Search Publications
The First Two Host Galaxies of X-Ray Flashes: XRF 011030 and XRF 020427
Berger, E.; Bloom, J. S.; Djorgovski, S. G. +4 more
Given the paucity of empirical constraints, the nature of the newly recognized phenomena called X-ray flashes (XRFs) has been an open question. However, with the recent detections of radio and X-ray afterglow it is finally possible to study the large- and small-scale environments of XRFs. We present Chandra, Hubble Space Telescope (HST), and Keck …
The Multiphase Absorption Systems toward PG 1206+459
Charlton, Jane C.; Churchill, Christopher W.; Palma, Christopher +1 more
A high-resolution (R=30,000) ultraviolet spectrum is presented, which covers Lyα and many low-, intermediate-, and high-ionization transitions in the three Mg II-selected absorption systems toward the quasar PG 1206+459. Three systems (A, B, and C), which are clustered within 1500 km s-1 at z~0.93, were originally identified in a spectr…
On the Size Difference between Red and Blue Globular Clusters
Brodie, Jean P.; Larsen, Søren S.
Several recent studies have reported a mean size difference of about 20% between the metal-rich and metal-poor subpopulations of globular clusters (GCs) in a variety of galaxies. In this paper, we investigate the possibility that the size difference might be a projection effect, resulting from a correlation between cluster size and galactocentric …
The Stellar Content of Henize 2-10 from Space Telescope Imaging Spectrograph Ultraviolet Spectroscopy
Calzetti, Daniela; Leitherer, Claus; Chandar, Rupali +1 more
We use new Space Telescope Imaging Spectrograph long-slit ultraviolet spectroscopy of region A in the nearby starbursting galaxy He 2-10 to examine properties of both compact individual super-star clusters and diffuse intracluster regions. The four most luminous clusters in our slit formed coevally 4-5 Myr ago and have lower mass estimates of seve…
An XMM-Newton Observation of 4U 1755-33 in Quiescence: Evidence of a Fossil X-Ray Jet
White, Nicholas E.; Angelini, Lorella
We report an XMM-Newton observation of the low-mass X-ray binary and black hole candidate 4U 1755-33. This source had been a bright persistent source for at least 25 yr, but in 1995 it entered an extended quiescent phase. 4U 1755-33 was not detected with an upper limit to the 2-10 keV luminosity of 3.6×1031d24kpc e…
A Turbulent Origin for Flocculent Spiral Structure in Galaxies. II. Observations and Models of M33
Cuillandre, Jean-Charles; Elmegreen, Bruce G.; Elmegreen, Debra Meloy +1 more
Fourier transform power spectra of azimuthal scans of the optical structure of M33 are evaluated for B, V, and R passbands and fitted to fractal models of continuum emission with superposed star formation. Power spectra are also determined for Hα. The best models have intrinsic power spectra with one-dimensional slopes of around -0.7+/-0.7, signif…
Chandra and XMM Observations of the Accretion Disk Corona Source 2S 0921-63
Kallman, T. R.; Angelini, L.; Boroson, B. +1 more
We analyze observations of the low-mass X-ray binary (LMXB) 2S 0921-63 obtained with the gratings and CCDs on Chandra and XMM. This object is a high-inclination system showing evidence for an accretion disk corona (ADC). Such a corona has the potential to constrain the properties of the heated accretion disk in this system and other LMXBs by exten…
Optical Pulse-Phased Photopolarimetry of PSR B0656+14
Halpern, J. P.; Martin, C.; Kern, B. +1 more
We have observed the optical pulse profile of PSR B0656+14 in 10 phase bins at a high signal-to-noise ratio, and have measured the linear polarization profile over 30% of the pulsar period with some significance. The pulse profile is double-peaked, with a bridge of emission between the two peaks, similar to gamma-ray profiles observed in other pul…
Adaptive Optics Imaging and Spectroscopy of Cygnus A. I. Evidence for a Minor Merger
Canalizo, Gabriela; Dahm, Scott E.; Antonucci, Robert +2 more
We present Keck II adaptive optics near-infrared imaging and spectroscopic observations of the central regions of the powerful radio galaxy Cyg A. The 0.05" resolution images clearly show an unresolved nucleus between two spectacular ionization/scattering cones. We report the discovery of a relatively bright (K'~19) secondary point sour…
The Identification of Infrared Synchrotron Radiation from Cassiopeia A
Rudnick, L.; Jones, T. J.; DeLaney, T. +1 more
We report the discovery of polarized flux at 2.2 µm from the bright shell of the ~320 yr old supernova remnant Cas A. The fractional polarizations are comparable at 6 cm and 2.2 µm, and the polarization angles are similar, demonstrating that synchrotron radiation from the same relativistic plasma is being observed at these widely separ…