54519706
The entrainment-limited evolution of FR II sources: maximum sizes and a possible connection to FR Is
We construct a simple theoretical model to investigate how entrainment gradually erodes high-speed FR II jets. This process is described by embedding a mixing-layer model developed originally to describe FR I objects in a self-similar model for the lobe structure of classical FR II sources. Following the classical FR II models, we assume that the lobe is dominated by the particles injected from the central jet. The entrainment produces a boundary shear layer which acts at the interface between the dense central jet and the less denser surrounding lobe, and the associated erosion of the jet places interesting limits on the maximum size of FR II sources. The model shows that this limit depends mainly on the initial bulk velocity of the relativistic jet triggered. The bulk velocities of FR IIs suggested by our model are in good agreement with that obtained from direct pc-scale observations on ordinary radio galaxies and quasars. Finally, we discuss how FR IIs may evolve into FR Is upon reaching their maximum, entrainment-limited sizes.
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.
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.
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.
119291530
Quantum Wave Equation of Photon
In this paper, we give the quantum wave equations of single photon when it is in the vacuum and medium. With these wave equations, we can study light interference and diffraction with the approach of quantum theory, and also can study the quantum property of photon when it is in a general crystal and photonic crystal. Otherwise, it can be applied in quantum optics and condensed matter feld.
126253177
Experimental measurement of the mass of the tau lepton at the Beijing Electron Positron Collider (BEPC)
119228702
Cosmological evolution of the Fanaroff–Riley type II source population
By combining a model for the evolution of the radio luminosity of an individual source with the radio luminosity function, we perform a multidimensional Monte Carlo simulation to investigate the cosmological evolution of the Fanaroff–Riley type II (FR II) radio galaxy population by generating large artificial samples. The properties of FR II sources are required to evolve with redshift in the artificial samples to fit the observations. Either the maximum jet age or the maximum density of the jet environment or both evolve with redshift. We also study the distribution of FR II source properties as a function of redshift. From currently available data we cannot constrain the shape of the distribution of environment density or age, but jet power is found to follow a power-law distribution with an exponent of approximately −2. This power-law slope does not change with redshift out to z = 0.6. We also find the distribution of the pressure in the lobes of FR II sources to evolve with redshift up to z ∼ 1.2.
118396565
Models of the Primordial Standard Clock
Oscillating massive fields in the primordial universe can be used as Standard Clocks. The ticks of these oscillations induce features in the density perturbations, which directly record the time evolution of the scale factor of the primordial universe, thus if detected, provide a direct evidence for the inflation scenario or the alternatives. In this paper, we construct a full inflationary model of primordial Standard Clock and study its predictions on the density perturbations. This model provides a full realization of several key features proposed previously. We compare the theoretical predictions from inflation and alternative scenarios with the Planck 2013 temperature data on Cosmic Microwave Background (CMB), and identify a statistically marginal but interesting candidate. We discuss how future CMB temperature and polarization data, non-Gaussianity analysis and Large Scale Structure data may be used to further test or constrain the Standard Clock signals.
119203742
Scalar-tensor Anticross-correlation Does Not Help to Reconcile the Tension Between BICEP2 and Planck
We examine the recent proposal that the anticross-correlation of the scalar and tensor primordial fluctuations reconciles the tension between BICEP2 and Planck observations. We show that unfortunately the contribution from the scalar-tensor correlation to the cosmic microwave background (CMB) temperature power spectrum vanishes once summed over the angular mode m so the tension between BICEP2 and Planck cannot be reconciled. The reason is that one has to use the spin-weighted spherical harmonics when projecting fields with nonzero spins into the CMB sky. These nonzero spin-weighted spherical harmonics are subject to orthogonality conditions when summed over the angular direction, and thus, the desired cross-correlation between the scalar and tensor perturbations in CMB map vanishes.