Search Publications
Dust aerosol, clouds, and the atmospheric optical depth record over 5 Mars years of the Mars Exploration Rover mission
Lemmon, Mark T.; Smith, Michael D.; Bell, James F., III +3 more
Dust aerosol plays a fundamental role in the behavior and evolution of the martian atmosphere. The first five Mars years of Mars Exploration Rover data provide an unprecedented record of the dust load at two sites. This record is useful for characterization of the atmosphere at the sites and as ground truth for orbital observations. Atmospheric ex…
AEGIS-X: Deep Chandra Imaging of the Central Groth Strip
Barmby, P.; Ivison, R. J.; Cooper, M. C. +22 more
We present the results of deep Chandra imaging of the central region of the Extended Groth Strip, the AEGIS-X Deep (AEGIS-XD) survey. When combined with previous Chandra observations of a wider area of the strip, AEGIS-X Wide (AEGIS-XW), these provide data to a nominal exposure depth of 800 ks in the three central ACIS-I fields, a region of approx…
Hubble Space Telescope Proper Motion (HSTPROMO) Catalogs of Galactic Globular Cluster. II. Kinematic Profiles and Maps
Anderson, Jay; van der Marel, Roeland P.; Watkins, Laura L. +1 more
We present kinematical analyses of 22 Galactic globular clusters using the Hubble Space Telescope proper motion catalogs recently presented in Bellini et al. For most clusters, this is the first proper-motion study ever performed, and, for many, this is the most detailed kinematic study of any kind. We use cleaned samples of bright stars to determ…
Are Compton-thick AGNs the Missing Link between Mergers and Black Hole Growth?
Bell, Eric F.; Kartaltepe, Jeyhan S.; Kocevski, Dale D. +12 more
We examine the host morphologies of heavily obscured active galactic nuclei (AGNs) at z∼ 1 to test whether obscured super-massive black hole growth at this epoch is preferentially linked to galaxy mergers. Our sample consists of 154 obscured AGNs with {N}{{H}}\gt {10}23.5 {{cm}}-2 and z\lt 1.5. Using visual classif…
Density and Charge of Pristine Fluffy Particles from Comet 67P/Churyumov-Gerasimenko
Lamy, P. L.; Szego, K.; Fulle, M. +38 more
The Grain Impact Analyzer and Dust Accumulator (GIADA) instrument on board ESA’s Rosetta mission is constraining the origin of the dust particles detected within the coma of comet 67 P/Churyumov-Gerasimenko (67P). The collected particles belong to two families: (i) compact particles (ranging in size from 0.03 to 1 mm), witnessing the presence of m…
Radio Loud AGNs are Mergers
Lotz, Jennifer M.; Chiaberge, Marco; Norman, Colin +1 more
We measure the merger fraction of Type 2 radio-loud and radio-quiet active galactic nuclei (AGNs) at z\gt 1 using new samples. The objects have Hubble Space Telescope (HST) images taken with Wide Field Camera 3 (WFC3) in the IR channel. These samples are compared to the 3CR sample of radio galaxies at z\gt 1 and to a sample of non-active galaxies.…
Accretion-powered Pulsations in an Apparently Quiescent Neutron Star Binary
Deller, Adam T.; Lyne, Andrew G.; Bogdanov, Slavko +10 more
Accreting millisecond X-ray pulsars (AMXPs) are an important subset of low-mass X-ray binaries (LMXBs) in which coherent X-ray pulsations can be observed during occasional, bright outbursts (X-ray luminosity {L}{{X}}∼ {10}36 {erg} {{{s}}}-1). These pulsations show that matter is being channeled onto the neutron sta…
Origin and Evolution of the Cometary Reservoirs
Dones, Luke; Brasser, Ramon; Kaib, Nathan +1 more
Comets have three known reservoirs: the roughly spherical Oort Cloud (for long-period comets), the flattened Kuiper Belt (for ecliptic comets), and, surprisingly, the asteroid belt (for main-belt comets). Comets in the Oort Cloud were thought to have formed in the region of the giant planets and then placed in quasi-stable orbits at distances of t…
Comet 67P/Churyumov-Gerasimenko sheds dust coat accumulated over the past four years
Langevin, Yves; Fischer, Henning; Briois, Christelle +22 more
Comets are composed of dust and frozen gases. The ices are mixed with the refractory material either as an icy conglomerate, or as an aggregate of pre-solar grains (grains that existed prior to the formation of the Solar System), mantled by an ice layer. The presence of water-ice grains in periodic comets is now well established. Modelling of infr…
First Detection of the Acoustic Oscillation Phase Shift Expected from the Cosmic Neutrino Background
Follin, Brent; Knox, Lloyd; Millea, Marius +1 more
The unimpeded relativistic propagation of cosmological neutrinos prior to recombination of the baryon-photon plasma alters gravitational potentials and therefore the details of the time-dependent gravitational driving of acoustic oscillations. We report here a first detection of the resulting shifts in the temporal phase of the oscillations, which…