Search Publications
The Origin of the 6.4 keV Line Emission and H2 Ionization in the Diffuse Molecular Gas of the Galactic Center Region
Terrier, R.; Tatischeff, V.; Chernyshov, D. O. +2 more
We investigate the origin of the diffuse 6.4 keV line emission recently detected by Suzaku and the source of H2 ionization in the diffuse molecular gas of the Galactic center (GC) region. We show that Fe atoms and H2 molecules in the diffuse interstellar medium of the GC are not ionized by the same particles. The Fe atoms are…
Water Ice in High Mass-loss Rate OH/IR Stars
Suh, Kyung-Won; Kwon, Young-Joo
We investigate water-ice features in spectral energy distributions (SEDs) of high mass-loss rate OH/IR stars. We use a radiative transfer code which can consider multiple components of dust shells to make model calculations for various dust species including water ice in the OH/IR stars. We find that the model SEDs are sensitively dependent on the…
Tangential Velocity of the Dark Matter in the Bullet Cluster from Precise Lensed Image Redshifts
Broadhurst, Tom; Zitrin, Adi; Umetsu, Keiichi +3 more
We show that the fast-moving component of the "Bullet Cluster" (1E0657-56) can induce potentially resolvable redshift differences between multiply lensed images of background galaxies. This moving cluster effect, due to the tangential peculiar velocity of the lens, can be expressed as the scalar product of the lensing deflection angle with the tan…
The X-Ray-Optical Relations for Nine Clusters at z = 0.7-1.1 from the ORELSE Survey
Fassnacht, C. D.; Kocevski, D. D.; Lemaux, B. C. +4 more
We use Chandra observations of nine optically and X-ray-selected clusters in five different structures at z ~ 0.7-1.1 from the Observations of Redshift Evolution in Large-Scale Environments survey to study diffuse X-ray emission from galaxy clusters. X-ray gas temperatures and bolometric rest-frame luminosities are measured for each cluster in the…
Stellar Populations in Compact Galaxy Groups: A Multi-wavelength Study of HCGs 16, 22, and 42, their Star Clusters, and Dwarf Galaxies
Konstantopoulos, I. S.; Mulchaey, J. S.; Gallagher, S. C. +10 more
We present a multi-wavelength analysis of three compact galaxy groups, Hickson compact groups (HCGs) 16, 22, and 42, which describe a sequence in terms of gas richness, from space- (Swift, Hubble Space Telescope (HST), and Spitzer) and ground-based (Las Campanas Observatory and Cerro Tololo Inter-American Observatory) imaging and spectroscopy. We …
Analysis of Sunspot Area over Two Solar Cycles
de Toma, G.; Chapman, G. A.; Preminger, D. G. +1 more
We examine changes in sunspots and faculae and their effect on total solar irradiance during solar cycles 22 and 23 using photometric images from the San Fernando Observatory. We find important differences in the very large spots between the two cycles, both in their number and time of appearance. In particular, there is a noticeable lack of very …
Dynamics of X-Ray-emitting Ejecta in the Oxygen-rich Supernova Remnant Puppis A Revealed by the XMM-Newton Reflection Grating Spectrometer
Katsuda, Satoru; Koyama, Katsuji; Uchida, Hiroyuki +4 more
Using the unprecedented spectral resolution of the reflection grating spectrometer (RGS) on board XMM-Newton, we reveal dynamics of X-ray-emitting ejecta in the oxygen-rich supernova remnant Puppis A. The RGS spectrum shows prominent K-shell lines, including O VII Heα forbidden and resonance, O VIII Lyα, O VIII Lyβ, and Ne IX Heα resonance, from a…
Helioseismic Investigation of Emerging Magnetic Flux in the Solar Convection Zone
Zhao, Junwei; Ilonidis, Stathis; Hartlep, Thomas
Helioseismology is capable of detecting signatures of emerging sunspot regions in the solar interior before they appear at the surface. Here we present measurements that show the rising motion of the acoustic travel-time perturbation signatures in the deep convection zone, and study the possible physical origin of these signatures using observatio…
Distribution of Magnetic Helicity Flux with Solar Cycles
Zhang, Hongqi; Yang, Shangbin
It is normally believed that a magnetic field transfers helicity from the solar subatmosphere into interplanetary space. This is based on the calculation of the injected magnetic helicity near the center of the solar disk between latitude ±30° of both solar hemispheres in the period 1996-2009. As one follows the long-term injection of magnetic hel…
The IMACS Cluster Building Survey. V. Further Evidence for Starburst Recycling from Quantitative Galaxy Morphologies
Dressler, Alan; Vulcani, Benedetta; Gladders, Michael D. +5 more
Using J- and K s-band imaging obtained as part of the IMACS Cluster Building Survey (ICBS), we measure Sérsic indices for 2160 field and cluster galaxies at 0.31 < z < 0.54. Using both mass- and magnitude-limited samples, we compare the distributions for spectroscopically determined passive, continuously star-forming, starburst, a…