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Sample records for superluminal propagating velocity

  1. Negative and Superluminal Group Velocity Propagation with Narrow Pulse in a Coaxial Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    OU Xiao-Juan; ZHOU Wei; LI Lin; TENG Li-Hu; FENG Bao-Ying; ZHENG Sheng-Feng; WANG Feng-Wei

    2007-01-01

    We investigate the propagation of electric signal along a spatially periodic impedance mismatched transmission line group. Anomalous dispersion is caused by the periodically mismatched impedance structure and a forbidden band appears near 8 MHz in transmission. The group velocity of the amplitude-modulated signal is augmented up to infinity, even -3.89c (c the speed of light in vacuum) in the forbidden region with the amplitude of the modulated signal increasing. When the carrier sinusoid signal is modulated in amplitude by the modulating sinusoid signal, of which the peak is superimposed with a narrow pulse at fivefold frequency, the superluminal group velocity also occurs. The experiment failed to show whether the propagation velocity of narrow pulse exceeds c or not.

  2. Superluminal Recession Velocities

    CERN Document Server

    Davis, T M; Davis, Tamara M.; Lineweaver, Charles H.

    2000-01-01

    Hubble's Law, v=HD (recession velocity is proportional to distance), is a theoretical result derived from the Friedmann-Robertson-Walker metric. v=HD applies at least as far as the particle horizon and in principle for all distances. Thus, galaxies with distances greater than D=c/H are receding from us with velocities greater than the speed of light and superluminal recession is a fundamental part of the general relativistic description of the expanding universe. This apparent contradiction of special relativity (SR) is often mistakenly remedied by converting redshift to velocity using SR. Here we show that galaxies with recession velocities faster than the speed of light are observable and that in all viable cosmological models, galaxies above a redshift of three are receding superluminally.

  3. Is OPERA Neutrino Superluminal Propagation similar to Gain-Assisted Superluminal Light Propagation

    CERN Document Server

    Pankovic, Vladan

    2011-01-01

    In this work we consider a possible conceptual similarity between recent, amazing OPERA experiment of the superluminal propagation of neutrino and experiment of the gain-assisted superluminal light propagation realized about ten years ago. Last experiment refers on the propagation of the light, precisely laser pulse through a medium, precisely caesium atomic gas, with characteristic anomalous dispersion and corresponding negative group-velocity index that implies superluminal propagation of the light through this medium. Nevertheless all this, at it has been pointed out by authors, "is not at odds with causality or special relativity", since it simply represents "a direct consequence of the classical interference between ... different frequency components". We observe that OPERA experiment is in many aspects conceptually very similar to the gain-assisted superluminal light propagation, including superposition of the neutrinos component and superluminality magnitudes. For this reason we suppose that OPERA expe...

  4. Superluminal propagation: Light cone and Minkowski spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Mugnai, D. [' Nello Carrara' Institute of Applied Physics, CNR Florence Research Area, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy)]. E-mail: d.mugnai@ifac.cnr.it

    2007-05-14

    Superluminal behavior has been extensively studied in recent years, especially with regard to the topic of superluminality in the propagation of a signal. Particular interest has been devoted to Bessel-X waves propagation, since some experimental results showed that these waves have both phase and group velocities greater that light velocity c. However, because of the lack of an exact definition of signal velocity, no definite answer about the signal propagation (or velocity of information) has been found. The present Letter is a short note that deals in a general way with this vexed question. By analyzing the field of existence of the Bessel X-pulse in pseudo-Euclidean spacetime, it is possible to give a general description of the propagation, and to overcome the specific question related to a definition of signal velocity.

  5. Invisibility cloaking without superluminal propagation

    Energy Technology Data Exchange (ETDEWEB)

    Perczel, Janos; Leonhardt, Ulf [School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews KY16 9SS (United Kingdom); Tyc, Tomas, E-mail: jp394@st-andrews.ac.uk, E-mail: tomtyc@physics.muni.cz, E-mail: ulf@st-andrews.ac.uk [Faculty of Science, Kotlarska 2 and Faculty of Informatics, Botanicka 68a, Masaryk University, 61137 Brno (Czech Republic)

    2011-08-15

    Conventional cloaking based on Euclidean transformation optics requires that the speed of light should tend to infinity on the inner surface of the cloak. Non-Euclidean cloaking still needs media with superluminal propagation. Here we show by giving an example that this is no longer necessary.

  6. Has superluminal light propagation been observed?

    OpenAIRE

    Zhang, Yuan-Zhong

    2000-01-01

    It says in the report$^1$ by Wang et al. that a negative group velocity $u=-c/310$ is obtained and that a pulse advancement shift 62-ns is measured. The authors claim that the negative group velocity is associated with superluminal light propagation and that the pulse advancement is not at odds with causality or special relativity. However, it is shown here that their conclusions above are not true. Furthermore, I give some suggestion concerning a re-definition of group-velocity and a new exp...

  7. Neutrino oscillations and superluminal propagation

    CERN Document Server

    Magueijo, Joao

    2011-01-01

    We digress on the implications of recent claims of superluminal neutrino propagation. No matter how we turn it around such behaviour is very odd and sits uncomfortably even within "far-fetched" theories. In the context of non-linear realizations of the Lorentz group (where superluminal misbehaviour is run of the mill) one has to accept rather contrived constructions to predict superluminal properties for the neutrino. The simplest explanation is to require that at least one of the mass states be tachyonic. We show that due to neutrino mixing, the flavor energy does not suffer from the usual runaway pathologies of tachyons. For non-tachyonic mass states the theories become more speculative. A neutrino specific dispersion relation is exhibited, rendering the amplitude of the effect reasonable for a standard Planck energy. This uses the fact that the beam energy is close to the geometrical average of the neutrino and Planck mass; or, seen in another way, the beam energy is unexceptional but its gamma factor is v...

  8. Bessel-X waves: superluminal propagation and the Minkowski space-time

    OpenAIRE

    Mugnai, D.

    2006-01-01

    Superluminal behavior has been extensively studied in recent years, especially with regard to the topic of superluminality in the propagation of a signal. Particular interest has been devoted to Bessel-X waves propagation, since some experimental results showed that these waves have both phase and group velocities greater that light velocity c. However, because of the lack of an exact definition of signal velocity, no definite answer about the signal propagation (or velocity of information) h...

  9. Gain-assisted superluminal propagation and rotary drag of photon and surface plasmon polaritons

    Science.gov (United States)

    Khan, Naveed; Amin Bacha, Bakht; Iqbal, Azmat; Ur Rahman, Amin; Afaq, A.

    2017-07-01

    Superluminal propagation of light is a well-established phenomenon and has motivated immense research interest that has led to state-of-the-art knowledge and potential applications in the emerging technology of quantum optics and photonics. This study presents a theoretical analysis of the gain-assisted superluminal light propagation in a four-level N -type atomic system by exploiting the scheme of electromagnetically induced gain and superluminal propagation of surface plasmon polaritons (SPPs) along the gain-assisted atomic-metal interface simultaneously. In addition, a theoretical demonstration is presented on the comparison between Fresnel's rotary photon drag and SPP drag in view of light polarization state rotation by rotating the coherent atomic medium and the atomic-metal interface, respectively. Analogous to photon drag in the superluminal anomalous dispersion region where light polarization rotation occurs opposite the rotation of the gain-assisted atomic medium, the rotation of the atomic-metal interface also rotates the polarization state of SPPs opposite the rotation of the interface. This further confirms the superluminal nature of SPPs propagating along the interface with negative group velocity. Rabi frequencies of the control and pump fields considerably modify both photon and SPP drag coefficients. Metal conductivity also controls SPP propagation.

  10. Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system

    Science.gov (United States)

    Hamide Kazemi, S.; Ghanbari, S.; Mahmoudi, M.

    2016-01-01

    The propagation of a probe laser field in a cavity optomechanical system with a Bose-Einstein condensate is studied. The transmission properties of the system are investigated and it is shown that the group velocity of the probe pulse field can be controlled by Rabi frequency of the pump laser field. The effect of the decay rate of the cavity photons on the group velocity is studied and it is demonstrated that for small values of the decay rates, the light propagation switches from subluminal to superluminal just by changing the Rabi frequency of the pump field. Then, the gain-assisted superluminal light propagation due to the cross-Kerr nonlinearity is established in cavity optomechanical system with a Bose-Einstein condensate. Such behavior can not appear in the pump-probe two-level atomic systems in the normal phase. We also find that the amplification is achieved without inversion in the population of the quantum energy levels.

  11. Superluminal light propagation via quantum interference in decay channels

    OpenAIRE

    Arun, R.

    2016-01-01

    We examine the propagation of a weak probe light through a coherently driven $Y$-type system. Under the condition that the excited atomic levels decay via same vacuum modes, the effects of quantum interference in decay channels are considered. It is found that the interference in decay channels results in a lossless anomalous dispersion between two gain peaks. We demonstrate that the probe pulse propagation can in principle be switched from subluminal to superluminal due to the decay-induced ...

  12. Unified interpretation of superluminal behaviors in wave propagation

    Energy Technology Data Exchange (ETDEWEB)

    Ranfagni, A. [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze (Italy); Viliani, G. [Dipartimento di Fisica, Universita di Trento, 38050 Povo, Trento (Italy); Ranfagni, C. [Facolta di Scienze Matematiche Fisiche e Naturali, Corso di Laurea in Fisica dell' Universita di Firenze, Firenze (Italy); Mignani, R. [Dipartimento di Fisica ' Edoardo Amaldi' , Universita degli Studi di Roma ' Roma Tre' , Via della Vasca Navale 84, 00146 Roma (Italy); Ruggeri, R. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sezione di Firenze, Firenze (Italy)], E-mail: rocco.ruggeri@isc.cnr.it; Ricci, A.M. [Istituto per le Telecomunicazioni e l' Elettronica della Marina Militare ' Giancarlo Vallauri' (Mariteleradar), Viale Italia 72, 57100 Livorno (Italy)

    2007-10-29

    By using two approaches, we demonstrate that superluminal behaviors in wave propagation can be attributed to mechanisms acting in the near-field limit. One approach is based on complex waves, while the other relies on a path-integral treatment of stochastic motion. The results of the two approaches are comparable, and suitable for interpreting the data obtained in microwave experiments; these experiments, over a wide range of distances, show a time advance which, in any case, is limited to nanoseconds.

  13. SGC Switching Between Subluminal to Superluminal Propagation in V-Type Atom

    Institute of Scientific and Technical Information of China (English)

    HAN Ding-An; GUO Hong; BAI Yan-Feng; SUN Hui; ZENG Ya-Guang

    2006-01-01

    For a V-type three-level atomic system with two closely spaced upper levels, we investigate the light pulse propagation properties with only one laser field. Due to spontaneously generated coherence, the group velocity of the light pulse can be changed from subluminal to superluminal. The effects of the field intensity and the two-upper level splitting on the group velocity are also shown. At last, an analytical expression for the group velocity is given in the case of a weak field.

  14. Superluminal Propagation Caused by Radiative Corrections in a Uniform Electromagnetic Field

    CERN Document Server

    Shiba, Noburo

    2012-01-01

    We consider the effect of radiative corrections on the maximum velocity of propagation of neutral scalar fields in a uniform electromagnetic field. The propagator of neutral scalar fields interacting with charged fields depends on the electromagnetic field through charged particle loops. The kinetic terms of the scalar fields are corrected and the maximum velocity of the scalar particle becomes greater or less than unity. We show that the maximum velocity becomes greater than unity in a simple example, a neutral scalar field coupled with two charged Dirac fields by Yukawa interaction. The maximum velocity depends on the frame of reference and causality is not violated. We discuss the possibility of this superluminal propagation in the Standard Model.

  15. Superluminal Velocities in the Synchronized Space-Time

    Directory of Open Access Journals (Sweden)

    Medvedev S. Yu.

    2014-07-01

    Full Text Available Within the framework of the non-gravitational generalization of the special relativity, a problem of possible superluminal motion of particles and signals is considered. It has been proven that for the particles with non-zero mass the existence of anisotropic light barrier with the shape dependent on the reference frame velocity results from the Tangherlini transformations. The maximal possible excess of neutrino velocity over the absolute velocity of light related to the Earth (using th e clock with instantaneous synchronization has been estimated. The illusoriness of t he acausality problem has been illustrated and conclusion is made on the lack of the upper limit of velocities of signals of informational nature.

  16. Gain-assisted superluminal microwave pulse propagation via four-wave mixing in superconducting phase quantum circuits

    CERN Document Server

    Sabegh, Z Amini; Maleki, M A; Mahmoudi, M

    2015-01-01

    We study the propagation and amplification of a microwave field in a four-level cascade quantum system which is realized in a superconducting phase quantum circuit. It is shown that by increasing the microwave pump tones feeding the system, the normal dispersion switches to the anomalous and the gain-assisted superluminal microwave propagation is obtained in this system. Moreover, it is demonstrated that the stimulated microwave field is generated via four-wave mixing without any inversion population in the energy levels of the system (amplification without inversion) and the group velocity of the generated pulse can be controlled by the external oscillating magnetic fluxes. We also show that in some special set of parameters, the absorption-free superluminal generated microwave propagation is obtained in superconducting phase quantum circuit system.

  17. `Superluminal' Photon Propagation in QED in Curved Spacetime is Dispersive and Causal

    CERN Document Server

    Hollowood, Timothy J

    2010-01-01

    It is now well-known that vacuum polarisation in QED can lead to superluminal low-frequency phase velocities for photons propagating in curved spacetimes. In a series of papers, we have shown that this quantum phenomenon is dispersive and have calculated the full frequency dependence of the refractive index, explaining in detail how causality is preserved and various familiar results from quantum field theory such as the Kramers-Kronig dispersion relation and the optical theorem are realised in curved spacetime. These results have been criticised in a recent paper by Akhoury and Dolgov arXiv:1003.6110 [hep-th], who assert that photon propagation is neither dispersive nor necessarily causal. In this note, we point out a series of errors in their work which have led to this false conclusion.

  18. Comment on: Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system

    Science.gov (United States)

    Macke, Bruno; Ségard, Bernard

    2016-09-01

    In a recent theoretical article [S.H. Kazemi, S. Ghanbari, M. Mahmoudi, Eur. Phys. J. D 70, 1 (2016)], Kazemi et al. claim to have demonstrated superluminal light transmission in an optomechanical system where a Bose-Einstein condensate serves as the mechanical oscillator. In fact the superluminal propagation is only inferred from the existence of a minimum of transmission of the system at the probe frequency. This condition is not sufficient and we show that, in all the cases where superluminal propagation is claimed by Kazemi et al., the propagation is in reality subluminal. Moreover, we point out that the system under consideration is not minimum-phase-shift. The Kramers-Kronig relations then only fix a lower limit to the group delay and we show that these two quantities have sometimes opposite signs.

  19. Comment on "Gain-assisted superluminal light propagation through a Bose-Einstein condensate cavity system"

    CERN Document Server

    Macke, Bruno

    2016-01-01

    In a recent theoretical article [Eur. Phys. J. D 70, 1 (2016)], Kazemi et al. claim to have demonstrated superluminal light transmission in an optomechanical system where a Bose-Einstein condensate serves as the mechanical oscillator. In fact the superluminal propagation is only inferred from the existence of a minimum of transmission of the system at the probe frequency. This condition is not sufficient and we show that, in all the cases where superluminal propagation is claimed by Kazemi et al., the propagation is in reality subluminal. Moreover, we point out that the system under consideration is not minimum-phase-shift. The Kramers-Kronig relations then only fix a lower limit to the group delay and we show that these two quantities have sometimes opposite signs.

  20. Study on the Superluminal Group Velocity in a Coaxial Photonic Crystal

    Institute of Scientific and Technical Information of China (English)

    LuGuizhen; HuangZhixun; GuanJian

    2004-01-01

    In this paper, the superluminal group velocity in a coaxial photonic crystal is studied. The simulation of the effective refraction index in coaxial photonic crystal is performed. The group velocity is calculated based on the transmission line equations and compared with experimental results.

  1. Sub- and super-luminal light propagation using a Rydberg state

    CERN Document Server

    Bharti, Vineet

    2016-01-01

    We present a theoretical study to investigate sub- and super-luminal light propagation in a rubidium atomic system consisting of a Rydberg state by using density matrix formalism. The analysis is performed in a 4-level vee+ladder system interacting with a weak probe, and strong control and switching fields. The dispersion and absorption profiles are shown for stationary atoms as well as for moving atoms by carrying out Doppler averaging at room temperature. We also present the group index variation with control Rabi frequency and observe that a transparent medium can be switched from sub- to super-luminal propagation in the presence of switching field. Finally, the transient response of the medium is discussed, which shows that the considered 4-level scheme has potential applications in absorptive optical switching.

  2. Wave propagation and group velocity

    CERN Document Server

    Brillouin, Léon

    1960-01-01

    Wave Propagation and Group Velocity contains papers on group velocity which were published during the First World War and are missing in many libraries. It introduces three different definitions of velocities: the group velocity of Lord Rayleigh, the signal velocity of Sommerfeld, and the velocity of energy transfer, which yields the rate of energy flow through a continuous wave and is strongly related to the characteristic impedance. These three velocities are identical for nonabsorbing media, but they differ considerably in an absorption band. Some examples are discussed in the last chapter

  3. Superluminal Propagation in Er3+-doped Fiber Bragg Grating

    Institute of Scientific and Technical Information of China (English)

    ZHUO Zhong-chang; SU Xue-mei; YU Yong-sen; ZHENG Wei; ZHANG Yu-shu

    2005-01-01

    The method to pump the FBG written into an Er3+-doped optical fiber is proposed to increase the group velocity of a probing pulse based on the facts that pump-induced process changes the refractive index and dispersion associated with the 4I15/2 -4I13/2 transition in Er3+-doped optical fiber. The system equations are derived. The effects of pump power and doping concentration on the group velocity are discussed.

  4. Diffraction effects in microwave propagation at the origin of superluminal behaviors

    Energy Technology Data Exchange (ETDEWEB)

    Ranfagni, A. [Istituto di Fisica Applicata ' Nello Carrara' , Consiglio Nazionale delle Ricerche, Via Madonna del Piano 10, 50019 Sesto Fiorentino, Firenze (Italy); Ricci, A.M. [Istituto per le Telecomunicazioni e l' Elettronica della Marina Militare ' Giancarlo Vallauri' (Mariteleradar), Viale Italia 72, 57100 Livorno (Italy); Ruggeri, R. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sezione di Firenze, Firenze (Italy)], E-mail: rocco.ruggeri@isc.cnr.it; Agresti, A. [Dipartimento di Fisica dell' Universita di Firenze, Firenze (Italy)

    2008-10-27

    Superluminal behaviors, as evidenced by the presence of forerunners, in advanced position with respect to the main luminal peak, have been revealed in microwave propagation experiments by using a radar technique. The results are interpreted on the basis of (fast) complex waves, usually considered only in the near-field region, but still surviving beyond this limit. Consideration of further diffraction effects, as due to geometrical limitations of the experimental set-up, allows for the obtainment of a plausible description of the results.

  5. Maximal refraction and superluminal propagation in a gaseous nanolayer

    CERN Document Server

    Keaveney, J; Sargsyan, A; Sarkisyan, D; Adams, C S

    2012-01-01

    We present an experimental measurement of the refractive index of high density Rb vapor in a gaseous atomic nanolayer. We use heterodyne interferometry to measure the relative phase shift between two copropagating laser beams as a function of the laser detuning and infer a peak index n = 1.26 \\pm 0.02, close to the theoretical maximum of 1.31. The large index has a concomitant large index gradient creating a region with steep anomalous dispersion where a sub-nanosecond optical pulse is advanced by >100 ps over a propagation distance of 390 nm, corresponding to a group index of -1x10^5, the largest negative group index measured to date.

  6. Universe of superluminal velocities: tests of astrophysics, from dogma-to reality

    Science.gov (United States)

    Chechelnitsky, A.

    The Barrier of speed of light is the most chained and, perhaps, the most unreasonable Interdiction of the standard (astro) physics and cosmology. Its theoretical bases are speculative and unconvincing, and it actually has not been proved by observations from the very beginning of its promulgations. Moreover, it is gradually increase a stream of the observational data frankly contradicting to the Barrier. This monumental Dogma substantially holds down the initiative of researchers and development of sciences about the Universe. Resolving proofs of absence of the Barrier and real existence of superluminal velocities can come, most likely, from the side of observational astrophysics, when appear fair predictions, based on the alternative theory. Predictions and observational Tests, in particular, are those. The advanced astrophysical researches will lead to accumulation of the precision data and construction of histograms of the velocities observable in the Universe (in the centers of galaxies, AGN, blazàrs, BL Lac, etc), which will show: i) Distribution of the transversal (in a picture plane) superluminal velocities has distinct peaks near to the values specified by the alternative theory: (in G[ -6] Shell) β =v/c: 1.77; 1.48; 1.25; 1.05; 0.88; 0.74; 0.62; 0.52; 0.44; (G[ -7] Shell) β =v/c:: 6.48 ; 5.45; 4.58; 3.85; 3.24; 2.72; 2.29; 1.92; 1.62; (G[ -8] Shell) β =v/c: 23.79; 20.00; 16.82; 14.14; 11.89; 10.00; 8.41; 7.07; 5.95 ii) The same peaks are available (already now, - and it can be shown on the basis of the spectroscopic data) in distribution (histograms) of beam (radial) superluminal velocities (with the same multiplicator M = 2 = 1.1892). iii) The predicted property of discreteness, quantization of superluminal velocities (as well as subluminal) velocities is the exclusive pattern, essentially distinguishing alternative representations (Wave Universe Concept [Chechelnitsky 1980-2004]; see, in particular, the bibliography in Advances in Space Research, v

  7. Propagation of Superluminous L-O Mode Waves During Geomagnetic Activities

    Institute of Scientific and Technical Information of China (English)

    XIAO Fuliang; CHEN Lunjin; ZHENG Huinan; ZHOU Qinghua; WANG Shui

    2008-01-01

    The effect of the azimuthal angle ψ of the wave vector k on the propagation characteristics of the superluminous L-O mode waves (together with a case of the R-X mode) during different geomagnetic activities using a three-dimensional (3D) ray-tracing method is investigated.This work is primarily an extension of our previous two-dimensional study in which the wave azimuthal angle was not considered.We present numerical simulations for this mode which is generated in the source cavity along a 70° night geomagnetic field line at the specific altitude of 1.5RE (where RE is the Earth's radius).It is found that,as in the two-dimensional case,the trajectory of L-O mode starting in the source meridian plane (or the wave azimuthal angle ψ=180°) can reach the lowest latitude;whereas it basically stays at relatively higher latitudes starting off the source meridian plane (or ψ≠180°).The results reveal that under appropriate conditions,the superluminous L-O mode waves may exist in the radiation belts of the Earth,but this remains to be supplemented by observational data.

  8. Green's function of a massless scalar field in curved space-time and superluminal phase velocity of the retarded potential

    CERN Document Server

    Dai, De-Chang

    2012-01-01

    We study a retarded potential solution of a massless scalar field in curved space-time. In a special ansatz for a particle at rest whose magnitude of the (scalar) charge is changing with time, we found an exact analytic solution. The solution indicates that the phase velocity of the retarded potential of a non-moving scalar charge is position dependent, and may easily be greater than the speed of light at a given point. In the case of the Schwarzschild space-time, at the horizon, the phase velocity becomes infinitely faster than the coordinate speed of light at that point. Superluminal phase velocity is relatively common phenomenon, with the the phase velocity of the massive Klein-Gordon field as the best known example. We discuss why it is possible to have modes with superluminal phase velocity even for a massless field.

  9. Compared propagation characteristics of superluminal and slow light in SOA and EDFA based on rectangle signals

    Science.gov (United States)

    Wang, Fu; Wang, Zhi; Wu, Chongqing; Sun, Zhenchao; Mao, Yaya; Liu, Lanlan; Li, Qiang

    2015-10-01

    Based on the general mechanism of the coherent population oscillations (CPO) in the Semiconductor optical amplifiers (SOA) and Erbium doped fiber amplifiers (EDFA), the group time delay of rectangle signal propagating in the active media is deduced. Compared with the sinusoidal signal, the time delay difference between the fundamental harmonics (FHFD: fundamental harmonic fractional delay) is first investigated in detail for the rectangle signal which is more popularly used in the digital signal systems. The plenty of simulations based on the propagation equations and some experiments for the sinusoidal and rectangle signals are used to analyze the differences and evaluate the slow and superluminal light effects. Furthermore, the time delay/advance always takes place accompanying with the signal distortion, which is evaluated by the total harmonic distortion (THD). The distortion caused by the SOA is smaller than that by the EDFA. A factor Q which is defined to evaluate the trade-off between the FHFD and the THD, shows that higher input power or higher optical gain is better for optical signal processing and optical telecommunications, and the SOA is more suitable for the higher modulation frequency (>10 GHz).

  10. Superluminal solutions to the Klein-Gordon equation and a causality problem

    CERN Document Server

    Borghardt, A A; Karpenko, D Y

    2003-01-01

    We present a new axially symmetric monochromatic free-space solution to the Klein-Gordon equation propagating with a superluminal group velocity and show that it gives rise to an imaginary part of the causal propagator outside the light cone. We address the question about causality of the spacelike paths and argue that the signal with a well-defined wavefront formed by the superluminal modes would propagate in vacuum with the light speed.

  11. Relativistic solitons and superluminal signals

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, Attilio [Technical Institute ' G. Cardano' , Piazza della Resistenza 1, Monterotondo, Rome 00015 (Italy)]. E-mail: solitone@yahoo.it

    2005-02-01

    Envelope solitons in the weakly nonlinear Klein-Gordon equation in 1 + 1 dimensions are investigated by the asymptotic perturbation (AP) method. Two different types of solitons are possible according to the properties of the dispersion relation. In the first case, solitons propagate with the group velocity (less than the light speed) of the carrier wave, on the contrary in the second case solitons always move with the group velocity of the carrier wave, but now this velocity is greater than the light speed. Superluminal signals are then possible in classical relativistic nonlinear field equations.

  12. Superluminal two-color light in a multiple Raman gain medium

    KAUST Repository

    Kudriašov, V.

    2014-09-17

    We investigate theoretically the formation of two-component light with superluminal group velocity in a medium controlled by four Raman pump fields. In such an optical scheme only a particular combination of the probe fields is coupled to the matter and exhibits superluminal propagation; the orthogonal combination is uncoupled. The individual probe fields do not have a definite group velocity in the medium. Calculations demonstrate that this superluminal component experiences an envelope advancement in the medium with respect to the propagation in vacuum.

  13. Superluminality and UV Completion

    CERN Document Server

    Shore, G M

    2007-01-01

    The idea that the existence of a consistent UV completion satisfying the fundamental axioms of local quantum field theory or string theory may impose positivity constraints on the couplings of the leading irrelevant operators in a low-energy effective field theory is critically discussed. Violation of these constraints implies superluminal propagation, in the sense that the low-frequency limit of the phase velocity $v_{\\rm ph}(0)$ exceeds $c$. It is explained why causality is related not to $v_{\\rm ph}(0)$ but to the high-frequency limit $v_{\\rm ph}(\\infty)$ and how these are related by the Kramers-Kronig dispersion relation, depending on the sign of the imaginary part of the refractive index $\\Ima n(\\w)$ which is normally assumed positive. Superluminal propagation and its relation to UV completion is investigated in detail in three theories: QED in a background electromagnetic field, where the full dispersion relation for $n(\\w)$ is evaluated numerically for the first time and the role of the null energy con...

  14. Limiting Superluminal Electron and Neutrino Velocities Using the 2010 Crab Nebula Flare and the IceCube PeV Neutrino Events

    Science.gov (United States)

    Stecker, Floyd W.

    2014-01-01

    The observation of two PetaelectronVolt (PeV)-scale neutrino events reported by Ice Cube allows one to place constraints on Lorentz invariance violation (LIV) in the neutrino sector. After first arguing that at least one of the PetaelectronVolt IceCube events was of extragalactic origin, I derive an upper limit for the difference between putative superluminal neutrino and electron velocities of less than or equal to approximately 5.6 x 10(exp -19) in units where c = 1, confirming that the observed PetaelectronVolt neutrinos could have reached Earth from extragalactic sources. I further derive a new constraint on the superluminal electron velocity, obtained from the observation of synchrotron radiation from the Crab Nebula flare of September, 2010. The inference that the greater than 1 GigaelectronVolt gamma-rays from synchrotron emission in the flare were produced by electrons of energy up to approx. 5.1 PetaelectronVolt indicates the nonoccurrence of vacuum Cerenkov radiation by these electrons. This implies a new, strong constraint on superluminal electron velocities delta(sub e) less than or equal to approximately 5 x 10(exp -21). It immediately follows that one then obtains an upper limit on the superluminal neutrino velocity alone of delta(sub v) less than or equal to approximately 5.6 x 10(exp -19), many orders of magnitude better than the time-of-flight constraint from the SN1987A neutrino burst. However, if the electrons are subluminal the constraint on the absolute value of delta(sub e) less than or equal to approximately 8 x 10(exp -17), obtained from the Crab Nebula gamma-ray spectrum, places a weaker constraint on superluminal neutrino velocity of delta(sub v) less than or equal to approximately 8 x 10(exp -17).

  15. Superluminal radiation by uniformly moving charges

    Science.gov (United States)

    Tomaschitz, Roman

    2003-03-01

    The emission of superluminal quanta (tachyons) by freely propagating particles is scrutinized. Estimates are derived for spontaneous superluminal radiation from electrons moving close to the speed of the Galaxy in the microwave background. This is the threshold velocity for tachyon radiation to occur, a lower bound. Quantitative estimates are also given for the opposite limit, tachyon radiation emitted by ultra-relativistic electrons in linear colliders and supernova shock waves. The superluminal energy flux is studied and the spectral energy density of the radiation is derived, classically as well as in second quantization. There is a transversal bosonic and a longitudinal fermionic component of the radiation. We calculate the power radiated, its angular dependence, the mean energy of the radiated quanta, absorption and emission rates, as well as tachyonic number counts. We explain how the symmetry of the Einstein /A-coefficients connects to time-symmetric wave propagation and to the Wheeler-Feynman absorber theory. A relation between the tachyon mass and the velocity of the Local Group of galaxies is suggested.

