Search Publications
Dominant Nuclear Outflow Driving Mechanisms in Powerful Radio Galaxies
O'Dea, Christopher P.; Axon, David J.; Koekemoer, Anton +4 more
In order to identify the dominant nuclear outflow mechanisms in active galactic nuclei, we have undertaken deep, high-resolution observations of two compact radio sources (PKS 1549-79 and PKS 1345+12) with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. Not only are these targets known to have powerful emission-line outflo…
A Deep Chandra, Very Large Array, and Spitzer Infrared Array Camera Study of the Very Low Luminosity Nucleus of the Elliptical NGC 821
Elvis, M.; Pellegrini, S.; Baldi, A. +5 more
The relatively nearby (distance = 24.1 Mpc) elliptical galaxy NGC 821 hosts an extreme example of a quiescent central massive black hole, for which deep Chandra observations revealed a nuclear source for the first time, with L2-10keV/LEdd~10-8. We present here a multiwavelength study of this nucleus, including Very…
Compton Telescope with a Coded Aperture Mask: Imaging with the INTEGRAL/IBIS Compton Mode
Laurent, P.; Lebrun, F.; Limousin, O. +1 more
Compton telescopes provide good sensitivity over a wide field of view in the difficult energy range from a few hundred keV to several MeV. Their angular resolution is, however, poor and strongly energy dependent. We present a novel experimental design associating a coded mask and a Compton detection unit to overcome these pitfalls. It maintains th…
Triggering Mechanism for the Filament Eruption on 2005 September 13 in NOAA Active Region 10808
Shibata, Kazunari; Okamoto, Takenori J.; Yokoyama, Takaaki +3 more
On 2005 September 13 a filament eruption accompanied by a halo coronal mass ejection (CME) occurred in the most flare-productive active region, NOAA 10808, in solar cycle 23. Using multiwavelength observations before the filament eruption on September 13, we investigate the processes leading to the catastrophic eruption. We find that the filament …
Helioseismic Test of Nonhomologous Solar Radius Changes with the 11 Year Activity Cycle
Kosovichev, A. G.; Lefebvre, S.; Rozelot, J. P.
Recent models of variations of the Sun's structure with the 11 year activity cycle by Sofia et al. predict strong nonhomologous changes of the radius of subsurface layers, due to subsurface magnetic fields and field-modulated turbulence. According to their best model, the changes of the surface radius may be 1000 times larger than those at the dep…
Thermal and Nonthermal Infrared Emission from M87
Egami, E.; Gordon, K. D.; Rieke, G. H. +2 more
We discuss images of M87 from 3.6 to 160 µm obtained with Spitzer. As found previously, there is an excess in the far-infrared over a simple power-law interpolation from the radio to the resolved nonthermal features in the mid-infrared and optical. We show that this excess is most likely due to warm dust in the galaxy itself and that the pro…
EF Chamaeleontis: Warm Dust Orbiting a Nearby 10 Myr Old Star
Zuckerman, B.; Song, Inseok; Rhee, Joseph H.
Most Vega-like stars have far-infrared excess (60 µm or longward in IRAS, ISO, or Spitzer MIPS bands) and contain cold dust (<~150 K) analogous to the Sun's Kuiper Belt region. However, dust in a region more akin to our asteroid belt and thus relevant to the terrestrial planet building process is warm and produces excess emission in mid-i…
Detection of CO Hot Spots Associated with Young Clusters in the Southern Starburst Galaxy NGC 1365
Ho, Paul T. P.; Mao, Rui-Qing; Matsushita, Satoki +2 more
We have used the Submillimeter Array for the first interferometric CO imaging toward the starburst-Seyfert nucleus of the southern barred spiral galaxy NGC 1365, which is one of the four galaxies within 30 Mpc that have L8-1000µm>=1011 Lsolar. Our mosaic maps of 12CO, 13CO, and C…
A Check for Consistency between Different Magnetic Helicity Measurements Based on the Helicity Conservation Principle
Moon, Yong-Jae; Chae, Jongchul; Lim, Eun-Kyung +1 more
Magnetic helicity is a useful quantity in characterizing the magnetic systems of solar active regions. The purpose of the present work is to check for consistency between the local correlation tracking (LCT) method used to measure helicity injection through the photosphere, and the linear force-free field (LFFF) method used to determine helicity i…
Clustered Star Formation in the Small Magellanic Cloud. A Spitzer/IRAC View of the Star-Forming Region NGC 602/N 90
Henning, Thomas; Gouliermis, Dimitrios A.; Quanz, Sascha P.
We present Spitzer/IRAC photometry on the star-forming H II region N 90, related to the young stellar association NGC 602 in the Small Magellanic Cloud. Our photometry revealed bright mid-infrared sources, which we classify with the use of a scheme based on templates and models of red sources in the Milky Way, and criteria recently developed from …