Search Publications
Coronal Plasma Motions near Footpoints of Active Region Loops Revealed from Spectroscopic Observations with Hinode EIS
Harra, Louise K.; Doschek, George A.; Hara, Hirohisa +4 more
The solar active region 10938 has been observed from the disk center to the west limb with the Hinode EUV Imaging Spectrometer. In the disk-center observation, subsonic upflow motions of tens of km s-1 and enhanced nonthermal velocities have been found near the footpoints of the active region loops assuming a single Gaussian approximati…
Emergence of a Helical Flux Rope under an Active Region Prominence
Shibata, Kazunari; Tsuneta, Saku; Shimizu, Toshifumi +12 more
Continuous observations were obtained of NOAA AR 10953 with the Solar Optical Telescope (SOT) on board the Hinode satellite from 2007 April 28 to May 9. A prominence was located over the polarity inversion line (PIL) to the southeast of the main sunspot. These observations provided us with a time series of vector magnetic fields on the photosphere…
Cosmic Evolution of Black Holes and Spheroids. III. The MBH-σ* Relation in the Last Six Billion Years
Treu, Tommaso; Malkan, Matthew A.; Blandford, Roger D. +1 more
We measure the evolution of the correlation between black hole mass and host spheroid velocity dispersion (MBH-σ*) over the last 6 billion years, by studying three carefully selected samples of active galaxies at z = 0.57, z = 0.36 and z < 0.1. For all three samples, virial black hole masses are consistently estimated usin…
The Evolution of AGN Host Galaxies: From Blue to Red and the Influence of Large-Scale Structures
Popesso, P.; Lehmer, B. D.; Alexander, D. M. +14 more
We present an analysis of 109 moderate-luminosity (41.9 <= log L0.5-8.0 keV <= 43.7) AGNs in the Extended Chandra Deep Field-South survey, which is drawn from 5549 galaxies from the COMBO-17 and GEMS surveys having 0.4 <= z<= 1.1. These obscured or optically weak AGNs facilitate the study of their host galaxies since the AGN…
Reconciling the Metallicity Distributions of Gamma-Ray Burst, Damped Lyα, and Lyman Break Galaxies at z ≈ 3
Prochaska, J. Xavier; Fynbo, Johan P. U.; Dessauges-Zavadsky, Miroslava +2 more
We test the hypothesis that the host galaxies of long-duration gamma-ray bursts (GRBs) as well as quasar-selected damped Lyα (DLA) systems are drawn from the population of UV-selected star-forming, high-z galaxies (generally referred to as Lyman break galaxies). Specifically, we compare the metallicity distributions of the GRB and DLA populations …
Comparing and Calibrating Black Hole Mass Estimators for Distant Active Galactic Nuclei
Treu, Tommaso; Malkan, Matthew A.; Woo, Jong-Hak +1 more
Black hole mass (MBH) is a fundamental property of active galactic nuclei (AGNs). In the distant universe, MBH is commonly estimated using the Mg II, Hβ, or Hα emission line widths and the optical/UV continuum or line luminosities as proxies for the characteristic velocity and size of the broad-line region. Although they all …
Relativistic Iron Emission Lines in Neutron Star Low-Mass X-Ray Binaries as Probes of Neutron Star Radii
Homan, Jeroen; Miller, Jon M.; Cackett, Edward M. +6 more
Using Suzaku observations of three neutron star low-mass X-ray binaries (Ser X-1, 4U 1820-30, and GX 349+2) we have found broad, asymmetric, relativistic Fe K emission lines in all three objects. These Fe K lines can be well fit by a model for lines from a relativistic accretion disk ("diskline"), allowing a measurement of the inner radius of the …
PPM-Extended (PPMX) - a catalogue of positions and proper motions
Schwan, H.; Scholz, R. -D.; Piskunov, A. E. +3 more
Aims: We build a catalogue PPM-Extended (PPMX) on the ICRS system which is complete down to a well-defined limiting magnitude and contains the best presently available proper motions suited for kinematic studies in the Galaxy.
Methods: We perform a rigorous weighted least-squares adjustment of individual observations, spread over more than a c…
Flows and Nonthermal Velocities in Solar Active Regions Observed with the EUV Imaging Spectrometer on Hinode: A Tracer of Active Region Sources of Heliospheric Magnetic Fields?
Culhane, J. L.; Doschek, G. A.; Mariska, J. T. +4 more
From Doppler velocity maps of active regions constructed from spectra obtained by the EUV Imaging Spectrometer (EIS) on the Hinode spacecraft we observe large areas of outflow (20-50 km s-1) that can persist for at least a day. These outflows occur in areas of active regions that are faint in coronal spectral lines formed at typical qui…
Chandra unveils a binary active galactic nucleus in Mrk 463
Guainazzi, Matteo; Bianchi, Stefano; Piconcelli, Enrico +2 more
We analyse Chandra, XMM-Newton and Hubble Space Telescope (HST) data of the double-nucleus Ultraluminous Infrared Galaxy (ULIRG), Mrk 463. The Chandra detection of two luminous (L2-10keV = 1.5 × 1043 and 3.8 × 1042 erg cm-2 s-1), unresolved nuclei in Mrk 463 indicates that this galaxy hosts a …