Search Publications
Magnetic signatures of plasma-depleted flux tubes in the Saturnian inner magnetosphere
André, N.; Gurnett, D. A.; Lewis, G. R. +12 more
Initial Cassini observations have revealed evidence for interchanging magnetic flux tubes in the inner Saturnian magnetosphere. Some of the reported flux tubes differ remarkably by their magnetic signatures, having a depressed or enhanced magnetic pressure relative to their surroundings. The ones with stronger fields have been interpreted previous…
Asteroseismic signatures of stellar magnetic activity cycles
Judge, P. G.; Dziembowski, W. A.; Metcalfe, T. S. +1 more
Observations of stellar activity cycles provide an opportunity to study magnetic dynamos under many different physical conditions. Space-based asteroseismology missions will soon yield useful constraints on the interior conditions that nurture such magnetic cycles, and will be sensitive enough to detect shifts in the oscillation frequencies due to…
Chandra X-Ray Sources in the Collapsed-Core Globular Cluster M30 (NGC 7099)
Heinke, Craig O.; Cohn, Haldan N.; Lugger, Phyllis M. +2 more
We report the detection of six discrete, low-luminosity (LX<1033 ergs s-1) X-ray sources, located within 12" of the center of the collapsed-core globular cluster M30 (NGC 7099), and a total of 13 sources within the half-mass radius, from a 50 ks Chandra ACIS-S exposure. Three sources lie within the very small up…
A 33 hour period for the Wolf-Rayet/black hole X-ray binary candidate NGC 300 X-1
Ehle, M.; Wilms, J.; Pollock, A. M. T. +4 more
Context: NGC 300 X-1 is the second extragalactic candidate, after IC 10 X-1, in the rare class of Wolf-Rayet/compact object X-ray binary systems exemplified in the Galaxy by Cyg X-3. From a theoretical point of view, accretion onto a black hole in a detached system is possible for large orbital periods only if the mass of the relativistic object i…
X-Ray Luminosity Functions of Normal Galaxies in the Great Observatories Origins Deep Survey
Mobasher, Bahram; Bauer, Franz; Norman, Colin +2 more
We present soft (0.5-2 keV) X-ray luminosity functions (XLFs) in the Great Observatories Origins Deep Survey (GOODS) fields derived for galaxies at z~0.25 and 0.75. SED fitting was used to estimate photometric redshifts and separate galaxy types, resulting in a sample of 40 early-type galaxies and 46 late-type galaxies. We estimate k-corrections f…
Continuous statistics of the Lyα forest at 0 < z < 1.6: the mean flux, flux distribution and autocorrelation from HST FOS spectra
Charlton, Jane; Tytler, David; Lubin, Dan +1 more
We measure the amount of absorption in the Lyα forest at 0 < z < 1.6 in Hubble Space Telescope Faint Object Spectrograph spectra of 74 quasi-stellar objects (QSOs). Starting with a 334 QSO sample compiled by Bechtold et al., we selected 74 QSOs that have the highest signal-to-noise ratio and complete coverage of rest-frame wavelengths 1070-1…
A search for ultra-compact dwarf galaxies in the Centaurus galaxy cluster
Infante, L.; Hilker, M.; Kissler-Patig, M. +2 more
Aims:Our aim is to extend the investigations of ultra-compact dwarf galaxies (UCD) beyond the well studied Fornax and Virgo clusters.
Methods: We measured spectroscopic redshifts of about 400 compact object candidates with 19.2 < V < 22.4 mag in the central region of the Centaurus galaxy cluster (d = 43 Mpc), using 3 pointings with VIMOS…
Molecular gas in NUclei of GAlaxies (NUGA). VII. NGC 4569, a large scale bar funnelling gas into the nuclear region
Tacconi, L. J.; Hunt, L. K.; Krips, M. +8 more
This work is part of the NUGA survey of CO emission in nearby active galaxies. We present observations of NGC 4569, a member of the Virgo Cluster. We analyse the molecular gas distribution and kinematics in the central region and we investigate a possible link to the strong starburst present at the nucleus. 70% of the [ 1.1±0.2] ×109 M<…
The XMM large scale structure survey: optical vs. X-ray classifications of active galactic nuclei and the unified scheme
Maccagni, D.; Chiappetti, L.; Ebrero, J. +25 more
Aims:Our goal is to characterize AGN populations by comparing their X-ray and optical classifications within the framework of the standard orientation-based unified scheme.
Methods: We present a sample of 99 spectroscopically identified (R ≤ 22 mag) X-ray selected point sources in the XMM-LSS survey which are significantly detected (≥3σ) in th…
Constraining the geometry of the neutron star RX J1856.5-3754
Ho, Wynn C. G.
RX J1856.5-3754 is one of the brightest, nearby isolated neutron stars (NSs), and considerable observational resources have been devoted to its study. In previous work, we found that our latest models of a magnetic, hydrogen atmosphere match well the entire spectrum, from X-rays to optical (with best-fitting NS radius R ~ 14 km, gravitational reds…