Search Publications
Modeling the Dispersal of an Active Region: Quantifying Energy Input into the Corona
Green, L. M.; Mackay, Duncan H.; van Ballegooijen, Aad
In this paper, a new technique for modeling nonlinear force-free fields directly from line-of-sight magnetogram observations is presented. The technique uses sequences of magnetograms directly as lower boundary conditions to drive the evolution of coronal magnetic fields between successive force-free equilibria over long periods of time. It is ill…
The Supernova Impostor Impostor SN 1961V: Spitzer Shows That Zwicky Was Right (Again)
Kochanek, C. S.; Stanek, K. Z.; Szczygiel, D. M.
SN 1961V, one of Zwicky's defining Type V supernovae (SNe), was a peculiar transient in NGC 1058 that has variously been categorized as either a true core-collapse SN leaving a black hole (BH) or neutron star (NS) remnant, or an eruption of a luminous blue variable star. The former case is suggested by its possible association with a decaying non-…
The Effect of Environment on Shear in Strong Gravitational Lenses
Zabludoff, Ann I.; Keeton, Charles R.; Momcheva, Ivelina G. +2 more
Using new photometric and spectroscopic data in the fields of nine strong gravitational lenses that lie in galaxy groups, we analyze the effects of both the local group environment and line-of-sight (LOS) galaxies on the lens potential. We use Monte Carlo simulations to derive the shear directly from measurements of the complex lens environment, p…
L1157-B1: Water and Ammonia as Diagnostics of Shock Temperature
Codella, C.; Ceccarelli, C.; Caselli, P. +5 more
We investigate the origin and nature of the profiles of water and ammonia observed toward the L1157-B1 clump as part of the HIFI CHESS survey using a new code coupling a gas-grain chemical model with a parametric shock model. First results from the unbiased survey reveal different molecular components at different excitation conditions coexisting …
The Cluster Lensing and Supernova Survey with Hubble (CLASH): Strong-lensing Analysis of A383 from 16-band HST/WFC3/ACS Imaging
Infante, L.; Zheng, W.; Molino, A. +38 more
We examine the inner mass distribution of the relaxed galaxy cluster A383 (z = 0.189), in deep 16 band Hubble Space Telescope/ACS+WFC3 imaging taken as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) multi-cycle treasury program. Our program is designed to study the dark matter distribution in 25 massive clusters, and balances…
Active and Passive Galaxies at z ~ 2: Rest-frame Optical Morphologies with WFC3
Trenti, M.; Oesch, P. A.; Carollo, C. M. +5 more
We use the high angular resolution in the near-infrared of the Wide Field Camera 3 (WFC3) on the Hubble Space Telescope to determine YHVz color-color-selection criteria to identify and characterize 1.5 < z < 3.5 galaxies in the Hubble Ultra Deep Field 2009 (HUDF09) and Early Release Science (GOODS-South) fields. The WFC3 NIR images reveal ga…
The Sun's Small-scale Magnetic Elements in Solar Cycle 23
Zhao, H.; Wang, J. X.; Jin, C. L. +1 more
With the unique database from the Michelson Doppler Imager on board the Solar and Heliospheric Observatory in an interval embodying solar cycle 23, the cyclic behavior of solar small-scale magnetic elements is studied. More than 13 million small-scale magnetic elements are selected, and the following results are found. (1) The quiet regions domina…
Star Formation Efficiency in the Cool Cores of Galaxy Clusters
Veilleux, Sylvain; Rupke, David S. N.; Mushotzky, Richard +2 more
We have assembled a sample of high spatial resolution far-UV (Hubble Space Telescope Advanced Camera for Surveys/Solar Blind Channel) and Hα (Maryland-Magellan Tunable Filter) imaging for 15 cool core galaxy clusters. These data provide a detailed view of the thin, extended filaments in the cores of these clusters. Based on the ratio of the far-UV…
Imaging the Molecular Gas Properties of a Major Merger Driving the Evolution of a z = 2.5 Submillimeter Galaxy
Walter, Fabian; Hodge, Jacqueline; Riechers, Dominik A. +6 more
We report the detection of spatially extended CO(J = 1→0) and CO(J = 5→4) emission in the z = 2.49 submillimeter galaxy (SMG) J123707+6214, using the Expanded Very Large Array and the Plateau de Bure Interferometer. The large molecular gas reservoir is spatially resolved into two CO(J = 1→0) components (northeast and southwest; previously identifi…
A Census of Baryons and Dark Matter in an Isolated, Milky Way Sized Elliptical Galaxy
Fabian, Andrew C.; Canizares, Claude R.; Humphrey, Philip J. +2 more
We present a study of the dark and luminous matter in the isolated elliptical galaxy NGC 720, based on deep X-ray observations made with the Chandra and Suzaku observatories. The gas properties are reliably measured almost to R 2500, allowing us to place good constraints on the enclosed mass and baryon fraction (fb ) within t…