Search Publications
The Major and Minor Galaxy Merger Rates at z < 1.5
Somerville, Rachel S.; Lotz, Jennifer M.; Primack, Joel R. +4 more
Calculating the galaxy merger rate requires both a census of galaxies identified as merger candidates and a cosmologically averaged "observability" timescale langT obs(z)rang for identifying galaxy mergers. While many have counted galaxy mergers using a variety of techniques, langT obs(z)rang for these techniques have been po…
Planck early results. VIII. The all-sky early Sunyaev-Zeldovich cluster sample
Kneissl, R.; Dahle, H.; Miville-Deschênes, M. -A. +235 more
We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6 to 29. Its high reliability (purity above 95%) is further ensur…
Birth of a relativistic outflow in the unusual γ-ray transient Swift J164449.3+573451
Berger, E.; Frail, D. A.; Kulkarni, S. R. +24 more
Active galactic nuclei, which are powered by long-term accretion onto central supermassive black holes, produce relativistic jets with lifetimes of at least one million years, and the observation of the birth of such a jet is therefore unlikely. Transient accretion onto a supermassive black hole, for example through the tidal disruption of a stray…
On Star Formation Rates and Star Formation Histories of Galaxies Out to z ~ 3
Koekemoer, Anton M.; Maiolino, Roberto; Daddi, Emanuele +23 more
We compare multi-wavelength star formation rate (SFR) indicators out to z ~ 3 in the GOODS-South field. Our analysis uniquely combines U to 8 µm photometry from FIREWORKS, MIPS 24 µm and PACS 70, 100, and 160 µm photometry from the PEP, and Hα spectroscopy from the SINS survey. We describe a set of conversions that lead to a cont…
Disequilibrium Carbon, Oxygen, and Nitrogen Chemistry in the Atmospheres of HD 189733b and HD 209458b
Moses, Julianne I.; Fortney, J. J.; Showman, A. P. +8 more
We have developed a one-dimensional photochemical and thermochemical kinetics and diffusion model to study the effects of disequilibrium chemistry on the atmospheric composition of "hot-Jupiter" exoplanets. Here we investigate the coupled chemistry of neutral carbon, hydrogen, oxygen, and nitrogen species on HD 189733b and HD 209458b and we compar…
The First Hundred Brown Dwarfs Discovered by the Wide-field Infrared Survey Explorer (WISE)
Kartaltepe, Jeyhan S.; Tsai, Chao-Wei; Cushing, Michael C. +38 more
We present ground-based spectroscopic verification of 6 Y dwarfs (see also Cushing et al.), 89 T dwarfs, 8 L dwarfs, and 1 M dwarf identified by the Wide-field Infrared Survey Explorer (WISE). Eighty of these are cold brown dwarfs with spectral types >=T6, six of which have been announced earlier by Mainzer et al. and Burgasser et al. We presen…
Defining the intrinsic AGN infrared spectral energy distribution and measuring its contribution to the infrared output of composite galaxies
Alexander, D. M.; Hickox, R. C.; Mullaney, J. R. +1 more
We use infrared spectroscopy and photometry to empirically define the intrinsic mid- to far-infrared spectral energy distribution (i.e. 6-100 µm SED) of thermal emission produced by typical (i.e. 2-10 keV luminosity, L2-10 keV∼ 1042-1044 erg s-1) active galactic nuclei (hereafter AGNs). The average…
Estimation of the XUV radiation onto close planets and their evaporation
Eiroa, C.; Ribas, I.; Solano, E. +5 more
Context. The current distribution of planet mass vs. incident stellar X-ray flux supports the idea that photoevaporation of the atmosphere may take place in close-in planets. Integrated effects have to be accounted for. A proper calculation of the mass loss rate through photoevaporation requires the estimation of the total irradiation from the who…
A salt-water reservoir as the source of a compositionally stratified plume on Enceladus
Kempf, S.; Postberg, F.; Srama, R. +2 more
The discovery of a plume of water vapour and ice particles emerging from warm fractures (`tiger stripes') in Saturn's small, icy moon Enceladus raised the question of whether the plume emerges from a subsurface liquid source or from the decomposition of ice. Previous compositional analyses of particles injected by the plume into Saturn's diffuse E…
Heating of the Solar Chromosphere and Corona by Alfvén Wave Turbulence
Cranmer, S. R.; van Ballegooijen, A. A.; DeLuca, E. E. +1 more
A three-dimensional magnetohydrodynamic (MHD) model for the propagation and dissipation of Alfvén waves in a coronal loop is developed. The model includes the lower atmospheres at the two ends of the loop. The waves originate on small spatial scales (less than 100 km) inside the kilogauss flux elements in the photosphere. The model describes the n…