18719624
Warm Molecular Gas in Galaxy-Galaxy Merger NGC 6090
We present Submillimeter Array observations of the CO (2-1) and (3-2) transitions toward the merging galaxies of NGC 6090. The high-resolution CO data reveal three gas concentrations. The main component is peaking in the overlap region between the two galaxies, where the near-IR and radio continuum emission are weak. The CO (2-1) emission from the face-on galaxy NGC 6090E is somewhat stronger than that from the edge-on galaxy NGC 6090W. The CO (3-2) emission peaks in the overlap region, similar to the CO (2-1) emission. More than 50% of the CO (3-2) emission arises from the 2'' (1.2 kpc) area of the overlap region. There appears to be CO (3-2) emission toward the nuclear region and the northwest arm of NGC 6090E, while no CO (3-2) emission is detected toward NGC 6090W. Unlike the CO gas, most of the radio continuum emission comes from NGC 6090E. The strong CO emission, together with the weak radio continuum emission, suggests that star formation in the overlap region has not proceeded long enough to produce significant numbers of supernovae that would be detectable from their radio continuum emission.
119282064
Topological field theory and thermal responses of interacting topological superconductors
We investigate the three-dimensional, time-reversal invariant topological superconductors with generic interaction by their response to external fields. The first description is a gravitational topological field theory, which gives a $Z_2$ classification of topological superconductors, and predicts a half-quantized thermal Hall effect on the surface. The second description introduces an s-wave proximity pairing field on the surface, and the associated topological defects give an integer $Z$ classification of the topological superconductors.
119548246
Subarcsecond Resolution Mid-Infrared Observations of Super Star Clusters in the Antennae (NGC 4038/4039)*
We present ground-based subarcsecond mid-infrared imaging and spectroscopy of young super star clusters in the overlap region of the merging galaxies NGC 4038/4039 (the Antennae) obtained with the VLT Imager and Spectrometer for mid-InfraRed (VISIR). With its unprecedented spatial resolution, VISIR begins for the first time to resolve the H II/photodissociation region complexes around the star-forming regions. In the N-band spectra of two young star clusters, unexpectedly low polycyclic aromatic hydrocarbon (PAH) emission is observed, compared to what is seen with the Infrared Space Observatory and with the Spitzer Space Telescope. We conclude that a large fraction of the PAH emission cannot be directly associated with the super star clusters but originates from an extended region of at least 215 pc radius around the clusters. In the distribution of [Ne II] 12.81 μm emission, a highly obscured cluster is discovered that does not have an optical or near-infrared counterpart.
119180657
THE STRUCTURE OF ACTIVE MERGER REMNANT NGC 6240 FROM IRAC OBSERVATIONS
NGC 6240 is a rare object in the local universe: an active merger remnant viewed at the point of merging where two active galactic nuclei are visible. We present IRAC data of this object, providing high-sensitivity maps of the stellar and PAH distribution in this complicated system. We use photometry to analyze the variation in these distributions with radius and provide an SED in the four IRAC bands: 3.6, 4.5, 5.8, and 8 μm. We fit the radial profiles of the 3.6 μm band to r1/4 and exponential profiles to evaluate the structure of the remnant. Finally, we compare the IRAC images with multiwavelength data and examine how outflows in the X-ray, Hα, and CO correlate with 8 μm emission. The results support the general picture of NGC 6240 as a system experiencing a major merger and transitioning from a disk galaxy to a spheroid. The sensitivity of IRAC to low surface brightness mid-infrared features provides detailed information on the extended distributions of stars and dust in this rare system.
925818
Topological order parameters for interacting topological insulators.
We propose a topological order parameter for interacting topological insulators, expressed in terms of the full Green's functions of the interacting system. We show that it is exactly quantized for a time-reversal invariant topological insulator, and it can be experimentally measured through the topological magneto-electric effect. This topological order parameter can be applied to both interacting and disordered systems, and used for determining their phase diagrams.
7625841
Topological Hamiltonian as an exact tool for topological invariants.