  16. Subluminal and Superluminal Phenomena in a Four-Level Atom

    Institute of Scientific and Technical Information of China (English)

    HAN Ding-An; ZENG Ya-Guang; CAO Hui

    2008-01-01

    In a four-level atomic system,we investigate the light pulse propagation properties interacting with only one laser field.It is shown that in the steady state,the group velocity of the light pulse can be changed from subluminal to superluminal by varying the field detuning.Meanwhile,the effects of the field intensity on the group velocity are also shown.At last,with special parameters,the analytical solution for the group index is also obtained.

  17. Propagation of a constant velocity fission wave

    Science.gov (United States)

    Deinert, Mark

    2011-10-01

    The ideal nuclear fuel cycle would require no enrichment, minimize the need fresh uranium, and produce few, if any, transuranic elements. Importantly, the latter goal would be met without the reprocessing. For purely physical reasons, no reactor system or fuel cycle can meet all of these objectives. However, a traveling-wave reactor, if feasible, could come remarkably close. The concept is simple: a large cylinder of natural (or depleted) uranium is subjected to a fast neutron source at one end, the neutrons would transmute the uranium downstream and produce plutonium. If the conditions were right, a self-sustaining fission wave would form, producing yet more neutrons which would breed more plutonium and leave behind little more than short-lived fission products. Numerical studies have shown that fission waves of this type are also possible. We have derived an exact solution for the propagation velocity of a fission wave through fertile material. The results show that these waves fall into a class of traveling wave phenomena that have been encountered in other systems. The solution places a strict conditions on the shapes of the flux, diffusive, and reactive profiles that would be required for such a phenomenon to persist. The results are confirmed numerically.

  18. Gamow's bicycle: The Appearance of Bodies at Relativistic Speeds and Apparent Superluminal Velocities

    CERN Document Server

    Nowojewski, A

    2005-01-01

    A human creates an image basing on the information delivered by photons that arrived at his retina simultaneously. Due to finite and constant velocity of light these photons left the moving body at different times, since not all points of the body are equidistant. In other words its image represents the body as it was in several different times i.e. it is distorted and does not correspond to its real appearance. The useful experimental arrangement is set and then used to derive the general expression that transforms two-dimensional stationary shapes to their apparent forms, which could be photographed once they are set in motion. It is then used to simulate the so-called Gamow's bicycle combined out of circles and straight lines. The simulation outlines two important aspects of bike's motion: apparent distance of two points and apparent velocity which are then discussed thoroughly. It is found that the approaching body is elongated and its apparent speed is greater than its real one (under certain conditions ...

  19. Superluminal reflection and transmission of light pulses via resonant four-wave mixing in cesium vapor.

    Science.gov (United States)

    Jiang, Qichang; Zhang, Yan; Wang, Dan; Ahrens, Sven; Zhang, Junxiang; Zhu, Shiyao

    2016-10-17

    We report the experimental manipulation of the group velocities of reflected and transmitted light pulses in a degenerate two-level atomic system driven by a standing wave, which is created by two counter-propagating light beams of equal frequencies but variable amplitudes. It is shown that the light pulse is reflected with superluminal group velocity while the transmitted pulse propagates from subluminal to superluminal velocities via changing the power of the backward coupling field. We find that the simultaneous superluminal light reflection and transmission can be reached when the power of the backward field becomes closer or equal to the forward power, in this case the periodical absorption modulation for photonic structure is established in atoms. The theoretical discussion shows that the anomalous dispersion associated with a resonant absorption dip within the gain peak due to four-wave mixing leads to the superluminal reflection, while the varying dispersion from normal to anomalous at transparency, transparency within absorption, and electromagnetically induced absorption windows leads to the subluminal to superluminal transmission.

  20. Velocity and directionality of the electrohysterographic signal propagation.

    Directory of Open Access Journals (Sweden)

    Lasse Lange

    Full Text Available OBJECTIVE: The initiation of treatment for women with threatening preterm labor requires effective distinction between true and false labor. The electrohysterogram (EHG has shown great promise in estimating and classifying uterine activity. However, key issues remain unresolved and no clinically usable method has yet been presented using EHG. Recent studies have focused on the propagation velocity of the EHG signals as a potential discriminator between true and false labor. These studies have estimated the propagation velocity of individual spikes of the EHG signals. We therefore focus on estimating the propagation velocity of the entire EHG burst recorded during a contraction in two dimensions. STUDY DESIGN: EHG measurements were performed on six women in active labor at term, and a total of 35 contractions were used for the estimation of propagation velocity. The measurements were performed using a 16-channel two-dimensional electrode grid. The estimates were calculated with a maximum-likelihood approach. RESULTS: The estimated average propagation velocity was 2.18 (±0.68 cm/s. No single preferred direction of propagation was found. CONCLUSION: The propagation velocities estimated in this study are similar to those reported in other studies but with a smaller intra- and inter-patient variation. Thus a potential tool has been established for further studies on true and false labor contractions.

  1. Variation of Quench Propagation Velocities in YBCO Cables

    CERN Document Server

    Härö, E.; Stenvall, A.; 10.1007/s10948-015-2976-y

    2015-01-01

    changes during the quench. Due to the large temperature margin between the operation and the current sharing temperatures, the normal zone does not propagate with the temperature front. This means that the temperature will rise in a considerably larger volume when compared to the quenched volume. Thus, the evolution of the temperature distribution below current sharing temperature Tcs after the quench onset affects the normal zone propagation velocity in HTS more than in LTS coils. This can be seen as an acceleration of the quench propagation velocities while the quench evolves when margin to Tcs is high. In this paper we scrutinize quench propagation in a stack of YBCO cables with an in-house finite element method software which solves the heat diffusion equation. We compute the longitudinal and transverse normal zone propagation velocities at various distances from the hot spot to demonstrate the distance-variation...

  2. Electrohysterography of labor contractions: propagation velocity and direction

    NARCIS (Netherlands)

    Mikkelsen, E.; Johansen, P.; Fuglsang-Frederiksen, A.; Uldbjerg, N.

    2013-01-01

    OBJECTIVE: Electrohysterographic assessment of the propagation velocity of uterine depolarization has been introduced as a promising predictor of preterm labor. Therefore, the objectives of this study were to characterize the uterine electrohysterographic signals during labor and to determine the pr

  3. Longitudinal propagation velocity of the normal zone in superconducting wires

    NARCIS (Netherlands)

    Kate, ten H.H.J.; Boschman, H.; Klundert, van de L.J.M.

    1987-01-01

    The longitudinal propagation of the normal zone in superconducting wires was experimentally investigated in order to evaluate existing analytical expressions which attempt to describe the propagation velocity in a more or less simple manner. The availability of a reliable expression is important for

  4. Inverse Doppler shift and control field as coherence generators for the stability in superluminal light

    Science.gov (United States)

    Ghafoor, Fazal; Bacha, Bakht Amin; Khan, Salman

    2015-05-01

    A gain-based four-level atomic medium for the stability in superluminal light propagation using control field and inverse Doppler shift as coherence generators is studied. In regimes of weak and strong control field, a broadband and multiple controllable transparency windows are, respectively, identified with significantly enhanced group indices. The observed Doppler effect for the class of high atomic velocity of the medium is counterintuitive in comparison to the effect of the class of low atomic velocity. The intensity of each of the two pump fields is kept less than the optimum limit reported in [M. D. Stenner and D. J. Gauthier, Phys. Rev. A 67, 063801 (2003), 10.1103/PhysRevA.67.063801] for stability in the superluminal light pulse. Consequently, superluminal stable domains with the generated coherence are explored.

  5. Superluminal antenna

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John; Earley, Lawrence M.; Krawczyk, Frank L.; Potter, James M.; Romero, William P.; Wang, Zhi-Fu

    2017-03-28

    A superluminal antenna element integrates a balun element to better impedance match an input cable or waveguide to a dielectric radiator element, thus preventing stray reflections and consequent undesirable radiation. For example, a dielectric housing material can be used that has a cutout area. A cable can extend into the cutout area. A triangular conductor can function as an impedance transition. An additional cylindrical element functions as a sleeve balun to better impedance match the radiator element to the cable.

  6. Lightning location with variable radio wave propagation velocity

    Science.gov (United States)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Sugier, Jacqueline; Fullekrug, Martin

    2016-04-01

    Lightning discharges can be located by triangulation of their broadband electromagnetic pulses in long-baseline (~500 km) radio receiver networks. Here we apply the time of arrival difference (TOA) method to electric field recordings with a low frequency radio receiver array consisting of four stations in western Europe. The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for the TOA calculation and it is normally assumed to be equal to the speed of light. However, the radio wave propagation depends for example on the frequency, ground conductivity and the ionospheric height and small variations can cause location differences from hundreds to thousands of meters, as demonstrated in this study. The radio wave propagation from two VLF transmissions at 20.9 kHz and 23.4 kHz are compared. The results show that the apparent phase velocities are 0.6% slower and 0.5% faster than the speed of light respectively. As a result, a variable velocity is implemented in the TOA method using continuously recorded data on the 8th August 2014, when a mesoscale convective system developed over central France. The lightning locations inferred with a variable wave propagation velocity are more clustered than those using a fixed velocity. The distribution of the lightning velocities in a given geographic area fits a normal distribution that is not centred at the speed of light. As a result, representative velocities can be calculated for smaller regions to generate a velocity map over a larger area of enhanced lightning activity. These results suggest a connection with the ground elevation and/or surface conductivity that might have an impact on the observed wave propagation velocities.

  7. Superluminality in the Bi- and Multi Galileon

    CERN Document Server

    de Fromont, Paul; Heisenberg, Lavinia; Matas, Andrew

    2013-01-01

    We re-explore the Bi- and Multi-Galileon models with trivial asymptotic conditions at infinity and show that propagation of superluminal fluctuations is a common and unavoidable feature of these theories, unlike previously claimed in the literature. We show that all Multi-Galileon theories containing a Cubic Galileon term exhibit superluminalities at large distances from a point source, and that even if the Cubic Galileon is not present one can always find sensible matter distributions in which there are superluminal modes at large distances. In the Bi-Galileon case we explicitly show that there are always superluminal modes around a point source even if the Cubic Galileon is not present. Finally, we briefly comment on the possibility of avoiding superluminalities by modifying the asymptotic conditions at infinity.

  8. Study of quench propagation velocity in superconducting magnets for UNK

    Energy Technology Data Exchange (ETDEWEB)

    Bogdanov, I.V.; Sheherbakov, P.A.; Snitko, V.P.; Tkachenko, N.P.; Vasiliev, L.M.; Vybornov, M.G.; Ziobin, A.V.

    1989-03-01

    Two superconducting magnet models, warm-iron and cold-iron designs are studied within the frames of work on UNK. The present note describes the method and results on measuring quench propagation velocity in the superconducting cables with a transport current in external field under the cooling conditions typical for those of the magnet winding. The results on measuring quench propagation velocities in warm-iron and cold-iron designs are presented. The results obtained for short samples and model coils are compared.

  9. Estimating propagation velocity through a surface acoustic wave sensor

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wenyuan (Oakdale, MN); Huizinga, John S. (Dellwood, MN)

    2010-03-16

    Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

  10. Estimating propagation velocity through a surface acoustic wave sensor

    Science.gov (United States)

    Xu, Wenyuan; Huizinga, John S.

    2010-03-16

    Techniques are described for estimating the propagation velocity through a surface acoustic wave sensor. In particular, techniques which measure and exploit a proper segment of phase frequency response of the surface acoustic wave sensor are described for use as a basis of bacterial detection by the sensor. As described, use of velocity estimation based on a proper segment of phase frequency response has advantages over conventional techniques that use phase shift as the basis for detection.

  11. Superluminal Black Holes

    CERN Document Server

    Dolgov, D S

    1993-01-01

    The new solution of the Einstein equations in empty space is presented. The solution is constructed using Schwarzschild solution but essentially differs from it. The basic properties of the solution are: the existence of a horizon which is a hyperboloid of one sheet moving along its axis with superluminal velocity, right signature of the metric outside the horizon and Minkovsky-flatness of it at infinity outside the horizon. There is also a discussion in the last chapter, including comparing with recent astronomical observations.

  12. Challenges Confronting Superluminal Neutrino Models

    Science.gov (United States)

    Evslin, Jarah

    2012-12-01

    This talk opens the CosPA2011 session on OPERA's superluminal neutrino claim. I summarize relevant observations and constraints from OPERA, MINOS, ICARUS, KamLAND, IceCube and LEP as well as observations of SN1987A. I selectively review some models of neutrino superluminality which have been proposed since OPERA's announcement, focusing on a neutrino dark energy model. Powerful theoretical constraints on these models arise from Cohen-Glashow bremsstrahlung and from phase space requirements for the initial neutrino production. I discuss these constraints and how they might be evaded in models in which the maximum velocities of both neutrinos and charged leptons are equal but only superluminal inside of a dense medium.

  13. Challenges Confronting Superluminal Neutrino Models

    CERN Document Server

    Evslin, Jarah

    2011-01-01

    This talk opens the CosPA2011 session on OPERA's superluminal neutrino claim. I summarize relevant observations and constraints from OPERA, MINOS, ICARUS, KamLAND, IceCube and LEP as well as observations of SN1987A. I selectively review some models of neutrino superluminality which have been proposed since OPERA's announcement, focusing on a neutrino dark energy model. Powerful theoretical constraints on these models arise from Cohen-Glashow bremsstrahlung and from phase space requirements for the initial neutrino production. I discuss these constraints and how they might be evaded in models in which the maximum velocities of both neutrinos and charged leptons are equal but only superluminal inside of a dense medium.

  14. Normal Wave Propagation Velocity in a Static Web.

    Science.gov (United States)

    1986-12-01

    34 " " ’ . " . " . " " . " , " " . " -" " " " . " " . " " " " . " * . - " " " , 4 . " . " . " " " . " " "." "-" "." " . . . . . " " " " -w A- INah . . . . . . - - 1 NORMAL WAVE PROPAGATION VELOCITY IN A STATIC WEB By

  15. Transverse, Propagating Velocity Perturbations in Solar Coronal Loops

    CERN Document Server

    De Moortel, I; Wright, A N; Hood, A W

    2015-01-01

    This short review paper gives an overview of recently observed transverse, propagating velocity perturbations in coronal loops. These ubiquitous perturbations are observed to undergo strong damping as they propagate. Using 3D numerical simulations of footpoint-driven transverse waves propagating in a coronal plasma with a cylindrical density structure, in combination with analytical modelling, it is demonstrated that the observed velocity perturbations can be understood in terms of coupling of different wave modes in the inhomogeneous boundaries of the loops. Mode coupling in the inhomogeneous boundary layers of the loops leads to the coupling of the transversal (kink) mode to the azimuthal (Alfven) mode, observed as the decay of the transverse kink oscillations. Both the numerical and analytical results show the spatial profile of the damped wave has a Gaussian shape to begin with, before switching to exponential decay at large heights. In addition, recent analysis of CoMP (Coronal Multi-channel Polarimeter)...

  16. Velocity requirements for causality violation

    CERN Document Server

    Modanese, Giovanni

    2013-01-01

    It is known that the hypothetical existence of superluminal signals would imply the logical possibility of active causal violation: an observer in relative motion with respect to a primary source could in principle emit secondary superluminal signals (triggered by the primary ones) which go back in time and deactivate the primary source before the initial emission. This is a direct consequence of the structure of the Lorentz transformations, sometimes called "Regge-Tolman paradox". It is straightforward to find a formula for the velocity of the moving observer required to produce the causality violation. When applied to some recent claims of slight superluminal propagation, this formula yields a required velocity very close to the speed of light; this raises some doubts about the real physical observability of such violations. We re-compute this velocity requirement introducing a realistic delay between the reception of the primary signal and the emission of the secondary. It turns out that for -any- delay it...

  17. Particle velocity non-uniformity and steady-wave propagation

    Science.gov (United States)

    Meshcheryakov, Yu. I.

    2017-03-01

    A constitutive equation grounded in dislocation dynamics is shown to be incapable of describing the propagation of shock fronts in solids. Shock wave experiments and theoretical investigations motivate an additional collective mechanism of stress relaxation that should be incorporated into the model through the standard deviation of the particle velocity, which is found to be proportional to the strain rate. In this case, the governing equation system results in a second-order differential equation of square non-linearity. Solution to this equation and calculations for D16 aluminum alloy show a more precise coincidence of the theoretical and experimental velocity profiles.

  18. Wave Scattering by Superluminal Spacetime Slab

    CERN Document Server

    Deck-Léger, Zoé-Lise

    2016-01-01

    Spacetime media offers new opportunities for wave manipulation. Here we study superluminal slabs, and show that the amplitudes of the reflected waves are controlled by the velocity of the medium. In addition, the backward wave continuously scans from the specular to the collinear angle. A diagrammatic method is provided for insight into the deflection angles. A fundamental symmetry between sub- and superluminal scattering is derived from this diagrammatic description.

  19. Mitral flow propagation velocity in non-sedated healthy cats

    OpenAIRE

    SILVA, A.C.; R.A.L. Muzzi; G. Oberlender; L.A.L. Muzzi; M.R. Coelho; R.B. Nogueira

    2014-01-01

    Mitral flow propagation velocity (Vp) is an index used to evaluate the left ventricular diastolic function. Its influence on human and small animal cardiopathies has been studied; however there are few reports evaluating this variable in domestic felines. In addition, there is a lack of studies in non-sedated healthy cats. Therefore, the purpose of this study was to establish values for Vp and its correlation with other echocardiographic indexes in non-sedated healthy cats in order to provide...

  20. Probing Superluminal Neutrinos Via Refraction

    OpenAIRE

    Stebbins, Albert

    2011-01-01

    One phenomenological explanation of superluminal propagation of neutrinos, which may have been observed by OPERA and MINOS, is that neutrinos travel faster inside of matter than in vacuum. If so neutrinos exhibit refraction inside matter and should exhibit other manifestations of refraction, such as deflection and reflection. Such refraction would be easily detectable through the momentum imparted to appropriately shaped refractive material inserted into the neutrino beam. For NuMI this could...

  1. Symmetry, causal structure and superluminality in Finsler spacetime

    CERN Document Server

    Chang, Zhe; Wang, Sai

    2012-01-01

    The superluminal behaviors of neutrinos were reported by the OPERA collaboration recently. It was also noticed by Cohen and Glashow that, in standard quantum field theory, the superluminal neutrinos would lose their energy via the Cherenkov-like process rapidly. Finslerian special relativity may provide a framework to cooperate with the OPERA neutrino superluminality without Cherenkov-like process. We present clearly the symmetry, causal structure and superluminality in Finsler spacetime. The principle of relativity and the causal law are preserved. The energy and momentum are well defined and conserved in Finslerian special relativity. The Cherenkov-like process is proved to be forbidden kinematically and the superluminal neutrinos would not lose energy in their distant propagations from CERN to the Gran Sasso Laboratory. The energy dependence of neutrino superluminality is studied based on the reported data of the OPERA collaboration as well as other groups.

  2. Apparent faster than light propagation from light sterile neutrinos

    CERN Document Server

    Hannestad, Steen

    2011-01-01

    Recent data from the OPERA experiment seem to point to neutrinos propagating faster than light. One possible physics explanation for such a result is the existence of light sterile neutrinos which can propagate in a higher dimensional bulk and achieve apparent superluminal velocities when measured by an observer confined to the 4D brane of the standard model. Such a model has the advantage of easily being able to explain the non-observation of superluminal neutrinos from SN1987A. Here we discuss the phenomenological implications of such a model and show that it can provide an explanation for the observed faster than light propagation of neutrinos.

  3. On the Superluminal Motion of Radio-Loud AGNs

    Indian Academy of Sciences (India)

    Zhi-Bin Zhang; Yi-Zhen Zhang

    2011-03-01

    Apparent superluminal motion of different radio-loud AGNs are similarly related with beaming effect. The cosmological expanding effect would play no part in the superluminal motion of radio galaxies, BL Lacertae objects as well as quasars.Meanwhile, we confirm that estimates for apparent velocity app and Doppler boosting factor based on multi-wavelength combination and variability are comparable.

  4. The Phantom of the OPERA: Superluminal Neutrinos

    CERN Document Server

    Ma, Bo-Qiang

    2011-01-01

    This report presents a brief review on the experimental measurements of the muon neutrino velocities from the OPERA, Fermilab and MINOS experiments and that of the (anti)-electron neutrino velocities from the supernova SN1987a, and consequently on the theoretical aspects to attribute the data as signals for superluminality of neutrinos. Different scenarios on how to understand and treat the background fields in the standard model extension frameworks are pointed out. Challenges on interpreting the OPERA result as a signal of neutrino superluminality are briefly reviewed and discussed. It is also pointed out that a covariant scenario of Lorentz violation can avoid the refutation on the OPERA experiment.

  5. Stimulated generation of superluminal light pulses via four-wave mixing.

    Science.gov (United States)

    Glasser, Ryan T; Vogl, Ulrich; Lett, Paul D

    2012-04-27

    We report on the four-wave mixing of superluminal pulses, in which both the injected and generated pulses involved in the process propagate with negative group velocities. Generated pulses with negative group velocities of up to v(g)=-1/880c are demonstrated, corresponding to the generated pulse's peak exiting the 1.7 cm long medium ≈50 ns earlier than if it had propagated at the speed of light in vacuum, c. We also show that in some cases the seeded pulse may propagate with a group velocity larger than c, and that the generated conjugate pulse peak may exit the medium even earlier than the amplified seed pulse peak. We can control the group velocities of the two pulses by changing the seed detuning and the input seed power.

  6. Superluminality in the Bi- and Multi-Galileon

    Science.gov (United States)

    de Fromont, Paul; de Rham, Claudia; Heisenberg, Lavinia; Matas, Andrew

    2013-07-01

    We re-explore the Bi- and Multi-Galileon models with trivial asymptotic conditions at infinity and show that propagation of superluminal fluctuations is a common and unavoidable feature of these theories, unlike previously claimed in the literature. We show that all Multi-Galileon theories containing a Cubic Galileon term exhibit superluminalities at large distances from a point source, and that even if the Cubic Galileon is not present one can always find sensible matter distributions in which there are superluminal modes at large distances. In the Bi-Galileon case we explicitly show that there are always superluminal modes around a point source even if the Cubic Galileon is not present. Finally, we briefly comment on the possibility of avoiding superluminalities by modifying the asymptotic conditions at infinity.

  7. Echocardiographic determinants of mitral early flow propagation velocity.

    Science.gov (United States)

    Barbier, Paolo; Grimaldi, Antonio; Alimento, Marina; Berna, Giovanni; Guazzi, Maurizio D

    2002-09-15

    Transmitral color Doppler early diastolic flow propagation velocity (Vp) has been correlated with the left ventricular (LV) relaxation time constant tau in dilated cardiomyopathy and ischemic heart disease. The aim of this study was to investigate the independent influence of LV systolic function and geometry, and of LV relaxation, on Vp in an unselected outpatient population. We studied 30 normal subjects and 130 patients (hypertensive LV hypertrophy, aortic valve stenosis or prosthesis, hypertrophic cardiomyopathy, coronary artery disease, dilated cardiomyopathy, aortic or mitral valve regurgitation). In all, we noninvasively measured LV geometry, mass, systolic function, wall motion dyssynergy, and diastolic function (abnormal relaxation or restrictive LV Doppler filling patterns). The Vp was similar in normal subjects and in patients (51 +/- 14 vs 53 +/- 25 cm/s). In normal subjects, the determinants of Vp at multiple regression analysis were isovolumic relaxation time, 2-dimensional cardiac index, and mitral E-wave velocity-time integral. In all, the main determinants were LV ejection fraction, percent of segmental wall dyssynergy, and isovolumic relaxation time and age. The Vp was highest in hypertrophic (75 +/- 25 cm/s, p <0.05 vs normal subjects) and lowest in dilated (35 +/- 13 cm/s, p = NS) cardiomyopathy. During multivariate analysis of variance, percent of wall dyssynergy (but not diffuse LV hypokinesia) independently reduced Vp (p = 0.02). The latter was not influenced by the LV filling pattern. Thus, in an unselected clinical population, prolonged relaxation per se does not influence Vp if LV systolic dysfunction and/or wall dyssynergy is absent-the latter factors are important independent determinants of Vp, which is determined by multiple factors.

  8. Extended Lorentz code of a superluminal particle

    CERN Document Server

    Ter-Kazarian, G

    2012-01-01

    While the OPERA experimental scrutiny is ongoing in the community, in the present article we construct a toy model of {\\it extended Lorentz code} (ELC) of the uniform motion, which will be a well established consistent and unique theoretical framework to explain the apparent violations of the standard Lorentz code (SLC), the possible manifestations of which arise in a similar way in all particle sectors. We argue that in the ELC-framework the propagation of the superluminal particle, which implies the modified dispersion relation, could be consistent with causality. Furthermore, in this framework, we give a justification of forbiddance of Vavilov-Cherenkov (VC)-radiation/or analog processes in vacuum. To be consistent with the SN1987A and OPERA data, we identify the neutrinos from SN1987A and the light as so-called {\\it 1-th type} particles carrying the {\\it individual Lorentz motion code} with the velocity of light $c_{1}\\equiv c$ in vacuum as maximum attainable velocity for all the 1-th type particles. Ther...

  9. Mitral flow propagation velocity in non-sedated healthy cats

    Directory of Open Access Journals (Sweden)

    A.C. Silva

    2014-02-01

    Full Text Available Mitral flow propagation velocity (Vp is an index used to evaluate the left ventricular diastolic function. Its influence on human and small animal cardiopathies has been studied; however there are few reports evaluating this variable in domestic felines. In addition, there is a lack of studies in non-sedated healthy cats. Therefore, the purpose of this study was to establish values for Vp and its correlation with other echocardiographic indexes in non-sedated healthy cats in order to provide new perspectives related to diastolic function in this species. Twenty-six clinically healthy cats were submitted to echocardiography to assess the animals' cardiac conditions. Variables such as age, heart rate (HR, body surface area (BSA, initial (E mitral and late (A mitral ventricular filling waves, isovolumic relaxation time (IVRT and E/IVRT relation were correlated to Vp. No proven relation between any of these variables and Vp was observed in this present study, except for HR and BSA. In the variability analysis, higher values were verified for inter-observer analysis. This study concludes that Vp proved to be an useful index for estimating left ventricular relaxation in non-sedated healthy domestic cats and provides reference ranges for this variable.

  10. Field test and theoretical analysis of electromagnetic pulse propagation velocity on crossbonded cable systems

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Bak, Claus Leth; Gudmundsdottir, Unnur Stella

    2014-01-01

    In this paper, the electromagnetic pulse propagation velocity on a three-phase cable system, consisting of three single core (SC) cables in flat formation with an earth continuity conductor is under study. The propagation velocity is an important parameter for most travelling wave off- and online...

  11. 光纤中基于布里渊激光振荡的超光速传输首次在实验上实现%Superluminal Propagation in Optical Fibers Based on Brillouin Lasing Oscillation First Demonstrated

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    上海交通大学物理系詹黎教授(图1)以及其博士研究生张亮(图2)首次在实验上实现了光纤中基于布里渊激光振荡的低损耗长距离超光速传输,其研究成果以"Superluminal propagation at negative groupvelocity in optical fibers based on Brillouin lasing oscillation"为标题发表在物理领域国际顶级期刊物理评论快报( Physical Review Letters)(Phys.Rev.Lett.,Vol.107,093903,2011).

  12. Propagation Curve and Velocity of Swallowing Pressure in Healthy Young Adults.

    Science.gov (United States)

    Matsubara, Keigo; Kumai, Yoshihiko; Samejima, Yasuhiro; Yumoto, Eiji

    2015-12-01

    The objective of this study is to construct a propagation curve and determine propagation velocities in young healthy adults examined using a 2.64-mm-diameter high-resolution manometry catheter with 36 circumferential sensors; to explore data reproducibility; and to determine whether the swallowing pressure (SP) propagation velocity correlated with bolus volume. Repeated measures with subjects serving as their own controls. Thirty healthy subjects (average age 25.3 years) swallowed saliva and 2, 5, and 10 mL of cold water to determine the maximum SP from the soft palate to the cervical esophagus. The SP propagation curve was obtained by plotting the duration to reach each SP peak. The SP propagation velocity was calculated for each region. These parameters were examined according to bolus size and gender. The intra-class correlation coefficient for estimating the SP propagation curves was >0.61 (i.e., highly consistent). The propagation velocity was maximal at the meso-hypopharynx and minimal at the UES and cervical esophagus. The SP propagation curve was very reproducible within any subject. Neither the water volume (with the exception of 2 and 5 mL) nor gender exerted any apparent effect on velocity in any region. However, the velocity was quite variable at the cervical esophagus.

  13. Ultrasonic Pulse Propagation in Constant-Group-Velocity Media.

    Science.gov (United States)

    1982-06-01

    Results are presented of calculations made of distortion experienced by ultrasonic pulses in transmission through dispersive constant-group-velocity media, and the effects that it may have on velocity measurements. Three types of pulses were considered; a pulsed sine wave of constant amplitude, a pulsed sine wave with amplitude varying as sine-squared, and a rectangular pulse. It is shown that the individual waves in the pulsed sine waves move with the phase velocity of a continuous wave, and the envelope moves with the group velocity

  14. Nonlinearity without Superluminality

    CERN Document Server

    Kent, A

    2002-01-01

    Quantum theory is compatible with special relativity. In particular, though measurements on entangled systems are correlated in a way that cannot be reproduced by local hidden variables, they cannot be used for superluminal signalling. As Gisin and Polchinski first pointed out, this is not true for general nonlinear modifications of the Schroedinger equation. Excluding superluminal signalling has thus been taken to rule out most nonlinear versions of quantum theory. The no superluminal signalling constraint has also been used for alternative derivations of the optimal fidelities attainable for imperfect quantum cloning and other operations. These results apply to theories satisfying the rule that their predictions for widely separated and slowly moving entangled systems can be approximated by non-relativistic equations of motion with respect to a preferred time coordinate. This paper describes a natural way in which this rule might fail to hold. In particular, it is shown that quantum readout devices which di...

  15. Is ‘Superluminal’Light Propagation Possible in Dispersive Media?

    Institute of Scientific and Technical Information of China (English)

    CHEN Kai; WU Ling-An; SHIH Yan-Hua

    2004-01-01

    @@ In a dispersive medium, different monochromatic modes of light have different phase velocities. Under special circumstances, a superposition of these modes results in an interesting effect wherein the group velocity (the velocity at which the peak of the wavepacket propagates) could be greater than c or even negative although the phase velocities of the modes are all less than c. Can this superluminal group velocity be used for information velocity of its component modes. Thus the maximum speed for information transfer, which involves the sending of a finite pulse, cannot be greater than the maximum phase velocity in the medium.

