Search Publications
The Mass Assembly History of Spheroidal Galaxies: Did Newly Formed Systems Arise via Major Mergers?
Treu, Tommaso; Ellis, Richard S.; Bundy, Kevin
We examine the properties of a morphologically selected sample of 0.4<z<1.0 spheroidal galaxies in the GOODS fields in order to ascertain whether or not their increase in abundance with time arises primarily from major mergers. To address this question, we determine the scaling relations between the dynamical mass Mdyn, determined…
The AU Microscopii Debris Disk: Multiwavelength Imaging and Modeling
Duchêne, Gaspard; Fitzgerald, Michael P.; Graham, James R. +2 more
Debris disks around main-sequence stars are produced by the destruction of unseen parent bodies. AU Microscopii (GJ 803) is a compelling object to study in the context of disk evolution across different spectral types, as it is an M dwarf whose nearly edge-on disk may be directly compared to that of its A5 V sibling β Pic. We resolve the disk from…
Evolution of Dust and Ice Features around FU Orionis Objects
Quanz, S. P.; Henning, Th.; van Boekel, R. +5 more
We present spectra for a sample of 14 FUors and two T Tauri stars observed with Spitzer or ISO. Based on the appearance of the 10 µm silicate feature, we define two categories of FUors. Objects showing the silicate feature in absorption (Category 1) are still embedded in a circumstellar envelope. The shape of the silicate bands is in good ag…
``Bursty'' Reconnection Following Solar Eruptions: MHD Simulations and Comparison with Observations
Lin, Jun; Riley, Pete; Mikić, Zoran +4 more
Posteruptive arcades are frequently seen in the aftermath of coronal mass ejections (CMEs). The formation of these loops at successively higher altitudes, coupled with the classic ``two-ribbon'' flare seen in Hα, are interpreted as reconnection of the coronal magnetic field that has been dragged outward by the CME. White-light observations of ``ra…
VLA and XMM-Newton Observations of the SNR W41/TeV Gamma-Ray Source HESS J1834-087
Wang, Q. D.; Leahy, D. A.; Li, Z. +1 more
The recently discovered extended TeV source HESS J1834-087 is associated with both a diffuse X-ray enhancement and a molecular cloud, projected at the center of an old radio supernova remnant, G23.3-0.3 (SNR W41). New H I observations from the VLA Galactic Plane Survey (VGPS) show unambiguous structures associated with W41 in the radial velocity r…
Why Do Some Intermediate Polars Show Soft X-Ray Emission? A Survey of XMM-Newton Spectra
Hellier, Coel; Evans, P. A.
We make a systematic analysis of the XMM-Newton X-ray spectra of intermediate polars (IPs) and find that, contrary to the traditional picture, most show a soft blackbody component. We compare the results with those from AM Her stars and deduce that the blackbody emission arises from reprocessing of hard X-rays, rather than from the blobby accretio…
First Stereoscopic Coronal Loop Reconstructions from STEREO SECCHI Images
Solanki, S. K.; Feng, L.; Inhester, B. +4 more
We present the first reconstruction of the three-dimensional shape of magnetic loops in an active region from two different vantage points based on simultaneously recorded images. The images were taken by the two EUVI telescopes of the SECCHI instrument on board the recently launched STEREO spacecraft when the heliocentric separation of the two sp…
The ERO Host Galaxy of GRB 020127: Implications for the Metallicity of GRB Progenitors
Berger, E.; Djorgovski, S. G.; Frail, D. A. +2 more
We present optical and near-IR observations of the host galaxy of GRB 020127, for which we measure R-Ks=6.2 mag. This is only the second GRB host to date classified as an ERO. The spectral energy distribution (SED) is typical of a dusty starburst galaxy, with a redshift z~1.9, a luminosity L~5L*, and an inferred stellar mass of M*<…
Effects of Downscattering on the Continuum and Line Spectra in a Powerful Wind Environment: Monte Carlo Simulations, Analytical Results, and Data Analysis
Laurent, Philippe; Titarchuk, Lev
In an earlier paper, the general formulation and results for photon reprocessing (downscattering) that included recoil and Comptonization effects due to divergence of the flow were presented. In a second paper we showed the Monte Carlo (MC) simulated continuum and line spectra. We also provided an analytical description of the simulated continuum …
Galactic Bulges from Hubble Space Telescope NICMOS Observations: Global Scaling Relations
Balcells, Marc; Graham, Alister W.; Peletier, Reynier F.
We investigate bulge and disk scaling relations using a volume-corrected sample of early- to intermediate-type disk galaxies in which, importantly, the biasing flux from additional nuclear components has been modeled and removed. Structural parameters are obtained from a seeing-convolved, bulge + disk + nuclear-component decomposition applied to n…