Search Publications
Evidence for Infrared-faint Radio Sources as z > 1 Radio-loud Active Galactic Nuclei
Siana, Brian; Norris, Ray P.; Huynh, Minh T. +1 more
Infrared-Faint Radio Sources (IFRSs) are a class of radio objects found in the Australia Telescope Large Area Survey which have no observable mid-infrared counterpart in the Spitzer Wide-area Infrared Extragalactic (SWIRE) survey. The extended Chandra Deep Field South now has even deeper Spitzer imaging (3.6-70 µm) from a number of Legacy su…
A Multi-Wavelength Spectral and Polarimetric Study of the Jet of 3C 264
Kastner, J. H.; Sparks, W. B.; Birkinshaw, M. +12 more
We present a comprehensive multi-band spectral and polarimetric study of the jet of 3C 264 (NGC 3862). Included in this study are three Hubble Space Telescope (HST) optical and ultraviolet polarimetry data sets, along with new and archival Very Large Array radio imaging and polarimetry, a re-analysis of numerous HST broadband data sets from the ne…
Helioseismic Detection of Deep Meridional Flow
Gough, Douglas; Hindman, Bradley W.
Steady meridional flow does not make any first-order perturbations to the frequencies of helioseismic normal modes. It does, however, Doppler shift the local wavenumber, thereby distorting the eigenfunctions. For high-degree modes, whose peaks in a power spectrum are blended into continuous ridges, the effect of the distortion is to shift the loca…
Quantifying the Evolving Magnetic Structure of Active Regions
Gallagher, Peter T.; McAteer, R. T. James; Conlon, Paul A. +1 more
The topical and controversial issue of parameterizing the magnetic structure of solar active regions has vital implications in the understanding of how these structures form, evolve, produce solar flares, and decay. This interdisciplinary and ill-constrained problem of quantifying complexity is addressed by using a two-dimensional wavelet transfor…
The Electrical Current Density Vector in the Inner Penumbra of a Sunspot
Martínez Pillet, V.; Ruiz Cobo, B.; Puschmann, K. G.
We determine the entire electrical current density vector in a geometrical three-dimensional volume of the inner penumbra of a sunspot from an inversion of spectropolarimetric data obtained with Hinode/SP. Significant currents are seen to wrap around the hotter, more elevated regions with lower and more horizontal magnetic fields that harbor stron…
The Difference in Narrow Fe Kα Line Emission Between Seyfert 1 and Seyfert 2 Galaxies
Wang, Jun-Xian; Liu, Teng
We compile a sample of 89 Seyfert galaxies with both [O IV] 25.89 µm line luminosities observed by Spitzer IRS and X-ray spectra observed by XMM-Newton EPIC. Using [O IV] emission as a proxy for active galactic nucleus (AGN) intrinsic luminosity, we find that although type 2 AGNs have higher line equivalent widths, the narrow Fe Kα lines in …
On Spectropolarimetric Measurements with Visible Lines
Bellot Rubio, L. R.; del Toro Iniesta, J. C.; Orozco Suárez, D.
The ability of new instruments for providing accurate inferences of vector magnetic fields and line-of-sight velocities of the solar plasma depends a great deal on the sensitivity to these physical quantities of the spectral lines chosen to be measured. Recently, doubts have been raised about visible Stokes profiles to provide a clear distinction …
The ACS LCID Project. IV. Detection of the Red Giant Branch Bump in Isolated Galaxies of the Local Group
Hidalgo, S. L.; Monelli, M.; Skillman, E. D. +4 more
We report the detection and analysis of the red giant branch (RGB) luminosity function bump in a sample of isolated dwarf galaxies in the Local Group. We have designed a new analysis approach comparing the observed color-magnitude diagrams (CMDs) with theoretical best-fit CMDs derived from precise estimates of the star formation histories of each …
XMM-Newton and FUSE Tentative Evidence for a WHIM Filament Along the Line of Sight to PKS 0558-504
Papadakis, I.; Elvis, M.; Nicastro, F. +5 more
We present a possible O VIII X-ray absorption line at z = 0.117 ± 0.001 which, if confirmed, will be the first one associated with a broad H I Lyβ (BLB: FWHM = 160+50 -30 km s-1) absorber. The absorber lies along the line of sight to the nearby (z = 0.1372) Seyfert 1 galaxy PKS 0558-504, consistent with being a WHI…
NGC 2992 in an X-ray High State Observed by XMM-Newton: Response of the Relativistic Fe Kα Line to the Continuum
Zheng, W.; Braito, V.; Yaqoob, T. +3 more
We present the analysis of an XMM-Newton observation of the Seyfert galaxy NGC 2992. The source was found in its highest level of X-ray activity yet detected, a factor ~23.5 higher in the 2-10 keV flux than the historical minimum. NGC 2992 is known to exhibit X-ray flaring activity on timescales of days to weeks, and the XMM-Newton data provide at…