  16. Propagator for a Time-Dependent Damped Harmonic Oscillator with a Force Quadratic in Velocity

    Institute of Scientific and Technical Information of China (English)

    HUANG Bo-Wen; GU Zhi-Yu; QIAN Shang-Wu

    2003-01-01

    The propagator for a time-dependent damped harmonic oscillator with a force quadratic in velocity isobtained by making a specific coordinate transformation and by using the method of time-dependent invariant.

  17. Flow propagation velocity is not a simple index of diastolic function in early filling. A comparative study of early diastolic strain rate and strain rate propagation, flow and flow propagation in normal and reduced diastolic function

    Directory of Open Access Journals (Sweden)

    Skjaerpe Terje

    2003-04-01

    Full Text Available Abstract Background Strain Rate Imaging shows the filling phases of the left ventricle to consist of a wave of myocardial stretching, propagating from base to apex. The propagation velocity of the strain rate wave is reduced in delayed relaxation. This study examined the relation between the propagation velocity of strain rate in the myocardium and the propagation velocity of flow during early filling. Methods 12 normal subjects and 13 patients with treated hypertension and normal systolic function were studied. Patients and controls differed significantly in diastolic early mitral flow measurements, peak early diastolic tissue velocity and peak early diastolic strain rate, showing delayed relaxation in the patient group. There were no significant differences in EF or diastolic diameter. Results Strain rate propagation velocity was reduced in the patient group while flow propagation velocity was increased. There was a negative correlation (R = -0.57 between strain rate propagation and deceleration time of the mitral flow E-wave (R = -0.51 and between strain rate propagation and flow propagation velocity and there was a positive correlation (R = 0.67 between the ratio between peak mitral flow velocity / strain rate propagation velocity and flow propagation velocity. Conclusion The present study shows strain rate propagation to be a measure of filling time, but flow propagation to be a function of both flow velocity and strain rate propagation. Thus flow propagation is not a simple index of diastolic function in delayed relaxation.

  18. A new heat propagation velocity prevails over Brownian particle velocities in determining the thermal conductivities of nanofluids

    Directory of Open Access Journals (Sweden)

    Chon Chan

    2011-01-01

    Full Text Available Abstract An alternative insight is presented concerning heat propagation velocity scales in predicting the effective thermal conductivities of nanofluids. The widely applied Brownian particle velocities in published literature are often found too slow to describe the relatively higher nanofluid conductivities. In contrast, the present model proposes a faster heat transfer velocity at the same order as the speed of sound, rooted in a modified kinetic principle. In addition, this model accounts for both nanoparticle heat dissipation as well as coagulation effects. This novel model of effective thermal conductivities of nanofluids agrees well with an extended range of experimental data.

  19. Normal zone propagation in adiabatic superconducting magnets: Pt. 1; Normal zone propagation velocity in superconducting composites

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Z.P.; Iwasa, Y. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Francis Bitter National Magnet Lab. Massachusetts Inst. of Tech., Cambridge, MA (United States). Plasma Fusion Center)

    1991-09-01

    A normal zone propagation model has been developed for superconducting composites under adiabatic conditions. It is based on the Whetstone-Roos model, originally developed for normal zone propagation in adiabatic wires of unclad superconductor. The model takes into account the temperature and magnetic field dependent material properties, for both superconductor and matrix metal. Analytical results agree well with experimental data. (author).

  20. On Superluminal Particles and the Extended Relativity Theories

    Science.gov (United States)

    Castro, Carlos

    2012-09-01

    Superluminal particles are studied within the framework of the Extended Relativity theory in Clifford spaces ( C-spaces). In the simplest scenario, it is found that it is the contribution of the Clifford scalar component π of the poly-vector-valued momentum which is responsible for the superluminal behavior in ordinary spacetime due to the fact that the effective mass {M} = sqrt{ M2 - π2 } is imaginary (tachyonic). However, from the point of view of C-space, there is no superluminal (tachyonic) behavior because the true physical mass still obeys M 2>0. Therefore, there are no violations of the Clifford-extended Lorentz invariance and the extended Relativity principle in C-spaces. It is also explained why the charged muons (leptons) are subluminal while its chargeless neutrinos may admit superluminal propagation. A Born's Reciprocal Relativity theory in Phase Spaces leads to modified dispersion relations involving both coordinates and momenta, and whose truncations furnish Lorentz-violating dispersion relations which appear in Finsler Geometry, rainbow-metrics models and Double (deformed) Special Relativity. These models also admit superluminal particles. A numerical analysis based on the recent OPERA experimental findings on alleged superluminal muon neutrinos is made. For the average muon neutrino energy of 17 GeV, we find a value for the magnitude |{M } | = 119.7 MeV that, coincidentally, is close to the mass of the muon m μ =105.7 MeV.

  1. Variable phase propagation velocity for long-range lightning location system

    Science.gov (United States)

    Liu, Zhongjian; Koh, Kuang Liang; Mezentsev, Andrew; Enno, Sven-Erik; Sugier, Jacqueline; Füllekrug, Martin

    2016-11-01

    The electromagnetic wave propagation velocity at low radio frequencies is an important input parameter for lightning location systems that use time of arrival (TOA) method. This velocity is normally fixed at or near the speed of light. However, this study finds that the radio waves from two submarine communication transmitters at 20.9 kHz and 23.4 kHz exhibit phase propagation velocities that are 0.51% slower and 0.64% faster than the speed of light as a result of sky wave contributions and ground effects. Therefore, a novel technique with a variable phase propagation velocity is implemented for the first time in the TOA method and applied to electric field recordings with a long-baseline lightning location system that consists of four radio receivers in western Europe. The lightning locations inferred from variable velocities improve the accuracy of locations inferred from a fixed velocity by 0.89-1.06 km when compared to the lightning locations reported by the UK MetOffice. The normal distributions of the observed phase propagation velocities in small geographic areas are not centered at the speed of light. Consequently, representative velocities can be calculated for many small geographic areas to produce a velocity map over central France where numerous lightning discharges occurred. This map reflects the impact of sky waves and ground effects on the calculation of lightning locations as a result of the network configuration. It is concluded that the use of variable phase propagation velocities mitigates the influence of sky waves and ground effects in long-range lightning location networks.

  2. Propagation velocities of laser-produced plasmas from copper wire targets and water droplets

    Science.gov (United States)

    Song, Kyo-Dong; Alexander, Dennis R.

    1994-01-01

    Experiments were performed to determine the plasma propagation velocities resulting from KrF laser irradiation of copper wire target (75 microns diameter) and water droplets (75 microns diameter) at irradiance levels ranging from 25 to 150 GW/sq cm. Plasma propagation velocities were measured using a streak camera system oriented orthogonally to the high-energy laser propagation axis. Plasma velocities were studied as a function of position in the focused beam. Results show that both the shape of the plasma formation and material removal from the copper wire are different and depend on whether the targets are focused or slightly defocused (approximately = 0.5 mm movement in the beam axis). Plasma formation and its position relative to the target is an important factor in determining the practical focal point during high-energy laser interaction with materials. At irradiance of 100 GW/sq cm, the air plasma has two weak-velocity components which propagate toward and away from the incident laser while a strong-velocity component propagates away from the laser beam as a detonation wave. Comparison of the measured breakdown velocities (in the range of 2.22-2.27 x 10(exp 5) m/s) for air and the value calculated by the nonlinear breakdown wave theory at irradiance of 100 GW/sq cm showed a quantitative agreement within approximately 50% while the linear theory and Gaussian pulse theory failed. The detonation wave velocities of plasma generated from water droplets and copper wire targets for different focused cases were measured and analyzed theoretically. The propagation velocities of laser-induced plasma liquid droplets obtained by previous research are compared with current work.

  3. Field signature for apparently superluminal particle motion

    Science.gov (United States)

    Land, Martin

    2015-05-01

    In the context of Stueckelberg's covariant symplectic mechanics, Horwitz and Aharonovich [1] have proposed a simple mechanism by which a particle traveling below light speed almost everywhere may exhibit a transit time that suggests superluminal motion. This mechanism, which requires precise measurement of the particle velocity, involves a subtle perturbation affecting the particle's recorded time coordinate caused by virtual pair processes. The Stueckelberg framework is particularly well suited to such problems, because it permits pair creation/annihilation at the classical level. In this paper, we study a trajectory of the type proposed by Horwitz and Aharonovich, and derive the Maxwell 4-vector potential associated with the motion. We show that the resulting fields carry a signature associated with the apparent superluminal motion, providing an independent test for the mechanism that does not require direct observation of the trajectory, except at the detector.

  4. Field signature for apparently superluminal particle motion

    CERN Document Server

    Land, Martin

    2016-01-01

    In the context of Stueckelberg's covariant symplectic mechanics, Horwitz and Aharonovich have proposed a simple mechanism by which a particle traveling below light speed almost everywhere may exhibit a transit time that suggests superluminal motion. This mechanism, which requires precise measurement of the particle velocity, involves a subtle perturbation affecting the particle's recorded time coordinate caused by virtual pair processes. The Stueckelberg framework is particularly well suited to such problems, because it permits pair creation/annihilation at the classical level. In this paper, we study a trajectory of the type proposed by Horwitz and Aharonovich, and derive the Maxwell 4-vector potential associated with the motion. We show that the resulting fields carry a signature associated with the apparent superluminal motion, providing an independent test for the mechanism that does not require direct observation of the trajectory, except at the detector.

  5. Cosmology with Superluminous Supernovae

    CERN Document Server

    Scovacricchi, Dario; Bacon, David; Sullivan, Mark; Prajs, Szymon

    2015-01-01

    We predict cosmological constraints for forthcoming surveys using Superluminous Supernovae (SLSNe) as standardisable candles. Due to their high peak luminosity, these events can be observed to high redshift (z~3), opening up new possibilities to probe the Universe in the deceleration epoch. We describe our methodology for creating mock Hubble diagrams for the Dark Energy Survey (DES), the "Search Using DECam for Superluminous Supernovae" (SUDSS) and a sample of SLSNe possible from the Large Synoptic Survey Telescope (LSST), exploring a range of standardisation values for SLSNe. We include uncertainties due to gravitational lensing and marginalise over possible uncertainties in the magnitude scale of the observations (e.g. uncertain absolute peak magnitude, calibration errors). We find that the addition of only ~100 SLSNe from SUDSS to 3800 Type Ia Supernovae (SNe Ia) from DES can improve the constraints on w and Omega_m by at least 20% (assuming a flat wCDM universe). Moreover, the combination of DES SNe Ia a...

  6. Experimental measurements of ultrasonic propagation velocity and attenuation in a magnetic fluid.

    Science.gov (United States)

    Motozawa, M; Iizuka, Y; Sawada, T

    2008-05-21

    The ultrasonic propagation velocity and attenuation in a magnetic fluid subjected to magnetic field are measured precisely. Various characteristic properties of ultrasonic propagation in magnetic fluid such as hysteresis and anisotropy are observed. These results show that the ultrasonic propagation velocity and attenuation are dependent upon the intensity and the length of time for which the magnetic field is applied. When the magnetic field is applied, some of the magnetic particles in the magnetic fluid form clustering structures that influence ultrasonic propagation in a magnetic fluid. Our results indicate that the inner structure of a magnetic fluid can be analysed experimentally and we discuss the application of this non-contact inspection of the clustering structures in a magnetic fluid by ultrasonic techniques.

  7. Pulse propagation near zero group-velocity dispersion in a femtosecond dye laser.

    Science.gov (United States)

    Salin, F; Grangier, P; Georges, P; Brun, A

    1990-12-01

    The propagation of femtosecond pulses in a colliding-pulse mode-locked dye laser near zero group-velocity dispersion is studied. The pulse spectrum is shown to exhibit a double-peak structure. This structure and its dependence on the intracavity dispersion can be explained by nonlinear pulse propagation near zero dispersion. A value for the third-order dispersion of the laser cavity is deduced and is found to be predominant for pulses shorter than 50 fsec.

  8. Propagation Velocities of Mesoscale Features from Along-Track Sea Level Anomalies

    Science.gov (United States)

    Roach, C. J.; Maximenko, N. A.

    2016-12-01

    Measurement and mapping of seal level anomaly (SLA) from satellite systems has revolutionized oceanography. However, the present standard gridded products may not properly factor propagation of mesoscale features into the optimal interpolation procedure used to produce the datasets. We present composites of SLA variance from SSALTO/DUACS to demonstrate that gridded-SLA variability is higher in proximity to high-repeat rate Jason satellite tracks. Correcting this bias could improve representation of mesoscale features away from Jason tracks, particularly at intermediate latitudes where the zonal separation of Jason tracks is large relative to the decorrelation scale. Properly resolving mesoscale features reduces errors in propagation velocities; eddy tracking and SLA variability with resulting decreased uncertainties in transport of heat and fresh water; less misidentification of striations as eddies (or vice versa) and lower uncertainties in eddy kinetic energy. To quantify some effects of this bias we use along-satellite-track SLA to generate empirical correlation functions for specific latitude and longitude bands. We then use singular value decomposition to remove seasonal signals and apply radon transforms to the residuals to obtain zonal propagation velocities. Preliminary analysis indicates qualitative agreement between our results, Fu (2009) and Chelton et al (2011) in the meridional structure of propagation velocities away from the equator, but suggests that use of the gridded dataset reduces the magnitude of zonal propagation velocities by 0.5-2 km/day

  9. Ultrasonic non destructive characterization of trabecular bone: estimation of the propagation velocity and attenuation

    Directory of Open Access Journals (Sweden)

    Bennamane A.

    2014-01-01

    Full Text Available The non destructive characterization of porous structures with ultrasonic waves allows determining the propagation velocities and the attenuation for diagnosis of diseased bone (e.g., osteoporosis by establishing correlations between ultrasonic parameters and their mineral density. Two compressional modes have been identified independently in bovine trabecular bone, a fast wave and a slow wave. The principal objective of this paper is to characterize the propagation velocity and ultrasonic attenuation as functions of frequency and porosity of bovine cancellous bone. The porosity of the used samples varies between 40 % and 75 %. A transmission technique is used. This method only requires the measurement of the specimen’s thickness and recording of two pulses: one without and one with the specimen inserted between the transmitting and receiving transducers. From the two pulses, the attenuation can be determined using spectral analysis. The attenuation coefficient increases nonlinearly over the frequency from 200 to 700 kHz. The experimental results show a strong correlation between the bone density, the measured propagation velocity and the attenuation. The measurement of these velocities allows determining the bone elastic parameters. This study confirms the sensitivity of the ultrasonic propagation velocity to the change of bone porosity. The potential of ultrasound in bone tissue characterization seems to provide interesting results and would lead to predict bone pathology and particularly permit better diagnosis of bone fragility.

  10. The Light Velocity Casimir Effect Does the Velocity of Light Increase when Propagating Between the Casimir Plates?

    CERN Document Server

    Ostoma, T; Ostoma, Tom; Trushyk, Mike

    1999-01-01

    We propose experiments that might be set up to detect the increase in the velocity of light in a vacuum in the laboratory frame for photons travelling between (and perpendicular to) the Casimir plates in a vacuum. The Casimir plates are two closely spaced, conductive plates, where an attractive force is observed to exist between the plates called the 'Casimir Force'. We propose that the velocity of light in a vacuum increases when propagating between two transparent Casimir Plates. We call this effect the 'Light Velocity Casimir Effect' or LVC effect. The LVC effect happens because the vacuum energy density in between the plates is lower than that outside the Casimir plates. The conductive plates disallow certain frequencies of electrically charged virtual particles to exist inside the plates, thus lowering the inside vacuum particle density, compared to the density outside the plates. The reduced (electrically charged) virtual particle density results in fewer photon scattering events inside the plates, whic...

  11. Imbalance of group velocities for amplitude and phase pulses propagating in a resonant atomic medium

    Science.gov (United States)

    Basalaev, M. Yu.; Taichenachev, A. V.; Yudin, V. I.

    2016-11-01

    The dynamics of light pulses with amplitude and phase modulations is investigated for a medium of resonant two-level atoms. It is shown that the pulse-like variations of the phase can be also described in terms of group velocity. It is found that in the nonlinear regime of atom-field interaction, the group velocities of amplitude and phase pulses can have a large imbalance. Namely, amplitude pulses travel at a velocity less than c , whereas the group velocity of phase pulses is greater than the velocity of light in free space or it is even negative. The predicted imbalance of the group velocities can be important in the case of chirped pulses propagating in a resonant medium.

  12. Control of superluminal transit through a heterogeneous medium

    CERN Document Server

    Kulkarni, M; Rao, V S C Manga; Gupta, S Dutta

    2004-01-01

    We consider pulse propagation through a two component composite medium (metal inclusions in a dielectric host) with or without cavity mirrors. We show that a very thin slab of such a medium, under conditions of localized plasmon resonance, can lead to significant superluminality with detectable levels of transmitted pulse. A cavity containing the heterogeneous medium is shown to lead to subluminal-to-superluminal transmission depending on the volume fraction of the metal inclusions. The predictions of phase time calculations are verified by explicit calculations of the transmitted pulse shapes. We also demonstrate the independence of the phase time on system width and the volume fraction under specific conditions.

  13. Theory and experiment on electromagnetic-wave-propagation velocities in stacked superconducting tunnel structures

    DEFF Research Database (Denmark)

    Sakai, S.; Ustinov, A. V.; Kohlstedt, H.

    1994-01-01

    Characteristic velocities of the electromagnetic waves propagating in vertically stacked Josephson transmission are theoretically discussed. An equation for solving n velocities of the waves in an n Josephson-junction stack is derived. The solutions of two- and threefold stacks are especially...... focused on. Furthermore, under the assumption that all parameters of the layers are equal, analytic solutions for a generic N-fold stack are presented. The velocities of the waves in two- and three-junction stacks by Nb-Al-AlOx-Nb systems are experimentally obtained by measuring the cavity resonance...

  14. The influence of physical properties on propagation velocity of seismic waves of the rocks

    Directory of Open Access Journals (Sweden)

    Radoslav Schügerl

    2010-01-01

    Full Text Available Dynamic load are very important for determination physical properties of the rocks. Dynamic load propagates in the rocks by seismic waves (subsurface waves – longitudinal and transverse, and surface – Rayleigh´s waves. Laboratory (ultrasound machine and hydraulic jack and field methods (cross – hole, down – hole and up – hole on the determination to propagation velocity of seismic waves of the rocks can be used. This article presents selected problems of the research of the influence of physical properties (bulk density, porosity, change of temperature, stage of saturation on propagation velocity of seismic waves of the rocks and compares the values of dynamic modulus of elasticity Edyn obtain by means of ultrasound machine and by hydraulic jack. These parameters were obtained by laboratory testing of sandstone samples from locality of Jánovce – Jablonov (Šibenik tunnel.

  15. Velocity mode transition of dynamic crack propagation in hyperviscoelastic materials: A continuum model study.

    Science.gov (United States)

    Kubo, Atsushi; Umeno, Yoshitaka

    2017-02-10

    Experiments of crack propagation in rubbers have shown that a discontinuous jump of crack propagation velocity can occur as energy release rate increases, which is known as the "mode transition" phenomenon. Although it is believed that the mode transition is strongly related to the mechanical properties, the nature of the mode transition had not been revealed. In this study, dynamic crack propagation on an elastomer was investigated using the finite element method (FEM) with a hyperviscoelastic material model. A series of pure shear test was carried out numerically with FEM simulations and crack velocities were measured under various values of tensile strain. As a result, our FEM simulations successfully reproduced the mode transition. The success of realising the mode transition phenomenon by a simple FEM model, which was achieved for the first time ever, helped to explain that the phenomenon occurs owing to a characteristic non-monotonic temporal development of principal stress near the crack tip.

  16. Velocity mode transition of dynamic crack propagation in hyperviscoelastic materials: A continuum model study

    Science.gov (United States)

    Kubo, Atsushi; Umeno, Yoshitaka

    2017-02-01

    Experiments of crack propagation in rubbers have shown that a discontinuous jump of crack propagation velocity can occur as energy release rate increases, which is known as the “mode transition” phenomenon. Although it is believed that the mode transition is strongly related to the mechanical properties, the nature of the mode transition had not been revealed. In this study, dynamic crack propagation on an elastomer was investigated using the finite element method (FEM) with a hyperviscoelastic material model. A series of pure shear test was carried out numerically with FEM simulations and crack velocities were measured under various values of tensile strain. As a result, our FEM simulations successfully reproduced the mode transition. The success of realising the mode transition phenomenon by a simple FEM model, which was achieved for the first time ever, helped to explain that the phenomenon occurs owing to a characteristic non-monotonic temporal development of principal stress near the crack tip.

  17. Helmholtz theorem and the v-gauge in the problem of superluminal and instantaneous signals in classical electrodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Chubykalo, Andrew; Espinoza, Augusto; Flores, Rolando Alvarado; Rodriguez, Alejandro Gutierrez [Universidad Autonoma de Zacatecas (Mexico). Unidad Academica de Fisica

    2011-07-01

    In this work we substantiate the applying of the Helmholtz vector decomposition theorem (H-theorem) to vector fields in classical electrodynamics. Using the H-theorem, within the framework of the two-parameter Lorentz-like gauge (so called V-gauge), we show that two kinds of magnetic vector potentials exist: one of them (solenoidal) can act exclusively with the velocity of light C and the other one (irrotational) with an arbitrary finite velocity V (including a velocity more than C). We show also that the irrotational component of the electric field has a physical meaning and can propagate exclusively instantaneously. We provide a theoretical rationale (within the framework of classical electrodynamics) of a series of well-known recent experiments, which detected superluminal signals. Finally, we affirm that applying the Helmholtz theorem to classical electrodynamics allows to conclude that in classical electrodynamics so called instantaneous action at a distance with the infinite velocity of interaction can take place as well as (within the framework of the v-gauge-theory) the superluminal action with a finite velocity of interaction. (author)

  18. Peak Stress Intensity Factor Governs Crack Propagation Velocity In Crosslinked UHMWPE

    Science.gov (United States)

    Sirimamilla, P. Abhiram; Furmanski, Jevan; Rimnac, Clare

    2013-01-01

    Ultra high molecular weight polyethylene (UHMWPE) has been successfully used as a bearing material in total joint replacement components. However, these bearing materials can fail as a result of in vivo static and cyclic loads. Crack propagation behavior in this material has been considered using the Paris relationship which relates fatigue crack growth rate, da/dN (mm/cycle) versus the stress intensity factor range, ΔK (Kmax-Kmin, MPa√m). However, recent work suggests that the crack propagation velocity of conventional UHMWPE is driven by the peak stress intensity (Kmax), not ΔK. The hypothesis of this study is that the crack propagation velocity of highly crosslinked and remelted UHMWPE is also driven by the peak stress intensity, Kmax, during cyclic loading, rather than by ΔK. To test this hypothesis, two highly crosslinked (65 kGy and 100 kGy) and remelted UHMWPE materials were examined. Frequency, waveform and R-ratio were varied between test conditions to determine the governing factor for fatigue crack propagation. It was found that the crack propagation velocity in crosslinked UHMWPE is also driven by Kmax and not ΔK, and is dependent on loading waveform and frequency in a predictable quasi-static manner. The current study supports that crack growth in crosslinked UHMWPE materials, even under cyclic loading conditions, can be described by a relationship between the velocity of crack growth, da/dt and the peak stress intensity, Kmax. The findings suggest that stable crack propagation can occur as a result of static loading only and this should be taken into consideration in design of UHMWPE total joint replacement components. PMID:23165898

  19. Peak stress intensity factor governs crack propagation velocity in crosslinked ultrahigh-molecular-weight polyethylene.

    Science.gov (United States)

    Sirimamilla, Abhiram; Furmanski, Jevan; Rimnac, Clare

    2013-04-01

    Ultrahigh-molecular-weight polyethylene (UHMWPE) has been successfully used as a bearing material in total joint replacement components. However, these bearing materials can fail as a result of in vivo static and cyclic loads. Crack propagation behavior in this material has been considered using the Paris relationship which relates fatigue crack growth rate, da/dN (mm/cycle) versus the stress intensity factor range, ΔK (Kmax - Kmin , MPa√m). However, recent work suggests that the crack propagation velocity of conventional UHMWPE is driven by the peak stress intensity (Kmax ), not ΔK. The hypothesis of this study is that the crack propagation velocity of highly crosslinked and remelted UHMWPE is also driven by the peak stress intensity, Kmax , during cyclic loading. To test this hypothesis, two highly crosslinked (65 kGy and 100 kGy) and remelted UHMWPE materials were examined. Frequency, waveform, and R-ratio were varied between test conditions to determine the governing factor for fatigue crack propagation. It was found that the crack propagation velocity in crosslinked UHMWPE is also driven by Kmax and not ΔK, and is dependent on loading waveform and frequency in a predictable quasistatic manner. This study supports that crack growth in crosslinked UHMWPE materials, even under cyclic loading conditions, can be described by a relationship between the velocity of crack growth, da/dt and the peak stress intensity, Kmax . The findings suggest that stable crack propagation can occur as a result of static loading only and this should be taken into consideration in design of UHMWPE total joint replacement components.

  20. THE TOPOGRAPHIC PARAMETER SENSITIVITY TO VORTICITY PROPAGATION AND TYPHOON TANGENTIAL VELOCITY CHANGES

    Institute of Scientific and Technical Information of China (English)

    YU Jin-hua

    2005-01-01

    A high resolution shallow-water model is designed to study the roles which the topographical parameter and latitudinal basic flow play in the propagation of vortex Rossby waves and typhoon tangential velocity changes. With no latitudinal flow, the horizontal scale effects of island terrain on the vortex Rossby waves propagation show that the disturbance vorticity follows a clockwise island-circulating path more significantly, the local maximum wind speed amplitude reduces more sharply, the maximum mean azimuthally tangential wind spins down more substantially, when the topographic horizontal scale augments. With the latitudinal basic flow, the evolution of local wind and mean velocity are affected by the distance changes between TC and the terrain and the time length of topographic action: the local wind amplitude intensifies and the mean velocity diminishes while the distance is shortening; the opposite is true while TC is away from the terrain gradually.

  1. Statistics of Superluminal Motion in Active Galactic Nuclei

    Institute of Scientific and Technical Information of China (English)

    Yong-Wei Zhang; Jun-Hui Fan

    2008-01-01

    We have collected an up-to-date sample of 123 superluminal sources (84 quasars, 27 BL Lac objects and 12 galaxies) and calculated the apparent velocities (βapp) for 224 components in the sources with the A-CDM model. We checked the relationships between their proper motions, redshifts,βapp and 5 GHz flux densities. Our analysis shows that the radio emission is strongly boosted by the Doppler effect. The superluminal motion and the relativistic beaming boosting effect are, to some extent, the same in active galactic nuclei.

  2. Superluminal light propagation in a bi-chromatically Raman-driven and Doppler-broadened N-type 4-level atomic system

    CERN Document Server

    Bacha, Bakht Amin; Ahmad, Iftikhar

    2013-01-01

    We investigate the behavior of fast light pulse propagation in an N-type Doppler-broadened 4-level atomic system using double Raman gain processes. This system displays novel and interesting results of two controllable pairs of the double gain lines profile with a control field. The detailed physics of the processes are explored having multiple controllable anomalous regions in the medium. In this set up, the system exhibits significant enhancement in the probing Gaussian pulse through the medium as compared with Ref. [L. J. Wang, A. Kuzmich, and A. Dogariu, Nature \\textbf{406}, 227(2000)]. The advance time of the retrieved Gaussian pulse is always greater than the advance time studied in the above said experiment. We analyzed that the pulse propagating through the medium with larger negative group index, $7.32\\times10^8$, leaves the medium almost undistorted and sooner by time $76.12 \\ ms$ than the pulse which leaves the medium of Wang \\emph{et al.}. The Gaussian pulse always remains almost undistorted at ou...

  3. Jet Stability and the Generation of Superluminal and Stationary Components

    Science.gov (United States)

    Agudo, Ivan; Gomez, Jose-Luis; Marti, Jose-Maria; Ibanez, Jose-Maria; Marscher, Alan P.; Alberdi, Antonio; Aloy, Miguel-Angel; Hardee, Philip E.

    2001-01-01

    We present a numerical simulation of the response of an expanding relativistic jet to the ejection of a superluminal component. The simulation has been performed with a relativistic time-dependent hydrodynamical code from which simulated radio maps are computed by integrating the transfer equations for synchrotron radiation. The interaction of the superluminal component with the underlying jet results in the formation of multiple conical shocks behind the main perturbation. These trailing components can be easily distinguished because they appear to be released from the primary superluminal component instead of being ejected from the core. Their oblique nature should also result in distinct polarization properties. Those appearing closer to the core show small apparent motions and a very slow secular decrease in brightness and could be identified as stationary components. Those appearing farther downstream are weaker and can reach superluminal apparent motions. The existence of these trailing components indicates that not all observed components necessarily represent major perturbations at the jet inlet; rather, multiple emission components can be generated by a single disturbance in the jet. While the superluminal component associated with the primary perturbation exhibits a rather stable pattern speed, trailing components have velocities that increase with distance from the core but move at less than the jet speed. The trailing components exhibit motion and structure consistent with the triggering of pinch modes by the superluminal component. The increase in velocity of the trailing components is an indirect consequence of the acceleration of the expanding fluid, which is assumed to be relativistically hot; if observed, such accelerations would therefore favor an electron-positron (as opposed to proton rest mass) dominated jet.

  4. An experiment to measure the one-way velocity of propagation of electromagnetic radiation

    Science.gov (United States)

    Kolen, P.; Torr, D. G.

    1982-01-01

    An experiment involving commercially available instrumentation to measure the velocity of the earth with respect to absolute space is described. The experiment involves the measurement of the one-way propagation velocity of electromagnetic radiation down a high-quality coaxial cable. It is demonstrated that the experiment is both physically meaningful and exceedingly simple in concept and in implementation. It is shown that with currently available commercial equipment one might expect to detect a threshold value for the component of velocity of the earth's motion with respect to absolute space in the equatorial plane of approximately 10 km/s, which greatly exceeds the velocity resolution required to detect the motion of the solar system with respect to the center of the galaxy.

