Search Publications
XMM-Newton timing mode observations of Mrk 421
Haberl, F.; Papadakis, I. E.; Brinkmann, W. +2 more
We present the results of a detailed temporal analysis of the bright BL Lac object Mrk 421 using the three available long timing mode observations by the EPIC PN camera. This detector mode is characterized by its long life time and is largely free of photon pile-up problems. The source was found in different intensity and variability states differ…
X-Ray Cluster Associated with the z = 1.063 CSS Quasar 3C 186: The Jet is Not Frustrated
Elvis, Martin; Cheung, C. C.; Bechtold, Jill +5 more
We report the Chandra discovery of an X-ray cluster at redshift z=1.063 associated with the compact steep spectrum (CSS) radio-loud quasar 3C 186 (Q0740+380). Diffuse X-ray emission is detected out to ~120 kpc from the quasar and contains 741+/-40 net counts. The X-ray spectrum of the extended emission shows strong Fe-line emission (EW=412 eV) at …
Panoramic Views of Cluster-Scale Assemblies Explored by Subaru Wide-Field Imaging
Shimasaku, Kazuhiro; Ohashi, Takaya; Kodama, Tadayuki +21 more
We have started PISCES project; a panoramic imaging and spectroscopic survey of distant clusters on Subaru. It exploits the unique wide-field imaging capability of Suprime-Cam, which provides a 34' × 27' field of view corresponding to a physical area of 16 × 13 Mpc2 at z ∼ 1. We plan to target 15 clusters at 0.4 ≲ z ≲ 1.3. We report on …
The Complex Star Formation History of NGC 1569
Leitherer, Claus; Greggio, L.; Tosi, M. +3 more
We present new results on the star formation history of the dwarf irregular galaxy NGC 1569. The data were obtained with the Hubble Space Telescope NICMOS/NIC2 in the F110W (J) and F160W (H) near-infrared (NIR) filters and interpreted with the synthetic color-magnitude diagram method. The galaxy has experienced complex star formation (SF) activity…
The Lensed Arc Production Efficiency of Galaxy Clusters: A Comparison of Matched Observed and Simulated Samples
Maoz, Dan; Rix, Hans-Walter; Bartelmann, Matthias +3 more
We compare the statistical properties of giant gravitationally lensed arcs produced in matched simulated and observed cluster samples. The observed sample consists of 10 X-ray-selected clusters at redshifts zc~0.2 imaged with HST by Smith et al. The simulated data set is produced by lensing the Hubble Deep Field, which serves as a backg…
Boron Depletion in F and G Dwarf Stars and the Beryllium-Boron Correlation
Deliyannis, Constantine P.; Steinhauer, Aaron; Boesgaard, Ann Merchant
Boron provides a special probe below the stellar surface since it survives to greater depths than do Li and Be. To search for B depletions we have observed B in 13 F and G dwarfs with large Be depletions; for comparison we have also obtained spectra of five stars that are undepleted in Li and Be. We have used HST with STIS to obtain spectra of the…
Diverse albedos of small trans-neptunian objects
Grundy, W. M.; Noll, K. S.; Stephens, D. C.
Discovery of trans-neptunian object (TNO) satellites and determination of their orbits has recently enabled estimation of the size and albedo of several small TNOs, extending the size range of objects having known size and albedo down into the sub-100 km range. In this paper we compute albedo and size estimates or limits for 20 TNOs, using a consi…
Supermassive black hole mass measurements for NGC 1300 and 2748 based on Hubble Space Telescope emission-line gas kinematics
Marconi, A.; Capetti, A.; Carollo, C. M. +18 more
We present Space Telescope Imaging Spectrograph emission-line spectra of the central regions of the spiral galaxies NGC 1300 and 2748. From the derived kinematics of the nuclear gas we have found evidence for central supermassive black holes in both galaxies. The estimated masses of the black holes in NGC 1300 and 2748 are (6.6+6.3…
The new ESA meteoroid model
Dikarev, V.; Grün, E.; Landgraf, M. +3 more
The orbital distributions of meteoroids in interplanetary space are revised in the ESA meteoroid model to account for recently obtained observational data and to comply with the constraints due to the orbital evolution under planetary gravity and Poynting-Robertson effects. Infrared observations of the zodiacal cloud by the COBE DIRBE instrument, …
A new reduction of the raw Hipparcos data
van Leeuwen, F.; Fantino, E.
We present an outline of a new reduction of the Hipparcos astrometric data, the justifications of which are described in the accompanying paper. The emphasis is on those aspects of the data analysis that are fundamentally different from the ones used for the catalogue published in 1997. The new reduction uses a dynamical modelling of the satellite…