Search Publications
The Survival of Dark Matter Halos in the Cluster Cl 0024+16
Treu, Tommaso; Ellis, Richard; Smail, Ian +5 more
Theories of structure formation in a cold dark matter dominated universe predict that massive clusters of galaxies assemble from the hierarchical merging of lower mass subhalos. Exploiting strong and weak gravitational lensing signals inferred from panoramic Hubble Space Telescope imaging data, we present a high-resolution reconstruction of the ma…
The Environments of Active Galactic Nuclei within the zCOSMOS Density Field
Finoguenov, A.; Kneib, J. -P.; Jahnke, K. +58 more
The impact of environment on active galactic nucleus (AGN) activity up to z ~ 1 is assessed by utilizing a mass-selected sample of galaxies from the 10k catalog of the zCOSMOS spectroscopic redshift survey. We identify 147 AGN by their X-ray emission as detected by XMM-Newton from a parent sample of 7234 galaxies. We measure the fraction of galaxi…
Linking Remote Imagery of a Coronal Mass Ejection to Its In Situ Signatures at 1 AU
Möstl, C.; Farrugia, C. J.; Temmer, M. +5 more
In a case study (2008 June 6-7) we report on how the internal structure of a coronal mass ejection (CME) at 1 AU can be anticipated from remote observations of white-light images of the heliosphere. Favorable circumstances are the absence of fast equatorial solar wind streams and a low CME velocity which allow us to relate the imaging and in situ …
Gemini Spectroscopic Survey of Young Star Clusters in Merging/Interacting Galaxies. III. The Antennae
Miller, Bryan W.; Konstantopoulos, Iraklis S.; Trancho, Gelys +1 more
We present optical spectroscopy of 16 star clusters in the merging galaxies NGC 4038/39 ("the Antennae") and supplement this data set with Hubble Space Telescope imaging. The age and metallicity of each cluster is derived through a comparison between the observed Balmer and metal line strengths with simple stellar population models. We then estima…
Nonlinear Force-free Modeling of a Long-lasting Coronal Sigmoid
van Ballegooijen, Adriaan; Savcheva, Antonia
A study of the magnetic configuration and evolution of a long-lasting quiescent coronal sigmoid is presented. The sigmoid was observed by Hinode/XRT and Transition Region and Coronal Explorer (TRACE) between 2007 February 6 and 12 when it finally erupted. We construct nonlinear force-free field models for several observations during this period, u…
Study of the Spectral and Temporal Characteristics of X-Ray Emission of the Gamma-Ray Binary LS 5039 with Suzaku
Yamaoka, Kazutaka; Takahashi, Tadayuki; Uchiyama, Yasunobu +6 more
We report on the results from Suzaku broadband X-ray observations of the galactic binary source LS 5039. The Suzaku data, which have continuous coverage of more than one orbital period, show strong modulation of the X-ray emission at the orbital period of this TeV gamma-ray emitting system. The X-ray emission shows a minimum at orbital phase ~0.1,…
X-Ray Absorption by WHIM in the Sculptor Wall
Humphrey, Philip J.; Buote, David A.; Gastaldello, Fabio +3 more
We present XMM Reflection Grating Spectrometer (RGS) and Chandra Low-Energy Transmission Grating (LETG) observations of the blazar, H 2356-309, located behind the Sculptor Wall, a large-scale galaxy structure expected to harbor high-density Warm-Hot Intergalactic Medium (WHIM). Our simultaneous analysis of the RGS and LETG spectra yields a 3σ dete…
Titan's Surface Brightness Temperatures
Pearl, J. C.; Flasar, F. M.; Coustenis, A. +17 more
Radiance from the surface of Titan can be detected from space through a spectral window of low opacity in the thermal infrared at 19 µm (530 cm-1). By combining Composite Infrared Spectrometer observations from Cassini's first four years, we have mapped the latitude distribution of zonally averaged surface brightness temperatures.…
The End of the White Dwarf Cooling Sequence in M4: An Efficient Approach
Anderson, Jay; Salaris, Maurizio; Bedin, Luigi R. +3 more
We use 14 orbits of Advanced Camera for Surveys observations to reach the end of the white dwarf cooling sequence in the globular cluster M4. Our photometry and completeness tests show that the end is located at magnitude m F606W = 28.5 ± 0.1, which implies an age of 11.6 ± 0.6 Gyr (internal errors only). This is consistent with the age…
FUSE Measurements of Far-Ultraviolet Extinction. III. The Dependence on R(V) and Discrete Feature Limits from 75 Galactic Sightlines
Gordon, Karl D.; Clayton, Geoffrey C.; Cartledge, Stefan
We present a sample of 75 extinction curves derived from Far Ultraviolet Spectroscopic Explorer (FUSE) far-ultraviolet spectra supplemented by existing International Ultraviolet Explorer (IUE) spectra. The extinction curves were created using the standard pair method based on a new set of dereddened FUSE+IUE comparison stars. Molecular hydrogen ab…