  5. Negative Group Velocity Pulse Propagation Through a Left-Handed Transmission Line

    CERN Document Server

    Jiang, Rong; Miao, Jing-Yuan; Liu, Xin-Meng

    2015-01-01

    In this paper, the microwave pulse propagation transferred through a left-handed transmission line using Complementary Omega-Like Structures (COLS) loaded was studied. There was a stop band in transmission from 5.6GHz to 6.1GHz, and the anomalous dispersion was causes in this band. Negative group velocity corresponds to the case in which the peak of the pulse exited before the peak of the incident pulse had entered the sample. The negative group velocity reached (-0.27c~-1.85c).

  6. Superluminal Neutrinos and Monopoles

    CERN Document Server

    Wang, Peng; Yang, Haitang

    2011-01-01

    In this letter, we show that superluminal neutrinos announced by OPERA could be explained by the existence of a monopole, which is left behind after the spontaneous symmetry braking (SSB) phase transition of some scalar fields in the universe. We assume the 't Hooft-Polyakov monopole couples to the neutrinos but not photon fields. The monopole causes effective metric to the neutrinos, different from the Minkovski one. We find that the monopoles have influences on neutrinos only within the range about $10^3$ cm. Neutrinos always arrive earlier than photons by the same amount of time, once there exists a monopole on or close to their trajectories. This result reconciles the contradiction between OPERA and supernova neutrinos.

  7. Cosmology with superluminous supernovae

    Science.gov (United States)

    Scovacricchi, D.; Nichol, R. C.; Bacon, D.; Sullivan, M.; Prajs, S.

    2016-02-01

    We predict cosmological constraints for forthcoming surveys using superluminous supernovae (SLSNe) as standardizable candles. Due to their high peak luminosity, these events can be observed to high redshift (z ˜ 3), opening up new possibilities to probe the Universe in the deceleration epoch. We describe our methodology for creating mock Hubble diagrams for the Dark Energy Survey (DES), the `Search Using DECam for Superluminous Supernovae' (SUDSS) and a sample of SLSNe possible from the Large Synoptic Survey Telescope (LSST), exploring a range of standardization values for SLSNe. We include uncertainties due to gravitational lensing and marginalize over possible uncertainties in the magnitude scale of the observations (e.g. uncertain absolute peak magnitude, calibration errors). We find that the addition of only ≃100 SLSNe from SUDSS to 3800 Type Ia Supernovae (SNe Ia) from DES can improve the constraints on w and Ωm by at least 20 per cent (assuming a flat wCDM universe). Moreover, the combination of DES SNe Ia and 10 000 LSST-like SLSNe can measure Ωm and w to 2 and 4 per cent, respectively. The real power of SLSNe becomes evident when we consider possible temporal variations in w(a), giving possible uncertainties of only 2, 5 and 14 per cent on Ωm, w0 and wa, respectively, from the combination of DES SNe Ia, LSST-like SLSNe and Planck. These errors are competitive with predicted Euclid constraints, indicating a future role for SLSNe for probing the high-redshift Universe.

  8. Latest Progress on Propagation Characteristics of Superluminous Waves and their Gyroresonance with Energetic Particles%超光速电磁波的传播特性及与高能粒子相互作用研究的新进展

    Institute of Scientific and Technical Information of China (English)

    肖伏良; 何兆国; 陈良旭; 贺艺华; 杨昶

    2011-01-01

    超光速(相速度大于光速)电磁波是广泛存在于空间等离子中的高频电磁波,总结了超光速电磁波的产生机制-回旋微波激射不稳定性,介绍了超光速波在地球磁层中的传播特性,分析了其从高纬极光源区传播到低纬区域的基本原因:磁暴时由于等离子层硕压缩,超光速波传播时不会遇上反射,从而能向下传播.重点介绍了超光速波产生的地球辐射带区域高能电子的随机加速与投掷角扩散过程.发现超光速波能量扩散过程一般大于投掷角扩散过程,在合适的条件下超光速波对高投掷角的高能电子主要起随机加速作用,而对低投掷角的高能电子主要起投掷角扩散作用.这些最新进展有助于进一步了解超光速电磁波的激发与传播特性,以及地球辐射带高能电子的动力学行为.%Superluminous (the phase speed higher than the speed of light) electromagnetic waves are widely present in the space plasma with high frequencies. Here, we briefly introduce their generation mechanism-Cyclotron Maser Instability ( CMI). We present discussion on the propagating characteristics of superluminous waves in the Earth's magnetosphere. During high geomagnetic activity, since the plasmapause position moves inward closer to the Earth, the superluminous waves can propagate from their source cavity downward and even through the equatorial plane due to no reflection. We focus on pitch angle scattering and stochastic acceleration of energetic electrons induced by superluminous waves in the radiation belts. Current works show that energy diffusion resulting from such waves is generally higher than pitch angle scattering. Under appropriate conditions, superluminous waves may contribute to both the stochastic acceleration of electrons with larger pitch angle and the loss process of electrons with smaller pitch angles. These recent progresses provide further understanding of the instability and propagation of

  9. How to measure propagation velocity in cardiac tissue: a simulation study

    Directory of Open Access Journals (Sweden)

    Andre C. Linnenbank

    2014-07-01

    Full Text Available To estimate conduction velocities from activation times in myocardial tissue, the average vector method computes all the local activation directions and velocities from local activation times and estimates the fastest and slowest propagation speed from these local values. The single vector method uses areas of apparent uniform elliptical spread of activation and chooses a single vector for the estimated longitudinal velocity and one for the transversal. A simulation study was performed to estimate the influence of grid size, anisotropy, and vector angle bin size. The results indicate that the average vector method can best be used if the grid- or bin-size is large, although systematic errors occur. The single vector method performs better, but requires human intervention for the definition of fiber direction. The average vector method can be automated.

  10. Relativistic jet with shock waves like model of superluminal radio source. Jet relativista con ondas de choque como modelo de radio fuentes superluminales

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, A.; Gomez, J.L.; Marcaide, J.M.

    1993-01-01

    The structure of the compact radio sources at milliarcsecond angular resolution can be explained in terms of shock waves propagating along bent jets. These jets consist of narrow-angle cones of plasma flowing at bulk relativistic velocities, within tangled magnetic fields, emitting synchrotron radiation. We have developed a numerical code which solves the synchrotron radiation transfer equations to compute the total and polarized emission of bent shocked relativistic jets, and we have applied it to reproduce the compact structure, kenimatic evolution and time flux density evolution of the superluminal radio source 4C 39.25 and to obtain its jet physical parameters. (Author) 23 ref.

  11. Direct observation of ultraslow hyperbolic polariton propagation with negative phase velocity

    Science.gov (United States)

    Yoxall, Edward; Schnell, Martin; Nikitin, Alexey Y.; Txoperena, Oihana; Woessner, Achim; Lundeberg, Mark B.; Casanova, Félix; Hueso, Luis E.; Koppens, Frank H. L.; Hillenbrand, Rainer

    2015-10-01

    Polaritons with hyperbolic dispersion are key to many emerging photonic technologies, including subdiffraction imaging, sensing and spontaneous emission engineering. Fundamental to their effective application are the lifetimes of the polaritons, as well as their phase and group velocities. Here, we combine time-domain interferometry and scattering-type near-field microscopy to visualize the propagation of hyperbolic polaritons in space and time, allowing the first direct measurement of all these quantities. In particular, we study infrared phonon polaritons in a thin hexagonal boron nitride waveguide exhibiting hyperbolic dispersion and deep subwavelength-scale field confinement. Our results reveal—in a natural material—negative phase velocity paired with a remarkably slow group velocity of 0.002c and lifetimes in the picosecond range. While these findings show the polariton's potential for mediating strong light-matter interactions and negative refraction, our imaging technique paves the way to explicit nanoimaging of polariton propagation characteristics in other two-dimensional materials, metamaterials and waveguides.

  12. Stochastic simulation for the propagation of high-frequency acoustic waves through a random velocity field

    Science.gov (United States)

    Lu, B.; Darmon, M.; Leymarie, N.; Chatillon, S.; Potel, C.

    2012-05-01

    In-service inspection of Sodium-Cooled Fast Reactors (SFR) requires the development of non-destructive techniques adapted to the harsh environment conditions and the examination complexity. From past experiences, ultrasonic techniques are considered as suitable candidates. The ultrasonic telemetry is a technique used to constantly insure the safe functioning of reactor inner components by determining their exact position: it consists in measuring the time of flight of the ultrasonic response obtained after propagation of a pulse emitted by a transducer and its interaction with the targets. While in-service the sodium flow creates turbulences that lead to temperature inhomogeneities, which translates into ultrasonic velocity inhomogeneities. These velocity variations could directly impact the accuracy of the target locating by introducing time of flight variations. A stochastic simulation model has been developed to calculate the propagation of ultrasonic waves in such an inhomogeneous medium. Using this approach, the travel time is randomly generated by a stochastic process whose inputs are the statistical moments of travel times known analytically. The stochastic model predicts beam deviations due to velocity inhomogeneities, which are similar to those provided by a determinist method, such as the ray method.

  13. The density and velocity of plasma bullets propagating along one dielectric tube

    Directory of Open Access Journals (Sweden)

    Longfei Ji

    2015-08-01

    Full Text Available This study shows that the propagation of plasma bullets along one dielectric tube is strongly affected by many discharge parameters, such as the waveform of applied voltage (AC or pulsed DC, peak voltage, He flow rate, and the frequency of AC voltage. Analysis indicates that the density and velocity of plasma bullets are mainly determined by the electric field at the front of plasma bullets. These discharge parameters may significantly influence the distribution of plasma potential along the tube, thus control the electric field at the front of plasma bullets and their propagation. An increase in the pulsed DC voltage with its rise time of <40-50 ns can lead to an obvious improvement in the electric field at the front of plasma bullets, resulting in generation of a plasma in the high density gas and a fast propagation of plasma bullets. He flowing through the tube can contribute to the surface diffusion of charged species, and greatly increase the electric field at the front of plasma bullets. During the propagation of plasma bullets, their density is decreased due to the surface recombination of charged species, such as electrons and ions.

  14. Neutrino superluminality without Cherenkov-like processes in Finslerian special relativity

    CERN Document Server

    Chang, Zhe; Wang, Sai; 10.1016/j.physletb.2012.03.002

    2012-01-01

    Recently, Cohen and Glashow [A.G. Cohen, S.L. Glashow, Phys. Rev. Lett. {\\bf 107}, 181803 (2011)] pointed out that the superluminal neutrinos reported by the OPERA would lose their energy rapidly via the Cherenkov-like process. The Cherenkov-like process for the superluminal particles would be forbidden if the principle of special relativity holds in any frame instead violated with a preferred frame. We have proposed that the Finslerian special relativity could account for the data of the neutrino superluminality (arXiv:1110.6673[hep-ph]). The Finslerian special relativity preserves the principle of special relativity and involves a preferred direction while consists with the causality. In this paper, we prove that the energy-momentum conservation is preserved and the energy-momentum is well defined in Finslerian special relativity. The Cherenkov-like process is forbidden in the Finslerian special relativity. Thus, the superluminal neutrinos would not lose energy in their distant propagation.

  15. Finite element analysis of solitary wave propagation by acoustic velocity method

    Science.gov (United States)

    Maruoka, Akira; Uchiyama, Ichiro; Kawahara, Mutsuto

    2017-01-01

    There is discontinuity between compressible and incompressible states in fluid flows. If we subtract the thermal effect from compressible fluid flows, we obtain adiabatic fluid flows, from which incompressible fluid flows are obtained if we let the acoustic velocity tend to infinity. Thus, we employ the idea of adiabatic fluid flows to solve incompressible flows. In the computation, the physical value of the acoustic velocity is employed. This idea corresponds to an extension of artificial compressibility under physical considerations. We present the new SUPG formulation of adiabatic fluid flows, by which not only the effect of SUPG but also those of PSPG and LSIC of incompressible fluid flows are derived. After the numerical verifications, three-dimensional solitary wave propagations are computed. Close agreement between computed and experimental values is obtained.

  16. Superluminal travel requires negative energies

    OpenAIRE

    Olum, Ken D.

    1998-01-01

    I investigate the relationship between faster-than-light travel and weak-energy-condition violation, i.e., negative energy densities. In a general spacetime it is difficult to define faster-than-light travel, and I give an example of a metric which appears to allow superluminal travel, but in fact is just flat space. To avoid such difficulties, I propose a definition of superluminal travel which requires that the path to be traveled reach a destination surface at an earlier time than any neig...

  17. Propagation velocity profile in a cross-section of a cardiac muscle bundle from PSpice simulation

    Directory of Open Access Journals (Sweden)

    Sperelakis Nicholas

    2006-08-01

    Full Text Available Abstract Background The effect of depth on propagation velocity within a bundle of cardiac muscle fibers is likely to be an important factor in the genesis of some heart arrhythmias. Model and methods The velocity profile of simulated action potentials propagated down a bundle of parallel cardiac muscle fibers was examined in a cross-section of the bundle using a PSpice model. The model (20 × 10 consisted of 20 chains in parallel, each chain being 10 cells in length. All 20 chains were stimulated simultaneously at the left end of the bundle using rectangular current pulses (0.25 nA, 0.25 ms duration applied intracellularly. The simulated bundle was symmetrical at the top and bottom (including two grounds, and voltage markers were placed intracellularly only in cells 1, 5 and 10 of each chain to limit the total number of traces to 60. All electrical parameters were standard values; the variables were (1 the number of longitudinal gap-junction (G-j channels (0, 1, 10, 100, (2 the longitudinal resistance between the parallel chains (Rol2 (reflecting the closeness of the packing of the chains, and (3 the bundle termination resistance at the two ends of the bundle (RBT. The standard values for Rol2 and RBT were 200 KΩ. Results The velocity profile was bell-shaped when there was 0 or only 1 gj-channel. With standard Rol2 and RBT values, the velocity at the surface of the bundle (θ1 and θ20 was more than double (2.15 × that at the core of the bundle (θ10, θ11. This surface:core ratio of velocities was dependent on the values of Rol2 and RBT. When Rol2 was lowered 10-fold, θ1 increased slightly and θ2decreased slightly. When there were 100 gj-channels, the velocity profile was flat, i.e. the velocity at the core was about the same as that at the surface. Both velocities were more than 10-fold higher than in the absence of gj-channels. Varying Rol2 and RBT had almost no effect. When there were 10 gj-channels, the cross-sectional velocity profile

  18. Influence of biologic factor on the velocity of propagation of pulse waves in vessels of living organisms

    Science.gov (United States)

    Sumets, Pavel

    2012-11-01

    In this work there has been examined a mathematical model illustrating propagation of a pulse wave, with biological activity of a blood vessel's walls taken into consideration. The influence of the biological factor was allowed for in the equations connecting stresses and deformations of the vessel's walls among themselves. There has been deduced a formula defining the pulse wave propagation velocity in an orthotropic resilient blood-filled vessel, influenced by the biological factor. The obtained results allow us to make a conclusion that stimulation of muscle fibers of the vessel's wall brings on an increase in the pulse wave propagation velocity.

  19. BDNF and NT-3 increase velocity of activity front propagation in unidimensional hippocampal cultures.

    Science.gov (United States)

    Jacobi, Shimshon; Soriano, Jordi; Moses, Elisha

    2010-12-01

    Neurotrophins are known to promote synapse development as well as to regulate the efficacy of mature synapses. We have previously reported that in two-dimensional rat hippocampal cultures, brain-derived neurotrophic factor (BDNF) and neurotrophin-3 significantly increase the number of excitatory input connections. Here we measure the effect of these neurotrophic agents on propagating fronts that arise spontaneously in quasi-one-dimensional rat hippocampal cultures. We observe that chronic treatment with BDNF increased the velocity of the propagation front by about 30%. This change is attributed to an increase in the excitatory input connectivity. We analyze the experiment using the Feinerman-Golomb/Ermentrout-Jacobi/Moses-Osan model for the propagation of fronts in a one-dimensional neuronal network with synaptic delay and introduce the synaptic connection probability between adjacent neurons as a new parameter of the model. We conclude that BDNF increases the number of excitatory connections by favoring the probability to form connections between neurons, but without significantly modifying the range of the connections (connectivity footprint).

  20. A note on superluminal neutrinos

    Science.gov (United States)

    Cutolo, A.

    2012-05-01

    Although characterized by a possible experimental error, the first results of the Opera experiment at CERN have opened up a hot discussion on the possibility of superluminal neutrinos already observed in some space events. In particular, Cohen and Glashow (CG) have considered it simply an error justifying their position on the basis of the bremsstrahlung of electron-positron pairs. In this paper, we would like to discuss this position also in view of the recent derivation of the superluminal limit as a consequence of the classical causality principle. Even if the final answer is related only to the review of all the experimental results, we believe that neutral particles (neutrinos, photons, etc.) might exhibit superluminal behavior also in view of the fact that the analysis performed by Cohen and Glashow does not contain any absolute limit, like that present in the case of the Cherenkov effect in vacuum, which is absolutely impossible, as its violation would require an infinite energy amount. CG conclusions are not in contrast with superluminal neutrinos, which, in turn, are fully compatible with the theoretical analysis reported as well.

  1. Popper's Experiment and Superluminal Communication

    CERN Document Server

    Gerjuoy, E; Gerjuoy, Edward; Sessler, Andrew M.

    2005-01-01

    We comment on Tabesh Qureshi, "Understanding Popper's Experiment," AJP 73, 541 (June 2005), in particular on the implications of its section IV. We show, in the situation envisaged by Popper, that analysis solely with conventional non-relativistic quantum mechanics suffices to exclude the possibility of superluminal communication.

  2. Conditions Under Which Megathrust Ruptures Propagate Through Shallow Velocity-Weakening Regions to the Trench

    Science.gov (United States)

    Dunham, E. M.; Kozdon, J. E.; Lotto, G. C.

    2012-12-01

    We have conducted dynamic rupture simulations of the 11 March 2011 Tohoku earthquake to identify conditions that permit megathrust ruptures to reach the trench, even when the uppermost portion of the plate interface is frictionally stable. Our models incorporate rate-and-state friction featuring depth-dependent properties that transition from velocity-weakening at depth to velocity-strengthening beneath the accretionary prism. Earthquake nucleation is thus restricted to greater depths, consistent with the lack of shallow seismicity near the trench. Despite this, we find that unless the uppermost velocity-strengthening section of the fault extends beyond about 50 km along dip, ruptures propagating upward from depth break through to the trench. Stress changes, carried by seismic waves released by deep slip, provide the necessary driving force that maintains propagation even in the absence of frictional weakening and stress drop. In our present set of simulations, we assume ideally elastic response of the off-fault material. We therefore caution that our conclusions will likely be modified by the occurrence of plastic deformation within the accretionary prism, which we are planning to explore in the near future. Our models are calibrated through comparison with seafloor deformation measurements and onshore 1-Hz GPS data. We explore the ability of these data sets to constrain frictional properties along the plate interface, particularly in the near-trench region. Our modeling efforts thus far suggest strong trade-offs between stress drop along the deeper part of the fault and the shallow frictional properties. In addition to our preferred model featuring a shallow velocity-strengthening section, we can equally well fit the data with velocity-weakening properties extending all the way to the trench, provided we decrease the average stress drop by reducing the initial effective normal stress. We are also examining the signature of extreme shallow slip in hydroacoustic

  3. Review of critical flow rate, propagation of pressure pulse, and sonic velocity in two-phase media

    Science.gov (United States)

    Hsu, Y.

    1972-01-01

    For single-phase media, the critical discharge velocity, the sonic velocity, and the pressure pulse propagation velocity can be expressed in the same form by assuming isentropic, equilibria processes. In two-phase mixtures, the same concept is not valid due to the existence of interfacial transports of momentum, heat, and mass. Thus, the three velocities should be treated differently and separately for each particular condition, taking into account the various transport processes involved under that condition. Various attempts are reviewed to predict the critical discharge rate or the propagation velocities by considering slip ratio (momentum change), evaporation (mass and heat transport), flow pattern, etc. Experimental data were compared with predictions based on various theorems. The importance is stressed of the time required to achieve equilibrium as compared with the time available during the process, for example, of passing a pressure pulse.

  4. Luminous phase of nanosecond discharge in deionized water: morphology, propagation velocity and optical emission

    Science.gov (United States)

    Šimek, Milan; Pongrác, Branislav; Babický, Václav; Člupek, Martin; Lukeš, Petr

    2017-07-01

    We employed the techniques of time-resolved intensified charge-coupled device (ICCD) microscopy and spectroscopy to register basic morphologic and emission fingerprints of micro-discharges produced in deionized water. Fast rise-time positive high-voltage pulses (full width at half maximum of ˜7 ns and amplitude of ˜100 kV) in a point-to-plane electrode geometry produced micro-discharges, either periodically or in a single-pulse regime with the energy of ˜0.1 J dissipated during a single discharge event. Time resolved ICCD images evidence typical streamer-like branched filamentary morphology. Luminous discharge filaments show very fast and approximately linear initial expansion of the length with propagation velocity of ˜2 × 105 m s-1. When the HV pulse reaches its maximum value, the length of the primary luminous filaments reaches ˜1.3 mm. After initial expansion, the length of luminous filaments collapses and can be characterised by velocity of ˜1.9 × 104 m s-1. The first collapse is followed by a second slightly slower expansion, which is driven by the arrival of a reflected HV pulse, and which can be roughly approximated by propagation velocity of ˜1.5 × 105 m s-1. The second collapse (occurring after second expansion) proceeds at a nearly identical velocity compared with the first one. By combining two ICCD based techniques, we have been able to associate, for the first time ever, characteristic emission spectra with the most important phases of the micro-discharge development. The UV-vis-NIR emission spectra show a broad-band continuum evolving during the first expansion and collapse, followed by the well-known HI/OI atomic lines occurring together with continuum emission during the second expansion and collapse. We conclude that bound-free and free-free radiative transitions are basic emission characteristics of the nanosecond discharge initiation mechanism in liquid water which does not involve the formation of vapour bubbles.

  5. Spatial Parallelism of a 3D Finite Difference, Velocity-Stress Elastic Wave Propagation Code

    Energy Technology Data Exchange (ETDEWEB)

    MINKOFF,SUSAN E.

    1999-12-09

    Finite difference methods for solving the wave equation more accurately capture the physics of waves propagating through the earth than asymptotic solution methods. Unfortunately. finite difference simulations for 3D elastic wave propagation are expensive. We model waves in a 3D isotropic elastic earth. The wave equation solution consists of three velocity components and six stresses. The partial derivatives are discretized using 2nd-order in time and 4th-order in space staggered finite difference operators. Staggered schemes allow one to obtain additional accuracy (via centered finite differences) without requiring additional storage. The serial code is most unique in its ability to model a number of different types of seismic sources. The parallel implementation uses the MP1 library, thus allowing for portability between platforms. Spatial parallelism provides a highly efficient strategy for parallelizing finite difference simulations. In this implementation, one can decompose the global problem domain into one-, two-, and three-dimensional processor decompositions with 3D decompositions generally producing the best parallel speed up. Because i/o is handled largely outside of the time-step loop (the most expensive part of the simulation) we have opted for straight-forward broadcast and reduce operations to handle i/o. The majority of the communication in the code consists of passing subdomain face information to neighboring processors for use as ''ghost cells''. When this communication is balanced against computation by allocating subdomains of reasonable size, we observe excellent scaled speed up. Allocating subdomains of size 25 x 25 x 25 on each node, we achieve efficiencies of 94% on 128 processors. Numerical examples for both a layered earth model and a homogeneous medium with a high-velocity blocky inclusion illustrate the accuracy of the parallel code.

  6. Spatial parallelism of a 3D finite difference, velocity-stress elastic wave propagation code

    Energy Technology Data Exchange (ETDEWEB)

    Minkoff, S.E.

    1999-12-01

    Finite difference methods for solving the wave equation more accurately capture the physics of waves propagating through the earth than asymptotic solution methods. Unfortunately, finite difference simulations for 3D elastic wave propagation are expensive. The authors model waves in a 3D isotropic elastic earth. The wave equation solution consists of three velocity components and six stresses. The partial derivatives are discretized using 2nd-order in time and 4th-order in space staggered finite difference operators. Staggered schemes allow one to obtain additional accuracy (via centered finite differences) without requiring additional storage. The serial code is most unique in its ability to model a number of different types of seismic sources. The parallel implementation uses the MPI library, thus allowing for portability between platforms. Spatial parallelism provides a highly efficient strategy for parallelizing finite difference simulations. In this implementation, one can decompose the global problem domain into one-, two-, and three-dimensional processor decompositions with 3D decompositions generally producing the best parallel speedup. Because I/O is handled largely outside of the time-step loop (the most expensive part of the simulation) the authors have opted for straight-forward broadcast and reduce operations to handle I/O. The majority of the communication in the code consists of passing subdomain face information to neighboring processors for use as ghost cells. When this communication is balanced against computation by allocating subdomains of reasonable size, they observe excellent scaled speedup. Allocating subdomains of size 25 x 25 x 25 on each node, they achieve efficiencies of 94% on 128 processors. Numerical examples for both a layered earth model and a homogeneous medium with a high-velocity blocky inclusion illustrate the accuracy of the parallel code.

  7. Wave propagation in double-porosity dual-permeability materials: Velocity and attenuation

    Science.gov (United States)

    Sharma, M. D.

    2017-08-01

    This study considers the propagation of harmonic plane waves in a double-porosity solid saturated by a viscous fluid. Two different porosities are supported with different permeabilities to facilitate the wave-induced fluid-flow in this composite material. The variation of the fluid content in the pores due to the wave-induced flow is expressed in terms of the dilatation of constituent particles in the porous aggregate. This fluid-flow can be considered through the constitutive relations with modified anelastic coefficients. The modified coefficients, being frequency dependent and complex, illustrate the dispersive and anelastic behaviour of double-porosity dual-permeability materials. Relevant equations of motion are solved to explain the propagation of three longitudinal waves and one transverse wave in double-porosity dual-permeability medium. A numerical example is considered to illustrate dispersion in velocity and attenuation of the four waves. Effect of wave-induced fluid-flow is analysed with changes in wave-inhomogeneity, pore-fluid viscosity and double-porosity structure.

  8. Observation of image pair creation and annihilation from superluminal scattering sources

    CERN Document Server

    Clerici, Matteo; Warburton, Ryan E; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2015-01-01

    The invariance of the speed of light implies a series of consequences related to our perception of simultaneity and of time itself. Whilst these consequences are experimentally well studied for subluminal speeds, the kinematics of superluminal motion lack direct evidence. Using high temporal resolution imaging techniques, we demonstrate that if a source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backwards. If the source changes its speed, crossing the interface between sub- and super-luminal propagation, we observe image pair annihilation and creation. These results show that it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone.

  9. The Shape of Superluminous Supernovae

    Science.gov (United States)

    Kohler, Susanna

    2016-11-01

    What causes the tremendous explosions of superluminous supernovae? New observations reveal the geometry of one such explosion, SN 2015bn, providing clues as to its source.A New Class of ExplosionsImage of a type Ia supernova in the galaxy NGC 4526. [NASA/ESA]Supernovae are powerful explosions that can briefly outshine the galaxies that host them. There are several different classifications of supernovae, each with a different physical source such as thermonuclear instability in a white dwarf, caused by accretion of too much mass, or the exhaustion of fuel in the core of a massive star, leading to the cores collapse and expulsion of its outer layers.In recent years, however, weve detected another type of supernovae, referred to as superluminous supernovae. These particularly energetic explosions last longer months instead of weeks and are brighter at their peaks than normal supernovae by factors of tens to hundreds.The physical cause of these unusual explosions is still a topic of debate. Recently, however, a team of scientists led by Cosimo Inserra (Queens University Belfast) has obtained new observations of a superluminous supernova that might help address this question.The flux and the polarization level (black lines) along the dominant axis of SN 2015bn, 24 days before peak flux (left) and 28 days after peak flux (right). Blue lines show the authors best-fitting model. [Inserra et al. 2016]Probing GeometryInserra and collaborators obtained two sets of observations of SN 2015bn one roughly a month before and one a month after the superluminous supernovas peak brightness using a spectrograph on the Very Large Telescope in Chile. These observations mark the first spectropolarimetric data for a superluminous supernova.Spectropolarimetry is the practice of obtaining information about the polarization of radiation from an objects spectrum. Polarization carries information about broken spatial symmetries in the object: only if the object is perfectly symmetric can it

  10. A lower bound for the velocity of quantum communications in the preferred frame

    Science.gov (United States)

    Cocciaro, B.; Faetti, S.; Fronzoni, L.

    2011-01-01

    An EPR experiment with polarized entangled photons is performed to test the Eberhard model. According to the Eberhard model, quantum correlations between space-like separated events are due to a superluminal communication signal propagating in a preferred frame. The coincidences between entangled photons passing through two polarizers aligned along a East-West axis are measured as a function of time during 21 sidereal days. No deviation from the predictions of the Quantum Theory is observed. Tacking into account for the experimental uncertainties, we infer that, if a preferred frame for superluminal signals exists which moves at velocity v→ with respect to the Earth, the modulus of the velocity of quantum communications in this frame has to be greater than vt≃0.6×10c for v<0.1c and for any arbitrary direction of v→.

  11. A lower bound for the velocity of quantum communications in the preferred frame

    Energy Technology Data Exchange (ETDEWEB)

    Cocciaro, B., E-mail: b.cocciaro@comeg.i [Liceo Scientifico XXV Aprile, via Milano 2, 56025 Pontedera (Italy); Faetti, S., E-mail: faetti@df.unipi.i [Dipartimento di Fisica and Polylab of INFM, Largo B. Pontecorvo, 56123 Pisa (Italy); Fronzoni, L., E-mail: fronzoni@df.unipi.i [Dipartimento di Fisica and INFMCRS-Soft, Largo B. Pontecorvo, 56123 Pisa (Italy)

    2011-01-17

    An EPR experiment with polarized entangled photons is performed to test the Eberhard model. According to the Eberhard model, quantum correlations between space-like separated events are due to a superluminal communication signal propagating in a preferred frame. The coincidences between entangled photons passing through two polarizers aligned along a East-West axis are measured as a function of time during 21 sidereal days. No deviation from the predictions of the Quantum Theory is observed. Tacking into account for the experimental uncertainties, we infer that, if a preferred frame for superluminal signals exists which moves at velocity {rvec v} with respect to the Earth, the modulus of the velocity of quantum communications in this frame has to be greater than v{sub t}{approx_equal}0.6x10{sup 4}c for v<0.1c and for any arbitrary direction of {rvec v}.

  12. Cytoarchitecture-Dependent Decrease in Propagation Velocity of Cortical Spreading Depression in the Rat Insular Cortex Revealed by Optical Imaging.

