Search Publications
The H I Content of E+A Galaxies
Dejonghe, H.; Pisano, D. J.; Freeman, K. +3 more
We present deep single-dish H I observations of a sample of six nearby E+A galaxies (0.05<z<0.1). A nonnegligible fraction of a local sample of E+As are detected in H I. In four galaxies, we have detected up to a few times 109 Msolar of neutral gas. These E+A galaxies are almost as gas-rich as spiral galaxies with compa…
Density Diagnostics of the Hot Plasma in AE Aquarii with XMM-Newton
Ishida, Manabu; Kunieda, Hideyo; Okada, Shunsaku +1 more
We report on XMM-Newton observations of the magnetic CV AE Aqr. High-resolution spectroscopy of the He-like triplet of N and O with the RGS has enabled us to measure the electron number density of the plasma as ~1011 cm-3. Incorporating this with the emission measure, we estimate the geometrical scale of the plasma emitting t…
A Time-dependent Leptonic Model for Microquasar Jets: Application to LS I +61 303
Gupta, S.; Böttcher, M.
The Galactic high-mass X-ray binary and jet source (microquasar) LS I +61 303 has recently been detected at TeV γ-ray energies by the MAGIC telescope. We have applied a time-dependent leptonic jet model to the broadband spectral energy distribution (SED), and we have suggested (although not unambiguously detected) an orbital modulation of the very…
Ultraviolet-bright, High-Redshift Ultraluminous Infrared Galaxies
Woodgate, Bruce; Teplitz, Harry; Williger, Gerard M. +3 more
We present Spitzer Space Telescope observations of the z=2.38 Lyα emitter overdensity associated with galaxy cluster J2143-4423, the largest known structure (110 Mpc) above z=2. We imaged 22 of the 37 known Lyα emitters within the filament-like structure, using the MIPS 24 µm band. We detected six of the Lyα emitters, including three of the …
The Latitudinal Excursion of Coronal Magnetic Field Lines in Response to Differential Rotation: MHD Simulations
Riley, Pete; Linker, Jon A.; Mikić, Zoran +1 more
Solar energetic particles, which are believed to originate from corotating interacting regions (CIRs) at low heliographic latitude, were observed by the Ulysses spacecraft even as it passed over the Sun's poles. One interpretation of this result is that high-latitude field lines intercepted by Ulysses connect to low-latitude CIRs at much larger he…
Solar Convection Zone Dynamics: How Sensitive Are Inversions to Subtle Dynamo Features?
Thompson, M. J.; Howe, R.; Komm, R. +5 more
The nearly 10 year span of medium-degree helioseismic data from the Global Oscillation Network Group and the Michelson Doppler Imager has allowed us to study the evolving flows in the solar convection zone over most of solar cycle 23. Using two independent two-dimensional rotation inversion techniques and extensive studies of the resolution using …
The Rate of Emergence of Magnetic Dipoles in Coronal Holes and Adjacent Quiet-Sun Regions
Abramenko, V. I.; Yurchyshyn, V. B.; Fisk, L. A.
Observations from the Michelson Doppler Imager and the EUV Imaging Telescope on the Solar and Heliospheric Observatory are analyzed to determine the rate of emergence of new magnetic flux in coronal holes and in surrounding regions on the quiet Sun. Coronal holes are regions where the open magnetic flux of the Sun, the component that forms the hel…
Analysis and Interpretation of Hard X-Ray Emission from the Bullet Cluster (1ES 0657-558), the Most Distant Cluster of Galaxies Observed by RXTE
Madejski, Greg; Petrosian, Vahé; Luli, Kevin
Evidence for nonthermal activity in clusters of galaxies is well established from radio observations of synchrotron emission by relativistic electrons. New windows in the extreme-ultraviolet and hard X-ray ranges have provided more powerful tools for the investigation of this phenomenon. Detections of hard X-rays in the 20-100 keV range have been …
A Spitzer IRAC Search for Substellar Companions of the Debris Disk Star ɛ Eridani
Stapelfeldt, K. R.; Fazio, G. G.; Marengo, M. +3 more
We have used the Infrared Array Camera (IRAC) on board the Spitzer Space Telescope to search for low-mass companions of the nearby debris disk star ɛ Eri. The star was observed in two epochs 39 days apart, with different focal plane rotation to allow the subtraction of the instrumental point-spread function, achieving a maximum sensitivity of 0.01…
The Araucaria Project: The Distance to NGC 300 from the Red Giant Branch Tip Using HST ACS Imaging
Bresolin, Fabio; Kudritzki, Rolf-Peter; Gieren, Wolfgang +2 more
We have used the Advanced Camera for Surveys on board the Hubble Space Telescope to obtain deep photometry of the NGC 300 spiral galaxy in the Sculptor group. The results have been used to derive an accurate distance determination based on the tip of the red giant branch distance estimator. Both edge-detection and maximum likelihood methods have b…