17257286
FRAGMENTATION AT THE EARLIEST PHASE OF MASSIVE STAR FORMATION
We present 1.3 mm continuum and spectral line images of two massive molecular clumps P1 and P2 in the G28.34+0.06 region with the Submillimeter Array (SMA). While the two clumps contain masses of 1000 and 880 M ?, respectively, P1 has a luminosity OF <102 L ?, and a lower gas temperature and smaller line width than P2. Thus, P1 appears to be at a much earlier stage of massive star formation than P2. The high-resolution SMA observations reveal two distinctive cores in P2 with masses of 97 and 49 M ?, respectively. The 4 GHz spectral bandpass captures line emission from CO isotopologues, SO, CH3OH, and CH3CN, similar to hot molecular cores harboring massive young stars. The P1 clump, on the other hand, is resolved into five cores along the filament with masses from 22 to 64 M ? and an average projected separation of 0.19 pc. Except 12CO, no molecular line emission is detected toward the P1 cores at a 1? rms of 0.1 K. Since strong 12CO and C18O emissions are seen with the single-dish telescope at a resolution of 11'', the nondetection of these lines with the SMA indicates a depletion factor up to 103. While the spatial resolution of the SMA is better than the expected Jeans length, the masses in P1 cores are much larger than the thermal Jeans mass, indicating the importance of turbulence and/or magnetic fields in cloud fragmentation. The hierarchical structures in the P1 region provide a glimpse of the initial phase of massive star and cluster formation.
53508261
Near-infrared interferometric observation of the Herbig Ae star HD 144432 with VLTI/AMBER
Aims. We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD 144432 with near-infrared VLTI/AMBER observations to investigate the structure of its inner dust disk. Methods. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H - and K -band visibilities, the near- and mid-infrared visibilities from the literature, and the spectral energy distribution (SED) of HD 144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions. Results. We derive a K -band ring-fit radius of 0.17 ± 0.01   AU and an H -band radius of 0.18 ± 0.01   AU (for a distance of 145   pc). This measured K -band radius of  ~0.17   AU lies in the range between the dust sublimation radius of  ~0.13   AU (predicted for a dust sublimation temperature of 1500   K and gray dust) and the prediction of models including backwarming (~0.27 AU). We find that an additional extended halo component is required in both the geometric and temperature-gradient modeling. In the best-fit temperature-gradient model, the disk consists of two components. The inner part of the disk is a thin ring with an inner radius of  ~0.21   AU, a temperature of  ~1600   K, and a ring thickness  ~0.02   AU. The outer part extends from  ~1   AU to  ~10   AU with an inner temperature of  ~400   K. We find that the disk is nearly face-on with an inclination angle of Conclusions. Our temperature-gradient modeling suggests that the near-infrared excess is dominated by emission from a narrow, bright rim located at the dust sublimation radius, while an extended halo component contributes  ~6% to the total flux at 2    μ m. The mid-infrared model emission has a two-component structure with  ~20% of the flux originating from the inner ring and the rest from the outer parts. This two-component structure is indicative of a disk gap, which is possibly caused by the shadow of a puffed-up inner rim.
16092683
Hollow core?
We carried out the Gaussian fitting to the profile of PSR B1237+25 and found that six components rather than five are necessary to make a good fit. In the central part, we found that the core emission is not filled pencil beam but is a small hollow cone. This implies that the impact angle could be β < 0.5◦. The “hollow core” is in agreement with Inverse Compton Scattering model of radio pulsars.
17261464
Black hole to bulge mass correlation in Active Galactic Nuclei: a test for the simple unified formation scheme
A mass correlation of central black holes and their spheroids similar to 0.002 (within a factor of three) is suggested by Hubble Space Telescope (HST) and various ground-based CCD photometries of early type galaxies. The near-IR images of quasar hosts and the emission line measurements of Broad Line Region for bright QSOs present a similar correlation, which supports the speculation of an evolutionary linkage between the early active QSO phase and the central black holes in normal galaxies. On the other hand, recent reverberation mapping of a sample of Seyferts shows a broad distribution of black hole to bulge mass ratio with a mean of similar to 10(-3.5), about one magnitude lower than the value in early type galaxies and bright QSOs. Adopting a simple unified formation scheme for QSOs and Seyferts, we will discuss in this letter the dependence of the black hole to bulge mass ratio in Active Galactic Nuclei (AGNs) on the environmental parameters of the host galaxies. We show a broad distribution of the mass correlation could be due to different velocity dispersion of the accreting gas from different Formation mechanism, and the mass ratio in normal galaxies and bright QSOs is probably a limit case of black hole evolution by merger enhanced accretion close to Eddington limit.
53371839
Transverse momentum resummation for color sextet and antitriplet scalar production at the LHC
We study the factorization and resummation of the transverse momentum spectrum of the color sextet and antitriplet scalars produced at the LHC based on soft-collinear effective theory. Compared to $$Z$$Z boson and Higgs production, a soft function is required to account for the soft gluon emission from the final-state colored scalar. The soft function is calculated at the next-to-leading order, and the resummation is performed at the approximate next-to-next-to-leading logarithmic accuracy. The non-perturbative effects and PDF uncertainties are also discussed.
54686029
Dynamic polarization effects in ion channeling through single-wall carbon nanotubes
Ion channeling through a single-wall carbon nanotube is simulated by solving Newton’s equations for ion motion at intermediate energies, under the action of both the surface-atom repulsive forces and the polarization forces due to the dynamic perturbation of the nanotube electrons. The atomic repulsion is described by a continuum potential based on the Thomas-Fermi-Moliere model, whereas the dynamic polarization of the nanotube electrons is described by a two-dimensional hydrodynamic model, giving rise to the transverse dynamic image force and the longitudinal stopping force. In the absence of centrifugal forces, a balance between the image force and the atomic repulsion is found to give rise to ion trajectories which oscillate over peripheral radial regions in the nanotube, provided the ion impact position is not too close to the nanotube wall, the impact angle is sufficiently small, and the incident speed is not too high. Otherwise, the ion is found to oscillate between the nanotube walls, passing over a local maximum of the potential in the center of the nanotube, which results from the image interaction. The full statistical analysis of 10 3 ion trajectories has been made to further demonstrate the actual effect of dynamic polarization on the ion channeling.
117426890
Age spread in galactic star forming region W3 Main
We present near-infrared JHKs imaging as well as K-band multi-object spectroscopy of the massive stellar content of W3 Main using LUCI at the LBT. We confirm 13 OB stars by their absorption line spectra in W3 Main and spectral types between O5V and B4V have been found. Three massive Young Stellar Objects are identified by their emission line spectra and near-infrared excess. From our spectrophotometric analysis of the massive stars and the nature of their surrounding HII regions we derive the evolutionary sequence of W3 Main and we find an age spread of 2–3 Myr.
123029043
Evidence of soft and collinear gluon emission ine+e− hadronic events
In the study of rapidity distributions of charged pions produced ine+e− annihilation at 29 GeV, we observe a significant dip in the rapidity distributions aty≈0 for events with low sphericity. A comparison of data with several QCD-based phenomenological models strongly suggests that this structure is related to the emission of multiple soft and/or collinear gluons.