag from the gas disk, and the tidal forces from two nearby stars in …
Intrinsic Absorption in the Spectrum of NGC 7469: Simultaneous Chandra, FUSE, and STIS Observations
Kaiser, Mary Elizabeth; Green, Richard F.; Scott, Jennifer E. +10 more
We present simultaneous X-ray, far-ultraviolet, and near-ultraviolet spectra of the Seyfert 1 galaxy NGC 7469 obtained with the Chandra X-Ray Observatory, the Far Ultraviolet Spectroscopic Explorer, and the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Previous nonsimultaneous observations of this galaxy found two distinct UV…
A Comparison of Surface Brightness Profiles for Ultracompact Dwarfs and Dwarf Elliptical Nuclei: Implications for the ``Threshing'' Scenario
Drinkwater, M. J.; De Propris, R.; Jones, J. B. +4 more
Using imaging from the Hubble Space Telescope, we derive surface brightness profiles for ultracompact dwarfs in the Fornax Cluster and for the nuclei of dwarf elliptical galaxies in the Virgo Cluster. Ultracompact dwarfs are more extended and have higher surface brightnesses than typical dwarf nuclei, while the luminosities, colors, and sizes of t…