Search Publications

Piecing together the X-ray background: bolometric corrections for active galactic nuclei

Fabian, A. C.; Vasudevan, R. V.

The X-ray background can be used to constrain the accretion history of supermassive black holes (SMBHs) in active galactic nuclei (AGN), with the SMBH mass density related to the energy density due to accretion. A knowledge of the hard X-ray bolometric correction, κ_2-10keV, is a vital input into these studies, as it allows us to constra…

Extremely fast acceleration of cosmic rays in a supernova remnant

Maeda, Yoshitomo; Takahashi, Tadayuki; Uchiyama, Yasunobu +2 more

Galactic cosmic rays (CRs) are widely believed to be accelerated by shock waves associated with the expansion of supernova ejecta into the interstellar medium. A key issue in this long-standing conjecture is a theoretical prediction that the interstellar magnetic field can be substantially amplified at the shock of a young supernova remnant (SNR) …

The Sloan Lens ACS Survey. IV. The Mass Density Profile of Early-Type Galaxies out to 100 Effective Radii

Treu, Tommaso; Gavazzi, Raphaël; Koopmans, Léon V. E. +5 more

We present a weak-lensing analysis of 22 early-type (strong) lens galaxies, based on deep HST images obtained as part of the Sloan Lens ACS Survey. Using advanced techniques to control systematic uncertainties, we show that weak-lensing signal is detected out to ~300 h^-1 kpc (at the mean lens redshift z=0.2). We analyze blank control fi…

The Rosetta Mission: Flying Towards the Origin of the Solar System

Richter, Ingo; Glassmeier, Karl-Heinz; Kührt, Ekkehard +2 more

The ROSETTA Mission, the Planetary Cornerstone Mission in the European Space Agency's long-term programme Horizon 2000, will rendezvous in 2014 with comet 67P/Churyumov-Gerasimenko close to its aphelion and will study the physical and chemical properties of the nucleus, the evolution of the coma during the comet's approach to the Sun, and the deve…

Evidence for Alfvén Waves in Solar X-ray Jets

Weber, M.; Golub, L.; Kano, R. +11 more

Coronal magnetic fields are dynamic, and field lines may misalign, reassemble, and release energy by means of magnetic reconnection. Giant releases may generate solar flares and coronal mass ejections and, on a smaller scale, produce x-ray jets. Hinode observations of polar coronal holes reveal that x-ray jets have two distinct velocities: one nea…

The X-Ray Telescope onboard Suzaku

Maeda, Yoshitomo; Ishida, Manabu; Kunieda, Hideyo +31 more

Monte Carlo Simulator and Ancillary Response Generator of Suzaku XRT/XIS System for Spatially Extended Source Analysis

Hamaguchi, Kenji; Miller, Eric D.; Maeda, Yoshitomo +31 more

We have developed a framework for the Monte Carlo simulations of X-Ray Telescope (XRT) and X-ray Imaging Spectrometer (XIS) on board Suzaku, mainly for the scientific analysis of spatially and spectroscopically complex celestial sources. A photon-by-photon instrumental simulator is built on the ANL platform, which has been successfully used in ASC…

The Masses of Nuclear Black Holes in Luminous Elliptical Galaxies and Implications for the Space Density of the Most Massive Black Holes

Filippenko, Alexei V.; Ho, Luis C.; Gebhardt, Karl +11 more

Black hole (BH) masses predicted from the M_•-σ relationship conflict with predictions from the M_•-L relationship for high-luminosity galaxies, such as brightest cluster galaxies (BCGs). The M_•-L relationship predicts that some BCGs may harbor BHs with M_• approaching 10¹⁰ M_solar, whi…

A Tale of Two Spicules: The Impact of Spicules on the Magnetic Chromosphere

Carlsson, Mats; Tsuneta, Saku; Shimizu, Toshifumi +11 more

We use high-resolution observations of the Sun in CaIIH (3968Å) from the Solar Optical Telescope on Hinode to show that there are at least two types of spicules that dominate the structure of the magnetic solar chromosphere. Both types are tied to the relentless magnetoconvective driving in the photosphere, but have very different dynamic properti…

The Hubble Diagram to Redshift >6 from 69 Gamma-Ray Bursts

Schaefer, Bradley E.

One of the few ways to measure the properties of dark energy is to extend the Hubble diagram (HD) to higher redshifts with gamma-ray bursts (GRBs). GRBs have at least five properties (their spectral lag, variability, spectral peak photon energy, time of the jet break, and the minimum rise time) that have correlations to the luminosity of varying q…