Search Publications
Ultraviolet Emission-line Correlations in HST/COS Spectra of Active Galactic Nuclei: Single-epoch Black Hole Masses
Shull, J. Michael; Tilton, Evan M.
Effective methods of measuring supermassive black hole masses in active galactic nuclei (AGNs) are of critical importance to studies of galaxy evolution. While there has been much success in obtaining masses through reverberation mapping, the extensive observing time required by this method has limited the practicality of applying it to large samp…
Signatures of Slow Solar Wind Streams from Active Regions in the Inner Corona
Berghmans, D.; Slemzin, V.; Harra, L. +3 more
The identification of solar-wind sources is an important question in solar physics. The existing solar-wind models (e.g., the Wang-Sheeley-Arge model) provide the approximate locations of the solar wind sources based on magnetic field extrapolations. It has been suggested recently that plasma outflows observed at the edges of active regions may be…
A high molecular fraction in a subdamped absorber at z = 0.56
Prochaska, J. Xavier; Tejos, Nicolas; Bechtold, Jill +8 more
Measuring rest-frame ultraviolet rotational transitions from the Lyman and Werner bands in absorption against a bright background continuum is one of the few ways to directly measure molecular hydrogen (H2). Here, we report the detection of absorption from H2 at z = 0.56 in a subdamped Lyα system with neutral hydrogen column …
The 3D Geometry of Active Region Upflows Deduced from Their Limb-to-Limb Evolution
Mandrini, C. H.; van Driel-Gesztelyi, L.; Démoulin, P. +1 more
We analyze the evolution of coronal plasma upflows from the edges of AR 10978, which has the best limb-to-limb data coverage with Hinode's EUV Imaging Spectrometer (EIS). We find that the observed evolution is largely due to the solar rotation progressively changing the viewpoint of nearly stationary flows. From the systematic changes in the upflo…
Planck intermediate results. II. Comparison of Sunyaev-Zeldovich measurements from Planck and from the Arcminute Microkelvin Imager for 11 galaxy clusters
Böhringer, H.; Kneissl, R.; Dahle, H. +204 more
A comparison is presented of Sunyaev-Zeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferometer, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk and White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Com…
RHESSI and TRACE Observations of Multiple Flare Activity in AR 10656 and Associated Filament Eruption
Kushwaha, Upendra; Joshi, Bhuwan; Veronig, Astrid M. +1 more
We present Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) and Transition Region and Coronal Explorer (TRACE) observations of multiple flare activity that occurred in the NOAA active region 10656 over a period of 2 hr on 2004 August 18. Out of four successive flares, three were class C events, and the final event was a major X1.8 sol…
Evolution of the 1919 Ejecta of V605 Aquilae
Sparks, William B.; Bond, Howard E.; Chesneau, O. +7 more
New imaging of V605 Aql, was obtained in 2009 with HST/WFPC2, which had a nova-like outburst in 1919, and is located at the center of the planetary nebula (PN), A58. This event has long been ascribed to a final helium shell flash, but it has been suggested recently that it may instead have been an ONe nova. The new images provide an 18 yr baseline…
Discovery of X-Ray Pulsation from the Geminga-like Pulsar PSR J2021+4026
Cheng, K. S.; Takata, J.; Wang, Y. +8 more
We report the discovery of an X-ray periodicity of ~265.3 ms from a deep XMM-Newton observation of the radio-quiet γ-ray pulsar, PSR J2021+4026, located at the edge of the supernova remnant G78.2+2.1 (γ-Cygni). The detected frequency is consistent with the γ-ray pulsation determined by the observation of the Fermi Gamma-ray Space Telescope at the …
Dark Matter Subhalos and the X-Ray Morphology of the Coma Cluster
Churazov, Eugene; Andrade-Santos, Felipe; Jones, Christine +4 more
Structure formation models predict that clusters of galaxies contain numerous massive subhalos. The gravity of a subhalo in a cluster compresses the surrounding intracluster gas and enhances its X-ray emission. We present a simple model, which treats subhalos as slow moving and gasless, for computing this effect. Recent weak lensing measurements b…
Interplanetary and geomagnetic consequences of 5 January 2005 CMEs associated with eruptive filaments
Möstl, Christian; Srivastava, Nandita; Chakrabarty, D. +2 more
On 5 January 2005, SoHO/LASCO observed the launch of two successive coronal mass ejections (CMEs) associated with the filament (active region and quiescent) structures. The eruptions resulted in two distinct magnetic clouds whose embedded flux-rope topology is modeled by the Grad-Shafranov (G-S) reconstruction technique. Filament plasma remnants i…