Vacuum Cherenkov effect in logarithmic nonlinear quantum theory

We describe the radiation phenomena which can take place in the physical vacuum such as Cherenkov-type shock waves. Their macroscopical characteristics - cone angle, flash duration, radiation yield and spectral distribution - are computed. It turns out that the radiation yield is proportional to the square of the proper energy scale of the vacuum which serves also as the vacuum instability threshold and the natural ultraviolet cutoff. While the analysis is mainly based on the theory engaging the logarithmic nonlinear quantum wave equation, some of the obtained results must be valid for any Lorentz-invariance-violating theory describing the vacuum by (effectively) continuous medium in the long-wavelength approximation.Comment: Updates: v2: changed title, added comments about vacuum instability and Hawking radiation, added some refs previously missed due to certain linguistic subtlety, v3 [pub]: removed comments about Hawking radiation (requested by referees as it requires a separate study), changed title, added more ref

Difference Image Analysis of Galactic Microlensing I. Data Analysis

This is a preliminary report on the application of Difference Image Analysis (DIA) to galactic bulge images. The aim of this analysis is to increase the sensitivity to the detection of gravitational microlensing. We discuss how the DIA technique simplifies the process of discovering microlensing events by detecting only objects which have variable flux. We illustrate how the DIA technique is not limited to detection of so called ``pixel lensing'' events, but can also be used to improve photometry for classical microlensing events by removing the effects of blending. We will present a method whereby DIA can be used to reveal the true unblended colours, positions and light curves of microlensing events. We discuss the need for a technique to obtain the accurate microlensing time scales from blended sources, and present a possible solution to this problem using the existing HST colour magnitude diagrams of the galactic bulge and LMC. The use of such a solution with both classical and pixel microlensing searches is discussed. We show that one of the major causes of systematic noise in DIA is differential refraction. A technique for removing this systematic by effectively registering images to a common airmass is presented. Improvements to commonly used image differencing techniques are discussed.Comment: 18 pages, 8 figures, uses AAS LaTEX 4.0, To appear in Astrophysical Journa

Spontaneous symmetry breaking and mass generation as built-in phenomena in logarithmic nonlinear quantum theory

Our primary task is to demonstrate that the logarithmic nonlinearity in the quantum wave equation can cause the spontaneous symmetry breaking and mass generation phenomena on its own, at least in principle. To achieve this goal, we view the physical vacuum as a kind of the fundamental Bose-Einstein condensate embedded into the fictitious Euclidean space. The relation of such description to that of the physical (relativistic) observer is established via the fluid/gravity correspondence map, the related issues, such as the induced gravity and scalar field, relativistic postulates, Mach's principle and cosmology, are discussed. For estimate the values of the generated masses of the otherwise massless particles such as the photon, we propose few simple models which take into account small vacuum fluctuations. It turns out that the photon's mass can be naturally expressed in terms of the elementary electrical charge and the extensive length parameter of the nonlinearity. Finally, we outline the topological properties of the logarithmic theory and corresponding solitonic solutions.Comment: Dedicated to memory of V. L. Ginzburg (1916-2009). Updates: (v2) chapter on BEC/fluid/gravity correspondence; (v3) comments on BEC-vacuum thermodynamics, induced relativity postulates, Mach's principle, Weyl curvature hypothesis, BEC-vacuum cosmology and origin of fundamental scalar field; (v4) appendix with quantum-informational arguments towards LogSE; (v5 [pub]) refs about superfluid vacuu

The Carlsberg Meridian Telescope CCD Drift Scan Survey

This paper contains the general data reduction methods used in processing the data from the Carlsberg Meridian Telescope CCD Drift Scan Survey. An efficient method to calibrate the fluctuations in the positions of the images caused by atmospheric turbulence is described. The external accuracy achieved is 36 mas in right ascension and declination. A description of the recently released catalogue is given.Comment: 13 pages 11 Figures (PS) Accepted for publication in A&A. The catalogue can be found at http://www.ast.cam.ac.uk/~dwe/SRF/cmc12

