Search Publications
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…
A 1010 Solar Mass Flow of Molecular Gas in the A1835 Brightest Cluster Galaxy
Fabian, A. C.; Egami, E.; Combes, F. +17 more
We report ALMA Early Science observations of the A1835 brightest cluster galaxy (BCG) in the CO (3-2) and CO (1-0) emission lines. We detect 5 × 1010 M ⊙ of molecular gas within 10 kpc of the BCG. Its ensemble velocity profile width of ~130 km s-1 FWHM is too narrow for the molecular clouds to be supported in the g…
Elemental Compositions of Two Extrasolar Rocky Planetesimals
Koester, D.; Zuckerman, B.; Xu, S. +2 more
We report Keck/HIRES and Hubble Space Telescope/COS spectroscopic studies of extrasolar rocky planetesimals accreted onto two hydrogen atmosphere white dwarfs, G29-38 and GD 133. In G29-38, eight elements are detected, including C, O, Mg, Si, Ca, Ti, Cr, and Fe while in GD 133, O, Si, Ca, and marginally Mg are seen. These two extrasolar planetesim…
The Lyman Alpha Reference Sample. II. Hubble Space Telescope Imaging Results, Integrated Properties, and Trends
Verhamme, Anne; Cannon, John M.; Hayes, Matthew +16 more
We report new results regarding the Lyα output of galaxies, derived from the Lyman Alpha Reference Sample, and focused on Hubble Space Telescope imaging. For 14 galaxies we present intensity images in Lyα, Hα, and UV, and maps of Hα/Hβ, Lyα equivalent width (EW), and Lyα/Hα. We present Lyα and UV radial light profiles and show they are well-fitted…