    Science.gov (United States)

    Fujita, Satoshi; Mizoguchi, Naoko; Aoki, Ryuhei; Cui, Yilong; Koshikawa, Noriaki; Kobayashi, Masayuki

    2016-04-01

    Cortical spreading depression (SD) is a self-propagating wave of depolarization accompanied by a substantial disturbance of the ionic distribution between the intra- and extracellular compartments. Glial cells, including astrocytes, play critical roles in maintenance of the extracellular environment, including ionic distribution. Therefore, SD propagation in the cerebral cortex may depend on the density of astrocytes. The present study aimed to examine the profile of SD propagation in the insular cortex (IC), which is located between the neocortex and paleocortex and is where the density of astrocytes gradually changes. The velocity of SD propagation in the neocortex, including the somatosensory, motor, and granular insular cortices (5.7 mm/min), was higher than that (2.8 mm/min) in the paleocortex (agranular insular and piriform cortices). Around thick vessels, including the middle cerebral artery, SD propagation was frequently delayed and sometimes disappeared. Immunohistological analysis of glial fibrillary acidic protein (GFAP) demonstrated the sparse distribution of astrocytes in the somatosensory cortex and the IC dorsal to the rhinal fissure, whereas the ventral IC showed a higher density of astrocytes. These results suggest that cortical cytoarchitectonic features, which possibly involve the distribution of astrocytes, are crucial for regulating the velocity of SD propagation in the cerebral cortex.

  13. Effects of Pre-Stress State and Propagation Velocity on Dynamic Fault Branching

    Science.gov (United States)

    Kame, N.; Rice, J. R.; Dmowska, R.

    2001-12-01

    Major earthquakes seldom rupture along single planar faults. Instead there exist geometric complexities, including fault bends, branches and stepovers, which affect the rupture process, including nucleation and arrest. Here we consider a mode II rupture which propagates along a planar fault and encounters an intersection with a branching fault that makes an angle with the main fault. Analyses based on elastic stress fields near propagating ruptures suggest that whether a branch path will be followed or not, and whether branching to the extensional or compressional side is favored, depend on both the rupture propagation velocity as the branch is approached and on the pre-stress state before rupture arrives. See Kame and Yamashita (GJI, 139, 345-358, 1999) and Poliakov, Dmowska and Rice (JGR subm. 2001, http://esag.harvard.edu/dmowska/PDR.pdf). The latter predicted that branching to the extensional side would be favored in all pre-stress states except for those in which the direction of maximum pre-compression Smax makes a shallow angle ψ with the fault plane. Angles ψ 45 ° result when the ratio is less than unity. Thus it is anticipated that the most favored side for rupture branching should switch from the extensional to the compressive side as we consider progressively larger σ oxx/σ oyy (which means progressively smaller ψ ). In order to test that and other predictions, we have adapted the elastodynamic boundary integral equation methodology of Kame and Yamashita to 2-dimensional Mode II ruptures along branched fault systems, to allow simulations of rupture in which the failure path is dynamically self-chosen. Failure in the modeling is described by a slip-weakening law for which the peak and residual strength, and strength at any particular amount of slip, is proportional to normal stress (-σ nn). Our current results are preliminary. Nevertheless, by comparing results for σ oxx/σ oyy = 0.8 with those for 1.4, we have established, e.g., that a 15

  14. Method for Estimating Harmonic Frequency Dependence of Diffusion Coefficient and Convective Velocity in Heat Pulse Propagation Experiment

    Science.gov (United States)

    Kobayashi, Tatsuya; Itoh, Kimitaka; Ida, Katsumi; Inagaki, Sigeru; Itoh, Sanae-I.

    2017-07-01

    In this paper we propose a new set of formulae for estimating the harmonic frequency dependence of the diffusion coefficient and the convective velocity in the heat pulse propagation experiment in order to investigate the transport hysteresis. The assumptions that are used to derive the formulae can result in dummy frequency dependences of the transport coefficients. It is shown that these dummy frequency dependences of the transport coefficients can be distinguished from the true frequency dependence due to the transport hysteresis by using a bidirectional heat pulse propagation manner, in which both the outward propagating heat pulse and the inward propagating heat pulse are analyzed. The validity of the new formulae are examined in a simple numerical calculation.

  15. Superluminal neutrinos at OPERA confront pion decay kinematics.

    Science.gov (United States)

    Cowsik, Ramanath; Nussinov, Shmuel; Sarkar, Utpal

    2011-12-16

    Violation of Lorentz invariance (VLI) has been suggested as an explanation of the superluminal velocities of muon neutrinos reported by OPERA. In this Letter, we show that the amount of VLI required to explain this result poses severe difficulties with the kinematics of the pion decay, extending its lifetime and reducing the momentum carried away by the neutrinos. We show that the OPERA experiment limits α=(ν(ν)-c)/c<4×10(-6). We then take recourse to cosmic-ray data on the spectrum of muons and neutrinos generated in Earth's atmosphere to provide a stronger bound on VLI: (ν-c)/c<10(-12).

  16. The influence of the Al stabilizer layer thickness on the normal zone propagation velocity in high current superconductors

    CERN Document Server

    Shilon, I.; Langeslag, S.A.E.; Martins, L.P.; ten Kate, H.H.J.

    2015-01-01

    The stability of high-current superconductors is challenging in the design of superconducting magnets. When the stability requirements are fulfilled, the protection against a quench must still be considered. A main factor in the design of quench protection systems is the resistance growth rate in the magnet following a quench. The usual method for determining the resistance growth in impregnated coils is to calculate the longitudinal velocity with which the normal zone propagates in the conductor along the coil windings. Here, we present a 2D numerical model for predicting the normal zone propagation velocity in Al stabilized Rutherford NbTi cables with large cross section. By solving two coupled differential equations under adiabatic conditions, the model takes into account the thermal diffusion and the current redistribution process following a quench. Both the temperature and magnetic field dependencies of the superconductor and the metal cladding materials properties are included. Unlike common normal zon...

  17. Spectrum formation in superluminous supernovae (Type I)

    Science.gov (United States)

    Mazzali, P. A.; Sullivan, M.; Pian, E.; Greiner, J.; Kann, D. A.

    2016-06-01

    The near-maximum spectra of most superluminous supernovae (SLSNe) that are not dominated by interaction with a H-rich circum-stellar medium (SLSN-I) are characterized by a blue spectral peak and a series of absorption lines which have been identified as O II. SN 2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/ultraviolet (UV) spectrum. Radiation transport methods are used to show that the spectra (not including SN 2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ˜10 000-15 000 km s-1, several lines form in the UV. O II lines, however, arise from very highly excited lower levels, which require significant departures from local thermodynamic equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is that they are energized by X-rays from the shock driven by a magnetar wind into the SN ejecta. The apparent lack of evolution of line velocity with time that characterizes SLSNe up to about maximum is another argument in favour of the magnetar scenario. The smooth UV continuum of SN 2011kl requires higher ejecta velocities (˜20 000 km s-1): line blanketing leads to an almost featureless spectrum. Helium is observed in some SLSNe after maximum. The high-ionization near-maximum implies that both He and H may be present but not observed at early times. The spectroscopic classification of SLSNe should probably reflect that of SNe Ib/c. Extensive time coverage is required for an accurate classification.

  18. Spectrum formation in Superluminous Supernovae (Type I)

    CERN Document Server

    Mazzali, P A; Pian, E; Greiner, J; Kann, D A; ARI-LJMU,; UK,; Garching, MPA; Germany,; Southampton, Univ; INAF-IASFBO,; Italy,; Pisa, SNS; Garching, MPE; Tautenburg,; Germany),

    2016-01-01

    The near-maximum spectra of most superluminous supernovae that are not dominated by interaction with a H-rich CSM (SLSN-I) are characterised by a blue spectral peak and a series of absorption lines which have been identified as OII. SN2011kl, associated with the ultra-long gamma-ray burst GRB111209A, also had a blue peak but a featureless optical/UV spectrum. Radiation transport methods are used to show that the spectra (not including SN2007bi, which has a redder spectrum at peak, like ordinary SNe Ic) can be explained by a rather steep density distribution of the ejecta, whose composition appears to be typical of carbon-oxygen cores of massive stars which can have low metal content. If the photospheric velocity is ~10000-15000 km/s, several lines form in the UV. OII lines, however, arise from very highly excited lower levels, which require significant departures from Local Thermodynamic Equilibrium to be populated. These SLSNe are not thought to be powered primarily by 56Ni decay. An appealing scenario is th...

  19. Ratio of left ventricular peak E-wave velocity to flow propagation velocity assessed by color M-mode Doppler echocardiography in first myocardial infarction

    DEFF Research Database (Denmark)

    Møller, J E; Søndergaard, E; Seward, J B;

    2000-01-01

    OBJECTIVES: To determine the ability of the ratio of peak E-wave velocity to flow propagation velocity (E/Vp) measured with color M-mode Doppler echocardiography to predict in-hospital heart failure and cardiac mortality in an unselected consecutive population with first myocardial infarction (MI......). BACKGROUND: Several experimental studies indicate color M-mode echocardiography to be a valuable tool in the evaluation of diastolic function, but data regarding the clinical value are lacking. METHODS: Echocardiography was performed within 24 h of arrival at the coronary care unit in 110 consecutive...... or =1.5 measured with color M-mode echocardiography is a strong predictor of in-hospital heart failure. Furthermore, E/Vp is superior to systolic measurements in predicting 35 day survival although Dt

  20. Observation of image pair creation and annihilation from superluminal scattering sources.

    Science.gov (United States)

    Clerici, Matteo; Spalding, Gabriel C; Warburton, Ryan; Lyons, Ashley; Aniculaesei, Constantin; Richards, Joseph M; Leach, Jonathan; Henderson, Robert; Faccio, Daniele

    2016-04-01

    The invariance of the speed of light is one of the foundational pillars of our current understanding of the universe. It implies a series of consequences related to our perception of simultaneity and, ultimately, of time itself. Whereas these consequences are experimentally well studied in the case of subluminal motion, the kinematics of superluminal motion lack direct evidence or even a clear experimental approach. We investigate kinematic effects associated with the superluminal motion of a light source. By using high-temporal-resolution imaging techniques, we directly demonstrate that if the source approaches an observer at superluminal speeds, the temporal ordering of events is inverted and its image appears to propagate backward. Moreover, for a source changing its speed and crossing the interface between subluminal and superluminal propagation regions, we observe image pair annihilation and creation, depending on the crossing direction. These results are very general and show that, regardless of the emitter speed, it is not possible to unambiguously determine the kinematics of an event from imaging and time-resolved measurements alone. This has implications not only for light, but also, for example, for sound and other wave phenomena.

  1. An analytical solution describing the propagation of positive injury signals in an axon: effect of dynein velocity distribution.

    Science.gov (United States)

    Kuznetsov, A V

    2013-01-01

    A model describing the propagation of positive injury signals from the lesion site in an axon towards the neuron soma is described. It is assumed that these signals are driven by dynein molecular motors. An analytical solution that accounts for the probability density function (pdf) of a dynein velocity distribution is obtained. Two examples of pdf of dynein velocity distributions that follow from the results published in Ross et al. (2006, Processive bidirectional motion of dynein-dynactin complexes in vitro. Nat Cell Biol. 8:562-570) and Deinhardt et al. (2006, Rab5 and Rab7 control endocytic sorting along the axonal retrograde transport pathway. Neuron 52:293-305) are considered. The effect of dynein velocity distribution on the rate of spreading of the signal wave is discussed. It is demonstrated that the obtained solution can be applied to the problem of how neurons measure the distance between the lesion site and the neuron soma.

  2. A lower bound for the velocity of quantum communications in the preferred frame

    CERN Document Server

    Cocciaro, Bruno; Fronzoni, Leone

    2010-01-01

    An EPR experiment with polarized entangled photons is performed to test the Eberhard model. According to the Eberhard model, quantum correlations between space-like separated events are due to a superluminal communication signal propagating in a preferred frame. The coincidences between entangled photons passing through two polarizers aligned along a Est-West axis are measured as a function of time during 21 sidereal days. No deviation from the predictions of the Quantum Theory is observed. Tacking into account for the experimental uncertainties, we infer that, if a preferred frame for superluminal signals exists, the velocity of quantum communications in this frame has to be greater than v_{t}=0.67 * 10^4 c.

  3. Superluminal Neutrinos from Special Relativity with de Sitter Space-time Symmetry

    OpenAIRE

    Yan, Mu-Lin; Xiao, Neng-Chao; Huang, Wei; Hu, Sen

    2011-01-01

    We explore the recent OPERA experiment of superluminal neutrinos in the framework of Special Relativity with de Sitter space-time symmetry (dS-SR). According to Einstein a photon is treated as a massless particle in the framework of Special Relativity. In Special Relativity (SR) we have the universal parameter $c$, the photon velocity $c_{photon}$ and the phase velocity of a light wave in vacuum $c_{wave}=\\lambda\

  4. On the propagation speed of evanescent modes

    Energy Technology Data Exchange (ETDEWEB)

    Barbero, A.P.L. [State Univ. of Campinas, Campinas (Brazil)]|[Universidad Federal Fluminense (Brazil); Hernandez Figueroa, H.E. [State Univ. of Campinas, Campinas (Brazil); Recami, E. [Istituto Nazionale di Fisica Nucleare, Milan (Italy)]|[Bergamo Univ., Bergamo (Italy). Fac. di Ingegneria]|[State Univ. of Campinas, Campinas (Brazil)

    2000-03-01

    The group velocity of evanescent waves (in undersized waveguides, for instance) was theoretically predicted, and has been experimentally verified, to be superluminal. By contrast, it is known that the precursor speed in vacuum cannot be larger than c. This paper, by computer simulations based on Maxwell equations only, shows the existence of both phenomena and verifies the actual possibility of superluminal group velocities, without violating the so-called (naive) Einstein causality.

  5. A multipoint determination of the propagation velocity of a sudden commencement across the polar ionosphere

    DEFF Research Database (Denmark)

    Engebretson, M.J.; Murr, D.L.; Hughes, W.J.

    1999-01-01

    We use magnetic field and riometer data, from ground observatories in both the Arctic and Antarctic regions to characterize the high-latitude propagation of a sudden storm commencement (SC) that occurred at; 0901 UT February '21, 1994. (1) high time resolution magnetic field data. from both hemis...... hemispheres indicate extremely rapid propagation of the initial part of the SC signal at high latitudes. An initial inflection point; was observed in the data front dawn sector stations in both polar caps nearly simultaneously (Delta t...

  6. Anomalous velocity enhancing of soliton, propagating in nonlinear PhC, due to its reflection from nonlinear ambient medium

    Science.gov (United States)

    Trofimov, Vyacheslav A.; Lysak, T. M.

    2016-05-01

    We demonstrate a new possibility of a soliton velocity control at its propagation in a nonlinear layered structure (1D photonic crystal) which is placed in a nonlinear ambient medium. Nonlinear response of the ambient medium, as well as the PhC layers, is cubic. At the initial time moment, a soliton is spread over a few layers of PhC. Then, soliton propagates across the layered structure because of the initial wave-vector direction presence for the laser beam. The soliton reaches the PhC faces and reflects from them or passes through the face. As a nonlinear medium surrounds the PhC, the laser beam obtains additional impulse after interaction with this medium and accelerates (or slows down or stops near the PhC face). Nonlinear response of the ambient medium can be additionally created by another laser beam which shines near the PhC faces.

  7. A Non-Mainstream Viewpoint on Apparent Superluminal Phenomena in AGN Jet

    Indian Academy of Sciences (India)

    Wen-Po Liu; Li-Yan Liu; Chun-Cheng Wang

    2014-09-01

    The group velocity of light in material around the AGN jet is acquiescently one ( as a unit), but this is only a hypothesis. Here, we re-derive apparent superluminal and Doppler formulas for the general case (it is assumed that the group velocity of light in the uniform and isotropic medium around a jet (a beaming model) is not necessarily equal to one, e.g., Araudo et al. (2010) thought that there may be dense clouds around AGN jet base), and show that the group velocity of light close to one could seriously affect apparent superluminal phenomena and Doppler effect in the AGN jet (when the viewing angle and Lorentz factor take some appropriate values).

  8. Magnetic Reconnection Processes Involving Modes Propagating in the Ion Diamagnetic Velocity Direction

    Science.gov (United States)

    Buratti, P.; Coppi, B.; Pucella, G.; Zhou, T.

    2013-10-01

    Experiments in weakly collisional plasma regimes, (e.g. neutral beam heated plasmas in the H-regime), measuring the Doppler shift associated with the plasma local rotation, have shown that the toroidal mode phase velocity vph in the frame with Er = 0 is in the direction of the ion diamagnetic velocity. For ohmically heated plasmas, with higher collisionalities, vph in the laboratory frame is in the direction of the electron diamagnetic velocity, but plasma rotation is reversed as well, and vph, in the Er = 0 frame, is in the ion diamagnetic velocity direction. Theoretically, two classes of reconnecting modes should emerge: drift-tearing modes and ``inductive modes'' that depend on the effects of a finite plasma inductivity. The former modes, with vph in the direction of the electron diamagnetic velocity, require the pre-excitation of a different kind of mode in order to become unstable in weakly collisional regimes. The second kind of modes has a growth rate associated with the relevant finite ion viscosity. A comprehensive theory is presented. Sponsored in part by the US DOE.

  9. Spectroscopy of superluminous supernova host galaxies

    DEFF Research Database (Denmark)

    Leloudas, G.; Kruehler, T.; Schulze, S

    2015-01-01

    Superluminous supernovae (SLSNe) are very bright explosions that were only discovered recently and that show a preference for occurring in faint dwarf galaxies. Understanding why stellar evolution yields different types of stellar explosions in these environments is fundamental in order to both...... uncover the elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In this paper, we present the first results of our project to study SUperluminous Supernova Host galaxIES, focusing on the sample for which we have obtained spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen...

  10. On the Lorentz Factor of Superluminal Sources

    CERN Document Server

    Onuchukwu, Chika Christian

    2013-01-01

    We investigate the properties of features seen within superluminal sources often referred to as components. Our result indicates a fairly strong correlation of r=0.6 for quasars, r=0.4 for galaxies, and r=0.8 for BL Lac objects in our sample between component sizes and distances from the stationary core. Assumption of free adiabatic expanding plasma enabled us to constrain in general the Lorentz factor for superluminal sources. Ourestimated Lorentz factor of 7 - 17 for quasars, 6 - 13 for galaxies and 4- 9 for BL Lac objects indicate that BL Lac have the lowest range of Lorentz factor.

  11. A search for the analogue to Cherenkov radiation by high energy neutrinos at superluminal speeds in ICARUS

    CERN Document Server

    Antonello, M.; Baibussinov, B.; Baldo Ceolin, M.; Benetti, P.; Calligarich, E.; Canci, N.; Carbonara, F.; Centro, S.; Cesana, A.; Cieslik, K.; Cline, D.B.; Cocco, A.G.; Dabrowska, A.; Dequal, D.; Dermenev, A.; Dolfini, R.; Farnese, C.; Fava, A.; Ferrari, A.; Fiorillo, G.; Gibin, D.; Gigli Berzolari, A.; Gninenko, S.; Guglielmi, A.; Haranczyk, M.; Holeczek, J.; Ivashkin, A.; Kisiel, J.; Kochanek, I.; Lagoda, J.; Mania, S.; Mannocchi, G.; Menegolli, A.; Meng, G.; Montanari, C.; Otwinowski, S.; Periale, L.; Piazzoli, A.; Picchi, P.; Pietropaolo, F.; Plonski, P.; Rappoldi, A.; Raselli, G.L.; Rossella, M.; Rubbia, C.; Sala, P.R.; Scantamburlo, E.; Scaramelli, A.; Segreto, E.; Sergiampietri, F.; Stefan, D.; Stepaniak, J.; Sulej, R.; Szarska, M.; Terrani, M.; Varanini, F.; Ventura, S.; Vignoli, C.; Wang, H.; Yang, X.; Zalewska, A.; Zaremba, K.; Cohen, A.

    2012-01-01

    The OPERA collaboration [1] has claimed evidence of superluminal propagation between CERN and the LNGS with . We find that the neutrino energy distribution of the ICARUS events in LAr agrees with the expectations from the Monte Carlo predictions from an unaffected energy distribution of beam from CERN. Our results therefore refute a superluminal interpretation of the OPERA result according to the Cohen and Glashow prediction [2] for a weak currents analog to Cherenkov radiation. In particular no events with a superluminal Cherenkov like e+e- pair or gamma emission have been directly observed inside the fiducial volume of the "bubble chamber like" ICARUS TPC-LAr detector, setting much stricter limits to the value of delta comparable with the one due to the observations from the SN1987A.

  12. Photography of shock waves during excimer laser ablation of the cornea. Effect of helium gas on propagation velocity.

    Science.gov (United States)

    Krueger, R R; Krasinski, J S; Radzewicz, C; Stonecipher, K G; Rowsey, J J

    1993-07-01

    Shadow photography of shock waves excited by means of a xenon chloride excimer laser was performed to determine the shock wave propagation velocity in air, nitrogen and helium. Energy densities between 500 and 2,000 mJ/cm2 were used to ablate a rotating rubber cylindrical target and porcine corneas. In ablating the rubber cylinder, a shock wave velocity of 3.3 km/s was generated in air and nitrogen at 40 ns; this decreased to 1.4 km/s at 320 ns. When helium was blown on the target, the velocity increased by a factor of approximately two, to 5.9 km/s at 40 ns and 2.7 km/s at 320 ns. We suggest that blowing helium on the surface of the cornea during excimer laser ablation may speed the dissipation of high-energy acoustic waves and gaseous particles, and thus reduce the exposure and transfer of heat energy to the surrounding tissue.

  13. Pair Production Constraints on Superluminal Neutrinos Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.

    2012-02-16

    We revisit the pair creation constraint on superluminal neutrinos considered by Cohen and Glashow in order to clarify which types of superluminal models are constrained. We show that a model in which the superluminal neutrino is effectively light-like can evade the Cohen-Glashow constraint. In summary, any model for which the CG pair production process operates is excluded because such timelike neutrinos would not be detected by OPERA or other experiments. However, a superluminal neutrino which is effectively lightlike with fixed p{sup 2} can evade the Cohen-Glashow constraint because of energy-momentum conservation. The coincidence involved in explaining the SN1987A constraint certainly makes such a picture improbable - but it is still intrinsically possible. The lightlike model is appealing in that it does not violate Lorentz symmetry in particle interactions, although one would expect Hughes-Drever tests to turn up a violation eventually. Other evasions of the CG constraints are also possible; perhaps, e.g., the neutrino takes a 'short cut' through extra dimensions or suffers anomalous acceleration in matter. Irrespective of the OPERA result, Lorentz-violating interactions remain possible, and ongoing experimental investigation of such possibilities should continue.

  14. Superluminality, Black Holes and Effective Field Theory

    CERN Document Server

    Goon, Garrett

    2016-01-01

    Under the assumption that a UV theory does not display superluminal behavior, we ask what constraints on superluminality are satisfied in the effective field theory (EFT). We study two examples of effective theories: quantum electrodynamics (QED) coupled to gravity after the electron is integrated out, and the flat-space galileon. The first is realized in nature, the second is more speculative, but they both exhibit apparent superluminality around non-trivial backgrounds. In the QED case, we attempt, and fail, to find backgrounds for which the superluminal signal advance can be made larger than the putative resolving power of the EFT. In contrast, in the galileon case it is easy to find such backgrounds, indicating that if the UV completion of the galileon is (sub)luminal, quantum corrections must become important at distance scales of order the Vainshtein radius of the background configuration, much larger than the naive EFT strong coupling distance scale. Such corrections would be reminiscent of the non-per...

  15. Emission of correlated photon pairs from superluminal perturbations in dispersive media

    CERN Document Server

    Piazza, Francesco Dalla; Cacciatori, Sergio Luigi; Faccio, Daniel

    2012-01-01

    We develop a perturbative theory that describes a superluminal refractive perturbation propagating in a dispersive medium and the subsequent excitation of the quantum vacuum zero-point fluctuations. We find a process similar to the anomalous Doppler effect: photons are emitted in correlated pairs and mainly within a Cerenkov-like cone, one on the forward and the other in backward directions. The number of photon pairs emitted from the perturbation increases strongly with the degree of superluminality and under realizable experimental conditions, it can reach up to ~0.01 photons per pulse. Moreover, it is in principle possible to engineer the host medium so as to modify the effective group refractive index. In the presence of "fast light" media, e.g. a with group index smaller than unity, a further ~10x enhancement may be achieved and the photon emission spectrum is characterized by two sharp peaks that, in future experiments would clearly identify the correlated emission of photon pairs.

  16. Self-accelerating Massive Gravity: Superluminality, Cauchy Surfaces and Strong Coupling

    CERN Document Server

    Motloch, Pavel; Joyce, Austin; Motohashi, Hayato

    2015-01-01

    Self-accelerating solutions in massive gravity provide explicit, calculable examples that exhibit the general interplay between superluminality, the well-posedness of the Cauchy problem, and strong coupling. For three particular classes of vacuum solutions, one of which is new to this work, we construct the conformal diagram for the characteristic surfaces on which isotropic stress-energy perturbations propagate. With one exception, all solutions necessarily possess spacelike characteristics, indicating perturbative superluminality. Foliating the spacetime with these surfaces gives a pathological frame where kinetic terms of the perturbations vanish, confusing the Hamiltonian counting of degrees of freedom. This frame dependence distinguishes the vanishing of kinetic terms from strong coupling of perturbations or an ill-posed Cauchy problem. We give examples where spacelike characteristics do and do not originate from a point where perturbation theory breaks down and where spacelike surfaces do or do not inte...

  17. Site response, shallow shear-wave velocity, and wave propagation at the San Jose, California, dense seismic array

    Science.gov (United States)

    Hartzell, S.; Carver, D.; Williams, R.A.; Harmsen, S.; Zerva, A.

    2003-01-01

    Ground-motion records from a 52-element dense seismic array near San Jose, California, are analyzed to obtain site response, shallow shear-wave velocity, and plane-wave propagation characteristics. The array, located on the eastern side of the Santa Clara Valley south of the San Francisco Bay, is sited over the Evergreen basin, a 7-km-deep depression with Miocene and younger deposits. Site response values below 4 Hz are up to a factor of 2 greater when larger, regional records are included in the analysis, due to strong surface-wave development within the Santa Clara Valley. The pattern of site amplification is the same, however, with local or regional events. Site amplification increases away from the eastern edge of the Santa Clara Valley, reaching a maximum over the western edge of the Evergreen basin, where the pre-Cenozoic basement shallows rapidly. Amplification then decreases further to the west. This pattern may be caused by lower shallow shear-wave velocities and thicker Quaternary deposits further from the edge of the Santa Clara Valley and generation/trapping of surface waves above the shallowing basement of the western Evergreen basin. Shear-wave velocities from the inversion of site response spectra based on smaller, local earthquakes compare well with those obtained independently from our seismic reflection/refraction measurements. Velocities from the inversion of site spectra that include larger, regional records do not compare well with these measurements. A mix of local and regional events, however, is appropriate for determination of site response to be used in seismic hazard evaluation, since large damaging events would excite both body and surface waves with a wide range in ray parameters. Frequency-wavenumber, plane-wave analysis is used to determine the backazimuth and apparent velocity of coherent phases at the array. Conventional, high-resolution, and multiple signal characterization f-k power spectra and stacked slowness power spectra are

  18. Phenomenological model of propagation of the elastic waves in a fluid-saturated porous solid with nonzero boundary slip velocity.

    Science.gov (United States)

    Tsiklauri, David

    2002-09-01

    It is known that a boundary slip velocity starts to play an important role when the length scale over which the fluid velocity changes approaches the slip length, i.e., when the fluid is highly confined, for example, fluid flow through porous rock or blood vessel capillaries. Zhu and Granick [Phys. Rev. Lett. 87, 096105 (2001)] have recently experimentally established the existence of a boundary slip in a Newtonian liquid. They reported typical values of the slip length of the order of few micrometers. In this light, the effect of introduction of the boundary slip into the theory of propagation of elastic waves in a fluid-saturated porous medium formulated by Biot [J. Acoust. Soc. Am. 28, 179-191 (1956)] is investigated. Namely, the effect of introduction of boundary slip upon the function F(kappa) that measures the deviation from Poiseuille flow friction as a function of frequency parameter kappa is studied. By postulating phenomenological dependence of the slip velocity upon frequency, notable deviations in the domain of intermediate frequencies in the behavior of F(kappa) are introduced with the incorporation of the boundary slip into the model. It is known that F(kappa) crucially enters Biot's equations, which describe dynamics of fluid-saturated porous solid. Thus, consequences of the nonzero boundary slip by calculating the phase velocities and attenuation coefficients of both rotational and dilatational waves with the variation of frequency are investigated. The new model should allow one to fit the experimental seismic data in circumstances when Biot's theory fails, as the introduction of phenomenological dependence of the slip velocity upon frequency, which is based on robust physical arguments, adds an additional degree of freedom to the model. In fact, it predicts higher than the Biot's theory values of attenuation coefficients of the both rotational and dilatational waves in the intermediate frequency domain, which is in qualitative agreement with the

  19. OPERA superluminal neutrinos and Kinematics in Finsler spacetime

    CERN Document Server

    Chang, Zhe; Wang, Sai

    2011-01-01

    The OPERA collaboration recently reported that muon neutrinos could be superluminal. More recently, Cohen and Glashow pointed that such superluminal neutrinos would be suppressed since they lose their energies rapidly via bremsstrahlung. In this Letter, we propose that Finslerian nature of spacetime could account for the superluminal phenomena of particles. The Finsler spacetime permits the existence of superluminal behavior of particles while the casuality still holds. A new dispersion relation is obtained in a class of Finsler spacetime. It is shown that the superluminal speed is linearly dependent on the energy per unit mass of the particle. We find that such a superluminal speed formula is consistent with data of OPERA, MINOS and Fermilab-1979 neutrino experiments as well as observations on neutrinos from SN1987a.

