Search Publications
Photometric Redshift Calibration Requirements for WFIRST Weak-lensing Cosmology: Predictions from CANDELS
Mobasher, Bahram; Rhodes, Jason; Capak, Peter +7 more
In order for the Wide-Field Infrared Survey Telescope (WFIRST) and other stage IV dark energy experiments (e.g., Large Synoptic Survey Telescope, LSST; and Euclid) to infer cosmological parameters not limited by systematic errors, accurate redshift measurements are needed. This accuracy can be met by using spectroscopic subsamples to calibrate the…
The Super Eight Galaxies: Properties of a Sample of Very Bright Galaxies at 7 < z < 8
Holwerda, Benne W.; Illingworth, Garth D.; Bouwens, Rychard J. +12 more
We present the Super Eight galaxies—a set of very luminous, high-redshift (7.1 < z < 8.0) galaxy candidates found in the Brightest of Reionizing Galaxies (BoRG) Survey fields. The original sample includes eight galaxies that are Y-band dropout objects with H-band magnitudes of m H < 25.5. Four of these objects were originally…
Can an Unobserved Concentration of Magnetic Flux Above the Poles of the Sun Resolve the Open Flux Problem?
Downs, Cooper; Riley, Pete; Linker, Jon A. +3 more
Global models of the extended solar corona, driven by observed photospheric magnetic fields, generally cannot reproduce the amplitude of the measured interplanetary magnetic field at 1 au (or elsewhere in the heliosphere), often underestimating it by a factor of two or more. Some modelers have attempted to resolve this “open flux” problem by adjus…
Particle-in-cell Simulations of Firehose Instability Driven by Bi-Kappa Electrons
Lazar, M.; Poedts, S.; Viñas, A. F. +4 more
We report the first results from particle-in-cell simulations of the fast-growing aperiodic electron firehose instability driven by the anisotropic bi-Kappa distributed electrons. Such electrons characterize space plasmas, e.g., solar wind and planetary magnetospheres. Predictions made by the linear theory for full wave-frequency and wave-vector s…
Cold Giant Planets Evaporated by Hot White Dwarfs
Gänsicke, Boris T.; Schreiber, Matthias R.; Toloza, Odette +2 more
Atmospheric escape from close-in Neptunes and hot Jupiters around Sun-like stars driven by extreme ultraviolet (EUV) irradiation plays an important role in the evolution of exoplanets and in shaping their ensemble properties. Intermediate and low mass stars are brightest at EUV wavelengths at the very end of their lives, after they have expelled t…
Modeling Mg II h, k and Triplet Lines at Solar Flare Ribbons
Kowalski, Adam F.; Carlsson, Mats; Tian, Hui +3 more
Observations from the Interface Region Imaging Spectrograph often reveal significantly broadened and non-reversed profiles of the Mg II h, k and triplet lines at flare ribbons. To understand the formation of these optically thick Mg II lines, we perform plane-parallel radiative hydrodynamics modeling with the RADYN code, and then recalculate the M…
A Momentum-conserving Accretion Disk Wind in the Narrow-line Seyfert 1 I Zwicky 1
Reeves, J. N.; Braito, V.
I Zwicky 1 (hereafter I Zw 1) is the prototype optical narrow-line Seyfert 1 galaxy. It is also a nearby (z = 0.0611), luminous quasi-stellar object (QSO), accreting close to the Eddington limit. XMM-Newton observations of I Zw 1 in 2015 reveal the presence of a broad and blueshifted P Cygni iron K profile, as observed through a blueshifted absorp…
The XMM-Newton/HST View of the Obscuring Outflow in the Seyfert Galaxy Mrk 335 Observed at Extremely Low X-Ray Flux
Komossa, S.; Mathur, Smita; Krongold, Yair +8 more
The Seyfert galaxy Mrk 335 is known for its frequent changes of flux and spectral shape in the X-ray band that occurred during recent years. These variations may be explained by the onset of a wind that previous, noncontemporaneous high-resolution spectroscopy in X-ray and UV bands located at accretion disk scale. A simultaneous new campaign by XM…
The Physical Origins of the Identified and Still Missing Components of the Warm-Hot Intergalactic Medium: Insights from Deep Surveys in the Field of Blazar 1ES1553+113
Johnson, Sean D.; Drout, Maria R.; Chen, Hsiao-Wen +11 more
The relationship between galaxies and the state/chemical enrichment of the warm-hot intergalactic medium (WHIM) expected to dominate the baryon budget at low-z provides sensitive constraints on structure formation and galaxy evolution models. We present a deep redshift survey in the field of 1ES1553+113, a blazar with a unique combination of ultra…
Precise Ages of Field Stars from White Dwarf Companions
Tian, Haijun; Rix, Hans-Walter; Fouesneau, Morgan +2 more
Observational tests of stellar and Galactic chemical evolution call for the joint knowledge of a star’s physical parameters, detailed element abundances, and precise age. For cool main-sequence (MS) stars the abundances of many elements can be measured from spectroscopy, but ages are very hard to determine. The situation is different if the MS sta…