Search Publications
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…
The Signature of 44Ti in Cassiopeia A Revealed by IBIS/ISGRI on INTEGRAL
Knödlseder, J.; Decourchelle, A.; Vink, J. +9 more
We report the detection of both the 67.9 and 78.4 keV 44Sc γ-ray lines in Cassiopeia A with the INTEGRAL IBIS/ISGRI instrument. Besides the robustness provided by spectroimaging observations, the main improvements compared to previous measurements are a clear separation of the two 44Sc lines together with an improved signific…
Penetrating the Deep Cover of Compton-thick Active Galactic Nuclei
Krolik, J. H.; Heckman, T. M.; Levenson, N. A. +2 more
We analyze observations obtained with the Chandra X-Ray Observatory of bright Compton-thick active galactic nuclei (AGNs), those with column densities in excess of 1.5×1024 cm-2 along the lines of sight. We therefore view the powerful central engines only indirectly, even at X-ray energies. Using high spatial resolution and c…
Swift Panchromatic Observations of the Bright Gamma-Ray Burst GRB 050525a
Sakamoto, T.; Campana, S.; Tagliaferri, G. +62 more
The bright gamma-ray burst GRB 050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a steeper slope ~0.15 days after the burst, indicative of a jet break. This jet break time combined with the to…