Search Publications
Helioseismic Ring Analyses of Artificial Data Computed for Two-dimensional Shearing Flows
Gough, Douglas; Thompson, Michael J.; Toomre, Juri +1 more
The local helioseismological technique of ring analysis has been crucial in the discovery of complex large-scale flows in the Sun's near-surface shear layer. However, current implementations of ring-analysis procedures assume that the flow field is horizontally homogeneous over the analysis region. This assumption is certainly incorrect, and in th…
XMM-Newton and Optical Follow-up Observations of Three New Polars from the Sloan Digital Sky Survey
Brinkmann, J.; Szkody, Paula; Schmidt, Gary D. +7 more
We report follow-up XMM-Newton and optical observations of three new polars found in the Sloan Digital Sky Survey. Simple modeling of the X-ray spectra, and consideration of the details of the X-ray and optical light curves corroborate the polar nature of these three systems and provide further insights into their accretion characteristics. During…
XMM-Newton Observations of Optically Selected Sloan Digital Sky Survey Clusters
Georgakakis, A.; Georgantopoulos, I.; Plionis, M. +1 more
We explore the X-ray properties of a subset of the optically selected Sloan Digital Sky Survey (SDSS) cluster sample of Goto et al. by analyzing seven public XMM-Newton pointings, with exposure times ranging from ~4 to 46 ks. There are in total 17 SDSS clusters out of which only eight are detected at X-ray wavelengths with f0.5-2keV>…
Colors of Luminous Bulges in Cluster MS 1054-03 and Field Galaxies at Redshifts z~0.83
Tran, Kim-Vy; Willmer, Christopher N. A.; Im, Myungshin +3 more
Using Hubble Space Telescope images, we separate the bulgelike (dubbed ``pbulge'') and disklike (``pdisk'') components of 71 galaxies in the rich cluster MS 1054-03 and of 21 in the field. Our key finding is that luminous pbulges are very red, with rest-frame U-B~0.45, while predicted colors are bluer by 0.20 mag. Moreover, these very red colors a…
Multiple Outbursts of a Cataclysmic Variable in the Globular Cluster M22
Sumi, T.; MOA Collaboration; Bond, I. A. +19 more
We present a 4 yr light curve of a cataclysmic variable in M22, based on an analysis of accumulated data from the Microlensing Observations in Astrophysics (MOA) microlensing survey. The position of the star coincides with that of a transient event observed by the Hubble Space Telescope (HST) in 1999, originally attributed to microlensing but late…
Photometric Redshift of the GRB 981226 Host Galaxy
Christensen, L.; Gorosabel, J.; Hjorth, J.
No optical afterglow was found for the dark burst GRB 981226, and hence no absorption redshift has been obtained. We here use ground-based and space imaging observations to analyze the spectral energy distribution (SED) of the host galaxy. By comparison with synthetic template spectra, we determine the photometric redshift of the GRB 981226 host t…
Discovery of an X-Ray Nova in M31
Williams, Benjamin F.; Kong, Albert K. H.; Murray, Stephen S. +2 more
We have obtained snapshot images of an X-ray nova in M31 from Chandra ACIS-I and the Hubble Space Telescope (HST) Advanced Camera for Surveys. The Chandra position of the X-ray nova was R.A.=00h44m06.68s 68+/-1.74s, decl.=+41deg12'20.0"+/-2.31" (J2000.0). A follow-up HST observation 24 days later reveale…
Identification of the Source Region of a ``Halo'' Coronal Mass Ejection Using Meter-Wavelength Radio Data
Ramesh, R.; Kathiravan, C.
We present meter-wavelength observations of the solar corona close to the onset of the ``halo'' coronal mass ejection (CME) of 1998 January 21 and estimate the change in electron density with time through a reproduction of the observed two-dimensional radio brightness distribution using a ray-tracing technique. Our calculations show that the avera…
High-Resolution Spectroscopy of X-Ray Quasars: Searching for the X-Ray Absorption from the Warm-Hot Intergalactic Medium
Canizares, Claude R.; Marshall, Herman L.; Fang, Taotao
We present a survey of six low- to moderate-redshift quasars with Chandra and XMM-Newton. The primary goal is to search for the narrow X-ray absorption lines produced by highly ionized metals in the warm-hot intergalactic medium. All the X-ray spectra can be fitted by a power law with the neutral hydrogen absorption method. The residuals that may …
Near-Infrared Properties of Faint X-Ray Sources from NICMOS Imaging in the Chandra Deep Fields
Teplitz, Harry I.; McCarthy, Patrick J.; Malkan, Matthew A. +2 more
We measure the near-infrared properties of 42 X-ray-detected sources from the Chandra Deep Fields North and South, the majority of which lie within the NICMOS Hubble Deep Field-North and Ultra Deep Field. We detect all 42 Chandra sources with NICMOS, with 95% brighter than H160=24.5. We find that X-ray sources are most often in the brig…