15682686
THE SPATIAL DISTRIBUTION OF ATOMIC CARBON EMISSION IN THE GIANT MOLECULAR CLOUD NGC 604-2
We have mapped a giant molecular cloud in the giant H II region NGC 604 in M33 in the 492 GHz 3P1 → 3P0 transition of neutral atomic carbon using the James Clerk Maxwell Telescope. We find the distribution of the [C I] emission to be asymmetric with respect to the CO J = 1 → 0 emission, with the peak of the [C I] emission offset toward the direction of the center of the H II region. In addition, the line ratio I/ICO is highest (~0.2) facing the H II region and lowest (0.1) away from it. These asymmetries indicate an edge-on morphology where the [C I] emission is strongest on the side of the cloud facing the center of the H II region and not detected at all on the opposite side This suggests that the sources of the incident flux creating C from the dissociation of CO are the massive stars of the H II region. The lowest line ratios are similar to what is observed in Galactic molecular clouds, while the highest are similar to starburst galaxies and other regions of intense star formation. The column density ratio, N(C)/N(H2) is a few ×10-6, in general agreement with models of photodissociation regions.
14127729
THE ORIGIN OF THE DUST ARCH IN THE HALO OF NGC 4631: AN EXPANDING SUPERBUBBLE?
We study the nature and the origin of the dust arch in the halo of the edge-on galaxy NGC 4631 detected by Neininger & Dumke. We present CO observations made using the new on-the-fly mapping mode with the Five College Radio Astronomy Observatory 14 m telescope and find no evidence for CO emission associated with the dust arch. Our examination of previously published H I data shows that, if previous assumptions about the dust temperature and gas/dust ratio are correct, then there must be molecular gas associated with the arch, below our detection threshold. If this is true, then the molecular mass associated with the dust arch is between 1.5 × 108 M⊙ and 9.7 × 108 M⊙, and likely toward the low end of the range. A consequence of this is that the maximum allowed value for the CO-to-H2 conversion factor is 6.5 times the Galactic value, but most likely closer to the Galactic value. The kinematics of the H I apparently associated with the dust arch reveals that the gas here is not part of an expanding shell or outflow but is instead two separate features (a tidal arm and a plume of H I sticking out into the halo) that are seen projected together and appear as a shell. Thus there is no connection between the dust "arch" and the hot X-ray–emitting gas that appears to surround the galaxy.
16833520
The H I Companions of H II Galaxies and Low Surface Brightness Dwarf Galaxies
I study the VLA H I survey of H II galaxies by Taylor et al. and the VLA H I survey of low surface brightness (LSB) dwarf galaxies by Taylor et al. to investigate the role of galaxy interactions in triggering the bursts of massive star formation seen in H II galaxies. Comparing the two surveys, I find that H II galaxies have companions more than twice as often as LSB dwarfs (p = 0.57 for H II galaxies, compared to p = 0.24 for LSB dwarfs). I examine the completeness of the companion samples detected by the two surveys. For the companions to H II galaxies, the sample is likely complete in the distribution of velocity separations from their parent galaxies but is probably missing some companions at large projected linear separations because of the finite size of the VLA primary beam. For the companions of LSB dwarfs, the small number of detections means their distributions in velocity and linear separation are poorly determined, but the LSB dwarfs were observed with the same observational setup as the H II galaxies, so they will have the same levels of completeness. Because the two samples were observed in exactly the same fashion, there will be no relative bias in the number of companions introduced in this way. In addition, the redshift distributions of the two samples are very similar, so there will not be a distance-related relative bias. Thus, I conclude that the difference in the number of H I rich companions is genuine, and signifies a difference in the local, small-scale environments between the two types of galaxy. I search through published galaxy catalogs to determine number of neighbors each galaxy has outside the area of the VLA observations. At these large separations, the number of neighbors is the same, within the errors, for the two types of galaxy. The high rate of companion occurrence at low separations for H II galaxies relative to LSB dwarfs supports the hypothesis that the bursts of star formation are triggered by galaxy interactions.
