Search Publications
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 …
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…
Three-dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations
Vourlidas, Angelos; Lugaz, Noé; Roussev, Ilia I. +6 more
We numerically model the coronal mass ejection (CME) event of 2003 October 28 that erupted from AR 10486 and propagated to Earth in less than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model is formulated by first arriving at a steady state corona and solar wind employing synoptic magnetograms. We initiate two CMEs fro…
Evidence for Merger Remnants in Early-Type Host Galaxies of Low-Redshift QSOs
Schweizer, François; Lacy, Mark; Stockton, Alan +4 more
We present results from a pilot HST ACS deep imaging study in broadband V of five low-redshift QSO host galaxies classified in the literature as ellipticals. The aim of our study is to determine whether these early-type hosts formed at high redshift and have since evolved passively, or whether they have undergone relatively recent mergers that may…
Quantitative Spectroscopy of 24 A Supergiants in the Sculptor Galaxy NGC 300: Flux-weighted Gravity-Luminosity Relationship, Metallicity, and Metallicity Gradient
Bresolin, Fabio; Kudritzki, Rolf-Peter; Urbaneja, Miguel A. +3 more
A quantitative spectral analysis of 24 A supergiants in the Sculptor Group spiral galaxy NGC 300 at a distance of 1.9 Mpc is presented. A new method is introduced to analyze low-resolution (~5 Å) spectra, which yields metallicities accurate to 0.2 dex including the uncertainties arising from the errors in Teff (5%) and log g (0.2 dex). …
Black Holes in Pseudobulges and Spheroidals: A Change in the Black Hole-Bulge Scaling Relations at Low Mass
Ho, Luis C.; Barth, Aaron J.; Greene, Jenny E.
We investigate the relationship between black hole mass and host galaxy properties for active galaxies with the lowest black hole masses currently known in galaxy nuclei. HST imaging confirms that the host galaxies have correspondingly low luminosity; they are ~1 mag below L*. In terms of morphology, ~60% of the members of the sample are disk domi…
Hubble Space Telescope STIS Optical Transit Transmission Spectra of the Hot Jupiter HD 209458b
Sing, David K.; Lecavelier des Etangs, A.; Vidal-Madjar, A. +2 more
We present the transmission spectra of the hot Jupiter HD 209458b taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. Our analysis combines data at two resolutions and applies a complete pixel-by-pixel limb-darkening correction to fully reveal the spectral line shapes of atmospheric absorption features. Terrestri…
High-Cadence Observations of a Global Coronal Wave by STEREO EUVI
Veronig, Astrid M.; Temmer, Manuela; Vršnak, Bojan
We report a large-scale coronal wave (so-called EIT wave) observed with high cadence by EUVI on board STEREO in association with the GOES B9.5 flare and double CME event on 2007 May 19. The EUVI instruments provide us with the unprecedented opportunity to study the dynamics of flare/CME associated coronal waves. The coronal wave under study reveal…