Search Publications
Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity
Kaaret, Philip; Yamaoka, Kazutaka; Kalemci, Emrah +3 more
Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate. An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion disk recedes at low accretion rate. Measurements of the location of the inner edge (R in) can be…
The Chandra Deep Protocluster Survey: Lyα Blobs are Powered by Heating, Not Cooling
Ivison, R. J.; Lehmer, B. D.; Smail, Ian +11 more
We present the results of a 400 ks Chandra survey of 29 extended Lyα emitting nebulae (Lyα Blobs, LABs) in the z = 3.09 protocluster in the SS A22 field. We detect luminous X-ray counterparts in five LABs, implying a large fraction of active galactic nuclei (AGN) in LABs, f AGN = 17+12 -7% down to L 2-32 keV <…
The volcanic history of central Elysium Planitia: Implications for martian magmatism
Mangold, N.; Pinet, P.; Baratoux, D. +3 more
Central Elysium Planitia (CEP) is located south of Elysium Mons. Back to the era of the Viking orbiters, clues accumulated in favor of recent volcanism in relation with ground water release and the formation of long sub-parallel fissures. Four aqueous flood channel systems emanate from linear fissures. Recent eruptions of low viscosity lavas origi…
Automated Solar Activity Prediction: A hybrid computer platform using machine learning and solar imaging for automated prediction of solar flares
Colak, T.; Qahwaji, R.
The importance of real-time processing of solar data especially for space weather applications is increasing continuously. In this paper, we present an automated hybrid computer platform for the short-term prediction of significant solar flares using SOHO/Michelson Doppler Imager images. This platform is called the Automated Solar Activity Predict…
Hubble Space Telescope Weak-lensing Study of the Galaxy Cluster XMMU J2235.3 - 2557 at z ~ 1.4: A Surprisingly Massive Galaxy Cluster When the Universe is One-third of its Current Age
Böhringer, H.; Ford, H. C.; Demarco, R. +8 more
We present a weak-lensing analysis of the z sime 1.4 galaxy cluster XMMU J2235.3 - 2557, based on deep Advanced Camera for Surveys images. Despite the observational challenge set by the high redshift of the lens, we detect a substantial lensing signal at the gsim8σ level. This clear detection is enabled in part by the high mass of the cluster, whi…
The Disappearance of the Progenitors of Supernovae 1993J and 2003gd
Smartt, Stephen J.; Maund, Justyn R.
Using images from the Hubble Space Telescope and the Gemini Telescope, we confirmed the disappearance of the progenitors of two type II supernovae (SNe) and evaluated the presence of other stars associated with them. We found that the progenitor of SN 2003gd, an M-supergiant star, is no longer observed at the SN location and determined its intrins…
Properties of Magnetohydrodynamic Waves in the Solar Photosphere Obtained with Hinode
Tsuneta, S.; Fujimura, D.
We report the observations of the magnetohydrodynamic (MHD) waves propagating along magnetic flux tubes in the solar photosphere. We identified 20 isolated strong peaks (8 peaks for pores and 12 peaks for intergranular magnetic structure) in the power spectra of the line-of-sight (LOS) magnetic flux, the LOS velocity, and the intensity for 14 diff…
Two-dimensional kinematics of SLACS lenses - II. Combined lensing and dynamics analysis of early-type galaxies at z = 0.08-0.33
Treu, Tommaso; Gavazzi, Raphaël; Czoske, Oliver +3 more
We present the first detailed analysis of the mass and dynamical structure of a sample of six early-type lens galaxies, selected from the Sloan Lens ACS Survey, in the redshift range 0.08 <~ z <~ 0.33. Both Hubble Space Telescope/Advanced Camera for Surveys (ACS) high-resolution imaging and Very Large Telescope Visible Multi-Object Spectrogr…
Host galaxy morphologies of X-ray selected AGN: assessing the significance of different black hole fuelling mechanisms to the accretion density of the Universe at z ~ 1.
Cooper, M. C.; Georgakakis, A.; Nandra, K. +7 more
We use morphological information of X-ray selected active galactic nuclei (AGN) hosts to set limits on the fraction of the accretion density of the Universe at z ~ 1 that is not likely to be associated with major mergers. Deep X-ray observations are combined with high-resolution optical data from the Hubble Space Telescope in the All-wavelength Ex…
Ground-based CCD astrometry with wide field imagers. III. WFI@2.2m proper-motion catalog of the globular cluster ω Centauri
Moretti, A.; Anderson, J.; Milone, A. P. +6 more
Context: ω Centauri is the most well studied Galactic Globular Cluster because of its numerous puzzling features: significant dispersion in metallicity, multiple populations, triple main-sequence, horizontal branch morphology, He-rich population(s), and extended star-formation history. Intensive spectroscopic follow-up observing campaigns targetin…