Search Publications
Discovery of a Highly Energetic X-Ray Pulsar Powering HESS J1813-178 in the Young Supernova Remnant G12.82-0.02
Gotthelf, E. V.; Halpern, J. P.
We report the discovery of 44.7 ms pulsations from the X-ray source CXOU J181335.1-174957 using data obtained with the XMM-Newton Observatory. PSR J1813-1749 lies near the center of the young radio supernova remnant G12.82-0.02, which overlaps the compact TeV source HESS J1813-178. This rotation-powered pulsar is the second most energetic in the G…
Spitzer 24 µm Detections of Starburst Galaxies in Abell 851
Fritz, Jacopo; Dressler, Alan; Rieke, George +4 more
Spitzer-MIPS 24 µm observations and ground-based optical imaging and spectroscopy of the rich galaxy cluster Abell 851 at z = 0.41 are used to derive and compare star formation rates from the mid-IR 24 µm and from [O II] λλ3727 emission. Many cluster galaxies have star formation rates SFR(24µm)/SFR([O II]) Gt 1, indicative of sta…
The Ellipticities of Cluster Early-type Galaxies from z ~ 1 to z ~ 0: No Evolution in the Overall Distribution of Bulge-to-Disk Ratios
Kelson, D. D.; Demarco, R.; van der Wel, A. +7 more
We have compiled a sample of early-type cluster galaxies from 0 < z < 1.3 and measured the evolution of their ellipticity distributions. Our sample contains 487 galaxies in 17 z>0.3 clusters with high-quality space-based imaging and a comparable sample of 210 galaxies in 10 clusters at z < 0.05. We select early-type galaxies (elliptica…
Explosive Events Associated with a Surge
Doyle, J. G.; Madjarska, M. S.; de Pontieu, B.
The solar atmosphere contains a wide variety of small-scale transient features. Here, we explore the interrelation between some of them such as surges, explosive events, and blinkers via simultaneous spectral and imaging data taken with the TRACE imager, the SUMER and Coronal Diagnostics Spectrometer (CDS) on board SOHO, and Swedish Vacuum Solar T…
The ~0.9 mJy Sample: A Mid-Infrared Spectroscopic Catalog of 150 Infrared-Luminous, 24 µm Selected Galaxies at 0.3 <= z <= 3.5
Fadda, Dario; Armus, Lee; Helou, George +6 more
We present a catalog of mid-infrared (MIR) spectra of 150 infrared (IR) luminous galaxies in the Spitzer extragalactic first look survey obtained with the IR spectrograph on board the Spitzer Space Telescope. The sample is selected to be brighter than ~0.9 mJy at 24 µm and it has a redshift distribution in the range [0.3, 3.5], with a peak a…
MMTF-Hα and HST-FUV Imaging of the Filamentary Complex in ABELL 1795
Veilleux, Sylvain; McDonald, Michael
We have obtained deep, high spatial resolution images of the central region of Abell 1795 at Hα and [N II] λ6583 with the Maryland-Magellan Tunable Filter (MMTF), and in the far-ultraviolet (FUV) with the Advanced Camera for Surveys solar blind channel on the Hubble Space Telescope (HST). The superb image quality of the MMTF data has made it possi…
Numerical Models of Travel-Time Inhomogeneities in Sunspots
Moradi, H.; Hanasoge, S. M.; Cally, P. S.
We investigate the direct contribution of strong, sunspot-like magnetic fields to helioseismic wave travel-time shifts via two numerical forward models, a three-dimensional ideal MHD solver and MHD ray theory. The simulated data cubes are analyzed using the traditional time-distance center-to-annulus measurement technique. We also isolate and anal…
Detection of a Companion Lens Galaxy Using the Mid-Infrared Flux Ratios of the Gravitationally Lensed Quasar H1413+117
Kochanek, Christopher S.; Agol, Eric; MacLeod, Chelsea L.
We present the first resolved mid-infrared (IR) (11 µm) observations of the four-image quasar lens H1413+117 using the Michelle camera on Gemini North. All previous observations (optical, near-IR, and radio) of this lens show a "flux anomaly," where the image flux ratios cannot be explained by a simple, central lens galaxy. We attempt to rep…
Suzaku Observation of the New Soft Gamma Repeater SGR 0501+4516 in Outburst
Sakamoto, T.; Tiengo, A.; Hurley, K. +17 more
We present the first Suzaku observation of the new Soft Gamma Repeater, SGR 0501+4516, performed on 2008 August 26, four days after the onset of bursting activity of this new member of the magnetar family. The soft X-ray persistent emission was detected with the X-ray Imaging Spectrometer (XIS) at a 0.5-10 keV flux of 3.8 × 10-11 erg s<…
On the Absence of Photospheric Net Currents in Vector Magnetograms of Sunspots Obtained from Hinode (Solar Optical Telescope/Spectro-Polarimeter)
Tiwari, Sanjiv Kumar; Venkatakrishnan, P.
Various theoretical and observational results have been reported regarding the presence/absence of net electric currents in the sunspots. The limited spatial resolution of the earlier observations perhaps obscured the conclusions. We have analyzed 12 sunspots observed from Hinode (Solar Optical Telescope/Spectro-polarimeter) to clarify the issue. …