We propose the concept of 'topological Hamiltonian' for topological insulators and superconductors in interacting systems. The eigenvalues of the topological Hamiltonian are significantly different from the physical energy spectra, but we show that the topological Hamiltonian contains the information of gapless surface states, therefore it is an exact tool for topological invariants.
14918025
Water abundance in molecular cloud cores
We present Submillimeter Wave Astronomy Satellite (SWAS) observations of the 110 → 101 transition of ortho-H2O at 557 GHz toward 12 molecular cloud cores. The water emission was detected in NGC 7538, ρ Oph A, NGC 2024, CRL 2591, W3, W3OH, Mon R2, and W33 and was not detected in TMC-1, L134N, and B335. We also present a small map of the H2O emission in S140. Observations of the H218O line were obtained toward S140 and NGC 7538, but no emission was detected. The abundance of ortho-H2O relative to H2 in the giant molecular cloud cores was found to vary between 6 × 10-10 and 1 × 10-8. Five of the cloud cores in our sample have previous H2O detections; however, in all cases the emission is thought to arise from hot cores with small angular extents. The H2O abundance estimated for the hot core gas is at least 100 times larger than in the gas probed by SWAS. The most stringent upper limit on the ortho-H2O abundance in dark clouds is provided in TMC-1, where the 3 σ upper limit on the ortho-H2O fractional abundance is 7 × 10-8.
119458784
An Analysis of the X-Ray Emission from the Supernova Remnant 3C 397
The ASCA SIS and ROSAT PSPC spectral data of the supernova remnant 3C 397 are analyzed with a two-component nonequilibrium ionization model. In addition, the ASCA SIS0 and SIS1 spectra are fitted simultaneously in an equilibrium case. The resulting values of the hydrogen column density yield a distance of ~8 kpc to 3C 397. It is found that the hard X-ray emission, containing S and Fe Kα lines, arises primarily from the hot component, while most of the soft emission, composed mainly of Mg, Si, and Fe L lines and continuum, is produced by the cool component. The emission measures suggest that the remnant evolves in a cloudy medium and imply that the supernova progenitor might not be a massive early-type star. The cool component is approaching ionization equilibrium. The ages estimated from the ionization parameters and dynamics are all much greater than the previous determination. We restore the X-ray maps using the ASCA SIS data and compare them with the ROSAT HRI and the NRAO VLA Sky Survey 20 cm maps. The morphology with two bright concentrations suggests a bipolar remnant encountering a denser medium in the west.
14726409
The distribution of water emission in M17SW
We present a 17-point map of the M17SW cloud core in the 110 → 101 transition of ortho-H2O at 557 GHz obtained with Submillimeter Wave Astronomy Satellite. Water emission was detected in 11 of the 17 observed positions. The line widths of the H2O emission vary between 4 and 9 km s-1 and are similar to other emission lines that arise in the M17SW core. A direct comparison is made between the spatial extent of the H2O emission and the 13CO J = 5 → 4 emission; the good agreement suggests that the H2O emission arises in the same warm, dense gas as the 13CO emission. A spectrum of the H218O line was also obtained at the center position of the cloud core, but no emission was detected. We estimate that the average abundance of ortho-H2O relative to H2 within the M17 dense core is approximately 1 × 10-9, 30 times smaller than the average for the Orion core. Toward the H II region/molecular cloud interface in M17SW the ortho-H2O abundance may be about 5 times larger than in the dense core.
125843454
Spin assignment for the pi h(11/2) X nu h11/2 yrast band in odd-odd Cs-124
18351437
Search for the Optical Counterparts of Southern Anomalous X-Ray Pulsars and Radio-Quiet Neutron Stars in Young Supernova Remnants
We report on our search for the optical counterparts of the Southern Hemisphere anomalous X-ray pulsar 1E1048.1-5937 and the radio-quiet neutron stars in supernova remnants Puppis A, RCW 103, and PKS 1209-52. The observations were carried out with the new MIT/CfA MagIC camera on the Magellan-I 6.5 m telescope in Chile. We present deep multiband optical images of the X-ray error circles for each of these targets and discuss the resulting candidates and limits.