Search Publications
Gamma-Ray Imaging of the 2003 October/November Solar Flares
Krucker, S.; Lin, R. P.; Smith, D. M. +3 more
We present RHESSI imaging of three flares (2003 October 28 and 29 and November 2) in the 2.223 MeV neutron-capture gamma-ray line with angular resolution as high as 35". Comparisons of imaged and spatially integrated fluences show that in all cases most, if not all, of the emission was confined to compact sources with size scales of tens of arcsec…
A Chandra Survey of Early-Type Galaxies. I. Metal Enrichment in the Interstellar Medium
Humphrey, Philip J.; Buote, David A.
We present a Chandra study of the emission-weighted metal abundances in 28 early-type galaxies, spanning ~3 orders of magnitude in X-ray luminosity (LX). We report constraints for Fe, O, Ne, Mg, Si, S, and Ni. We find no evidence of the very subsolar Fe abundance (ZFe) historically reported, confirming a trend in recent obser…
The Stellar Masses and Star Formation Histories of Galaxies at z ~ 6: Constraints from Spitzer Observations in the Great Observatories Origins Deep Survey
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +3 more
Using the deep Spitzer Infrared Array Camera (IRAC) observations of the Great Observatories Origins Deep Survey (GOODS), we study the stellar masses and star formation histories of galaxies at z~6 based on the i775-band dropout sample selected from the GOODS fields. In total, we derive stellar masses for 53 i775-band dropouts…
A Prominent Accretion Disk in the Low-Hard State of the Black Hole Candidate SWIFT J1753.5-0127
Miller, J. M.; Homan, J.; Miniutti, G.
We report on simultaneous XMM-Newton and RXTE observations of the stellar mass black hole candidate SWIFT J1753.5-0127. The source was observed in the ``low-hard'' state, during the decline of a hard outburst. The inner accretion disk is commonly assumed to be radially truncated in the low-hard state, and it has been suggested that this property m…
XMM-Newton Archival Study of the Ultraluminous X-Ray Population in Nearby Galaxies
Reynolds, Christopher S.; Mushotzky, Richard F.; Winter, Lisa M.
We present the results of an archival XMM-Newton study of the bright X-ray point sources (LX>1038 ergs s-1) in 32 nearby galaxies. From our list of approximately 100 point sources, we attempt to determine if there is a low-state counterpart to the ultraluminous X-ray (ULX) population, searching for a soft-hard s…
Chemical Compositions of Red Giant Stars in Old Large Magellanic Cloud Globular Clusters
Stetson, Peter B.; Johnson, Jennifer A.; Ivans, Inese I.
We have observed 10 red giant stars in four old Large Magellanic Cloud globular clusters with the high-resolution spectrograph MIKE on the Magellan Landon Clay 6.5 m telescope. The stars in our sample have up to 20 elemental abundance determinations for the α-, iron peak, and neutron-capture element groups. We have also derived abundances for the …
Clusters at Half Hubble Time: Galaxy Structure and Colors in RX J0152.7-1357 and MS 1054-03
Ford, H. C.; Demarco, R.; Tran, Kim-Vy H. +12 more
We study the photometric and structural properties of spectroscopically confirmed members in the two massive X-ray-selected z~0.83 galaxy clusters MS 1054-03 and RX J0152.7-1357 using three-band mosaic imaging with the Hubble Space Telescope Advanced Camera for Surveys. The samples include 105 and 140 members of RX J0152.7-1357 and MS 1054-03, res…
RHESSI and SOHO CDS Observations of Explosive Chromospheric Evaporation
Milligan, Ryan O.; Gallagher, Peter T.; Mathioudakis, Mihalis +3 more
Simultaneous observations of explosive chromospheric evaporation are presented using data from the Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI) and the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory. For the first time, cospatial imaging and spectroscopy have been used to observe explosive ev…
Streaming Motions toward the Supermassive Black Hole in NGC 1097
Robinson, Andrew; Marconi, Alessandro; Axon, David J. +5 more
We have used GMOS-IFU and high-resolution HST-ACS observations to map, in unprecedented detail, the gas velocity field and structure within the 0.7 kpc circumnuclear ring of the SBb LINER/Seyfert 1 galaxy NGC 1097. We find clear evidence of radial streaming motions associated with spiral structures leading to the unresolved (<3.5 pc) nucleus, w…
Detection of the 205 µm [N II] Line from the Carina Nebula
Stark, A. A.; Stacey, G. J.; Oberst, T. E. +7 more
We report the first detection of the 205 µm 3P1-->3P0 [N II] line from a ground-based observatory using a direct detection spectrometer. The line was detected from the Carina star formation region using the South Pole Imaging Fabry-Perot Interferometer (SPIFI) on the Antarctic Submillimeter Telescope and R…