Search Publications
Composition of Titan's lower atmosphere and simple surface volatiles as measured by the Cassini-Huygens probe gas chromatograph mass spectrometer experiment
Atreya, S. K.; Lunine, J. I.; Kasprzak, W. T. +7 more
The Cassini-Huygens probe gas chromatograph mass spectrometer (GCMS) determined the composition of the Titan atmosphere from ∼140 km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4), and molecular hydrogen (H
Metals in the Exosphere of the Highly Irradiated Planet WASP-12b
Fossati, L.; Kolb, U.; Collier Cameron, A. +17 more
We present near-UV transmission spectroscopy of the highly irradiated transiting exoplanet WASP-12b, obtained with the Cosmic Origins Spectrograph on the Hubble Space Telescope. The spectra cover three distinct wavelength ranges: NUVA (2539-2580 Å), NUVB (2655-2696 Å), and NUVC (2770-2811 Å). Three independent methods all reveal enhanced transit d…
The Quasar Accretion Disk Size-Black Hole Mass Relation
Kochanek, C. S.; Morgan, Nicholas D.; Morgan, Christopher W. +1 more
We use the microlensing variability observed for 11 gravitationally lensed quasars to show that the accretion disk size at a rest-frame wavelength of 2500 Å is related to the black hole mass by log(R 2500/cm) = (15.78 ± 0.12) + (0.80 ± 0.17)log(M BH/109 M sun). This scaling is consistent with the expecta…
A Low-Magnetic-Field Soft Gamma Repeater
Tiengo, A.; Götz, D.; Mereghetti, S. +8 more
Soft gamma repeaters (SGRs) and anomalous x-ray pulsars form a rapidly increasing group of x-ray sources exhibiting sporadic emission of short bursts. They are believed to be magnetars, that is, neutron stars powered by extreme magnetic fields, B ~ 1014 to 1015 gauss. We report on a soft gamma repeater with low magnetic field…
A 158 µm [C II] Line Survey of Galaxies at z ~ 1-2: An Indicator of Star Formation in the Early Universe
Stacey, G. J.; Benford, D. J.; Staguhn, J. G. +5 more
We have detected the 158 µm [C II] line from 12 galaxies at z ~ 1-2. This is the first survey of this important star formation tracer at redshifts covering the epoch of maximum star formation in the universe and quadruples the number of reported high-z [C II] detections. The line is very luminous, between <0.024% and 0.65% of the far-infr…
The XMM-Newton Wide-field Survey in the Cosmos Field (XMM-COSMOS): Demography and Multiwavelength Properties of Obscured and Unobscured Luminous Active Galactic Nuclei
Finoguenov, A.; Aussel, H.; Le Floc'h, E. +64 more
We report the final optical identifications of the medium-depth (~60 ks), contiguous (2 deg2) XMM-Newton survey of the COSMOS field. XMM-Newton has detected ~1800 X-ray sources down to limiting fluxes of ~5 × 10-16, ~3 × 10-15, and ~7 × 10-15 erg cm-2 s-1 in the 0.5-2 keV, 2-10 keV,…
Observations of Mass Loss from the Transiting Exoplanet HD 209458b
France, Kevin; Stocke, John T.; Yang, Hao +4 more
Using the new Cosmic Origins Spectrograph on the Hubble Space Telescope, we obtained moderate-resolution, high signal/noise ultraviolet spectra of HD 209458 and its exoplanet HD 209458b during transit, both orbital quadratures, and secondary eclipse. We compare transit spectra with spectra obtained at non-transit phases to identify spectral featur…
Detection of a dark substructure through gravitational imaging
Vegetti, S.; Treu, T.; Gavazzi, R. +2 more
We report the detection of a dark substructure - undetected in the Hubble Space Telescope HST ACS F814W image - in the gravitational lens galaxy SDSSJ0946+1006 (the `double Einstein ring'), through direct gravitational imaging. The detection of a small mass concentration in the surface density maps, at 4.3 kpc from the galaxy centre, has a strong …
Ancient ocean on Mars supported by global distribution of deltas and valleys
Hynek, Brian M.; di Achille, Gaetano
The climate of early Mars could have supported a complex hydrological system and possibly a northern hemispheric ocean covering up to one-third of the planet's surface. This notion has been repeatedly proposed and challenged over the past two decades, and remains one of the largest uncertainties in Mars research. Here, we used global databases of …
Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction
Böhringer, H.; Arnaud, M.; Pratt, G. W. +6 more
We examine the radial entropy distribution and its scaling using 31 nearby galaxy clusters from the representative XMM-Newton cluster structure survey (REXCESS), a sample in the temperature range 2-9 keV selected in X-ray luminosity only, with no bias toward any particular morphological type. The entropy profiles are robustly measured at least out…