Search Publications
Observational constraints on the physics behind the evolution of active galactic nuclei since z∼ 1
Cooper, M. C.; Juneau, S.; Georgakakis, A. +7 more
We explore the evolution with redshift of the rest-frame colours and space densities of active galactic nuclei (AGN) hosts (relative to normal galaxies) to shed light on the dominant mechanism that triggers accretion on to supermassive black holes as a function of cosmic time. Data from serendipitous wide-area XMM surveys of the Sloan Digital Sky …
Quasi-ballistic and superdiffusive transport for impulsive solar particle events
Zimbardo, G.; Trotta, E. M.
Context. The propagation of solar energetic particles encompasses a number of transport regimes, which goes from diffusive transport to scatter-free propagation. On the other hand, numerical simulations in the presence of magnetic turbulence, as well as the analysis of propagating particles accelerated at interplanetary shocks, show that superdiff…
The scaling of X-ray variability with luminosity in ultra-luminous X-ray sources
Zezas, A.; Papadakis, I.; Reig, P. +1 more
Aims: We investigate the relationship between the X-ray variability amplitude and X-ray luminosity for a sample of 14 bright ultra-luminous X-ray sources (ULXs) with XMM-Newton/EPIC data, and compare it with the well-established, similar relationship for active galactic nuclei (AGN).
Methods: We computed the normalised excess variance in…
Mid-infrared Period-luminosity Relations of RR Lyrae Stars Derived from the WISE Preliminary Data Release
Bloom, Joshua S.; Richards, Joseph W.; Butler, Nathaniel R. +1 more
Interstellar dust presents a significant challenge to extending parallax-determined distances of optically observed pulsational variables to larger volumes. Distance ladder work at mid-infrared wavebands, where dust effects are negligible and metallicity correlations are minimized, has been largely focused on few-epoch Cepheid studies. Here we pre…
EUV lines observed with EIS/Hinode in a solar prominence
Heinzel, P.; Schmieder, B.; Watanabe, T. +1 more
Context. During a multi-wavelength observation campaign with Hinode and ground-based instruments, a solar prominence was observed for three consecutive days as it crossed the western limb of the Sun in April 2007.
Aims: We report on observations obtained on 26 April 2007 using EIS (Extreme ultraviolet Imaging Spectrometer) on Hinode. They are…
Hinode observations and 3D magnetic structure of an X-ray bright point
Del Zanna, G.; Maclean, R. C.; Alexander, C. E.
Aims: We present complete Hinode Solar Optical Telescope (SOT), X-Ray Telescope (XRT)and EUV Imaging Spectrometer (EIS) observations of an X-ray bright point (XBP) observed on the 10, 11 of October 2007 over its entire lifetime (~12 h). We aim to show how the measured plasma parameters of the XBP change over time and also what kind of similar…
Implementation of cartographic symbols for planetary mapping in geographic information systems
Jaumann, R.; van Gasselt, S.; Nass, A. +1 more
The steadily growing international interest in the exploration of planets in our Solar System and many advances in the development of space-sensor technology have led to the launch of a multitude of planetary missions to Mercury, Venus, the Earth's moon, Mars and various Outer-Solar System objects, such as the Jovian and Saturnian satellites. Came…
Testing Photometric Diagnostics for the Dynamical State and Possible Intermediate-mass Black Hole Presence in Globular Clusters
Baumgardt, Holger; Noyola, Eva
Surface photometry is a necessary tool to establish the dynamical state of star clusters. We produce realistic HST-like images from N-body models of star clusters with and without central intermediate-mass black holes (IMBHs) in order to measure their surface brightness profiles. The models contain ~600,000 individual stars, black holes of various…
AKARI detections of hot dust in luminous infrared galaxies. Search for dusty active galactic nuclei
Ohyama, Y.; Matsuhara, H.; Oyabu, S. +10 more
Aims: We present a new sample of active galactic nuclei (AGNs) identified using the catalog of the AKARI Mid-infrared (MIR) All-Sky Survey. Our MIR search has the advantage of detecting AGNs that are obscured at optical wavelengths by extinction.
Methods: We first selected AKARI 9 µm excess sources with F(9 µm)/F(KS
Hubble Space Telescope Photometry of Globular Clusters in M81
Nantais, Julie B.; Huchra, John P.; Zezas, Andreas +2 more
We perform aperture photometry and profile fitting on 419 globular cluster (GC) candidates with mV <= 23 mag identified in Hubble Space Telescope/Advanced Camera for Surveys BVI imaging, and estimate the effective radii of the clusters. We identify 85 previously known spectroscopically confirmed clusters, and newly identify 136 objec…