  20. Causal ubiquity in quantum physics. A superluminal and local-causal physical ontology

    Energy Technology Data Exchange (ETDEWEB)

    Neelamkavil, Raphael

    2014-07-01

    A fixed highest criterial velocity (of light) in STR (special theory of relativity) is a convention for a layer of physical inquiry. QM (Quantum Mechanics) avoids action-at-a-distance using this concept, but accepts non-causality and action-at-a-distance in EPR (Einstein-Podolsky-Rosen-Paradox) entanglement experiments. Even in such allegedly [non-causal] processes, something exists processually in extension-motion, between the causal and the [non-causal]. If STR theoretically allows real-valued superluminal communication between EPR entangled particles, quantum processes become fully causal. That is, the QM world is sub-luminally, luminally and superluminally local-causal throughout, and the Law of Causality is ubiquitous in the micro-world. Thus, ''probabilistic causality'' is a merely epistemic term.

  1. Stochastic model in microwave propagation

    Energy Technology Data Exchange (ETDEWEB)

    Ranfagni, A. [“Nello Carrara” Institute of Applied Physics, CNR Florence Research Area, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy); Mugnai, D., E-mail: d.mugnai@ifac.cnr.it [“Nello Carrara” Institute of Applied Physics, CNR Florence Research Area, Via Madonna del Piano 10, 50019 Sesto Fiorentino (Italy)

    2011-11-28

    Further experimental results of delay time in microwave propagation are reported in the presence of a lossy medium (wood). The measurements show that the presence of a lossy medium makes the propagation slightly superluminal. The results are interpreted on the basis of a stochastic (or path integral) model, showing how this model is able to describe each kind of physical system in which multi-path trajectories are present. -- Highlights: ► We present new experimental results on electromagnetic “anomalous” propagation. ► We apply a path integral theoretical model to wave propagation. ► Stochastic processes and multi-path trajectories in propagation are considered.

  2. On the Lorentz factor of superluminal sources

    Institute of Scientific and Technical Information of China (English)

    Chika Christian Onuchukwu; Augustine A.Ubachukwu

    2013-01-01

    We investigate the properties of features seen within superluminal sources often referred to as components.Our result indicates a fairly strong correlation of r ~ 0.5 for quasars,r ~ 0.4 for galaxies and r ~ 0.7 for BL Lac objects in our sample between component sizes and distances from the stationary core.The assumption of free adiabatic expanding plasma enables us to constrain the Lorentz factor for superluminal sources.Our estimated Lorentz factor of γ ~ 9-13 for quasars,γ ~ 7-11for galaxies and γ ~ 4-9 for BL Lac objects indicates that BL Lacs have the lowest range of Lorentz factors.

  3. Motor patterns of the small intestine explained by phase-amplitude coupling of two pacemaker activities: the critical importance of propagation velocity.

    Science.gov (United States)

    Huizinga, Jan D; Parsons, Sean P; Chen, Ji-Hong; Pawelka, Andrew; Pistilli, Marc; Li, Chunpei; Yu, Yuanjie; Ye, Pengfei; Liu, Qing; Tong, Mengting; Zhu, Yong Fang; Wei, Defei

    2015-09-15

    Phase-amplitude coupling of two pacemaker activities of the small intestine, the omnipresent slow wave activity generated by interstitial cells of Cajal of the myenteric plexus (ICC-MP) and the stimulus-dependent rhythmic transient depolarizations generated by ICC of the deep muscular plexus (ICC-DMP), was recently hypothesized to underlie the orchestration of the segmentation motor pattern. The aim of the present study was to increase our understanding of phase-amplitude coupling through modeling. In particular the importance of propagation velocity of the ICC-DMP component was investigated. The outcome of the modeling was compared with motor patterns recorded from the rat or mouse intestine from which propagation velocities within the different patterns were measured. The results show that the classical segmentation motor pattern occurs when the ICC-DMP component has a low propagation velocity (velocity in the same order of magnitude as that of the slow wave activity (∼1 cm/s), cluster type propulsive activity occurs which is in fact the dominant propulsive activity of the intestine. Hence, the only difference between the generation of propagating cluster contractions and the Cannon-type segmentation motor pattern is the propagation velocity of the low-frequency component, the rhythmic transient depolarizations originating from the ICC-DMP. Importantly, the proposed mechanism explains why both motor patterns have distinct rhythmic waxing and waning of the amplitude of contractions. The hypothesis is brought forward that the velocity is modulated by neural regulation of gap junction conductance within the ICC-DMP network.

  4. Superluminal Neutrinos from Special Relativity with de Sitter Space-time Symmetry

    CERN Document Server

    Yan, Mu-Lin; Huang, Wei

    2011-01-01

    We explore the recent OPERA experiment of superluminal neutrinos in the framework of Special Relativity with de Sitter space-time symmetry (dS-SR). According to Einstein, the photon is treated as the massless particle in the SR mechanics. The meanings of the universal parameter $c$ and the photon velocity $c_{photon}$ in SR have been analyzed. $c$ can be determined by means of the velocity-composition law in SR kinematically. And $c_{photon}$ is determined by the dispersion relations of SR. It is revealed that $c=c_{photon}$ in Einstein's Special Relativity (E-SR), but $c\

  5. Engineering of second generation HTS coated conductor architecture to enhance the normal zone propagation velocity in various operating conditions

    Science.gov (United States)

    Lacroix, C.; Sirois, F.; Fournier Lupien, J.-H.

    2017-06-01

    The effects of operating conditions, critical current and stabilizer geometry on the normal zone propagation velocity (NZPV) of second generation (2G) high-temperature superconductor (HTS) coated conductors (CCs) are investigated using finite element simulations. The NZPV of tapes with a low interfacial resistance between the HTS and stabilizer layers are first compared with tapes with a current flow diverter (CFD) architecture. Our results indicates that the CFD concept increases the NZPV for the whole range of operating temperatures investigated (10-77 K). In particular, for an operating temperature of 77 K and an operating current of 0.9I c, our numerical results indicate that the NZPV of a 2G HTS CC with a CFD architecture and a 2 μm thick stabilizer layer could reach a value of 50 m s-1. Furthermore, numerical simulations realized on the effect of the stabilizer geometry on the NZPV of 2G HTS CCs revealed that putting most of the stabilizer on the substrate side can enhance the NZPV by a factor of 7 or more, even for tape with thick stabilizer (20 μm or more). This is particularly promising for improving quench detection in applications requiring a thick stabilizer such as superconducting coils.

  6. Resolving 7 problems with OPERA's superluminal neutrino experiment

    CERN Document Server

    Ehrlich, Robert

    2011-01-01

    Physicists have raised many troubling inconsistencies with the OPERA claim of superluminal neutrinos that cast doubt on its validity. This paper examines ways that 7 of these inconsistencies can be resolved. It also discusses evidence that the electron neutrino is superluminal, based on previously published cosmic ray observations, and secondarily a re-examination of tritium beta decay data.

  7. Comment on ``Observation of Superluminal Behaviors in Wave Propagation''

    Science.gov (United States)

    Bigelow, N. P.; Hagen, C. R.

    2001-07-01

    Two Comments on the Letter by D. Mugnai, A. Ranfagni, and R. Ruggeri, Phys. Rev. Lett. 84, 4830 (2000). Points similar to those made in the following two Comments were made in papers by S. Glasgow and J. Peatross, by M. Peshkin, by L. C. Cune and M. Apostol, by W. Luis Mochán and V. L. Brudny, and by C. Altucci, C. de Lisio, B. Preziosi, and S. Solimeno.

  8. Superluminal propagation and broadband omnidirectional antireflection in optical reflectionless potentials

    CERN Document Server

    Thekkekara, L V; Kasture, Sachin; Mulay, Gajendra; Gupta, S Dutta

    2013-01-01

    Reflectionless potentials (RPs) represent a class of potentials that offer total transmission in the context of one dimensional scattering. Optical realization of RPs in stratified medium can exhibit broadband omnidirectional antireflection property. In addition to the antireflection property, RPs are also expected to demonstrate negative delay. We designed refractive index profiles conforming to RPs and realize them in stratified media consisting of Al2O3 and TiO2 heterolayers. In these structures we observed < 1% reflection over the broad wavelength range of 350 nm to 2500 nm for angles of incidence 0 - 50 degrees. The observed reflection and transmission response of RPs are polarization independent. A negative delay of about 31 fsec with discernible pulse narrowing was observed in passage through two RPs. These RPs can be interesting for optical instrumentation as broadband, omni-directional antireflection coatings as well as in pulse control and transmission applications like delay lines.

  9. Superluminal Propagation and Acausality of Nonlinear Massive Gravity

    CERN Document Server

    Deser, S; Ong, Y C; Waldron, A

    2013-01-01

    Massive gravity is an old idea: trading geometry for mass. Much effort has been expended on establishing a healthy model, culminating in the current ghost-free version. We summarize here our recent findings -- that it is still untenable -- because it is locally acausal: CTC solutions can be constructed in a small neighborhood of any event.

  10. Enhanced Sensitivity in a Superluminal Single Mode DPAL Cavity at Room Temperature

    Science.gov (United States)

    Abi-Salloum, Tony; Yablon, Joshua; Tseng, Shih; Shahriar, Selim

    2012-06-01

    The note beat between two counter-propagating beams in a cavity is used to measure the effective change of the length of the cavity or interferometer for applications such as optical gyroscopes, vibrometers, and gravitational wave detectors. We show in this talk how a superluminal single mode laser cavity can enhance the measured note beat dramatically. We consider the inhomogeneous broadening case and study the dependence of the enhancement factor on few key parameters. We also show how Diode Pump Alkali Lasers (DPAL) are excellent candidates for such devices. Using a Rubidium based DPAL, we study the characteristics of these lasers and their effect on the proposed enhanced sensitivity.

  11. Propagation of light through small clouds of cold interacting atoms

    CERN Document Server

    Jennewein, S; Greffet, J -J; Browaeys, A

    2015-01-01

    We demonstrate experimentally that a cloud of cold atoms with a size comparable to the wavelength of light can induce large group delays on a laser pulse when the laser is tightly focused on it and is close to an atomic resonance. Delays as large as -10 ns are observed, corresponding to "superluminal" propagation with negative group velocities as low as -300 m/s. Strikingly, this large delay is associated with a moderate extinction owing to the very small size of the cloud and to the light-induced interactions between atoms. It implies that a large phase shift is imprinted on the continuous laser beam, and opens interesting perspectives for applications to quantum technologies.

  12. Propagation of light through small clouds of cold interacting atoms

    Science.gov (United States)

    Jennewein, S.; Sortais, Y. R. P.; Greffet, J.-J.; Browaeys, A.

    2016-11-01

    We demonstrate experimentally that a dense cloud of cold atoms with a size comparable to the wavelength of light can induce large group delays on a laser pulse when the laser is tightly focused on it and is close to an atomic resonance. Delays as large as -10 ns are observed, corresponding to "superluminal" propagation with negative group velocities as low as -300 m /s . Strikingly, this large delay is associated with a moderate extinction owing to the very small size of the dense cloud. It implies that a large phase shift is imprinted on the continuous laser beam. Our system may thus be useful for applications to quantum technologies, such as variable delay line for individual photons or phase imprint between two beams at the single-photon level.

  13. Superluminal Energy Transmission in the Goos-Hanchen Shift of Total Reflection

    CERN Document Server

    Wang, Z Y

    2011-01-01

    This paper is to give a counter example for the theory of relativity. Firstly, the dispersion relation of surface electromagnetic waves is corresponding to that of a tachyon where the coefficient of proportionality is the squared Planck constant. Then we prove the energy flow velocity S/w of the Goos-Hanchen shift in vacuum is cn.sinI>c as well according to electrodynamics. These two different ways lead to a same conclusion that energy transport in the Goos-Hanchen effect of total reflection is faster than light. It is also helpful to study the tachyon of particle physics and superluminal motion observed in astronomy,etc.

  14. Slow to superluminal light waves in thin 3D photonic crystals.

    Science.gov (United States)

    Galisteo-López, J F; Galli, M; Balestreri, A; Patrini, M; Andreani, L C; López, C

    2007-11-12

    Phase measurements on self-assembled three-dimensional photonic crystals show that the group velocity of light can flip from small positive (slow) to negative (superluminal) values in samples of a few mum size. This phenomenon takes place in a narrow spectral range around the second-order stop band and follows from coupling to weakly dispersive photonic bands associated with multiple Bragg diffraction. The observations are well accounted for by theoretical calculations of the phase delay and of photonic states in the finite-sized systems.

  15. Causal ubiquity in quantum physics a superluminal and local-causal physical ontology

    CERN Document Server

    Neelamkavil, Raphael

    2014-01-01

    A fixed highest criterial velocity (of light) in STR (special theory of relativity) is a convention for a layer of physical inquiry. QM (Quantum Mechanics) avoids action-at-a-distance using this concept, but accepts non-causality and action-at-a-distance in EPR (Einstein-Podolsky-Rosen-Paradox) entanglement experiments. Even in such allegedly non-causal processes, something exists processually in extension-motion, between the causal and the non-causal. If STR theoretically allows real-valued superluminal communication between EPR entangled particles, quantum processes become fully causal. That

  16. Visualization of superluminal pulses inside a white light cavity using plane wave spatio temporal transfer functions.

    Science.gov (United States)

    Yum, H N; Jang, Y J; Liu, X; Shahriar, M S

    2012-08-13

    In a white light cavity (WLC), the group velocity is superluminal over a finite bandwidth. For a WLC-based data buffering system we recently proposed, it is important to visualize the behavior of pulses inside such a cavity. The conventional plane wave transfer functions, valid only over space that is translationally invariant, cannot be used for the space inside WLC or any cavity, which is translationally variant. Here, we develop the plane wave spatio temporal transfer function (PWSTTF) method to solve this problem, and produce visual representations of a Gaussian input pulse incident on a WLC, for all times and positions.

  17. Rapidly Rising Transients in the Supernova - Superluminous Supernova Gap

    CERN Document Server

    Arcavi, Iair; Howell, D Andrew; Bildsten, Lars; Leloudas, Giorgos; Hardin, Delphine; Prajs, Szymon; Perley, Daniel A; Svirski, Gilad; Gal-Yam, Avishay; Katz, Boaz; McCully, Curtis; Cenko, S Bradley; Lidman, Chris; Sullivan, Mark; Valenti, Stefano; Astier, Pierre; Balland, Cristophe; Carlberg, Ray G; Conley, Alex; Fouchez, Dominique; Guy, Julien; Pain, Reynald; Palanque-Delabrouille, Nathalie; Perrett, Kathy; Pritchet, Chris J; Regnault, Nicolas; Rich, James; Ruhlmann-Kleider, Vanina

    2015-01-01

    We present observations of four rapidly rising (t_{rise}~10d) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M_{peak}~-20) - one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey (SNLS). The light curves resemble those of SN 2011kl, recently shown to be associated with an ultra-long-duration gamma ray burst (GRB), though no GRB was seen to accompany our SNe. The rapid rise to a luminous peak places these events in a unique part of SN phase space, challenging standard SN emission mechanisms. Spectra of the PTF event formally classify it as a Type II SN due to broad Halpha emission, but an unusual absorption feature, which can be interpreted as either high velocity Halpha (though deeper than in previously known cases) or Si II (as seen in Type Ia SNe), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM) and magnetar spindown can not r...

  18. RAPIDLY RISING TRANSIENTS IN THE SUPERNOVA—SUPERLUMINOUS SUPERNOVA GAP

    Energy Technology Data Exchange (ETDEWEB)

    Arcavi, Iair; Howell, D. Andrew [Las Cumbres Observatory Global Telescope, 6740 Cortona Dr., Suite 102, Goleta, CA 93111 (United States); Wolf, William M. [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Bildsten, Lars; McCully, Curtis; Valenti, Stefano [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Leloudas, Giorgos; Gal-Yam, Avishay; Katz, Boaz [Department of Particle Physics and Astrophysics, The Weizmann Institute of Science, Rehovot, 76100 (Israel); Hardin, Delphine; Astier, Pierre; Balland, Cristophe [LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France); Prajs, Szymon; Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Perley, Daniel A. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Svirski, Gilad [Racah Institute for Physics, The Hebrew University, Jerusalem 91904 (Israel); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Lidman, Chris [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Carlberg, Ray G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada); Conley, Alex, E-mail: iarcavi@lcogt.net [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States); and others

    2016-03-01

    We present observations of four rapidly rising (t{sub rise} ≈ 10 days) transients with peak luminosities between those of supernovae (SNe) and superluminous SNe (M{sub peak} ≈ −20)—one discovered and followed by the Palomar Transient Factory (PTF) and three by the Supernova Legacy Survey. The light curves resemble those of SN 2011kl, recently shown to be associated with an ultra-long-duration gamma-ray burst (GRB), though no GRB was seen to accompany our SNe. The rapid rise to a luminous peak places these events in a unique part of SN phase space, challenging standard SN emission mechanisms. Spectra of the PTF event formally classify it as an SN II due to broad Hα emission, but an unusual absorption feature, which can be interpreted as either high velocity Hα (though deeper than in previously known cases) or Si ii (as seen in SNe Ia), is also observed. We find that existing models of white dwarf detonations, CSM interaction, shock breakout in a wind (or steeper CSM), and magnetar spin down cannot readily explain the observations. We consider the possibility that a “Type 1.5 SN” scenario could be the origin of our events. More detailed models for these kinds of transients and more constraining observations of future such events should help to better determine their nature.

  19. Group velocity of neutrino waves

    Science.gov (United States)

    Indumathi, D.; Kaul, Romesh K.; Murthy, M. V. N.; Rajasekaran, G.

    2012-03-01

    We follow up on the analysis of Mecozzi and Bellini (arxiv:arXiv:1110.1253v1) where they showed, in principle, the possibility of superluminal propagation of neutrinos, as indicated by the recent OPERA result. We refine the analysis by introducing wave packets for the superposition of energy eigenstates and discuss the implications of their results with realistic values for the mixing and mass parameters in a full three neutrino mixing scenario. Our analysis shows the possibility of superluminal propagation of neutrino flavour in a very narrow range of neutrino parameter space. Simultaneously this reduces the number of observable events drastically. Therefore, the OPERA result cannot be explained in this frame-work.

  20. Group velocity of neutrino waves

    CERN Document Server

    Indumathi, D; Murthy, M V N; Rajasekaran, G

    2011-01-01

    We follow up on the analysis of Mecozzi and Bellini (arXiv:1110:1253v1) where they showed, in principle, the possibility of superluminal propagation of neutrinos, as indicated by the recent OPERA result. We refine the analysis by introducing wave packets for the superposition of energy eigenstates and discuss the implications of their results with realistic values for the mixing and mass parameters in a full three neutrino mixing scenario. Our analysis shows the possibility of superluminal propagation of neutrino flavour in a very narrow range of neutrino parameter space. However, the explanation of the OPERA result is outside this possibility. This result, if confirmed by other experiments, can be explained through matter effects via a possible new interaction.

  1. Mathematical modeling of velocity and number density profiles of particles across the flame propagation through a micro-iron dust cloud.

    Science.gov (United States)

    Bidabadi, Mehdi; Haghiri, Ali; Rahbari, Alireza

    2010-04-15

    In this study, an attempt has been made to analytically investigate the concentration and velocity profiles of particles across flame propagation through a micro-iron dust cloud. In the first step, Lagrangian particle equation of motion during upward flame propagation in a vertical duct is employed and then forces acting upon the particle, such as thermophoretic force (resulted from the temperature gradient), gravitation and buoyancy are introduced; and consequently, the velocity profile as a function of the distance from the leading edge of the combustion zone is extracted. In the resumption, a control volume above the leading edge of the combustion zone is considered and the change in the particle number density in this control volume is obtained via the balance of particle mass fluxes passing through it. This study explains that the particle concentration at the leading edge of the combustion zone is more than the particle agglomeration in a distance far from the flame front. This increase in the particle aggregation above the combustion zone has a remarkable effect on the lower flammability limits of combustible particle cloud. It is worth noticing that the velocity and particle concentration profiles show a reasonable compatibility with the experimental data.

  2. Self-action of propagating and standing Lamb waves in the plates exhibiting hysteretic nonlinearity: Nonlinear zero-group velocity modes.

    Science.gov (United States)

    Gusev, Vitalyi E; Lomonosov, Alexey M; Ni, Chenyin; Shen, Zhonghua

    2017-09-01

    An analytical theory accounting for the influence of hysteretic nonlinearity of micro-inhomogeneous plate material on the Lamb waves near the S1 zero group velocity point is developed. The theory predicts that the main effect of the hysteretic quadratic nonlinearity consists in the modification of the frequency and the induced absorption of the Lamb modes. The effects of the nonlinear self-action in the propagating and standing Lamb waves are expected to be, respectively, nearly twice and three times stronger than those in the plane propagating acoustic waves. The theory is restricted to the simplest hysteretic nonlinearity, which is influencing only one of the Lamé moduli of the materials. However, possible extensions of the theory to the cases of more general hysteretic nonlinearities are discussed as well as the perspectives of its experimental testing. Applications include nondestructive evaluation of micro-inhomogeneous and cracked plates. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Nonlocal Quantum Information Transfer Without Superluminal Signalling and Communication

    Science.gov (United States)

    Walleczek, Jan; Grössing, Gerhard

    2016-09-01

    It is a frequent assumption that—via superluminal information transfers—superluminal signals capable of enabling communication are necessarily exchanged in any quantum theory that posits hidden superluminal influences. However, does the presence of hidden superluminal influences automatically imply superluminal signalling and communication? The non-signalling theorem mediates the apparent conflict between quantum mechanics and the theory of special relativity. However, as a `no-go' theorem there exist two opposing interpretations of the non-signalling constraint: foundational and operational. Concerning Bell's theorem, we argue that Bell employed both interpretations, and that he finally adopted the operational position which is associated often with ontological quantum theory, e.g., de Broglie-Bohm theory. This position we refer to as "effective non-signalling". By contrast, associated with orthodox quantum mechanics is the foundational position referred to here as "axiomatic non-signalling". In search of a decisive communication-theoretic criterion for differentiating between "axiomatic" and "effective" non-signalling, we employ the operational framework offered by Shannon's mathematical theory of communication, whereby we distinguish between Shannon signals and non-Shannon signals. We find that an effective non-signalling theorem represents two sub-theorems: (1) Non-transfer-control (NTC) theorem, and (2) Non-signification-control (NSC) theorem. Employing NTC and NSC theorems, we report that effective, instead of axiomatic, non-signalling is entirely sufficient for prohibiting nonlocal communication. Effective non-signalling prevents the instantaneous, i.e., superluminal, transfer of message-encoded information through the controlled use—by a sender-receiver pair —of informationally-correlated detection events, e.g., in EPR-type experiments. An effective non-signalling theorem allows for nonlocal quantum information transfer yet—at the same time

  4. The effects of pressure, temperature, and pore water on velocities in Westerly granite. [for seismic wave propagation

    Science.gov (United States)

    Spencer, J. W., Jr.; Nur, A. M.

    1976-01-01

    A description is presented of an experimental assembly which has been developed to conduct concurrent measurements of compressional and shear wave velocities in rocks at high temperatures and confining pressures and with independent control of the pore pressure. The apparatus was used in studies of the joint effects of temperature, external confining pressure, and internal pore water on sonic velocities in Westerly granite. It was found that at a given temperature, confining pressure has a larger accelerating effect on compressional waves in dry rock, whereas at a given confining pressure, temperature has a larger retarding effect on shear waves.

  5. SN 2012au: A GOLDEN LINK BETWEEN SUPERLUMINOUS SUPERNOVAE AND THEIR LOWER-LUMINOSITY COUNTERPARTS

    Energy Technology Data Exchange (ETDEWEB)

    Milisavljevic, Dan; Soderberg, Alicia M.; Margutti, Raffaella; Drout, Maria R.; Marion, G. Howie; Sanders, Nathan E.; Lunnan, Ragnhild; Chornock, Ryan; Berger, Edo; Foley, Ryan J.; Challis, Pete; Kirshner, Robert P.; Dittmann, Jason; Bieryla, Allyson; Kamble, Atish; Chakraborti, Sayan [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hsiao, Eric Y. [Carnegie Observatories, Las Campanas Observatory, Colina El Pino, Casilla 601 (Chile); Fesen, Robert A.; Parrent, Jerod T. [6127 Wilder Lab, Department of Physics and Astronomy, Dartmouth College, Hanover, NH 03755 (United States); Levesque, Emily M., E-mail: dmilisav@cfa.harvard.edu [CASA, Department of Astrophysical and Planetary Sciences, University of Colorado, 389-UCB, Boulder, CO 80309 (United States); and others

    2013-06-20

    We present optical and near-infrared observations of SN 2012au, a slow-evolving supernova (SN) with properties that suggest a link between subsets of energetic and H-poor SNe and superluminous SNe. SN 2012au exhibited conspicuous Type-Ib-like He I lines and other absorption features at velocities reaching Almost-Equal-To 2 Multiplication-Sign 10{sup 4} km s{sup -1} in its early spectra, and a broad light curve that peaked at M{sub B} = -18.1 mag. Models of these data indicate a large explosion kinetic energy of {approx}10{sup 52} erg and {sup 56}Ni mass ejection of M{sub Ni} Almost-Equal-To 0.3 M{sub Sun} on par with SN 1998bw. SN 2012au's spectra almost one year after explosion show a blend of persistent Fe II P-Cyg absorptions and nebular emissions originating from two distinct velocity regions. These late-time emissions include strong [Fe II], [Ca II], [O I], Mg I], and Na I lines at velocities {approx}> 4500 km s{sup -1}, as well as O I and Mg I lines at noticeably smaller velocities {approx}< 2000 km s{sup -1}. Many of the late-time properties of SN 2012au are similar to the slow-evolving hypernovae SN 1997dq and SN 1997ef, and the superluminous SN 2007bi. Our observations suggest that a single explosion mechanism may unify all of these events that span -21 {approx}< M{sub B} {approx}< -17 mag. The aspherical and possibly jetted explosion was most likely initiated by the core collapse of a massive progenitor star and created substantial high-density, low-velocity Ni-rich material.

  6. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    Science.gov (United States)

    Ghorbanpour Arani, A.; Roudbari, M. A.

    2014-11-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler-Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics.

  7. Surface stress, initial stress and Knudsen-dependent flow velocity effects on the electro-thermo nonlocal wave propagation of SWBNNTs

    Energy Technology Data Exchange (ETDEWEB)

    Ghorbanpour Arani, A., E-mail: aghorban@kashanu.ac.ir [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of); Institute of Nanoscience and Nanotechnology, University of Kashan, Kashan, Islamic Republic of Iran (Iran, Islamic Republic of); Roudbari, M.A. [Faculty of Mechanical Engineering, University of Kashan, Kashan, Islamic Republic of Iran. (Iran, Islamic Republic of)

    2014-11-01

    This paper investigates the electro-thermal nonlocal wave propagation of fluid-conveying single-walled Boron Nitride nanotubes (SWBNNTs) using nonlocal piezoelasticity with surface stress, initial stress and Knudsen-dependent flow velocity effect. SWBNNT is embedded in a vicsoelastic medium which is simulated as visco-Pasternak foundation. Using Euler–Bernoulli beam (EBB) model, Hamilton's principle and nonlocal piezoelasticity theory, the higher order governing equation is derived. A detailed parametric study is conducted, focusing on the combined effects of the electric parameters, viscoelastic medium, initial stress, surface stress, Knudsen number (Kn) and small scale on the wave propagation behaviour of the fluid-conveying SWBNNT. The results show that for smaller values of wave number the dispersion relation for different fluid viscosities seems to be similar. At the higher values of wave numbers, increase in the wave frequency values is remarkable due to increase in fluid viscosity. The electric field as a smart controller, surface effect, initial stress, temperature change and slip velocity effect have significant role on the wave frequency. The results of this work is hoped to be of use in design and manufacturing of smart MEMS/NEMS in advanced medical applications such as drug delivery systems with great applications in biomechanics.

  8. Velocity and pattern of ice propagation and deep supercooling in woody stems of Castanea sativa, Morus nigra and Quercus robur measured by IDTA.

    Science.gov (United States)

    Neuner, Gilbert; Xu, Bingcheng; Hacker, Juergen

    2010-08-01

    Infrared differential thermal analysis (IDTA) was used to monitor the velocity and pattern of ice propagation and deep supercooling of xylem parenchyma cells (XPCs) during freezing of stems of Castanea sativa L., Morus nigra L. and Quercus robur L. that exhibit a macro- and ring-porous xylem. Measurements were conducted on the surface of cross- and longitudinal stem sections. During high-temperature freezing exotherms (HTEs; -2.8 to -9.4°C), initial freezing was mainly observed in the youngest year ring of the sapwood (94%), but occasionally elsewhere (older year rings: 4%; bark: 2%). Initially, ice propagated rapidly in the largest xylem conduits. This resulted in a distinct freezing pattern of concentric circles in C. sativa and M. nigra. During HTEs, supercooling of XPCs became visible in Q. robur stems, but not in the other species that have narrower pith rays. Intracellular freezing of supercooled XPCs of Q. robur became visible by IDTA during low-temperature freezing exotherms (<-17.4 °C). Infrared differential thermal analysis revealed the progress and the two-dimensional pattern of XPC freezing. XPCs did not freeze at once, but rather small cell groups appeared to freeze at random anywhere in the xylem. By IDTA, ice propagation and deep supercooling in stems can be monitored at meaningful spatial and temporal resolutions.

  9. Tracing the propagation of cosmic rays in the Milky Way halo with Fermi-LAT observations of high- and intermediate-velocity clouds

    CERN Document Server

    Tibaldo, L

    2015-01-01

    Cosmic rays up to at least PeV energies are usually described in the framework of an elementary scenario that involves acceleration by objects that are located in the disk of the Milky Way, such as supernova remnants or massive star-forming regions, and then diffusive propagation throughout the Galaxy. Details of the propagation process are so far inferred mainly from the composition of cosmic rays measured near the Earth and then extrapolated to the whole Galaxy. The details of the propagation in the Galactic halo and the escape into the intergalactic medium remain uncertain. The densities of cosmic rays in specific locations can be traced via the gamma rays they produce in inelastic collisions with clouds of interstellar gas. Therefore, we analyze 73 months of Fermi-LAT data from 300 MeV to 10 GeV in the direction of several high- and intermediate-velocity clouds that are located in the halo of the Milky Way. These clouds are supposed to be free of internal sources of cosmic rays and hence any gamma-ray emi...

