Search Publications
z ~ 7-10 Galaxies in the HUDF and GOODS Fields: UV Luminosity Functions
Franx, Marijn; Illingworth, Garth D.; Bouwens, Rychard J. +1 more
We use all available deep optical ACS and near-IR data over both the HUDF and the two GOODS fields to search for star-forming galaxies at zgtrsim 7 and constrain the UV LF within the first 700 Myr. Our data set includes ~23 arcmin2 of deep NICMOS J + H data and ~248 arcmin2 of ground-based (ISAAC+MOIRCS) data, coincident with…
Swift BAT Survey of AGNs
Gehrels, N.; Mushotzky, R. F.; Barthelmy, S. +5 more
We present the results of the analysis of the first 9 months of data of the Swift BAT survey of AGNs in the 14-195 keV band. Using archival X-ray data or follow-up Swift XRT observations, we have identified 129 (103 AGNs) of 130 objects detected at | b| > 15° and with significance >4.8 σ. One source remains unidentified. These same X-ray dat…
The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
Anderson, J.; Milone, A. P.; Sarajedini, A. +13 more
Photometry with the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) reveals that the subgiant branch (SGB) of the globular cluster NGC 1851 splits into two well-defined branches. If the split is due only to an age effect, the two SGBs would imply two star formation episodes separated by ~1 Gyr. We discuss other anomalies in NGC 1851 t…
Revealing the Properties of Dark Matter in the Merging Cluster MACS J0025.4-1222
Treu, Tommaso; Bradač, Maruša; Allen, Steven W. +5 more
We constrain the physical nature of dark matter using the newly identified massive merging galaxy cluster MACS J0025.4-1222. As was previously shown by the example of the Bullet Cluster (1E 0657-56), such systems are ideal laboratories for detecting isolated dark matter and distinguishing between cold dark matter (CDM) and other scenarios (e.g., s…
Nonlinear Force-free Field Modeling of a Solar Active Region around the Time of a Major Flare and Coronal Mass Ejection
Aulanier, G.; Schrijver, C. J.; Amari, T. +14 more
Solar flares and coronal mass ejections are associated with rapid changes in field connectivity and are powered by the partial dissipation of electrical currents in the solar atmosphere. A critical unanswered question is whether the currents involved are induced by the motion of preexisting atmospheric magnetic flux subject to surface plasma flows…
An Infrared Survey of Brightest Cluster Galaxies. II. Why are Some Brightest Cluster Galaxies Forming Stars?
Baum, Stefi A.; O'Dea, Christopher P.; Sarazin, Craig L. +12 more
Quillen et al. presented an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies with optical line emission located in the cores of X-ray-luminous clusters. They found that at least half of these sources have signs of excess IR emission. Here we discuss the nature of the IR emission and its implications for cool core cl…
Unveiling Obscured Accretion in the Chandra Deep Field-South
Pozzi, F.; Fiore, F.; Vignali, C. +10 more
We make use of deep HST, VLT, Spitzer, and Chandra data on the Chandra Deep Field-South to constrain the number of Compton-thick AGNs in this field. We show that sources with high 24 µm-to-optical flux ratios and red colors form a distinct source population, and that their infrared luminosity is dominated by AGN emission. Analysis of the X-r…
Hinode SOT Observations of Solar Quiescent Prominence Dynamics
Tsuneta, Saku; Shimizu, Toshifumi; Okamoto, Takenori J. +9 more
We report findings from multihour 0.2'' resolution movies of solar quiescent prominences (QPs) observed with the Solar Optical Telescope (SOT) on the Hinode satellite. The observations verify previous findings of filamentary downflows and vortices in QPs. SOT observations also verify large-scale transverse oscillations in QPs, with periods of 20-4…
Recent Structural Evolution of Early-Type Galaxies: Size Growth from z = 1 to z = 0
Franx, Marijn; Illingworth, Garth D.; van der Wel, Arjen +4 more
Strong size and internal density evolution of early-type galaxies between z ~ 2 and the present has been reported by several authors. Here we analyze samples of nearby and distant (z ~ 1) galaxies with dynamically measured masses in order to confirm the previous, model-dependent results and constrain the uncertainties that may play a role. Velocit…
Small-Scale Energy Cascade of the Solar Wind Turbulence
Alexandrova, O.; Carbone, V.; Veltri, P. +1 more
Magnetic fluctuations in the solar wind are distributed according to Kolmogorov's power law f-5/3 below the ion cyclotron frequency fci. Above this frequency, the observed steeper power law is usually interpreted in two different ways, as a dissipative range of the solar wind turbulence, or another turbulent cascade, the natu…