Search Publications
Narrow Iron Kα Lines in Active Galactic Nuclei: Evolving Populations?
Zhou, Xin-Lin; Wang, Jian-Min
We assemble a sample consisting of 66 active galactic nuclei (AGNs) from the literature and from the XMM-Newton archive in order to investigate the origin of the 6.4 keV narrow iron Kα line (NIKAL). The X-ray Baldwin effect of the NIKAL is confirmed in this sample. We find that the equivalent width (EW) of the NIKAL is more strongly inversely corr…
Magnetic Flux Ropes in the Solar Photosphere: The Vector Magnetic Field under Active Region Filaments
Lites, B. W.
This study is an observational search for evidence of prominence-associated magnetic flux ropes at the photospheric level in plage regions away from sunspots. Although there are a few cases of supposed flux rope geometry in the photosphere of complex sunspot regions (notably ``δ sunspots''), such cases appear to be fairly rare and therefore do not…
Reddening, Absorption, and Decline Rate Corrections for a Complete Sample of Type Ia Supernovae Leading to a Fully Corrected Hubble Diagram to v < 30,000 km s-1
Saha, A.; Tammann, G. A.; Reindl, B. +1 more
Photometric (BVI) and redshift data corrected for streaming motions are compiled for 111 ``Branch-normal,'' four 1991T-like, seven 1991bg-like, and two unusual supernovae of Type Ia (SNe Ia). Color excesses E(B-V)host of normal SNe Ia, due to the absorption of the host galaxy, are derived by three independent methods, giving excellent a…
The Evolution of the Optical and Near-Infrared Galaxy Luminosity Functions and Luminosity Densities to z~2
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +4 more
Using Hubble Space Telescope and ground-based U through Ks photometry from the Great Observatories Origins Deep Survey, we measure the evolution of the luminosity function and luminosity density in the rest-frame optical (U, B, and R) to z~2, bridging the poorly explored ``redshift desert'' between z~1 and ~2. We also use deep near-infr…
Spectroscopic Confirmation of Multiple Red Galaxy-Galaxy Mergers in MS 1054-03 (z = 0.83)1,
Franx, Marijn; Kelson, Daniel D.; Illingworth, Garth D. +3 more
We present follow-up spectroscopy of the galaxy cluster MS 1054-03 (z=0.83) confirming that at least six of the nine merging galaxy pairs identified by van Dokkum et al. in 1999 are indeed bound systems: they have projected separations of Rs<10 h-1 kpc and relative line-of-sight velocities of Δv<165 km s-1. F…
Highly Ionized Iron Absorption Lines from Outflowing Gas in the X-Ray Spectrum of NGC 1365
Zezas, A.; Bianchi, S.; Elvis, M. +4 more
We present the discovery of four absorption lines in the X-ray spectrum of the Seyfert galaxy NGC 1365, at energies between 6.7 and 8.3 keV. The lines are detected with high statistical confidence (from >20 σ for the strongest to ~4 σ for the weakest) in two XMM-Newton observations 60 ks long. We also detect the same lines, with a lower signal-…
The Binarity of η Carinae Revealed from Photoionization Modeling of the Spectral Variability of the Weigelt Blobs B and D
Bruhweiler, F.; Gull, T.; Verner, E.
We focus on two Hubble Space Telescope Space Telescope Imaging Spectrograph (HST STIS) spectra of the Weigelt blobs B and D, extending from 1640 to 10400 Å, one recorded during the 1998 minimum (1998 March) and the other recorded in 1999 February, early in the following broad maximum. The spatially resolved spectra suggest two distinct ionization …
Measuring the Cosmic Evolution of Dark Energy with Baryonic Oscillations in the Galaxy Power Spectrum
Glazebrook, Karl; Blake, Chris
We use Monte Carlo techniques to simulate the ability of future large high-redshift galaxy surveys to measure the temporal evolution of the dark energy equation of state w(z), using the baryonic acoustic oscillations in the clustering power spectrum as a ``standard ruler.'' Our analysis utilizes only the oscillatory component of the power spectrum…
X-Ray/Ultraviolet Campaign on the Mrk 279 AGN Outflow: Constraining Inhomogeneous Absorber Models
Kriss, Gerard A.; Kaastra, Jelle; Korista, Kirk T. +3 more
We investigate the applicability of inhomogeneous absorber models in the formation of active galactic nucleus outflow absorption troughs. The models we explore are limited to monotonic gradients of absorbing column densities in front of a finite emission source. Our main finding is that simple power-law and Gaussian distributions are hard-pressed …
Far-Ultraviolet Spectroscopy of Magnetic Cataclysmic Variables
Szkody, Paula; Sion, Edward M.; Gänsicke, Boris T. +4 more
We have obtained Hubble Space Telescope (HST) STIS data for a total of 11 polars as part of a program aimed at compiling a homogeneous database of high-quality far-ultraviolet (FUV) spectra for a large number of cataclysmic variables (CVs). Of the 11 polars, eight were found in a state of low accretion activity (V347 Pav, VV Pup, V834 Cen, BL Hyi,…