Search Publications
High-redshift supernova rates measured with the gravitational telescope A 1689
Dahle, H.; Lidman, C.; Amanullah, R. +12 more
Aims: We present a ground-based, near-infrared search for lensed supernovae behind the massive cluster Abell 1689 at z = 0.18, which is one of the most powerful gravitational telescopes that nature provides.
Methods: Our survey was based on multi-epoch J-band observations with the HAWK-I instrument on VLT, with supporting optical data fr…
Is there any evidence that ionized outflows quench star formation in type 1 quasars at z < 1?
Maiolino, R.; Marconi, A.; Brusa, M. +6 more
Aims: The aim of this paper is to test the basic model of negative active galactic nuclei (AGN) feedback. According to this model, once the central black hole accretes at the Eddington limit and reaches a certain critical mass, AGN driven outflows blow out gas, suppressing star formation in the host galaxy and self-regulating black hole growt…
The XXL Survey. VI. The 1000 brightest X-ray point sources
Chiappetti, L.; Paltani, S.; Lidman, C. +36 more
Context. X-ray extragalactic surveys are ideal laboratories for the study of the evolution and clustering of active galactic nuclei (AGN). Usually, a combination of deep and wide surveys is necessary to create a complete picture of the population. Deep X-ray surveys provide the faint population at high redshift, while wide surveys provide the rare…
Anatomy of the AGN in NGC 5548. VI. Long-term variability of the warm absorber
Kaastra, J. S.; Kriss, G. A.; Bianchi, S. +13 more
Context. We observed the archetypal Seyfert 1 galaxy NGC 5548 in 2013-2014 in the context of an extensive multiwavelength campaign involving several satellites, which revealed the source to be in an extraordinary state of persistent heavy obscuration.
Aims: We re-analyzed the archival grating spectra obtained by XMM-Newton and Chandra between…
The cause of spatial structure in solar He I 1083 nm multiplet images
Joshi, Jayant; Carlsson, Mats; Leenaarts, Jorrit +2 more
Context. The He I 1083 nm is a powerful diagnostic for inferring properties of the upper solar chromosphere, in particular for the magnetic field. The basic formation of the line in one-dimensional models is well understood, but the influence of the complex three-dimensional structure of the chromosphere and corona has however never been investiga…
A textbook example of ram-pressure stripping in the Hydra A/A780 cluster
Rossetti, M.; Molendi, S.; De Grandi, S. +7 more
In the current epoch, one of the main mechanisms driving the growth of galaxy clusters is the continuous accretion of group-scale halos. In this process, the ram pressure applied by the hot intracluster medium on the gas content of the infalling group is responsible for stripping the gas from its dark-matter halo, which gradually leads to the viri…
GK Persei and EX Hydrae: Intermediate polars with small magnetospheres
Werner, K.; Ducci, L.; Doroshenko, V. +2 more
Observed hard X-ray spectra of intermediate polars are determined mainly by the accretion flow velocity at the white dwarf surface, which is normally close to the free-fall velocity. This allows us to estimate the white dwarf masses as the white dwarf mass-radius relation M - R and the expected free-fall velocities at the surface are well known. T…
Electrical properties and porosity of the first meter of the nucleus of 67P/Churyumov-Gerasimenko. As constrained by the Permittivity Probe SESAME-PP/Philae/Rosetta
Le Gall, Alice; Seidensticker, Klaus J.; Fischer, Hans-Herbert +7 more
Context. Comets are primitive objects, remnants of the volatile-rich planetesimals from which the solar system condensed. Knowing their structure and composition is thus crucial for the understanding of our origins. After the successful landing of Philae on the nucleus of 67P/Churyumov-Gerasimenko in November 2014, for the first time, the Rosetta …
Photospheric and coronal magnetic fields in six magnetographs. I. Consistent evolution of the bashful ballerina
Mursula, Kalevi; Virtanen, Ilpo
Aims: We study the long-term evolution of photospheric and coronal magnetic fields and the heliospheric current sheet (HCS), especially its north-south asymmetry. Special attention is paid to the reliability of the six data sets used in this study and to the consistency of the results based on these data sets.
Methods: We use synoptic ma…
Revealing the broad iron Kα line in Cygnus X-1 through simultaneous XMM-Newton, RXTE, and INTEGRAL observations
Grinberg, Victoria; Pottschmidt, Katja; Staubert, Rüdiger +15 more
We report on the analysis of the broad Fe Kα line feature of Cyg X-1 in the spectra of four simultaneous hard intermediate state observations made with the X-ray Multiple Mirror mission (XMM-Newton), the Rossi X-ray Timing Explorer (RXTE), and the International Gamma-Ray Astrophysics Laboratory (INTEGRAL). The high quality of the XMM-Newton data t…