Search Publications
Suzaku Observations of Active Galactic Nuclei Detected in the Swift BAT Survey: Discovery of a ``New Type'' of Buried Supermassive Black Holes
Ueda, Yoshihiro; Terashima, Yuichi; Mushotzky, Richard +6 more
We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of NH~=1023.5-1024
New Constraints on the Lyman Continuum Escape Fraction at z~1.3
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +8 more
We examine deep far-UV (1600 Å) imaging of the HDF-N and the HUDF to search for leaking Lyman continuum radiation from starburst galaxies at z~1.3. There are 21 (primarily sub-L*) galaxies with spectroscopic redshifts between 1.1<z<1.5, and none are detected in the far-UV. We fit stellar population templates to the galaxies' optic…
A Keck Survey for Gravitationally Lensed Lyα Emitters in the Redshift Range 8.5<z<10.4: New Constraints on the Contribution of Low-Luminosity Sources to Cosmic Reionization
Richard, Johan; Smith, Graham P.; Stark, Daniel P. +3 more
We discuss new observational constraints on the abundance of faint high-redshift Lyα emitters secured from a deep Keck near-infrared spectroscopic survey that utilizes the strong magnification provided by lensing galaxy clusters. In each of nine clusters, we have undertaken a systematic ``blind'' search for line emission with NIRSPEC in the J band…
The loss of ions from Venus through the plasma wake
Coates, A. J.; Kallio, E.; Fedorov, A. +47 more
Venus, unlike Earth, is an extremely dry planet although both began with similar masses, distances from the Sun, and presumably water inventories. The high deuterium-to-hydrogen ratio in the venusian atmosphere relative to Earth's also indicates that the atmosphere has undergone significantly different evolution over the age of the Solar System. P…
Iron Line and Diffuse Hard X-Ray Emission from the Starburst Galaxy M82
Heckman, Timothy M.; Strickland, David K.
We examine the properties of the diffuse hard X-ray emission in the classic starburst galaxy M82. We use new Chandra ACIS-S observations in combination with reprocessed archival Chandra ACIS-I and XMM-Newton observations. We find that E~6.7 keV Fe Heα emission is present in the central |r|<200 pc, |z|<100 pc of M82 in all data sets, in addit…
COSBO: The MAMBO 1.2 Millimeter Imaging Survey of the COSMOS Field
Lutz, D.; Aussel, H.; Menten, K. M. +20 more
The inner 20×20 arcmin2 of the COSMOS field was imaged at 250 GHz (1.2 mm) to an rms noise level of ~1 mJy per 11" beam using the Max-Planck Millimeter Bolometer Array (MAMBO-2) at the IRAM 30 m telescope. We detect 15 sources at significance between 4 and 7 σ, 11 of which are also detected at 1.4 GHz with the VLA with a flux density &g…
Hydrocarbon lakes on Titan
Showman, Adam P.; Lorenz, Ralph D.; Lunine, Jonathan I. +1 more
The Huygens Probe detected dendritic drainage-like features, methane clouds and a high surface relative humidity (∼50% ) on Titan in the vicinity of its landing site [Tomasko, M.G., and 39 colleagues, 2005. Nature 438, 765-778; Niemann, H.B., and 17 colleagues, 2005. Nature 438, 779-784], suggesting sources of methane that replenish this gas again…
Magnetospheric configurations from a high-resolution data-based magnetic field model
Sitnov, M. I.; Tsyganenko, N. A.
We present first results of the magnetospheric magnetic field modeling, based on large sets of spacecraft data and a high-resolution expansion for the field of equatorial currents. In this approach, the field is expanded into a sum of orthogonal basis functions of different scales, capable to reproduce arbitrary radial and azimuthal variations of …
Correlations between Cassini VIMS spectra and RADAR SAR images: Implications for Titan's surface composition and the character of the Huygens Probe Landing Site
Nicholson, Philip D.; Sotin, Christophe; Barnes, Jason W. +24 more
Titan's vast equatorial fields of RADAR-dark longitudinal dunes seen in Cassini RADAR synthetic aperture images correlate with one of two dark surface units discriminated as "brown" and "blue" in Visible and Infrared Mapping Spectrometer (VIMS) color composites of short-wavelength infrared spectral cubes (RGB as 2.0, 1.6, 1.3 µm). In such co…
A method for the direct determination of the surface gravities of transiting extrasolar planets
Wheatley, Peter J.; Southworth, John; Sams, Giles
We show that the surface gravity of a transiting extrasolar planet can be calculated from only the spectroscopic orbit of its parent star and the analysis of its transit light curve. This does not require additional constraints, such as are often inferred from theoretical stellar models or model atmospheres. The surface gravity of the planet can t…