Search Publications
Empirical Reconstruction and Numerical Modeling of the First Geoeffective Coronal Mass Ejection of Solar Cycle 24
Howard, R. A.; Rouillard, A. P.; Wood, B. E. +2 more
We analyze the kinematics and morphology of a coronal mass ejection (CME) from 2010 April 3, which was responsible for the first significant geomagnetic storm of solar cycle 24. The analysis utilizes coronagraphic and heliospheric images from the two STEREO spacecraft, and coronagraphic images from SOHO/LASCO. Using an empirical three-dimensional …
A Compton-thick Active Galactic Nucleus at z ~ 5 in the 4 Ms Chandra Deep Field South
Ptak, A.; Brandt, W. N.; Fiore, F. +13 more
We report the discovery of a Compton-thick active galactic nucleus (AGN) at z = 4.76 in the 4 Ms Chandra Deep Field South. This object was selected as a V-band dropout in HST/ACS images and previously recognized as an AGN from optical spectroscopy. The 4 Ms Chandra observations show a significant (~4.2σ) X-ray detection at the V-band dropout posit…
X-ray Emission from Two Infrared-selected Galaxy Clusters at z > 1.4 in the IRAC Shallow Cluster Survey
Stern, D.; Vikhlinin, A.; Dey, A. +17 more
We report the X-ray detection of two z > 1.4 infrared-selected galaxy clusters from the IRAC Shallow Cluster Survey (ISCS). We present new data from the Hubble Space Telescope and the W. M. Keck Observatory that spectroscopically confirm cluster ISCS J1432.4+3250 at z = 1.49, the most distant of 18 confirmed z > 1 clusters in the ISCS to dat…
Temperature Distribution of a Non-flaring Active Region from Simultaneous Hinode XRT and EIS Observations
DeLuca, Edward E.; Landi, Enrico; Testa, Paola +2 more
We analyze coordinated Hinode X-ray Telescope (XRT) and Extreme Ultraviolet Imaging Spectrometer (EIS) observations of a non-flaring active region to investigate the thermal properties of coronal plasma taking advantage of the complementary diagnostics provided by the two instruments. In particular, we want to explore the presence of hot plasma in…
Plasma Heating During a Coronal Mass Ejection Observed By the Solar and Heliospheric Observatory
Raymond, J. C.; Korreck, K. E.; Murphy, N. A.
We perform a time-dependent ionization analysis to constrain plasma heating requirements during a fast partial halo coronal mass ejection (CME) observed on 2000 June 28 by the Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and Heliospheric Observatory (SOHO). We use two methods to derive densities from the UVCS measurements, includin…
New Optical/Ultraviolet Counterparts and the Spectral Energy Distributions of Nearby, Thermally Emitting, Isolated Neutron Stars
van Kerkwijk, M. H.; Kaplan, D. L.; Ho, W. C. G. +1 more
We present Hubble Space Telescope optical and ultraviolet photometry for five nearby, thermally emitting neutron stars. With these measurements, all seven such objects have confirmed optical and ultraviolet counterparts. Combining our data with archival space-based photometry, we present spectral energy distributions for all sources and measure th…
X-Ray Spectral Constraints for z ≈ 2 Massive Galaxies: The Identification of Reflection-dominated Active Galactic Nuclei
Daddi, E.; Lehmer, B. D.; Alexander, D. M. +18 more
We use the 4 Ms Chandra Deep Field-South (CDF-S) survey to place direct constraints on the ubiquity of z ≈ 2 heavily obscured active galactic nuclei (AGNs) in K < 22 BzK-selected galaxies. Forty-seven (≈21%) of the 222 BzK-selected galaxies in the central region of the CDF-S are detected at X-ray energies, 11 (≈5%) of which have hard X-ray spec…
XMM-Newton X-ray and Ultraviolet Observations of the Fast Nova V2491 Cyg during the Supersoft Source Phase
Ness, J. -U.; Hernanz, M.; Sala, G. +12 more
Two XMM-Newton observations of the fast classical nova V2491 Cyg were carried out in short succession on days 39.93 and 49.62 after discovery, during the supersoft source (SSS) phase, yielding simultaneous X-ray and UV light curves and high-resolution X-ray spectra. The first X-ray light curve is highly variable, showing oscillations with a period…
X-Ray Spectroscopy of the High-mass X-Ray Binary Pulsar Centaurus X-3 over Its Binary Orbit
Paul, Biswajit; Naik, Sachindra; Ali, Zulfikar
We present a comprehensive spectral analysis of the high-mass X-ray binary (HMXB) pulsar Centaurus X-3 with the Suzaku observatory covering nearly one orbital period. The light curve shows the presence of extended dips which are rarely seen in HMXBs. These dips are seen up to as high as ~40 keV. The pulsar spectra during the eclipse, out-of-eclips…
A CANDELS WFC3 Grism Study of Emission-line Galaxies at z ~ 2: A Mix of Nuclear Activity and Low-metallicity Star Formation
Finkelstein, Steven L.; Bell, Eric F.; Dickinson, Mark +26 more
We present Hubble Space Telescope Wide Field Camera 3 (WFC3) slitless grism spectroscopy of 28 emission-line galaxies at z ~ 2, in the GOODS-S region of the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey. The high sensitivity of these grism observations, with >1σ detections of emission lines to f > 2.5 × 10-18 erg …