15184441
A High-Resolution Mosaic of Molecular Gas in Stephan’s Quintet
We present high-resolution 12CO J = 1-0 observations of the molecular gas in the Hickson compact group Stephan's Quintet (HCG 92). Our observations consist of multiple pointings and mosaics covering all the regions where CO and star formation have been detected. Within the 100'' field of view centered on the easternmost tidal tail, we detect three clumps of emission that may be partially resolved at our resolution of 8''; two of these are new detections not previously seen in ISM studies of this region. Two of these clumps lie in the optical tidal tail, while the third lies to the southeast and is coincident with a large H I feature, but it does not correspond to any features at other wavelengths. We also tentatively detect CO emission from the star-forming regions in the "old tail" corresponding to recent star formation activity detected in recent UV and Hα observations. Observations of the rest of the compact group do not show detections, even though strong emission was detected with single-dish telescopes, which suggests that the CO emission originates from a diffuse molecular gas cloud or from at least three separate clumps with separations greater than around 3 kpc.
14490517
Discovery of Molecular Gas in the Outflow and Tidal Arms around M82
We present the first fully sampled map of 12CO (1-0) emission from M82 covering the entire galaxy. Our map contains an ~12 × 15 kpc2 area. We find that extraplanar CO emission, previously reported at short distances above the galactic plane, extends to heights of up to 6 kpc above the disk. Some of this emission is associated with tidal arms seen in H I, implying either that M82 contained substantial amounts of molecular gas in the outer disk or that molecular gas formed after the tidal features. CO emission along the direction of the outflow extends to distances of ~3 kpc above and below the disk. At this distance, the line is shifted in velocity ~100 km s-1 and has the same sense as the galactic outflow from the central starburst. This implies that molecular gas may be entrained into the outflow.
119471275
A Chern-Simons-like action for closed-string field theory
A Chern-Simons-like action is proposed for closed-string field theory. The action involves auxiliary fields of arbitrary ghost number and is defined in terms of the closed-string operations integral , Q and, analogous to those introduced by Witten (1986) in the construction of open-string field theory. The action is an extension of one proposed for free closed strings and bears a formal relationship to 2+1 gravity analogous to that between open-string field theory and (2+1)-dimensional Yang-Mills theory.
37539171
Search for disoriented chiral condensate at the Fermilab Tevatron
We present results from MiniMax (Fermilab T-864), a small test/experiment at the Fermilab Tevatron designed to search for the production of a disoriented chiral condensate (DCC) in p-p(bar sign) collisions at {radical}(s)=1.8 TeV in the forward direction, {approx}3.4<{eta}<{approx}4.2. Data, consisting of 1.3x10{sup 6} events, are analyzed using the robust observables developed in an earlier paper. The results are consistent with generic, binomial-distribution partition of pions into charged and neutral species. Limits on DCC production in various models are presented. (c) 2000 The American Physical Society.
121446915
Generating function zeros for hadron multiparticle distributions
A theorem is proved that delineates criteria for the radii of the annulus of the zeros in the complex plane of the generating function for factorial moments as it applies to high-energy charged-hadron multiproduction. It is shown how this theorem and the general features of the negative binomial distribution provide an explanation of the distribution of generating-function zeros along an open circular ring of approximately unit radius found in simulations and collider data. {copyright} {ital 1997} {ital The American Physical Society}
121598535
Stochastic quantization of gauge theories
Abstract The equivalence between a scalar quantum field theory in D dimensions and its classical counterpart in D + 2 dimensions which is coupled to an external random source with Gaussian correlations was observed by previous authors. This stochastic quantization is extended to gauge theories. The proof exploits the supersymmetry formalism suggested by Parisi and Sourlas.
15060218
Observing Disoriented Chiral Condensates
We speculate that, in very high energy hadronic collisions, large fireballs may be produced with interiors which have anomalous chiral order parameters. Such a process would result in radiation of pions with distinctive momentum and isospin distributions, and may provide an explanation of Centauro and related phenomena in cosmic-ray events. The phenomenology of such events is reviewed, with emphasis on the possibility of observing such phenomena at Fermilab experiment T-864 (MiniMax), or at a Full Acceptance Detector (FAD) at the SSC.