Search Publications
Enhanced Lensing Rate by Clustering of Massive Galaxies: Newly Discovered Systems in the Slacs Fields
Treu, Tommaso; Marshall, Philip J.; Newton, Elisabeth R.
Galaxy-scale strong gravitational lens systems are useful for a variety of astrophysical applications. However, their use is limited by the relatively small samples of lenses known to date. It is thus important to develop efficient ways to discover new systems both in present and forthcoming data sets. For future large high-resolution imaging surv…
Evolution of the Lyα Halos Around High-Redshift Radio Galaxies
Dickinson, Mark; Dey, Arjun; Zirm, Andrew W. +1 more
We have obtained the first constraints on extended Lyα emission at z ~ 1 in a sample of five radio galaxies. We detect Lyα emission from four of the five galaxies. The Lyα luminosities range from 0.1-4 × 1043 erg s-1 and are much smaller than those observed for halos around higher redshift radio galaxies. If the z ≈ 1 radio g…
Numerical experiments on plasmoids entering a transverse magnetic field
Gunell, H.; Nilsson, H.; Brenning, N. +3 more
Plasma from the Earth's magnetosheath has previously been observed inside the magnetosphere. Inhomogeneities in the magnetosheath plasma, here called plasmoids, can impact the magnetopause and doing so set up a polarizing field that allows it to penetrate the magnetopause and enter the magnetosphere. A set of simulations of plasmoids with differen…
The Fermi/LAT Sky as Seen by INTEGRAL/IBIS
Bird, A. J.; Ubertini, P.; Bassani, L. +3 more
In this Letter we present the result of the cross correlation between the fourth INTEGRAL/IBIS soft gamma-ray catalog, in the range 20-100 keV, and the Fermi LAT bright source list of objects emitting in the 100 MeV-100 GeV range. The main result is that only a minuscule part of the more than 720 sources detected by INTEGRAL and the population of …
Chandra Discovery of an Intermediate Polar in Baade's Window
Laycock, Silas; van den Berg, Maureen; Grindlay, Jonathan E. +2 more
We have discovered an intermediate polar (IP) in the 100 ks Chandra observation of Baade's window (BW), a low extinction region at about 4° south of the Galactic center. The source exhibits large X-ray modulations at a period of 1028.4 s in the 0.3-8 keV band. The X-ray spectral fit with a power-law model shows that the integrated spectrum is intr…
Realization of X-ray telescopes-from design to performance
Aschenbach, Bernd
For more than 45 years the building of X-ray telescopes for solar and astronomical observations has been practised with significant performance improvement. The various techniques applied are reviewed emphazising the impact of proper mirror material choice, grinding and polishing improvements and the role of metrology.
Study of Ribbon Separation and Magnetic Reconnection Rates in a Two-Ribbon Flare
Zhang, H.; Wang, H.; Xie, W.
In this paper, we present a study of the correlation between the speed of flare ribbon separation and the magnetic flux density during the 10 April 2001 solar flare. The study includes the section of the neutral line containing the flare core and its peripheral area. This event shows clear two-ribbon structure and inhomogeneous magnetic fields alo…
A Pilot Search for Population III Supernova Candidates in the Spitzer/IRAC Dark Field
Krick, Jessica; Surace, Jason; Moustakas, Leonidas A. +1 more
We have undertaken a systematic search for candidate supernovae from high-redshift Population III stars in a field that has been observed with repeated imaging on a cadence of 2-3 weeks over a 2.2 year baseline, the Spitzer/IRAC Dark Field. The individual epochs reach a typical 5σ depth of 1 µJy in IRAC Channel 1 (3.6 µm). Requiring a …
Tidal Stripping of Globular Clusters in the Virgo Cluster
Coenda, Valeria; Muriel, Hernán; Donzelli, Carlos
With the aim of finding evidence of tidal stripping of globular clusters (GCs) we analyzed a sample of 13 elliptical galaxies taken from the ACS Virgo Cluster Survey (VCS). These galaxies belong to the main concentration of the Virgo Cluster (VC) and present absolute magnitudes -18.5 < Mz < -22.5. We used the public GC catalog of …
The Flux of Open and Toroidal Interplanetary Magnetic Field as a Function of Heliolatitude and Solar Cycle
Schwadron, Nathan A.; Smith, Charles W.; Connick, David E.
We examine 45 years of near-Earth interplanetary observations as recorded in the National Space Science Data Center OMNI data set and 18 years of observations by the Ulysses spacecraft. We find that recent claims for a 50+ year low in interplanetary magnetic field intensity are substantiated, that the low flux levels can be attributed to open magn…