Search Publications
A Precise Cluster Mass Profile Averaged from the Highest-quality Lensing Data
Broadhurst, Tom; Zitrin, Adi; Coe, Dan +3 more
We outline our methods for obtaining high-precision mass profiles, combining independent weak-lensing distortion, magnification, and strong-lensing measurements. For massive clusters, the strong- and weak-lensing regimes contribute equal logarithmic coverage of the radial profile. The utility of high-quality data is limited by the cosmic noise fro…
The First Detection of Blue Straggler Stars in the Milky Way Bulge
Brown, Thomas M.; Anderson, Jay; Livio, Mario +8 more
We report the first detections of Blue Straggler Stars (BSS) in the bulge of the Milky Way. Proper motions from extensive space-based observations along a single sight line allow us to separate a sufficiently clean and well-characterized bulge sample such that we are able to detect a small population of bulge objects in the region of the color-mag…
The Strength and Radial Profile of the Coronal Magnetic Field from the Standoff Distance of a Coronal Mass Ejection-driven Shock
Gopalswamy, Nat; Yashiro, Seiji
We determine the coronal magnetic field strength in the heliocentric distance range 6-23 solar radii (Rs) by measuring the shock standoff distance and the radius of curvature of the flux rope during the 2008 March 25 coronal mass ejection imaged by white-light coronagraphs. Assuming the adiabatic index, we determine the Alfvén Mach number, and hen…
First Results from the 3D-HST Survey: The Striking Diversity of Massive Galaxies at z > 1
Schmidt, Kasper B.; van Dokkum, Pieter G.; Franx, Marijn +26 more
We present first results from the 3D-HST program, a near-IR spectroscopic survey performed with the Wide Field Camera 3 (WFC3) on the HST. We have used 3D-HST spectra to measure redshifts and Hα equivalent widths (EWHα) for a complete, stellar mass-limited sample of 34 galaxies at 1 < z < 1.5 with M star > 1011<…
Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State
Pottschmidt, Katja; Wilms, Jörn; Tramper, Frank +7 more
Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states." Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source pa…
Herschel Measurements of Molecular Oxygen in Orion
Caselli, Paola; Li, Di; Viti, Serena +32 more
We report observations of three rotational transitions of molecular oxygen (O2) in emission from the H2 Peak 1 position of vibrationally excited molecular hydrogen in Orion. We observed the 487 GHz, 774 GHz, and 1121 GHz lines using the Heterodyne Instrument for the Far Infrared on the Herschel Space Observatory, having veloc…
Secular Evolution and a Non-evolving Black-hole-to-galaxy Mass Ratio in the Last 7 Gyr
Koekemoer, Anton M.; Trump, Jonathan R.; Jahnke, Knud +6 more
We present new constraints on the ratio of black hole (BH) mass to total galaxy stellar mass at 0.3 < z < 0.9 for a sample of 32 type-1 active galactic nuclei (AGNs) from the XMM-COSMOS survey covering the range M BH ~ 107.2 - 8.7 M sun. Virial M BH estimates based on Hβ are available from the COSM…
Numerical Investigation of a Coronal Mass Ejection from an Anemone Active Region: Reconnection and Deflection of the 2005 August 22 Eruption
Gombosi, T. I.; Shibata, K.; Lugaz, N. +3 more
We present a numerical investigation of the coronal evolution of a coronal mass ejection (CME) on 2005 August 22 using a three-dimensional thermodynamic magnetohydrodynamic model, the space weather modeling framework. The source region of the eruption was anemone active region (AR) 10798, which emerged inside a coronal hole. We validate our modele…
Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model
Winebarger, Amy R.; Warren, Harry P.; Kashyap, Vinay L. +2 more
The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that heating events occur rapidly enough to keep high-temperature active region loops close to equilibrium. In this …
Connection Between the Accretion Disk and Jet in the Radio Galaxy 3C 111
Rothschild, Richard E.; McHardy, Ian M.; Rivers, Elizabeth +13 more
We present the results of extensive multi-frequency monitoring of the radio galaxy 3C 111 between 2004 and 2010 at X-ray (2.4-10 keV), optical (R band), and radio (14.5, 37, and 230 GHz) wave bands, as well as multi-epoch imaging with the Very Long Baseline Array (VLBA) at 43 GHz. Over the six years of observation, significant dips in the X-ray li…