Analysis of latitude observations for detection of crustal movements

Analysis of latitude observations for detection of earth crust movement

Lunar Impact Flash Locations from NASA's Lunar Impact Monitoring Program

Meteoroids are small, natural bodies traveling through space, fragments from comets, asteroids, and impact debris from planets. Unlike the Earth, which has an atmosphere that slows, ablates, and disintegrates most meteoroids before they reach the ground, the Moon has little-to-no atmosphere to prevent meteoroids from impacting the lunar surface. Upon impact, the meteoroid's kinetic energy is partitioned into crater excavation, seismic wave production, and the generation of a debris plume. A flash of light associated with the plume is detectable by instruments on Earth. Following the initial observation of a probable Taurid impact flash on the Moon in November 2005,1 the NASA Meteoroid Environment Office (MEO) began a routine monitoring program to observe the Moon for meteoroid impact flashes in early 2006, resulting in the observation of over 330 impacts to date. The main objective of the MEO is to characterize the meteoroid environment for application to spacecraft engineering and operations. The Lunar Impact Monitoring Program provides information about the meteoroid flux in near-Earth space in a size range-tens of grams to a few kilograms-difficult to measure with statistical significance by other means. A bright impact flash detected by the program in March 2013 brought into focus the importance of determining the impact flash location. Prior to this time, the location was estimated to the nearest half-degree by visually comparing the impact imagery to maps of the Moon. Better accuracy was not needed because meteoroid flux calculations did not require high-accuracy impact locations. But such a bright event was thought to have produced a fresh crater detectable from lunar orbit by the NASA spacecraft Lunar Reconnaissance Orbiter (LRO). The idea of linking the observation of an impact flash with its crater was an appealing one, as it would validate NASA photometric calculations and crater scaling laws developed from hypervelocity gun testing. This idea was dependent upon LRO finding a fresh impact crater associated with one of the impact flashes recorded by Earth-based instruments, either the bright event of March 2013 or any other in the database of impact observations. To find the crater, LRO needed an accurate area to search. This Technical Memorandum (TM) describes the geolocation technique developed to accurately determine the impact flash location, and by association, the location of the crater, thought to lie directly beneath the brightest portion of the flash. The workflow and software tools used to geolocate the impact flashes are described in detail, along with sources of error and uncertainty and a case study applying the workflow to the bright impact flash in March 2013. Following the successful geolocation of the March 2013 flash, the technique was applied to all impact flashes detected by the MEO between November 7, 2005, and January 3, 2014

Physical and spectroscopic characterisation of samarium doped magnesium tellurite glass embedded silver nanoparticles

Three series of samarium doped magnesium tellurite glasses embedded with silver nanoparticles (Ag NPs) of composition (89-x)TeO2-10MgO-1Sm2O3-xAgCl with 0 ≤ x ≤ 1.0 mol%, (89.6-x)TeO2-10MgO-(x)Sm2O3-0.4AgCl with 0.2 ≤ x ≤ 1.2 mol% and 88.6TeO2-10MgO-(x)Sm2O3-(1.4-x)AgCl with 0.2 ≤ x ≤ 1.0 mol% were prepared using melt quenching technique. It is found that the glass samples are yellowish in colour depending on their compositions. The existence of broad hump in X-ray diffraction (XRD) pattern verifies the amorphous nature of glasses and the presence of silver nanoparticles with average diameter of 16.94 nm in the glass matrix is confirmed by transmission electron microscope (TEM) image. The glass density (ρ), molar volume (Vm) and ionic packing density (Vt) are in the range of (4.91-5.51) g cm-3 , (27.13-30.46) cm3 mol-1 and (0.444-0.498), respectively. The samples exhibit glass stability up to 102oC which indicates the enhancement in ability of glass formation. The fourier transform infrared (FTIR) and Raman spectra reveal modification in network structures which is evident from the shifted vibrational wave-number of TeO4 and TeO3 structural units located around 600 cm-1 and 700 cm-1, respectively. Two surface plasmon resonance (SPR) peaks are detected at 550 nm for transverse oscillation and 578 nm for longitudinal oscillation from ultraviolet-visible (UV-Vis) absorption spectra. The optical energy band gap and Urbach energy are found in the range of (2.81-3.13) eV and (0.18-0.26) eV, respectively. Refractive index and electronic polarisability have also been calculated and found in the range of (2.35-2.45) and (6.68-7.51) Å3, respectively. The absorption measurement is complemented with determination of bonding characteristic of Sm3+ and ligand via calculations of nephelauxetic ratio and Racah parameters. It is found that the addition of Sm3+ and Ag0 alters the electron distribution which leads to the increase of the covalent bond between Sm and ligand. The glass samples are excited under 554 nm excitation wavelength and the emission spectra are found to consist of a single emission band corresponding to 4G5/2→6H11/2 transition. The intensity enhancement of such transition rises up to 3 times compare to glass without Ag NPs which is attributed to the local field effect and energy transfer from Ag0 to Sm3+. The quality factor, Q is also obtained in the range of 19.20-24.25 which is due to the phonon loss during the non-radiative emission. Meanwhile, decay half-life is determined in the range of (1.4405-1.4459) μs depending on composition. The properties of this glass are very much dependent on the concentration of Sm3+ and Ag NPs. This type of glass has a wide potential to be used as red laser medium and in various photonic applications

On the sources of astrometric anomalous refraction

Over a century ago, astronomers using transit telescopes to determine precise stellar positions were hampered by an unexplained periodic shifting of the stars they were observing. With the advent of CCD transit telescopes in the past three decades, this unexplained motion, now known as anomalous refraction, is again being observed. Anomalous refraction is described as a low frequency, large angular scale motion of the entire image plane with respect to the celestial coordinate system as observed and defined by previous astrometric catalogs. These motions of typically several tenths of an arcsecond with timescales on the order of ten minutes are ubiquitous to drift-scan groundbased astrometric measurements regardless of location or telescopes used and have been attributed to the effect of tilting of equal-density layers of the atmosphere. The cause of this tilting has often been attributed to atmospheric gravity waves, but never confirmed. Although theoretical models of atmospheric refraction show that atmospheric gravity waves are a plausible cause of anomalous refraction, an observational campaign specifically directed at defining this relationship provides clear evidence that anomalous refraction is not consistent with the passage of atmospheric gravity waves. The source of anomalous refraction is found to be meter scale slowly evolving coherent dynamical structures in the boundary-layer below 60 meters