Search Publications
General Relativistic Flux Modulations from Disk Instabilities in Sagittarius A*
Melia, Fulvio; Goldwurm, Andrea; Bélanger, Guillaume +2 more
Near-IR and X-ray flares have been detected from the supermassive black hole Sgr A* at the center of our Galaxy with a (quasi-)period of ~17-20 minutes, suggesting an emission region only a few Schwarzschild radii above the event horizon. The latest X-ray flare, detected with XMM-Newton, is notable for its detailed light curve, yielding not only t…
IR Background Anisotropies in Spitzer GOODS Images and Constraints on First Galaxies
Dickinson, Mark; Ferguson, Henry C.; Wright, Edward L. +6 more
We describe the angular power spectrum of unresolved 3.6 µm IR light in Spitzer GOODS fields. The amplitude of the anisotropy spectrum decreases with the decreasing flux threshold to which resolved sources are removed from images. When all pixels above a flux threshold of 24.6 Vega magnitudes are removed, the power spectrum of the remaining …
AEGIS: The Diversity of Bright Near-IR-selected Distant Red Galaxies
Cooper, M. C.; Georgakakis, A.; Koekemoer, A. +10 more
We use deep and wide near-infrared (NIR) imaging from the Palomar telescope combined with DEEP2 spectroscopy and HST and Chandra imaging to investigate the nature of galaxies that are red in NIR colors. We locate these ``distant red galaxies'' (DRGs) through the color cut (J-K)Vega>2.3 over 0.7 deg2, where we find 1010 DRG…
Morphologies of Galaxies in and around a Protocluster at z = 2.300
Pettini, Max; Erb, Dawn K.; Shapley, Alice E. +4 more
We present results from the first robust investigation of galaxy morphology as a function of environment at z>1.5. Our study is motivated by the fact that star-forming galaxies contained within a protocluster at z=2.3 in the HS 1700+64 field have significantly older ages and larger stellar masses on average than those at similar redshifts but m…
Fine Structures in the White-Light Solar Corona at the 2006 Eclipse
Rušin, V.; Druckmüller, M.; Saniga, M. +1 more
Observations of the total solar eclipse of 2006 March 29, as it crossed Africa from southwest to northeast into a Greek island and beyond, allowed correlations with near-simultaneous coronal observations from several spacecraft, including SOHO and TRACE. New methods of compositing images allow the recovery of higher resolution (1"-2") on coronal f…
Hard X-Ray Emission of the Microquasar GX 339-4 in the Low/Hard State
Rodriguez, J.; Malzac, J.; Joinet, A. +4 more
We present the analysis of the high-energy emission of the Galactic black hole binary GX 339-4 in a low/hard state at the beginning of its 2004 outburst. The data from 273 ks of INTEGRAL observations, spread over 4 weeks, are analyzed, along with the existing simultaneous RXTE HEXTE and PCA data. During this period, the flux increases by a factor …
The Plasma Structure of the Cygnus Loop from the Northeastern Rim to the Southwestern Rim
Miller, Eric D.; Katsuda, Satoru; Tsunemi, Hiroshi +1 more
The Cygnus Loop was observed from the northeast to the southwest with XMM-Newton. We divided the observed region into two parts, the north and the south path, and studied the X-ray spectra along the two. The spectra can be well fitted either by a one-component nonequilibrium ionization (NEI) model or by a two-component NEI model. The rim regions c…
The Cause of Photospheric and Helioseismic Responses to Solar Flares: High-Energy Electrons or Protons?
Kosovichev, A. G.
Analysis of the hydrodynamic and helioseismic effects in the photosphere during the solar flare of 2002 July 23, observed by MDI/SOHO, and high-energy images from RHESSI show that these effects are closely associated with sources of the hard X-ray emission but that no such effects existed in the centroid region of the flare's gamma-ray emission. T…
A Shell of Thermal X-Ray Emission Surrounding the Young Crab-like Remnant 3C 58
Gotthelf, E. V.; Helfand, D. J.; Newburgh, L.
Deep X-ray imaging spectroscopy of the bright pulsar wind nebula 3C 58 confirms the existence of an embedded thermal X-ray shell surrounding the pulsar PSR J0205+6449. Radially resolved spectra obtained with the XMM-Newton telescope are well characterized by a power-law model with the addition of a soft thermal emission component in varying propor…
The Planet Host Star γ Cephei: Physical Properties, the Binary Orbit, and the Mass of the Substellar Companion
Torres, Guillermo
The bright, K1 III-IV star γ Cep has been reported previously to have a possibly substellar companion in a ~2.5 yr orbit, as well as an unseen stellar companion at a larger separation. We determine for the first time the three-dimensional orbit of the latter, accounting also for the perturbation from the closer object. We combine new and existing …