Search Publications
EUV Spectral Line Formation and the Temperature Structure of Active Region Fan Loops: Observations with Hinode/EIS and SDO/AIA
Warren, Harry P.; Young, Peter R.; Brooks, David H.
With the aim of studying active region fan loops using observations from the Hinode EUV Imaging Spectrometer (EIS) and Solar Dynamics Observatory Atmospheric Imaging Assembly (AIA), we investigate a number of inconsistencies in modeling the absolute intensities of Fe VIII and Si VII lines, and address why spectroheliograms formed from these lines …
Galactic-scale Absorption Outflow in the Low-luminosity Quasar IRAS F04250-5718: Hubble Space Telescope/Cosmic Origins Spectrograph Observations
Kriss, Gerard A.; Kaastra, Jelle; Behar, Ehud +17 more
We present absorption line analysis of the outflow in the quasar IRAS F04250-5718. Far-ultraviolet data from the Cosmic Origins Spectrograph on board the Hubble Space Telescope reveal intrinsic narrow absorption lines from high ionization ions (e.g., C IV, N V, and O VI) as well as low ionization ions (e.g., C II and Si III). We identify three kin…
Searching for the trigger of the active galactic nucleus quasi-periodic oscillation: 8 years of RE J1034+396
Done, Chris; Middleton, Matthew; Uttley, Phil
RE J1034+396 is one of the most extreme narrow-line type 1 Seyfert galaxies detected thus far, showing the only quasi-periodic oscillation (QPO) reliably detected in an active galactic nucleus (AGN). Comparison with similar spectral and timing properties observed in the black hole X-ray binary (BHB) GRS 1915+105 suggests that RE J1034+396 is a sup…
SWAP-SECCHI Observations of a Mass-loading Type Solar Eruption
Berghmans, David; Mierla, Marilena; Zhukov, Andrei N. +2 more
We present a three-dimensional reconstruction of an eruption that occurred on 2010 April 3 using observations from SWAP on board PROBA2 and SECCHI on board STEREO. The event unfolded in two parts: an initial flow of cooler material confined to a height low in the corona, followed by a flux rope eruption higher in the corona. We conclude that mass …
XMM-Newton/Sloan Digital Sky Survey: Star Formation Efficiency in Galaxy Clusters and Constraints on the Matter-density Parameter
Reiprich, Thomas H.; Schneider, Peter; Zhang, Yu-Ying +1 more
It is believed that the global baryon content of clusters of galaxies is representative of the matter distribution of the universe, and can, therefore, be used to reliably determine the matter-density parameter Ωm. This assumption is challenged by the growing evidence from optical and X-ray observations that the total baryon mass fracti…
X-Ray and Ultraviolet Emission from the Recurrent Nova RS Ophiuchi in Quiescence: Signatures of Accretion and Shocked Gas
Nelson, T.; Mukai, K.; Sokoloski, J. L. +2 more
RS Ophiuchi is a recurrent nova system that experiences outbursts every ~20 years, implying accretion at a high rate onto a massive white dwarf. However, previous X-ray observations of the system in quiescence have detected only faint emission that is difficult to reconcile with the high accretion rate (>2 × 10-8 M sun yr<…
Hubble Space Telescope Observations of Field Ultracool Dwarfs at High Galactic Latitude
Ryan, R. E.; Yan, L.; Fan, X. +8 more
We present a sample of 17 newly discovered ultracool dwarf candidates later than ~M8, drawn from 231.90 arcmin2 of Hubble Space Telescope Wide Field Camera 3 infrared imaging. By comparing the observed number counts for 17.5 <= J 125 <= 25.5 AB mag to an exponential disk model, we estimate a vertical scale height of z <…
Whistler turbulence forward cascade: Three-dimensional particle-in-cell simulations
Chang, Ouliang; Wang, Joseph; Peter Gary, S.
The first fully three-dimensional particle-in-cell (PIC) simulation of whistler turbulence in a magnetized, homogeneous, collisionless plasma has been carried out. An initial relatively isotropic spectrum of long-wavelength whistlers is imposed upon the system, with an initial electron β = 0.10. As in previous two-dimensional simulations of whistl…
The relationship between star formation rates, local density and stellar mass up to z ∼ 3 in the GOODS NICMOS Survey
Jogee, S.; Conselice, C. J.; Buitrago, F. +6 more
We investigate the relation between star formation rates and local galaxy environment for a stellar-mass-selected galaxy sample in the redshift range 1.5 ≤z≤ 3. We use near-infrared imaging from an extremely deep Hubble Space Telescope survey, the GOODS NICMOS Survey (GNS), to measure local galaxy densities based on the nearest neighbour approach,…
The Old Environment of the Faint Calcium-rich Supernova SN 2005cz
Leonard, Douglas C.; Neill, James D.; James, Phil A. +5 more
The supernova SN 2005cz has recently attracted some attention due to the fact that it was spectroscopically similar to type Ib supernovae (SNe Ib), a class that is presumed to result from the core collapse of massive stars, yet it occurred in an elliptical galaxy, where one expects very few massive stars to exist. Two explanations for this remarka…