Search Publications
Small-scale Properties of Atomic Gas in Extended Disks of Galaxies
Bowen, David V.; Tripp, Todd M.; York, Donald G. +4 more
We present high-resolution H I 21 cm observations with the Karl G. Jansky Very Large Array for three H I rich galaxies in absorption against radio quasars. Our sample contains six sightlines with impact parameters from 2.6 to 32.4 kpc. We detected a narrow H I absorber of FWHM 1.1 km s-1 at 444.5 km s-1 toward SDSS J122106.85…
Core and Wing Densities of Asymmetric Coronal Spectral Profiles: Implications for the Mass Supply of the Solar Corona
Young, P. R.; Klimchuk, J. A.; Patsourakos, S.
Recent solar spectroscopic observations have shown that coronal spectral lines can exhibit asymmetric profiles, with enhanced emissions at their blue wings. These asymmetries correspond to rapidly upflowing plasmas at speeds exceeding ≈50 km s-1. Here, we perform a study of the density of the rapidly upflowing material and compare it wi…
Magnetic Helicity of the Global Field in Solar Cycles 23 and 24
Pevtsov, A. A.; Pipin, V. V.
For the first time we reconstruct the magnetic helicity density of the global axisymmetric field of the Sun using the method proposed by Brandenburg et al. and Pipin et al. To determine the components of the vector potential, we apply a gauge which is typically employed in mean-field dynamo models. This allows for a direct comparison of the recons…
Classification of X-Ray Sources in the XMM-Newton Serendipitous Source Catalog: Objects of Special Interest
Lin, Dacheng; Webb, Natalie A.; Barret, Didier
We analyze 18 sources that showed interesting properties of periodicity, very soft spectra, and/or large long-term variability in X-rays in our project of classification of sources from the 2XMMi-DR3 catalog, but were poorly studied in the literature, in order to investigate their nature. Two hard sources show X-ray periodicities of ~1.62 hr (2XMM…
A Far-IR View of the Starburst-driven Superwind in NGC 2146
Murphy, E. J.; Armus, L.; Hunt, L. K. +19 more
NGC 2146, a nearby luminous infrared galaxy, presents evidence for outflows along the disk minor axis in all gas phases (ionized, neutral atomic, and molecular). We present an analysis of the multi-phase, starburst-driven superwind in the central 5 kpc as traced in spatially resolved spectral line observations, using far-IR Herschel PACS spectrosc…
High-energy Emission of the First Millisecond Pulsar
Cheng, K. S.; Takata, J.; Ng, C. -Y. +2 more
We report on X-ray and gamma-ray observations of the millisecond pulsar (MSP) B1937+21 taken with the Chandra X-ray Observatory, XMM-Newton, and the Fermi Large Area Telescope. The pulsar X-ray emission shows a purely non-thermal spectrum with a hard photon index of 0.9 ± 0.1, and is nearly 100% pulsed. We found no evidence of varying pulse profil…
Constraining the Disk Masses of the Class I Binary Protostar GV Tau
Sheehan, Patrick D.; Eisner, Josh A.
We present new spatially resolved 1.3 mm imaging with CARMA of the GV Tau system. GV Tau is a Class I binary protostar system in the Taurus Molecular Cloud, the components of which are separated by 1.''2. Each protostar is surrounded by a protoplanetary disk, and the pair may be surrounded by a circumbinary envelope. We analyze the data using deta…
Reversal of Fortune: Increased Star Formation Efficiencies in the Early Histories of Dwarf Galaxies?
Conroy, Charlie; Weisz, Daniel R.; Madau, Piero
On dwarf galaxy scales, the different shapes of the galaxy stellar mass function and the dark halo mass function require a star-formation efficiency (SFE) in these systems that is currently more than 1 dex lower than that of Milky Way-size halos. Here, we argue that this trend may actually be reversed at high redshift. Specifically, by combining t…
Exploring the X-Ray and γ-Ray Properties of the Redback Millisecond Pulsar PSR J1723-2837
Cheng, K. S.; Takata, J.; Kong, A. K. H. +5 more
We have investigated the X-ray and γ-ray properties of the redback millisecond pulsar PSR J1723-2837 with XMM-Newton, Chandra, and Fermi. We have discovered the X-ray orbital modulation of this binary system with a minimum that coincides with the phases of radio eclipse. The X-ray emission is clearly non-thermal in nature, which can be described w…
The Active Galactic Nucleus Population in X-Ray-selected Galaxy Groups at 0.5 < z < 1.1
Mulchaey, John S.; Bauer, Franz E.; Finoguenov, Alexis +6 more
We use Chandra data to study the incidence and properties of active galactic nuclei (AGNs) in 16 intermediate redshift (0.5 < z < 1.1) X-ray-selected galaxy groups in the Chandra Deep Field-South. We measure an AGN fraction of f(LX,H \gt 1042;MR < {-20}) = 8.0-2.3+3.0% at \bar{z} ∼ 0.…