Search Publications
Lifting the Veil on Obscured Accretion: Active Galactic Nuclei Number Counts and Survey Strategies for Imaging Hard X-Ray Missions
Rigby, J. R.; Treister, E.; Ballantyne, D. R. +2 more
Finding and characterizing the population of active galactic nuclei (AGNs) that produces the X-ray background (XRB) is necessary to connect the history of accretion to observations of galaxy evolution at longer wavelengths. The year 2012 will see the deployment of the first hard X-ray imaging telescope which, through deep extragalactic surveys, wi…
Direct N-body simulations of globular clusters - I. Palomar 14
Kroupa, Pavel; Hilker, Michael; Küpper, Andreas H. W. +3 more
We present the first ever direct N-body computations of an old Milky Way globular cluster over its entire lifetime on a star-by-star basis. Using recent GPU hardware at Bonn University, we have performed a comprehensive set of N-body calculations to model the distant outer halo globular cluster Palomar 14 (Pal 14). Pal 14 is unusual in that its me…
The central black hole mass of the high-σ but low-bulge-luminosity lenticular galaxy NGC 1332
Saglia, R. P.; Nowak, N.; Thomas, J. +3 more
The masses of the most massive supermassive black holes (SMBHs) predicted by the MBH-σ and MBH-L relations appear to be in conflict. Which of the two relations is the more fundamental one remains an open question. NGC 1332 is an excellent example that represents the regime of conflict. It is a massive lenticular galaxy which …
Images of the Extended Outer Regions of the Debris Ring around HR 4796 A
Kuzuhara, M.; Tamura, M.; Ishii, M. +48 more
We present high-contrast images of HR 4796 A taken with Subaru/HiCIAO in the H band, resolving the debris disk in scattered light. The application of specialized angular differential imaging methods allows us to trace the inner edge of the disk with high precision and reveals a pair of "streamers" extending radially outward from the ansae. Using a…
Thermodynamics of the Solar Corona and Evolution of the Solar Magnetic Field as Inferred from the Total Solar Eclipse Observations of 2010 July 11
Morgan, Huw; Habbal, Shadia Rifai; Daw, Adrian +7 more
We report on the first multi-wavelength coronal observations, taken simultaneously in white light, Hα 656.3 nm, Fe IX 435.9 nm, Fe X 637.4 nm, Fe XI 789.2 nm, Fe XIII 1074.7 nm, Fe XIV 530.3 nm, and Ni XV 670.2 nm, during the total solar eclipse of 2010 July 11 from the atoll of Tatakoto in French Polynesia. The data enabled temperature differenti…
Numerical Simulation of Dust in a Cometary Coma: Application to Comet 67P/Churyumov-Gerasimenko
Combi, Michael R.; Rubin, Martin; Tenishev, Valeriy
The Rosetta spacecraft is en route to comet 67P/Churyumov-Gerasimenko for a rendezvous, landing, and extensive orbital phase beginning in 2014. With a limited amount of available observational data, planning of the mission as well as the interpretation of measurements obtained by instruments on board the spacecraft requires modeling of the dusty/g…
Modeling Mars' ionosphere with constraints from same-day observations by Mars Global Surveyor and Mars Express
Tellmann, Silvia; Pätzold, Martin; Withers, Paul +3 more
We have analyzed a brief period of same-day observations of the Martian ionosphere using data obtained in December 2004 from the Mars Global Surveyor (MGS) and Mars Express (MEX) radio occultation experiments. These data were taken shortly after sunrise under solstice conditions in both hemispheres, with MGS in the summer (northern) hemisphere at …
The Temperature Dependence of Solar Active Region Outflows
Stenborg, Guillermo; Warren, Harry P.; Ugarte-Urra, Ignacio +1 more
Spectroscopic observations with the EUV Imaging Spectrometer (EIS) on Hinode have revealed large areas of high-speed outflows at the periphery of many solar active regions. These outflows are of interest because they may connect to the heliosphere and contribute to the solar wind. In this paper, we use slit rasters from EIS in combination with nar…
Multi-scale Anti-correlation Between Electron Density and Magnetic Field Strength in the Solar Wind
Tu, C. -Y.; Marsch, E.; Rème, H. +4 more
This work focuses on the relation between the electron density and the magnetic field strength in the solar wind, and aims to reveal its compressive nature and to determine the level of compressibility. For this purpose, we choose a period of quiet solar wind data obtained at 1 AU by the Cluster C1 satellite. The electron density is derived with a…
Twist and Connectivity of Magnetic Field Lines in the Solar Active Region NOAA 10930
Kusano, K.; Shiota, D.; Inoue, S. +2 more
Twist and connectivity of magnetic field lines in the flare-productive active region NOAA 10930 are investigated in terms of the vector magnetograms observed by the Solar Optical Telescope on board the Hinode satellite and the nonlinear force-free field (NLFFF) extrapolation. First, we show that the footpoints of magnetic field lines reconstructed…