Search Publications
On the distances of planetary nebulae
Smith, Haywood
Past calibrations of statistical distance scales for planetary nebulae have been problematic, especially with regard to `short' versus `long' scales. Reconsidering the calibration process naturally involves examining the precision and especially the systematic errors of various distance methods. Here, we present a different calibration strategy, n…
The magnetic field and spectral variability of the He-weak star HR 2949
Stahl, O.; Rivinius, Th.; Wade, G. A. +6 more
We analyse a high-resolution spectropolarimetric data set collected for the He-weak B3p IV star HR 2949. The Zeeman effect is visible in the circularly polarized component of numerous spectral lines. The longitudinal magnetic field varies between approximately -650 and +150 G. The polar strength of the surface magnetic dipole is calculated to be 2…
(No) dimming of X-ray clusters beyond z ∼ 1 at fixed mass: crude redshifts and masses from raw X-ray and SZ data
Sunyaev, R.; Churazov, E.; Vikhlinin, A.
Scaling relations in the Λ cold dark matter cosmology predict that for a given mass the clusters formed at larger redshift are hotter, denser and therefore more luminous in X-rays than their local z ∼ 0 counterparts. This effect overturns the decrease in the observable X-ray flux so that it does not decrease at z > 1, similar to the SZ signal. …
A SLUGGS and Gemini/GMOS combined study of the elliptical galaxy M60: wide-field photometry and kinematics of the globular cluster system
Spitler, Lee R.; Forbes, Duncan A.; Romanowsky, Aaron J. +20 more
We present new wide-field photometry and spectroscopy of the globular clusters (GCs) around NGC 4649 (M60), the third brightest galaxy in the Virgo cluster. Imaging of NGC 4649 was assembled from a recently obtained Hubble Space Telescope/Advanced Camera for Surveys mosaic, and new Subaru/Suprime-Cam and archival Canada-France-Hawaii Telescope/Meg…
XMM-Newton large program on SN1006 - I. Methods and initial results of spatially resolved spectroscopy
Vink, Jacco; Miceli, Marco; Bocchino, Fabrizio +2 more
Based on our newly developed methods and the XMM-Newton large program of SN1006, we extract and analyse the spectra from 3596 tessellated regions of this supernova remnant (SNR) each with 0.3-8 keV counts >104. For the first time, we map out multiple physical parameters, such as the temperature (kT), electron density (ne),…
Direction of interstellar hydrogen flow in the heliosphere: theoretical modelling and comparison with SOHO/SWAN data
Katushkina, O. A.; Izmodenov, V. V.; Alexashov, D. B.
The analysis of SOlar and Heliospheric Observatory (SOHO) Solar Wind ANisotropies (SWAN) data for backscattered solar Lyman α radiation performed by Lallement et al. showed for the first time that the average direction of interstellar hydrogen flow in the heliosphere is deflected by several degrees relative to the original direction of the interst…
The composite nature of Dust-Obscured Galaxies (DOGs) at z ∼ 2-3 in the COSMOS field - I. A far-infrared view
Berta, S.; Magnelli, B.; Lutz, D. +19 more
Dust-Obscured Galaxies (DOGs) are bright 24 µm-selected sources with extreme obscuration at optical wavelengths. They are typically characterized by a rising power-law continuum of hot dust (TD ∼ 200-1000 K) in the near-IR indicating that their mid-IR luminosity is dominated by an active galactic nucleus (AGN). DOGs with a fainter…
Evidence for a pressure discontinuity at the position of the Coma relic from Planck Sunyaev-Zel'dovich effect data
Bertoldi, F.; Basu, K.; Klein, U. +2 more
Radio relics are Mpc-scale diffuse synchrotron sources found in galaxy cluster outskirts. They are believed to be associated with large-scale shocks propagating through the intracluster medium, although the connection between radio relics and the cluster merger shocks is not yet proven conclusively. We present a first tentative detection of a pres…
Variability of the coronal line region in NGC 4151
Ferland, Gary J.; Steenbrugge, Katrien C.; Landt, Hermine +1 more
We present the first extensive study of the coronal line variability in an active galaxy. Our data set for the nearby source NGC 4151 consists of six epochs of quasi-simultaneous optical and near-infrared spectroscopy spanning a period of about 8 yr and five epochs of X-ray spectroscopy overlapping in time with it. None of the coronal lines showed…
A radio and X-ray study of the merging cluster A2319
Rudnick, Lawrence; Jeltema, Tesla E.; Storm, Emma
A2319 is a massive, merging galaxy cluster with a previously detected radio halo that roughly follows the X-ray emitting gas. We present the results from recent observations of A2319 at ∼20 cm with the Karl G. Jansky Very Large Array and a re-analysis of the X-ray observations from XMM-Newton, to investigate the interactions between the thermal an…