Search Publications
Ultra-faint Ultraviolet Galaxies at z ~ 2 behind the Lensing Cluster A1689: The Luminosity Function, Dust Extinction, and Star Formation Rate Density
Teplitz, Harry I.; Richard, Johan; Scarlata, Claudia +8 more
We have obtained deep ultraviolet imaging of the lensing cluster A1689 with the WFC3/UVIS camera onboard the Hubble Space Telescope in the F275W (30 orbits) and F336W (4 orbits) filters. These images are used to identify z ~ 2 star-forming galaxies via their Lyman break, in the same manner that galaxies are typically selected at z >= 3. Because…
Evidence for Particle Re-acceleration in the Radio Relic in the Galaxy Cluster PLCKG287.0+32.9
Nonino, M.; van Weeren, R. J.; Röttgering, H. J. A. +5 more
Radio relics are diffuse radio sources observed in galaxy clusters, probably produced by shock acceleration during cluster-cluster mergers. Their large size, of the order of 1 Mpc, indicates that the emitting electrons need to be (re)accelerated locally. The usually invoked diffusive shock acceleration models have been challenged by recent observa…
Abundant Molecular Gas and Inefficient Star Formation in Intracluster Regions: Ram Pressure Stripped Tail of the Norma Galaxy ESO137-001
Combes, Françoise; Sun, Ming; Jáchym, Pavel +2 more
For the first time, we reveal large amounts of cold molecular gas in a ram-pressure-stripped tail, out to a large "intracluster" distance from the galaxy. With the Actama Pathfinder EXperiment (APEX) telescope, we have detected 12CO(2-1) emission corresponding to more than 109 M ⊙ of H2 in three Hα brigh…
The Reflection Component from Cygnus X-1 in the Soft State Measured by NuSTAR and Suzaku
Hailey, Charles J.; Fürst, Felix; Pottschmidt, Katja +21 more
The black hole binary Cygnus X-1 was observed in late 2012 with the Nuclear Spectroscopic Telescope Array (NuSTAR) and Suzaku, providing spectral coverage over the ~1-300 keV range. The source was in the soft state with a multi-temperature blackbody, power law, and reflection components along with absorption from highly ionized material in the sys…
Slow Evolution of the Specific Star Formation Rate at z > 2: The Impact of Dust, Emission Lines, and a Rising Star Formation History
Franx, Marijn; Labbé, Ivo; Oesch, Pascal +4 more
We measure the evolution of the specific star formation rate (sSFR = SFR/M stellar) between redshift 4 and 6 to assess the reported "constant" sSFR at z > 2. We derive stellar masses and star formation rates (SFRs) for a large sample of 750 z ~ 4-6 galaxies in the GOODS-S field by fitting stellar population models to their spectral e…
Confirmation via the Continuum-fitting Method that the Spin of the Black Hole in Cygnus X-1 Is Extreme
Steiner, James F.; Remillard, Ronald A.; McClintock, Jeffrey E. +6 more
In Gou et al., we reported that the black hole primary in the X-ray binary Cygnus X-1 is a near-extreme Kerr black hole with a spin parameter a * > 0.95 (3σ). We confirm this result while setting a new and more stringent limit: a * > 0.983 at the 3σ (99.7%) confidence level. The earlier work, which was based on an analy…
Imaging and Spectroscopic Observations of Magnetic Reconnection and Chromospheric Evaporation in a Solar Flare
Reeves, Katharine K.; Chen, Bin; Liu, Wei +5 more
Magnetic reconnection is believed to be the dominant energy release mechanism in solar flares. The standard flare model predicts both downward and upward outflow plasmas with speeds close to the coronal Alfvén speed. Yet, spectroscopic observations of such outflows, especially the downflows, are extremely rare. With observations of the newly launc…
SN 2010jl: Optical to Hard X-Ray Observations Reveal an Explosion Embedded in a Ten Solar Mass Cocoon
Hailey, Charles J.; Filippenko, Alexei V.; Cenko, S. Bradley +24 more
Some supernovae (SNe) may be powered by the interaction of the SN ejecta with a large amount of circumstellar matter (CSM). However, quantitative estimates of the CSM mass around such SNe are missing when the CSM material is optically thick. Specifically, current estimators are sensitive to uncertainties regarding the CSM density profile and the e…
Velocity Dispersions and Dynamical Masses for a Large Sample of Quiescent Galaxies at z > 1: Improved Measures of the Growth in Mass and Size
Ellis, Richard S.; Belli, Sirio; Newman, Andrew B.
We present Keck LRIS spectroscopy for a sample of 103 massive (M > 1010.6 M ⊙) galaxies with redshifts 0.9 < z < 1.6. Of these, 56 are quiescent with high signal-to-noise absorption line spectra, enabling us to determine robust stellar velocity dispersions for the largest sample yet available beyond a redshift of 1. …
Whistler Mode Waves and the Electron Heat Flux in the Solar Wind: Cluster Observations
Maksimovic, M.; Alexandrova, O.; de Conchy, Y. +5 more
The nature of the magnetic field fluctuations in the solar wind between the ion and electron scales is still under debate. Using the Cluster/STAFF instrument, we make a survey of the power spectral density and of the polarization of these fluctuations at frequencies f in [1, 400] Hz, during five years (2001-2005), when Cluster was in the free sola…