  10. Superluminal Motion and Polarization in Blazars

    Institute of Scientific and Technical Information of China (English)

    Jun-Hui Fan; Yong-Jiu Wang; Jiang-He Yang; Cheng-Yue Su

    2004-01-01

    A relativistic beaming model has been successfully used to explain the observed properties of active galactic nuclei (AGNs). In this model there are two emission components, a boosted one and an unbeamed one, shown up in the radio band as the core and lobe components. The luminosity ratio of the core to the lobe is defined as the core-dominance parameter (R = LCore/LLobe) The de-beamed radio luminosity (Ldbjet) in the jet is assumed to be proportional to the unbeamed luminosity (Lub) in the co-moving frame, i.e., f = Ldbjet/Lub and f is determined in our previous paper. We further discuss the relationship between BL Lacertae objects(BLs) and flat spectrum radio quasars (FSRQs), which are subclasses of blazars with different degrees of polarization, using the calculated values of the ratio f for a sample of superluminal blazars. We found 1) that the BLs show smaller averaged Doppler factors and Lorentz factors, larger viewing angles and higher coredominance parameters than do the FSRQs, and 2) that in the polarization-core dominance parameter plot (P - log R) the BLs and FSRQs occupy a scattered region, but in a revised plot (logP/c(m) - logR), they gather around two different lines, suggesting that they have some different intrinsic properties.

  11. Super-luminous supernovae from PESSTO

    CERN Document Server

    Nicholl, M; Jerkstrand, A; Inserra, C; Chen, T -W; Kotak, R; Valenti, S; Howell, D A; McCrum, M; Margheim, S; Rest, A; Benetti, S; Fraser, M; Gal-Yam, A; Smith, K W; Sullivan, M; Young, D R; Baltay, C; Hadjiyska, E; McKinnon, R; Rabinowitz, D; Walker, E S; Feindt, U; Nugent, P; Lawrence, A; Mead, A; Anderson, J P; Sollerman, J; Taddia, F; Leloudas, G; Mattila, S; Elias-Rosa, N

    2014-01-01

    We present optical spectra and light curves for three hydrogen-poor super-luminous supernovae followed by the Public ESO Spectroscopic Survey of Transient Objects (PESSTO). Time series spectroscopy from a few days after maximum light to 100 days later shows them to be fairly typical of this class, with spectra dominated by Ca II, Mg II, Fe II and Si II, which evolve slowly over most of the post-peak photospheric phase. We determine bolometric light curves and apply simple fitting tools, based on the diffusion of energy input by magnetar spin-down, \\Ni decay, and collision of the ejecta with an opaque circumstellar shell. We investigate how the heterogeneous light curves of our sample (combined with others from the literature) can help to constrain the possible mechanisms behind these events. We have followed these events to beyond 100-200 days after peak, to disentangle host galaxy light from fading supernova flux and to differentiate between the models, which predict diverse behaviour at this phase. Models p...

  12. Superluminous Supernovae: No Threat from Eta Carinae

    Science.gov (United States)

    Thomas, Brian; Melott, A. L.; Fields, B. D.; Anthony-Twarog, B. J.

    2008-05-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of 1044 Joules. It was proposed that the progenitor may have been a massive evolved star similar to η Carinae, which resides in our own galaxy at a distance of about 2.3 kpc. η Carinae appears ready to detonate. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma-Ray Burst oriented toward the Earth, η Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over 104 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possible effect of supernovae, endocrine disruption induced by blue light near the peak of the optical spectrum. This is a possibility for nearby supernovae at distances too large to be considered "dangerous” for other reasons. However, due to reddening and extinction by the interstellar medium, η Carinae is unlikely to trigger such effects to any significant degree.

  13. Superluminous supernovae: No threat from Eta Carinae

    CERN Document Server

    Thomas, Brian C; Fields, Brian D; Anthony-Twarog, Barbara J

    2007-01-01

    Recently Supernova 2006gy was noted as the most luminous ever recorded, with a total radiated energy of ~10^44 Joules. It was proposed that the progenitor may have been a massive evolved star similar to Eta Carinae, which resides in our own galaxy at a (poorly determined) distance of ~2.5 kpc. Eta Carinae appears ready to detonate, and in fact had an outburst in 1843. Although it is too distant to pose a serious threat as a normal supernova, and given its rotation axis is unlikely to produce a Gamma Ray Burst oriented toward the Earth, Eta Carinae is about 30,000 times nearer than 2006gy, and we re-evaluate it as a potential superluminous supernova. We find that given the large ratio of emission in the optical to the X-ray, atmospheric effects are negligible. Ionization of the atmosphere and concomitant ozone depletion are unlikely to be important. Any cosmic ray effects should be spread out over ~10^4 y, and similarly unlikely to produce any serious perturbation to the biosphere. We also discuss a new possib...

  14. First stars, hypernovae, and superluminous supernovae

    Science.gov (United States)

    Nomoto, Ken'Ichi

    2016-07-01

    After the big bang, production of heavy elements in the early universe takes place starting from the formation of the first (Pop III) stars, their evolution, and explosion. The Pop III supernova (SN) explosions have strong dynamical, thermal, and chemical feedback on the formation of subsequent stars and evolution of galaxies. However, the nature of Pop III stars/supernovae (SNe) have not been well-understood. The signature of nucleosynthesis yields of the first SN can be seen in the elemental abundance patterns observed in extremely metal-poor (EMP) stars. We show that the abundance patterns of EMP stars, e.g. the excess of C, Co, Zn relative to Fe, are in better agreement with the yields of hyper-energetic explosions (Hypernovae, (HNe)) rather than normal supernovae. We note the large variation of the abundance patterns of EMP stars propose that such a variation is related to the diversity of the GRB-SNe and posssibly superluminous supernovae (SLSNe). For example, the carbon-enhanced metal-poor (CEMP) stars may be related to the faint SNe (or dark HNe), which could be the explosions induced by relativistic jets. Finally, we examine the various mechanisms of SLSNe.

  15. Tachyons, Lamb shifts and superluminal chaos

    Science.gov (United States)

    Tomaschitz, R.

    2000-10-01

    An elementary account on the origins of cosmic chaos in an open and multiply connected universe is given; there is a finite region in the open 3-space in which the world-lines of galaxies are chaotic, and the mixing taking place in this chaotic nucleus of the universe provides a mechanism to create equidistribution. The galaxy background defines a distinguished frame of reference and a unique cosmic time order; in this context superluminal signal transfer is studied. Tachyons are described by a real Proca field with negative mass square, coupled to a current of subluminal matter. Estimates on tachyon mixing in the geometric optics limit are derived. The potential of a static point source in this field theory is a damped periodic function. We treat this tachyon potential as a perturbation of the Coulomb potential, and study its effects on energy levels in hydrogenic systems. By comparing the induced level shifts to high-precision Lamb shift measurements and QED calculations, we suggest a tachyon mass of 2.1 keV/c2 and estimate the tachyonic coupling strength to subluminal matter. The impact of the tachyon field on ground state hyperfine transitions in hydrogen and muonium is investigated. Bounds on atomic transition rates effected by tachyon radiation as well as estimates on the spectral energy density of a possible cosmic tachyon background radiation are derived.

  16. Search for Anisotropic Light Propagation as a Function of Laser Beam Alignment Relative to the Earth's Velocity Vector

    Directory of Open Access Journals (Sweden)

    Navia C. E.

    2007-01-01

    Full Text Available A laser diffraction experiment was conducted to study light propagation in air. The experiment is easy to reproduce and it is based on simple optical principles. Two optical sensors (segmented photo-diodes are used for measuring the position of diffracted light spots with a precision better than 0.1 μ m. The goal is to look for signals of anisotropic light propagation as function of the laser beam alignment to the Earth’s motion (solar barycenter motion obtained by COBE. Two raster search techniques have been used. First, a laser beam fixed in the laboratory frame scans in space due to Earth’s rotation. Second, a laser beam mounted on a turntable system scans actively in space by turning the table. The results obtained with both methods show that the course of light rays are affected by the motion of the Earth, and a predominant first order quantity with a Δ c/c = − β (1 + 2 a cos θ signature with ˉ a = − 0.393 ± 0.032 describes well the experimental results. This result differs in amount of 21% from the Special Relativity Theory prediction and that supplies the value of a = − 1 2 (isotropy.

  17. How superluminal motion can lead to backward time travel

    CERN Document Server

    Nemiroff, Robert J

    2015-01-01

    It is commonly asserted that superluminal particle motion can enable backward time travel, but little has been written providing details. It is shown here that the simplest example of a "closed loop" event -- a twin paradox scenario where a single spaceship both traveling out and returning back superluminally -- does {\\it not} result in that ship straightforwardly returning to its starting point before it left. However, a more complicated scenario -- one where the superluminal ship first arrives at an intermediate destination moving subluminally -- can result in backwards time travel. This intermediate step might seem physically inconsequential but is shown to break Lorentz-invariance and be oddly tied to the sudden creation of a pair of spacecraft, one of which remains and one of which annihilates with the original spacecraft.

  18. Minimum Length - Maximum Velocity

    CERN Document Server

    Panes, Boris

    2011-01-01

    We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example we can predict the ratio between the minimum lengths in space and time using the results from OPERA about superluminal neutrinos.

  19. 超光速:可能与不可能%On the Superluminal Movement:Possible and Impossible?

    Institute of Scientific and Technical Information of China (English)

    黄政新

    2012-01-01

    The OPERA experimental results indicate that neutrinos move even faster than the speed of light,which triggers extensive skepticism with regards of Einstein's assertion that superluminal movement does not exists in nature.This paper first makes a brief review to the history of tachyon(faster-than-light particle) research home and abroad in the past half-century.It then points out that:(1) there is no solid and sufficient reason in Einstein's assertion that superluminal movement does not exists in nature;(2) so far there is no solid experimental foundation for those currently established superluminal theories;(3) a correct superluminal theory should return to special relativity under extreme conditions(i.e.when the velocity approaches the speed of light).%"奥佩拉"(OPERA)实验结果显示中微子运动得比光速还快。这引起许多人对爱因斯坦关于自然界不存在超光速运动这一断言的怀疑。本文回顾了半个世纪以来国内外快子(超光速粒子)研究的简要历史。接着,本文指出:(1)爱因斯坦断言自然界不存在超光速运动是没有充分理由的;(2)所有已建立的超光速理论都没有坚实的实验基础;(3)一个正确的超光理论在极限条件下(当速度趋于光速时)时应当回归狭义相对论。

  20. The evolution of superluminous supernova LSQ14mo and its interacting host galaxy system

    CERN Document Server

    Chen, T -W; Smartt, S J; Mazzali, P A; Yates, R M; Moriya, T J; Inserra, C; Langer, N; Kruehler, T; Pan, Y -C; Kotak, R; Galbany, L; Schady, P; Wiseman, P; Greiner, J; Schulze, S; Man, A W S; Jerkstrand, A; Smith, K W; Dennefeld, M; Baltay, C; Bolmer, J; Kankare, E; Knust, F; Maguire, K; Rabinowitz, D; Rostami, S; Sullivan, M; Young, D R

    2016-01-01

    We present and analyse an extensive dataset of the superluminous supernova LSQ14mo (z = 0.256), consisting of a multi-colour lightcurve from -30 d to +70 d in the rest-frame and a series of 6 spectra from PESSTO covering -7 d to +50 d. This is among the densest spectroscopic coverage, and best-constrained rising lightcurve, for a fast-declining hydrogen-poor superluminous supernova. The bolometric lightcurve can be reproduced with a millisecond magnetar model with ~ 4 M_sol ejecta mass, and the temperature and velocity evolution is also suggestive of a magnetar as the power source. Spectral modelling indicates that the SN ejected ~ 6 M_sol of CO-rich material with a kinetic energy of ~ 7 x 10^51 erg, and suggests a partially thermalised additional source of luminosity between -2 d and +22 d. This may be due to interaction with a shell of material originating from pre-explosion mass loss. We further present a detailed analysis of the host galaxy system of LSQ14mo. PESSTO and GROND imaging show three spatially ...

  1. Superluminal motion in a compact steep spectrum radio source 3C 138

    CERN Document Server

    Shen, Z Q; Kameno, S; Chen, Y J

    2001-01-01

    We present the results of 5 GHz VLBI observations of a compact steep spectrum source 3C 138. The data are consistent with the western end being the location of the central activity. The observed offset between different frequencies in the central region of 3C 138 can be accounted for by a frequency dependent shift of the synchrotron self-absorbed core. Our new measurements confirm the existence of a superluminal motion, but its apparent velocity of 3.3c is three times slower than the reported one. This value is consistent with the absence of parsec-scale counter-jet emission in the inner region, but seems still too high to allow the overall counter-jet to be seen in terms of Doppler boosting of an intrinsically identical jet. Either an interaction of jet with central dense medium, or an intrinsically asymmetrical jet must be invoked to reconcile the detected superluminal speed with the observed large scale asymmetry in 3C 138.

  2. Special relativity and superluminal motions: a discussion of some recent experiments

    Energy Technology Data Exchange (ETDEWEB)

    Recami, E. [Istituto Nazionale di Fisica Nucleare, Milan (Italy)]|[Bergamo Univ., Bergamo (Italy). Fac. di Ingegneria]|[State Univ. of Campinas, Campinas (Brazil); Fontana, F. [Pirelli Cavi, Milan (Italy). R and D sector; Garavaglia, R. [Milan Univ., Milan (Italy). Dipt. di Scienze dell' Informazione

    2000-03-01

    Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay and Rennes led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction. For instance, localized wavelet-type solutions of Maxwell equations have been found, both theoretically and experimentally, that travel with superluminal speed. Even mounic and electronic neutrinos - it has been proposed - might be tachyons, since their square mass appears to be negative. With regard to the first mentioned experiments, it was very recently claimed by Guenter Nimtz that those results with evanescent waves or tunnelling photons - implying superluminal signal and impulse transmission - violate Einstein causality. This note, on the contrary, discusses that all such results do not place relativistic causality in jeopardy, even if they refer to actual tachyonic motions. In fact, special relativity can cope even with also the known paradoxes , devised for faster than light motion, even if this is not widely recognized. Here the paper shows, in detail and rigorously, how to solve the oldest casual paradox. originally proposed by Tolman, which is the kernel of many further tachyon paradoxes. The key to the solution is a careful application of tachyon mechanics, as it unambiguously follows from special relativity.

  3. A no-cost improved velocity-stress staggered-grid finite-difference scheme for modelling seismic wave propagation

    Science.gov (United States)

    Etemadsaeed, Leila; Moczo, Peter; Kristek, Jozef; Ansari, Anooshiravan; Kristekova, Miriam

    2016-10-01

    We investigate the problem of finite-difference approximations of the velocity-stress formulation of the equation of motion and constitutive law on the staggered grid (SG) and collocated grid (CG). For approximating the first spatial and temporal derivatives, we use three approaches: Taylor expansion (TE), dispersion-relation preserving (DRP), and combined TE-DRP. The TE and DRP approaches represent two fundamental extremes. We derive useful formulae for DRP and TE-DRP approximations. We compare accuracy of the numerical wavenumbers and numerical frequencies of the basic TE, DRP and TE-DRP approximations. Based on the developed approximations, we construct and numerically investigate 14 basic TE, DRP and TE-DRP finite-difference schemes on SG and CG. We find that (1) the TE second-order in time, TE fourth-order in space, 2-point in time, 4-point in space SG scheme (that is the standard (2,4) VS SG scheme, say TE-2-4-2-4-SG) is the best scheme (of the 14 investigated) for large fractions of the maximum possible time step, or, in other words, in a homogeneous medium; (2) the TE second-order in time, combined TE-DRP second-order in space, 2-point in time, 4-point in space SG scheme (say TE-DRP-2-2-2-4-SG) is the best scheme for small fractions of the maximum possible time step, or, in other words, in models with large velocity contrasts if uniform spatial grid spacing and time step are used. The practical conclusion is that in computer codes based on standard TE-2-4-2-4-SG, it is enough to redefine the values of the approximation coefficients by those of TE-DRP-2-2-2-4-SG for increasing accuracy of modelling in models with large velocity contrast between rock and sediments.

  4. A Blind Pilot: Who is a Super-Luminal Observer?

    Directory of Open Access Journals (Sweden)

    Rabounski D.

    2008-04-01

    Full Text Available This paper discusses the nature of a hypothetical super-luminal observer who, as well as a real (sub-light speed observer, perceives the world by light waves. This consideration is due to that fact that the theory of relativity permits different frames of reference, including light-like and super-luminal reference frames. In analogy with a blind pilot on board a supersonic jet aeroplane (or missile, perceived by blind people, it is concluded that the light barrier is observed in the framework of only the light signal exchange experiment.

  5. An experimental study of wave propagation and velocity distributions in a vertically driven time-dependent granular gas

    Science.gov (United States)

    Perez, John Anthony

    Averaged over appropriate space and time scales the dynamics of highly fluidized granular systems are often reminiscent of molecular fluid flows. As a result, theoretical efforts to describe these systems have borrowed heavily from continuum mechanics, particularly hydrodynamics. This has led to various proposed granular hydrodynamic theories which have been used to simulate granular materials in various states of confinement and excitation. These studies suggest that a continuum model for granular gasses can accurately reproduce the mean density, velocity and temperature profiles for an experimental granular gas. This thesis contributes to this body of work by presenting an experimental study of the hydrodynamic fields and velocity distributions within a vertically driven quasi-2D granular gas. We have taken pictures as fast as possible of a time-dependent granular gas using a high-speed CCD camera. We have extracted the positions and velocities of 57-564 particles per frame over 400 GB of raw images collected at 3700 fps. We used this data to compute the density, velocity and temperature fields as functions of time and space to a very high resolution. This approach led to the discovery of novel substructures within the hydrodynamic fields which would have been overlooked had we chosen to average over a drive cycle as earlier studies have done. In particular, the high spatial resolution available from our measurements reveals a serrated substructure in the shock waves which has not been reported before. This substructure is the result of collisional momentum transport . One of the current issues in formulating a granular continuum model is how to incorporate local and non-local dependencies between stress and strain correctly. In this thesis we demonstrate that the collisional transfer of momentum produces a non-local effect in the stress tensor which plays a major role in determining the mean flow. Current models have incorporated only the collisional or

  6. Alterations in left ventricular structure and diastolic function in professional football players: assessment by tissue Doppler imaging and left ventricular flow propagation velocity.

    Science.gov (United States)

    Tumuklu, M Murat; Ildizli, Muge; Ceyhan, Koksal; Cinar, Cahide Soydas

    2007-02-01

    Long-term regular exercise is associated with physiologic and morphologic cardiac alterations. Tissue Doppler imaging (TDI) and ventricular early flow propagation velocity (Vp) are new tolls in the evaluation of myocardial function. We sought to compare TDI and Vp findings in professional football players and age-adjusted sedentary controls to assess the effect of regular athletic training on myocardial function. Twenty-four professional football players and age-, sex-, and weight-adjusted 20 control subjects underwent standard Doppler echocardiography pulsed TDI, performed parasternal four-chamber views by placing sample volume septal and lateral side of mitral annulus and lateral tricuspid annulus. Vp values were obtained by measuring the slope delineated by first aliasing velocity from the mitral tips toward the apex by using apical four-chamber color M-mode Doppler images. Age, body surface area, blood pressure, and heart rate were comparable between two groups. Football players had significantly increased LV mass, mass index (due to both higher wall thickness and end-diastolic diameter), end-systolic and end-diastolic volume, left atrial diameter, and decreased transmitral diastolic late velocity. In athletes TDI analysis showed significantly increased mitral annulus septal DTI peak early diastolic (e) velocity (0.22 +/- 0.04 vs 0.19 +/- 0.04, P velocity (0.19 +/- 0.03 vs 0.16 +/- 0.02, P velocity ratio (1.96 +/- 0.41 and 1.66 +/- 0.23, P velocity (E) to e in both lateral (4.72 +/- 1.20 vs 5.95 +/- 1.38, P = 0.007) and septal (3.90 +/- 0.80 vs 5.25 +/- 1.50, P = 0.002) side of mitral annulus were significantly lower in athletes. In Vp evaluation, we found higher Vp values (60.52 +/- 6.95 in athletes and 56.56 +/- 4.24 in controls, P = 0.03) in football players. Professional football playing is associated with morphologic alteration in left ventricle and left atrium and improvement in left ventricle diastolic function that can be detected by TDI and Vp. These

  7. There is Neither Classical Bug with a Superluminal Shadow Nor Quantum Absolute Collapse Nor (Subquantum) Superluminal Hidden Variable

    CERN Document Server

    Pankovic, V; Krmar, M; Radovanovic, M; Pankovic, Vladan; Predojevic, Milan; Krmar, Miodrag; Radovanovic, Milan

    2005-01-01

    In this work we analyse critically Griffiths's example of the classical superluminal motion of a bug shadow. Griffiths considers that this example is conceptually very close to quantum nonlocality or superluminality,i.e. quantum breaking of the famous Bell inequality. Or, generally, he suggests implicitly an absolute asymmetric duality (subluminality vs. superluminality) principle in any fundamental physical theory.It, he hopes, can be used for a natural interpretation of the quantum mechanics too. But we explain that such Griffiths's interpretation retires implicitly but significantly from usual, Copenhagen interpretation of the standard quantum mechanical formalism. Within Copenhagen interpretation basic complementarity principle represents, in fact, a dynamical symmetry principle (including its spontaneous breaking, i.e. effective hiding by measurement). Similarly, in other fundamental physical theories instead of Griffiths's absolute asymmetric duality principle there is a dynamical symmetry (including it...

  8. Stream ambient noise, spectrum and propagation of sounds in the goby Padogobius martensii: sound pressure and particle velocity.

    Science.gov (United States)

    Lugli, Marco; Fine, Michael L

    2007-11-01

    The most sensitive hearing and peak frequencies of courtship calls of the stream goby, Padogobius martensii, fall within a quiet window at around 100 Hz in the ambient noise spectrum. Acoustic pressure was previously measured although Padogobius likely responds to particle motion. In this study a combination pressure (p) and particle velocity (u) detector was utilized to describe ambient noise of the habitat, the characteristics of the goby's sounds and their attenuation with distance. The ambient noise (AN) spectrum is generally similar for p and u (including the quiet window at noisy locations), although the energy distribution of u spectrum is shifted up by 50-100 Hz. The energy distribution of the goby's sounds is similar for p and u spectra of the Tonal sound, whereas the pulse-train sound exhibits larger p-u differences. Transmission loss was high for sound p and u: energy decays 6-10 dB10 cm, and sound pu ratio does not change with distance from the source in the nearfield. The measurement of particle velocity of stream AN and P. martensii sounds indicates that this species is well adapted to communicate acoustically in a complex noisy shallow-water environment.

  9. Hole-burning in an Autler-Townes doublet and in superluminal (subluminal) Electromagnetically induced transparency of a light pulse via a joint nonlinear coherent Kerr effect and Doppler broadening

    CERN Document Server

    Bacha, Bakhtt A; Ahmad, Iftikhar

    2013-01-01

    We investigate the behavior of light pulse propagation in a 4-level double Lambda atomic system under condition of electromagnetically induced transparency. The Fano type interference effect and spectral hole burning appears in the the dynamics of the absorption-dispersion spectra caused by the joint nonlinear coherence Kerr effect and Doppler broadening. The coherent Kerr effect exhibits an enhancement (reduction) in superluminal (subluminal) in negative (in positive) group index while the Doppler broadening generates multiple hole burning in the Autler-Townes like spectra of this system. The hole burning in addition with coherent Kerr effect on the spectral profile influences the dynamics of subluminal and superluminal of the probe pulse through the medium. The characteristics of superluminality and subluminality modified by considering cold-Kerr-free medium and hot-Kerr-dependent mediums. The light pulse delays and advances in different regions of dispersion medium with the Doppler broadening and coherent ...

  10. Holographic View of the Brain Memory Mechanism Based on Evanescent Superluminal Photons

    Directory of Open Access Journals (Sweden)

    Takaaki Musha

    2012-08-01

    Full Text Available D. Pollen and M. Trachtenberg proposed the holographic brain theory to help explain the existence of photographic memories in some people. They suggested that such individuals had more vivid memories because they somehow could access a very large region of their memory holograms. Hameroff suggested in his paper that cylindrical neuronal microtubule cavities, or centrioles, function as waveguides for the evanescent photons for quantum signal processing. The supposition is that microtubular structures of the brain function as a coherent fiber bundle set used to store holographic images, as would a fiber-optic holographic system. In this paper, the author proposes that superluminal photons propagating inside the microtubules via evanescent waves could provide the access needed to record or retrieve a quantum coherent entangled holographic memory.

  11. Superluminal Physics and Instantaneous Physics as New Trends in Research

    Directory of Open Access Journals (Sweden)

    Smarandache F.

    2012-01-01

    Full Text Available In a similar way as passing from Euclidean Geometry to Non-Euclidean Geometry, we can pass from Subluminal Physics to Superluminal Physics, and further to Instantaneous Physics. In the lights of two consecutive successful CERN experiments with superlumi- nal particles in the Fall of 2011, we believe that these two new fields of research should begin developing.

  12. Superluminal Phenomena and the Quantum Preferred Frame

    CERN Document Server

    Rembielinski, J

    2000-01-01

    Motivated by a number of recent experiments, we discuss in this paper a speculative but physically admissible form and solutions of effective Maxwell-like equations describing propagation of electromagnetic field in a medium which ``feels'' a quantum preferred frame.

  13. Biot's theory of propagation of elastic waves in a fluid-saturated porous solid revisited introduction of non-zero boundary slip velocity

    CERN Document Server

    Tsiklauri, D

    2001-01-01

    It is known that a boundary slip velocity starts to play important role when the length scale over which the fluid velocity changes approaches the slip length, i.e. when the fluid is highly confined, for example, fluid flow through porous rock or blood vessel capillaries. Craig et al. [Phys. Rev. Lett., 87, 054504 (2001)] have recently experimentally established existence of a boundary slip in a Newtonian liquid. We investigate the effect of introduction of the boundary slip into the theory of propagation of elastic waves in a fluid-saturated porous medium formulated by Biot [J. Acoust. Soc. Am., 28, 179 (1956)]. Namely, we study the effect of introduction of boundary slip upon the function F(kappa) that measures the deviation from Poiseuille flow friction as a function of frequency parameter kappa. We found substantial deviations, especially in the asymptotical limit of high frequencies, in the behavior of F(kappa) with the incorporation of the boundary slip into the model. It is known that F(kappa) cruciall...

  14. Superluminal Neutrinos and a Curious Phenomenon in the Relativistic Quantum Hamilton-Jacobi Equation

    CERN Document Server

    Matone, Marco

    2011-01-01

    OPERA's results, if confirmed, pose the question of superluminal neutrinos. We investigate the kinematics defined by the quantum version of the relativistic Hamilton-Jacobi equation, i.e. E^2=p^2c^2+m^2c^4+2mQc^2, with Q the quantum potential of the free particle. The key point is that the quantum version of the Hamilton-Jacobi equation is a third-order differential equation, so that it has integration constants which are missing in the Schr\\"odinger and Klein-Gordon equations. In particular, a non-vanishing imaginary part of an integration constant leads to a quantum correction to the expression of the velocity which is curiously in agreement with OPERA's results.

  15. X-ray Dips Followed by Superluminal Ejections as Evidence for An Accretion Disc Feeding the Jet in A Radio Galaxy

    Science.gov (United States)

    Marscher, Alan P.; Jorstad, Svetlana G.; Gomez, Jose-Luis; Aller, Margo F.; Terasranta, Harri; Lister, Matthew L.; Stirling, Alastair, M.

    2002-01-01

    Accretion onto black holes is thought to power the relativistic jets and other high-energy phenomena in both active galactic nuclei (AGNs) and the "microquasar" binary systems located in our Galaxy. However, until now there has been insufficient multifrequency monitoring to establish a direct observational link between the black hole and the jet in an AGE. This contrasts with the case of microquasars, in which superluminal features appear and propagate down the radio jet shortly after sudden decreases in the X-ray flux. Such an X-ray dip is most likely caused by the disappearance of a section of the inner accretion disc, part of which falls past the event horizon and the remainder of which is injected into the jet. This infusion of energy generates a disturbance that propagates down the jet, creating the appearance of a superluminal bright spot. Here we report the results of three years of intensive monitoring of the X-ray and radio emission of the Seyfert-like radio galaxy 3C 120. As in the case of microquasars, dips in the X-ray emission are followed by ejections of bright superluminal knots in the radio jet. Comparison of the characteristic length and time scales allows us to infer that the rotational states of the black holes in these two objects are different.

  16. Superluminal Motion Found In Milky Way

    Science.gov (United States)

    1994-08-01

    Researchers using the Very Large Array (VLA) have discovered that a small, powerful object in our own cosmic neighborhood is shooting out material at nearly the speed of light -- a feat previously known to be performed only by the massive cores of entire galaxies. In fact, because of the direction in which the material is moving, it appears to be traveling faster than the speed of light -- a phenomenon called "superluminal motion." This is the first superluminal motion ever detected within our Galaxy. During March and April of this year, Dr. Felix Mirabel of the Astrophysics Section of the Center for Studies at Saclay, France, and Dr. Luis Rodriguez of the Institute of Astronomy at the National Autonomous University in Mexico City and NRAO, observed "a remarkable ejection event" in which the object shot out material in opposite directions at 92 percent of the speed of light, or more than 171,000 miles per second. This event ejected a mass equal to one-third that of the moon with the power of 100 million suns. Such powerful ejections are well known in distant galaxies and quasars, millions and billions of light-years away, but the object Mirabel and Rodriguez observed is within our own Milky Way Galaxy, only 40,000 light-years away. The object also is much smaller and less massive than the core of a galaxy, so the scientists were quite surprised to find it capable of accelerating material to such speeds. Mirabel and Rodriguez believe that the object is likely a double-star system, with one of the stars either an extremely dense neutron star or a black hole. The neutron star or black hole is the central object of the system, with great mass and strong gravitational pull. It is surrounded by a disk of material orbiting closely and being drawn into it. Such a disk is known as an accretion disk. The central object's powerful gravity, they believe, is pulling material from a more-normal companion star into the accretion disk. The central object is emitting jets of

  17. Speed of the CERN Neutrinos released on 22.9.2011 - Was stated superluminality due to neglecting General Relativity?

    CERN Document Server

    Kundt, Wolfgang

    2011-01-01

    During the years 2009 to 2011, neutrino beams were fired repeatedly from CERN towards a detector in Italy's Gran Sasso tunnel, some 4 deg south and 7 deg east of CERN, at a distance of 730.5 km, in the shape of short bunches of particles. Their time of flight (2.5 msec) was measured at high accuracy (nsec) with caesium clocks (Reich 2011). Remarkably, the CNGS team found a deficit of 61 nsec compared with propagation at the speed of light, and concluded at superluminal speeds, of order 10$^{-4.6}$. In this communication, I will argue that this is the first experiment to test Einstein's theory for the (weak) gravity field of Earth, with the result that the neutrinos propagated (just) luminally.

