Search Publications
Reconstruction of Cluster Masses Using Particle Based Lensing. I. Application to Weak Lensing
Goldberg, David M.; Deb, Sanghamitra; Ramdass, Vede J.
We present Particle Based Lensing (PBL), a new technique for gravitational lensing mass reconstructions of galaxy clusters. Traditionally, most methods have employed either a finite inversion or gridding to turn observational lensed galaxy ellipticities into an estimate of the surface mass density of a galaxy cluster. We approach the problem from …
New XMM-Newton Analysis of Three Bright X-Ray Sources in M31 Globular Clusters, Including a New Black Hole Candidate
Stiele, H.; Pietsch, W.; Haberl, F. +6 more
We present a detailed analysis of three globular cluster X-ray sources in the XMM-Newton extended survey of M31. The X-ray counterpart to the M31 globular cluster Bo 45 (XBo 45) was observed with XMM-Newton on 2006 December 26. Its combined pn+MOS 0.3-10 keV light curve was seen to vary by ~10%, and its 0.3-7.0 keV emission spectrum was well descr…
A Comparison of Weak-Lensing Measurements from Ground- and Space-Based Facilities
Ellis, Richard S.; Massey, Richard; Rhodes, Jason +2 more
We assess the relative merits of weak-lensing surveys, using overlapping imaging data from the ground-based Subaru telescope and the Hubble Space Telescope (HST). Our tests complement similar studies undertaken with simulated data. From observations of 230,000 matched objects in the 2 deg2 COSMOS field, we identify the limit at which fa…
The Host Galaxy and the Extended Emission-Line Region of the Radio Galaxy 3C 79
Fu, Hai; Stockton, Alan
We present extensive ground-based spectroscopy and HST imaging of 3C 79, an FR II radio galaxy associated with a luminous extended emission-line region (EELR). Surface brightness modeling of an emission-line-free HST R-band image reveals that the host galaxy is a massive elliptical with a compact companion 0.8'' away and 4 mag fainter. …
Galaxy Clusters in the IRAC Dark Field. I. Growth of the Red Sequence
Surace, J. A.; Yan, L.; Krick, J. E. +4 more
Using three newly identified galaxy clusters at z ~ 1 (photometric redshift) we measure the evolution of the galaxies within clusters from high redshift to the present day by studying the growth of the red cluster sequence. The clusters are located in the Spitzer Infrared Array Camera (IRAC) Dark Field, an extremely deep mid-infrared survey near t…
The Intermediate Polar EI UMa: A Prepolar Cataclysmic Variable
Mukai, Koji; Ringwald, F. A.; Welsh, William F. +1 more
We present optical and X-ray time series photometry of EI UMa that reveal modulation at 746 and 770 s, which we interpret as the white dwarf spin and spin-orbit sidebands. These detections, combined with previous X-ray studies, establish EI UMa as an intermediate polar. We estimate the mass accretion rate to be ~3.6 × 1017 g s-1
Modeling UX Ursae Majoris: An Abundance of Challenges
Szkody, Paula; Sion, Edward M.; Godon, Patrick +2 more
We present a system model for optical and far-UV spectra of the nova-like variable UX UMa involving a white dwarf, secondary star, gas stream, hot spot, and accretion disk using our code BINSYN and based on an initially adopted system distance. Calculated SED intensity data successfully fit successive tomographically extracted annuli longward of t…
Ultraviolet Observations of the X-Ray Photoionized Wind of Cygnus X-1 during X-Ray Soft/High State
Bolton, C. T.; Vrtilek, S. D.; Gies, D. +2 more
High-resolution ultraviolet observations of Cygnus X-1 were obtained at two epochs roughly 1 year apart using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope. Orbital phase ranges around phiorb = 0 and 0.5 were covered at each epoch, and the spectra show P Cygni line features from high (N V, C IV, Si IV) and absor…
The Chandra ACIS Survey of M33 (ChASeM33): Investigating the Hot Ionized Medium in NGC 604
Blair, William P.; Hughes, John P.; Ghavamian, Parviz +7 more
NGC 604 is the largest H II region in M33, second only within the Local Group to 30 Dor, and is important as a laboratory for understanding how massive young stellar clusters interact with the surrounding interstellar medium. Here we present deep (300 ks) X-ray imagery of NGC 604 obtained as part of the Chandra ACIS Survey of M33 (ChASeM33), which…
Comparison of Heliospheric In Situ Data with the Quasi-steady Solar Wind Models
Riley, P.; Lepri, S. T.; Antiochos, S. K. +2 more
The standard theory for the solar-heliospheric magnetic field is the so-called quasi-steady model in which the field is determined by the observed magnetic flux at the photosphere and the balance between magnetic and plasma forces in the corona. In this model, the solar magnetic flux that opens to the heliosphere can increase or decrease as the ph…