  18. Multifrequency observations of the superluminal quasar 3C 345

    Science.gov (United States)

    Bregman, J. N.; Glassgold, A. E.; Huggins, P. J.; Neugebauer, G.; Soifer, B. T.; Matthews, K.; Roellig, T. P. L.; Bregman, J. D.; Witteborn, F. C.; Lester, D. F.

    1986-01-01

    Attention is given to the continuum properties of the superluminal quasar 3C 345, on the basis of radio, optical, IR, and X-ray frequency monitorings, as well as by means of simultaneous multifrequency spectra extending from the radio through the X-ray bands. Radio outbursts, which appear to follow IR-optical outbursts by about one year, first occur at the highest frequencies, as expected from optical depth effects; the peak flux is nevertheless often reached at several frequencies at once. The beginning of outbursts, as defined by mm-measurements, corresponds to the appearance of the three known 'superluminal' components. An increase in the X-ray flux during 1979-1980 corresponds to increased radio flux, while the IR flux changes in the opposite sense.

  19. The hypothesis of superluminal neutrinos: Comparing OPERA with other data

    DEFF Research Database (Denmark)

    Drago, A.; Masina, I.; Pagliara, G.

    2012-01-01

    The OPERA Collaboration reported evidence for muonic neutrinos traveling slightly faster than light in vacuum. While waiting further checks from the experimental community, here we aim at exploring some theoretical consequences of the hypothesis that muonic neutrinos are superluminal, considering...... in particular the tachyonic and the Coleman-Glashow cases. We show that a tachyonic interpretation is not only hardly reconciled with OPERA data on energy dependence, but that it clashes with neutrino production from pion and with neutrino oscillations. A Coleman-Glashow superluminal neutrino beam would also...... have problems with pion decay kinematics for the OPERA setup; it could be easily reconciled with SN1987a data, but then it would be very problematic to account for neutrino oscillations. Copyright (C) EPLA, 2012...

  20. Superluminal Spot Pair Events in Astronomical Settings: Sweeping Beams

    CERN Document Server

    Nemiroff, Robert J

    2014-01-01

    Sweeping beams of light can cast spots moving with superluminal speeds across scattering surfaces. Such faster-than-light speeds are well-known phenomena that do not violate special relativity. It is shown here that under certain circumstances, superluminal spot pair creation and annihilation events can occur that provide unique information to observers. These spot pair events are {\\it not} particle pair events -- they are the sudden creation or annihilation of a pair of relatively illuminated spots on a scattering surface. Real spot pair illumination events occur unambiguously on the scattering surface when spot speeds diverge, while virtual spot pair events are observer dependent and perceived only when real spot radial speeds cross the speed of light. Specifically, a virtual spot pair creation event will be observed when a real spot's speed toward the observer drops below $c$, while a virtual spot pair annihilation event will be observed when a real spot's radial speed away from the observer rises above $c...

  1. The hypothesis of superluminal neutrinos: Comparing OPERA with other data

    DEFF Research Database (Denmark)

    Drago, A.; Masina, I.; Pagliara, G.

    2012-01-01

    The OPERA Collaboration reported evidence for muonic neutrinos traveling slightly faster than light in vacuum. While waiting further checks from the experimental community, here we aim at exploring some theoretical consequences of the hypothesis that muonic neutrinos are superluminal, considering...... in particular the tachyonic and the Coleman-Glashow cases. We show that a tachyonic interpretation is not only hardly reconciled with OPERA data on energy dependence, but that it clashes with neutrino production from pion and with neutrino oscillations. A Coleman-Glashow superluminal neutrino beam would also...... have problems with pion decay kinematics for the OPERA setup; it could be easily reconciled with SN1987a data, but then it would be very problematic to account for neutrino oscillations. Copyright (C) EPLA, 2012...

  2. Multi-Epoch Spectroscopy of Hydrogen-Poor Superluminous Supernovae

    Science.gov (United States)

    Quimby, Robert; De Cia, Annalisa; Gal-Yam, Avishay; Leloudas, Giorgos; Lunnan, Ragnhild; Perley, Daniel A.; Vreeswijk, Paul; Yan, Lin

    2016-06-01

    A growing sample of intrinsically rare supernovae is being uncovered by wide-field synoptic surveys, such as the Palomar Transient Factory (PTF). A fraction of these events have been labeled "superluminous supernovae" due to their peak luminosities, which can exceed normal supernovae by factors of 10 to 100. The power sources for these events and thus their connection to normal luminosity supernovae remains uncertain. Here we present results from 134 spectroscopic observations of 17 hydrogen-poor superluminous supernovae (SLSN-I) discovered by PTF. We select our targets from the full PTF sample using only spectroscopic information; we do not employ the traditional cut in absolute magnitude (e.g. M physical insights into the nature of these explosions offered by this unique dataset.

  3. Controlling group velocity in a superconductive quantum circuit

    Institute of Scientific and Technical Information of China (English)

    Qiu Tian-Hui; Yang Guo-Jian

    2012-01-01

    We investigate the controllable group velocity of a microwave probe field in a superconductive quantum circuit (SQC) pumped by microwave fields,and the use of such a SQC function as an artificial A-type three-level atom.The exchange between the subluminal and the superluminal states of the probe field can be realized simply by sweeping the pumping intensity,and the superluminal state is usually realized with a lower absorption.This work is one of the efforts to extend the study of electromagnetically induced transparency and its related properties from the lightwave band to the microwave band.

  4. Graviton propagation within the context of the D-material universe

    CERN Document Server

    Elghozi, Thomas; Sakellariadou, Mairi

    2016-01-01

    Motivated by the recent breakthrough of the detection of Gravitational Waves (GW) from coalescent black holes by the aLIGO interferometers, we study the propagation of GW in the {\\sl D-material universe}, which we have recently shown to be compatible with large-scale structure and inflationary phenomenology. The medium of D-particles induces an effective mass for the graviton, as a consequence of the formation of recoil-velocity field condensates due to the underlying Born-Infeld dynamics. There is a competing effect, due to a super-luminal refractive index, as a result of the gravitational energy of D-particles acting as a dark matter component, with which propagating gravitons interact. We examine conditions for the condensate under which the latter effect is sub-leading. We argue that if quantum fluctuations of the recoil velocity are relatively strong, which can happen in the current era of the universe, then the condensate, and hence the induced mass of the graviton, can be several orders of magnitude la...

  5. THE SUPERLUMINAL CHARACTER OF THE COMPACT STEEP SPECTRUM QUASAR 3C-216

    NARCIS (Netherlands)

    VENTURI, T; PEARSON, TJ; BARTHEL, PD; HERBIG, T

    We report the results of fourth epoch VLBI observations at 4990.99 MHz, with a resolution of approximately 1 mas, of the compact steep-spectrum quasar 3C 216. Superluminal motion in this object is confirmed. Although a constant superluminal expansion at upsilon(app) = 3.9c +/- 0.6 is not ruled out,

  6. Minimum length-maximum velocity

    Science.gov (United States)

    Panes, Boris

    2012-03-01

    We study a framework where the hypothesis of a minimum length in space-time is complemented with the notion of reference frame invariance. It turns out natural to interpret the action of the obtained reference frame transformations in the context of doubly special relativity. As a consequence of this formalism we find interesting connections between the minimum length properties and the modified velocity-energy relation for ultra-relativistic particles. For example, we can predict the ratio between the minimum lengths in space and time using the results from OPERA on superluminal neutrinos.

  7. Would Superluminal Influences Violate the Principle of Relativity?

    CERN Document Server

    Peacock, Kent A

    2013-01-01

    It continues to be alleged that superluminal influences of any sort would be inconsistent with special relativity for the following three reasons: (i) they would imply the existence of a distinguished' frame; (ii) they would allow the detection of absolute motion; and (iii) they would violate the relativity of simultaneity. This paper shows that the first two objections rest upon very elementary misunderstandings of Minkowski geometry and lingering Newtonian intuitions about instantaneity. The third objection has a basis, but rather than invalidating the notion of faster than light influences it points the way to more general conceptions of simultaneity that could allow for quantum nonlocality in a natural way.

  8. An Extended Model for Interaction Between Left-hand Superluminous Waves and Magnetospheric Electrons

    Institute of Scientific and Technical Information of China (English)

    Xiao Fuliang; Zheng Huinan; Wang Shui

    2005-01-01

    The left-hand superluminous electromagnetic waves, L-O mode and L-X mode, can be excited and observed in the auroral cavity of the Earth during the magnetic storms. The two modes can propagate into outer radiation zone and encounter enhanced resonant interactions with the trapped energetic electrons over a wide range of magnetosphere. A current first-order resonant model is extended to evaluate the stochastic acceleration of electrons by the L-O mode and L-X mode at the higher-order resonance. Similar to the first-order resonance, L-O mode can produce significant acceleration of electrons at the higher harmonic resonances over a wide range of wave normal angles and spatial regions. However, the higher harmonic resonance's contribution for significant electron acceleration by L-X mode is less than that of the first order resonance,with the requirement of higher minimum energies, e.g., ~1 MeV in the outer radiation belt. This indicates that L-O mode may be one of the efficient mechanisms for the stochastic acceleration of electrons within the outer radiation zone.

  9. Extreme Supernova Models for the Superluminous Transient ASASSN-15lh

    CERN Document Server

    Chatzopoulos, E; Vinko, J; Nagy, A P; Wiggins, B K; Even, W P

    2016-01-01

    The recent discovery of the unprecedentedly superluminous transient ASASSN-15lh (or SN 2015L) challenges all the power-input models that have been proposed for superluminous supernovae. Here we examine some of the few viable interpretations of ASASSN-15lh in the context of a stellar explosion, involving combinations of one or more power inputs. We model the lightcurve of ASASSN-15lh with a hybrid model that includes contributions from magnetar spin-down energy and hydrogen-poor circumstellar interaction. We also investigate models of pure circumstellar interaction with a massive hydrogen-deficient shell and discuss about the lack of interaction features in the observed spectra. We find that ASASSN-15lh can be best modeled by the energetic core-collapse of a ~40 Msun supernova interacting with a hydrogen-poor shell of ~20 Msun. The circumstellar shell and progenitor mass are consistent with a rapidly rotating pulsational pair-instability supernova progenitor as required for strong interaction following the fin...

  10. Extended Linear and Nonlinear Lorentz Transformations and Superluminality

    Directory of Open Access Journals (Sweden)

    Dara Faroughy

    2013-01-01

    Full Text Available Two broad scenarios for extended linear Lorentz transformations (ELTs are modeled in Section 2 for mixing subluminal and superluminal sectors resulting in standard or deformed energy-momentum dispersions. The first scenario is elucidated in the context of four diverse realizations of a continuous function f ( v , with 0 ≤ f ( v ≤ 1 and f ( 0 = f ( c = 1 , which is fitted in the ELT. What goes in the making of the ELT in this scenario is not the boost speed v , as ascertained by two inertial observers in uniform relative motion (URM, but v × f ( v . The second scenario infers the preexistence of two rest-mass-dependent superluminal speeds whereby the ELTs are finite at the light speed c . Particle energies are evaluated in this scenario at c for several particles, including the neutrinos, and are auspiciously found to be below the GKZ energy cutoff and in compliance with a host of worldwide ultrahigh energy cosmic ray data. Section 3 presents two broad scenarios involving a number of novel nonlinear LTs (NLTs featuring small Lorentz invariance violations (LIVs, as well as resurrecting the notion of simultaneity for limited spacetime events as perceived by two observers in URM. These inquiries corroborate that NLTs could be potent tools for investigating LIVs past the customary LTs.

  11. Space-time measures for subluminal and superluminal motions

    CERN Document Server

    Calvo-Mozo, Benjam\\'\\in

    2014-01-01

    In present work we examine the implications on both, space-time measures and causal structure, of a generalization of the local causality postulate by asserting its validity to all motion regimes, the subluminal and superluminal ones. The new principle implies the existence of a denumerable set of metrical null cone speeds, \\{$c_k\\}$, where $c_1$ is the speed of light in vacuum, and $c_k/c \\simeq \\epsilon^{-k+1}$ for $k\\geq2$, where $\\epsilon^2$ is a tiny dimensionless constant which we introduce to prevent the divergence of the $x, t$ measures in Lorentz transformations, such that their generalization keeps $c_k$ invariant and as the top speed for every regime of motion. The non divergent factor $\\gamma_k$ equals $k\\epsilon^{-1}$ at speed $c_k$. We speak then of $k-$timelike and $k-$null intervals and of k-timelike and k-null paths on space-time, and construct a causal structure for each regime. We discuss also the possible transition of a material particle from the subluminal to the first superluminal regim...

  12. Design of a superluminal ring laser gyroscope using multilayer optical coatings with huge group delay.

    Science.gov (United States)

    Qu, Tianliang; Yang, Kaiyong; Han, Xiang; Wu, Suyong; Huang, Yun; Luo, Hui

    2014-01-01

    We propose and analyze a superluminal ring laser gyroscope (RLG) using multilayer optical coatings with huge group delay (GD). This GD assisted superluminal RLG can measure the absolute rotation with a giant sensitivity-enhancement factor of ~10(3); while, the broadband FWHM of the enhancement factor can reach 20 MHz. This superluminal RLG is based on a traditional RLG with minimal re-engineering, and beneficial for miniaturization according to theoretical calculation. The idea of using GD coatings as a fast-light medium will shed lights on the design and application of fast-light sensors.

  13. Pulsational Pair-instability Model for Superluminous Supernova PTF12dam: Interaction and Radioactive Decay

    Science.gov (United States)

    Tolstov, Alexey; Nomoto, Ken’ichi; Blinnikov, Sergei; Sorokina, Elena; Quimby, Robert; Baklanov, Petr

    2017-02-01

    Being a superluminous supernova, PTF12dam can be explained by a 56Ni-powered model, a magnetar-powered model, or an interaction model. We propose that PTF12dam is a pulsational pair-instability supernova, where the outer envelope of a progenitor is ejected during the pulsations. Thus, it is powered by a double energy source: radioactive decay of 56Ni and a radiative shock in a dense circumstellar medium. To describe multicolor light curves and spectra, we use radiation-hydrodynamics calculations of the STELLA code. We found that light curves are well described in the model with 40 M⊙ ejecta and 20–40 M⊙ circumstellar medium. The ejected 56Ni mass is about 6 M⊙, which results from explosive nucleosynthesis with large explosion energy (2–3) × 1052 erg. In comparison with alternative scenarios of pair-instability supernova and magnetar-powered supernova, in the interaction model, all the observed main photometric characteristics are well reproduced: multicolor light curves, color temperatures, and photospheric velocities.

  14. Modified definition of group velocity and electromagnetic energy conservation equation

    CERN Document Server

    Wang, Changbiao

    2013-01-01

    The classical definition of group velocity has two flaws: (a) the group velocity can be greater than the phase velocity in a non-dispersive medium; (b) the definition is not consistent with the principle of relativity. To remove the flaws, a modified definition is proposed. A criterion is set up to identify the justification of group velocity definition. A "superluminal power flow" is constructed to show that the electromagnetic energy conservation equation cannot uniquely define the power flow if the principle of Fermat is not taken into account.

  15. Constraints and tests of the OPERA superluminal neutrinos.

    Science.gov (United States)

    Bi, Xiao-Jun; Yin, Peng-Fei; Yu, Zhao-Huan; Yuan, Qiang

    2011-12-09

    The superluminal neutrinos detected by OPERA indicate Lorentz invariance violation (LIV) of the neutrino sector at the order of 10(-5). We study the implications of the result in this work. We find that such a large LIV implied by OPERA data will make the neutrino production process π → μ + ν(μ) kinematically forbidden for a neutrino energy greater than about 5 GeV. The OPERA detection of neutrinos at 40 GeV can constrain the LIV parameter to be smaller than 3×10(-7). Furthermore, the neutrino decay in the LIV framework will modify the neutrino spectrum greatly. The atmospheric neutrino spectrum measured by the IceCube Collaboration can constrain the LIV parameter to the level of 10(-12). The future detection of astrophysical neutrinos of galactic sources is expected to be able to give an even stronger constraint on the LIV parameter of neutrinos.

  16. On the impossibility of superluminal travel: the warp drive lesson

    CERN Document Server

    Barceló, Carlos; Liberati, Stefano

    2010-01-01

    The question of whether it is possible or not to surpass the speed of light is already centennial. The special theory of relativity took the existence of a speed limit as a principle, the light postulate, which has proven to be enormously predictive. Here we discuss some of its twists and turns when general relativity and quantum mechanics come into play. In particular, we discuss one of the most interesting proposals for faster than light travel: warp drives. Even if one succeeded in creating such spacetime structures, it would be still necessary to check whether they would survive to the switching on of quantum matter effects. Here, we show that the quantum back-reaction to warp-drive geometries, created out of an initially flat spacetime, inevitably lead to their destabilization whenever superluminal speeds are attained. We close this investigation speculating the possible significance of this further success of the speed of light postulate.

  17. "OPERA superluminal neutrinos explained by spontaneous emission and stimulated absorption"

    CERN Document Server

    Torrealba, Rafael

    2011-01-01

    In this work it is shown, that for short 3ns neutrino pulses reported by OPERA, a relativistic shape deforming effect of the neutrino distribution function due to spontaneous emission, produces an earlier arrival of 65.8ns in agreement with the reported 62.1ns\\pm 3.7ns, with a RMS of 16.4ns explaining the apparent superluminal effect. It is also shown, that early arrival of long 10500ns neutrinos pulse to Gran Sasso, by 57.8ns with respect to the speed of light, could be explained by a shape deforming effect due to a combination of stimulated absorption and spontaneous emission, while traveling by the decay tunnel that acts as a LASER tube.

  18. Propagation peculiarities of mean field massive gravity

    Directory of Open Access Journals (Sweden)

    S. Deser

    2015-10-01

    Full Text Available Massive gravity (mGR describes a dynamical “metric” on a fiducial, background one. We investigate fluctuations of the dynamics about mGR solutions, that is about its “mean field theory”. Analyzing mean field massive gravity (m‾GR propagation characteristics is not only equivalent to studying those of the full non-linear theory, but also in direct correspondence with earlier analyses of charged higher spin systems, the oldest example being the charged, massive spin 3/2 Rarita–Schwinger (RS theory. The fiducial and mGR mean field background metrics in the m‾GR model correspond to the RS Minkowski metric and external EM field. The common implications in both systems are that hyperbolicity holds only in a weak background-mean-field limit, immediately ruling both theories out as fundamental theories; a situation in stark contrast with general relativity (GR which is at least a consistent classical theory. Moreover, even though both m‾GR and RS theories can still in principle be considered as predictive effective models in the weak regime, their lower helicities then exhibit superluminal behavior: lower helicity gravitons are superluminal as compared to photons propagating on either the fiducial or background metric. Thus our approach has uncovered a novel, dispersive, “crystal-like” phenomenon of differing helicities having differing propagation speeds. This applies both to m‾GR and mGR, and is a peculiar feature that is also problematic for consistent coupling to matter.

  19. Discussions of the Quantum Superluminality%论量子超光速性

    Institute of Scientific and Technical Information of China (English)

    黄志洵

    2012-01-01

    chief study.In 1985,we proposed the model of quantum potential barrier equivalent circuit.In 1991,we first indicated that there could be the wave velocity v p 0 and v g 0 in the evanescent waves mode of the waveguide below cut off and the book "An Introduction to the Theory of waveguide Below Cut-off "made me get the First National Scientific and Technology Book Award of China.Moreover,in 2003 we through an experiment in the coaxial photonic crystal,a superluminal group velocity of(1.5 ~ 2.4) c are observed in the stop-band of frequency.In 2005,we suggested the term of General Information Velocity(GIV);and in 2010,we suggested the term of Quantum Superluminality(QS),and also suggested remodel the existing accelerator to discover the superluminal strange electron.Now,this paper discusses some problems of Quantum Superluminality profoundly,such as the velocity definition of the microscopic particles,the relation between the EPR thinking and the faster-than-light research,the interaction speed of the quantum entangle-state,superluminality of the quantum tunneling,the negative wave velocity,QS of the Casimir effect.We show that the unite of Quantum Optics(QO) and classical physical sujects are becoming more important.Since 2000,the negative group velocity experiments are always employing some atomic metal(such as Cs、Ka、Rb) vapor for tests.It make full use of the latest achievement in laser science and technology,then it was modern physical experiment in QO,not the classical physical experiment.The negative group velocity not only the special situation of faster-than-light,but also has the features: the exiting pulse’s peak can appear to exit the medium before the peak of the input pulse enters.So it was different that of classical causality.Although that knowledges and discovers of QS are widen and lively,then it greatly inspired us;but it is not the immediate conclusion that answers some questions about the possibility of material,energy and information according to

  20. Particle propagation and effective space-time in gravity's rainbow

    Science.gov (United States)

    Garattini, Remo; Mandanici, Gianluca

    2012-01-01

    Based on the results obtained in our previous study on gravity’s rainbow, we determine the quantum corrections to the space-time metric for the Schwarzschild and the de Sitter background, respectively. We analyze how quantum fluctuations alter these metrics, inducing modifications on the propagation of test particles. Significantly enough, we find that quantum corrections can become relevant not only for particles approaching the Planck energy but, due to the one-loop contribution, even for low-energy particles as far as Planckian length scales are considered. We briefly compare our results with others obtained in similar studies and with the recent experimental OPERA announcement of superluminal neutrino propagation.

  1. Particle propagation and effective space-time in Gravity's Rainbow

    CERN Document Server

    Garattini, Remo

    2011-01-01

    Basing on the results obtained in a our previous study on Gravity's Rainbow, we determine the quantum corrections to the space-time metric for the Schwarzschild and the de Sitter background, respectively. We analyze how quantum fluctuations alter these metrics inducing modifications on the propagation of test particles. Significantly enough we find that quantum corrections can become relevant not only for particles approaching the Planck energy but, due to the one loop contribution, even for low-energy particles as far as Planckian length scales are considered. We briefly compare our results with others obtained in similar studies and with the recent experimental OPERA announcement of superluminal neutrino propagation.

  2. A sub-solar metallicity is required for superluminous supernova progenitors

    CERN Document Server

    Chen, T -W; Yates, R M; Nicholl, M; Krühler, T; Schady, P; Dennefeld, M; Inserra, C

    2016-01-01

    Host galaxy properties provide strong constraints on the stellar progenitors of superluminous supernovae. By comparing a sample of 18 low-redshift superluminous supernova hosts to a volume-limited galaxy population in the local Universe, we show that sub-solar metallici- ties seems to be a requirement. All superluminous supernovae in hosts with high measured gas-phase metallicities are found to explode at large galactocentric radii, indicating that the metallicity at the explosion site is likely lower than the integrated host value. We also confirm that high specific star-formation rates are a feature of superluminous supernova host galaxies, but interpret this as simply a consequence of the anti-correlation between gas-phase metallic- ity and specific star-formation rate and the requirement of on-going star formation to produce young, massive stars greater than ~ 10-20 M_sun . Based on our sample, we propose an upper limit of ~ 0.5 Z_sun for forming superluminous supernova progenitors (assuming an N2 metal- ...

  3. Super-luminous supernovae: 56Ni power versus magnetar radiation

    CERN Document Server

    Dessart, Luc; Waldman, Roni; Livne, Eli; Blondin, Stephane

    2012-01-01

    Much uncertainty surrounds the origin of super-luminous supernovae (SNe). Motivated by the discovery of the Type Ic SN2007bi, we study its proposed association with a pair-instability SN (PISN). We compute stellar-evolution models for primordial ~200Msun stars, simulating the implosion/explosion due to the pair-production instability, and use them as inputs for detailed non-LTE time-dependent radiative-transfer simulations that include non-local energy deposition and non-thermal processes. We retrieve the basic morphology of PISN light curves from red-supergiant, blue-supergiant, and Wolf-Rayet (WR) star progenitors. Although we confirm that a progenitor 100Msun helium core (PISN model He100) fits well the SN2007bi light curve, the low ratios of its kinetic energy and 56Ni mass to the ejecta mass, similar to standard core-collapse SNe, conspire to produce cool photospheres, red spectra subject to strong line blanketing, and narrow line profiles, all conflicting with SN2007bi observations. He-core models of in...

  4. Spectropolarimetry of Superluminous Supernovae: Insight into Their Geometry

    Science.gov (United States)

    Inserra, C.; Bulla, M.; Sim, S. A.; Smartt, S. J.

    2016-11-01

    We present the first spectropolarimetric observations of a hydrogen-free superluminous supernova (SLSN) at z = 0.1136, namely SN 2015bn. The transient shows significant polarization at both of the observed epochs: one 24 days before maximum light in the rest-frame, and the other at 27 days after peak luminosity. Analysis of the Q - U plane suggests the presence of a dominant axis and no physical departure from the main axis at either epoch. The polarization spectrum along the dominant axis is characterized by a strong wavelength dependence and an increase in the signal from the first to the second epoch. We use a Monte Carlo code to demonstrate that these properties are consistent with a simple toy model that adopts an axisymmetric ellipsoidal configuration for the ejecta. We find that the wavelength dependence of the polarization is possibly due to a strong wavelength dependence in the line opacity, while the higher level of polarization at the second epoch is a consequence of the increase in the asphericity of the inner layers of the ejecta or the fact that the photosphere recedes into less spherical layers. The geometry of the SLSN is similar to that of stripped-envelope core-collapse SNe connected to GRB, while the overall evolution of the ejecta shape could be consistent with a central engine.

  5. Spectral evolution of superluminal components in parsec-scale jets

    CERN Document Server

    Mimica, P; Agudo, I; Martí, J M; Gómez, J L; Miralles, J A

    2008-01-01

    (Abridged) We present numerical simulations of the spectral evolution and radio emission of superluminal components in relativistic jets. We have developed an algorithm (SPEV) for the transport of a population of non-thermal particles (NTPs). For very large values of the ratio of gas pressure to magnetic field energy density ($\\sim 6\\times 10^4$), quiescent over-pressured jet models show substantial spectral evolution compared to models whithout radiative losses. Larger values of the magnetic field yield much shorter jets. Larger magnetic fields result in shorter losses-dominated regimes, with a rapid and intense radiation of energy. We also show that jets with a positive photon spectral index may result if the lower limit $\\gamma_min$ of the NTP energy distribution is placed close or above a threshold $\\gamma_M$, where the synchrotron function R has its maximum. A temporary increase of the Lorentz factor at the jet inlet produces a traveling perturbation that appears in the synthetic maps as a radio componen...

  6. The Trails of Superluminal Jet Components in 3C 111

    Science.gov (United States)

    Kadler, M.; Ros, E.; Perucho, M.; Kovalev, Y. Y.; Homan, D. C.; Agudo, I.; Kellermann, K. I.; Aller, M. F.; Aller, H. D.; Lister, M. L.; Zensus, J. A.

    2007-01-01

    The parsec-scale radio jet of the broad-line radio galaxy 3C 111 has been monitored since 1995 as part of the 2cm Survey and MOJAVE monitoring observations conducted with the VLBA. Here, we present results from 18 epochs of VLBA observations of 3C 111 and from 18 years of radio flux density monitoring observations conducted at the University of Michigan. A major radio flux-density outburst of 3C 111 occurred in 1996 and was followed by a particularly bright plasma ejection associated with a superluminal jet component. This major event allows us to study a variety of processes associated with outbursts of radio-loud AGN in much greater detail than possible in other cases: the primary perturbation gives rise to the formation of a forward and a backward-shock, which both evolve in characteristically different ways and allow us to draw conclusions about the workflow of jet-production events; the expansion, acceleration and recollimation of the ejected jet plasma in an environment with steep pressure and density gradients are revealed; trailing components are formed in the wake of the primary perturbation as a result of Kelvin- Helmholtz instabilities from the interaction of the jet with the external medium. The jet-medium interaction is further scrutinized by the linear-polarization signature of jet components traveling along the jet and passing a region of steep pressure/density gradients.

  7. The Trails of Superluminal Jet Components in 3C111

    CERN Document Server

    Kadler, M; Perucho, M; Kovalev, Y Y; Homan, D C; Agudo, I; Kellermann, K I; Aller, M F; Aller, H D; Lister, M L; Zensus, J A

    2008-01-01

    In 1996, a major radio flux-density outburst occured in the broad-line radio galaxy 3C111. It was followed by a particularly bright plasma ejection associated with a superluminal jet component, which has shaped the parsec-scale structure of 3C111 for almost a decade. Here, we present results from 18 epochs of Very Long Baseline Array (VLBA) observations conducted since 1995 as part of the VLBA 2 cm Survey and MOJAVE monitoring programs. This major event allows us to study a variety of processes associated with outbursts of radio-loud AGN in much greater detail than has been possible in other cases: the primary perturbation gives rise to the formation of a leading and a following component, which are interpreted as a forward and a backward-shock. Both components evolve in characteristically different ways and allow us to draw conclusions about the work flow of jet-production events; the expansion, acceleration and recollimation of the ejected jet plasma in an environment with steep pressure and density gradien...

  8. Zooming In on the Progenitors of Superluminous Supernovae With HST

    CERN Document Server

    Lunnan, R; Berger, E; Rest, A; Fong, W; Scolnic, D; Jones, D; Soderberg, A M; Challis, P M; Drout, M R; Foley, R J; Huber, M E; Kirshner, R P; Leibler, C; Marion, G H; McCrum, M; Milisavljevic, D; Narayan, G; Sanders, N E; Smartt, S J; Smith, K W; Tonry, J L; Burgett, W S; Chambers, K C; Flewelling, H; Kudritzki, R -P; Wainscoat, R J; Waters, C

    2014-01-01

    We present Hubble Space Telescope rest-frame ultraviolet imaging of the host galaxies of 16 hydrogen-poor superluminous supernovae (SLSNe), including 11 events from the Pan-STARRS Medium Deep Survey. Taking advantage of the superb angular resolution of HST, we characterize the galaxies' morphological properties, sizes and star formation rate densities. We determine the SN locations within the host galaxies through precise astrometric matching, and measure physical and host-normalized offsets, as well as the SN positions within the cumulative distribution of UV light pixel brightness. We find that the host galaxies of H-poor SLSNe are irregular, compact dwarf galaxies, with a median half-light radius of just 0.9 kpc. The UV-derived star formation rate densities are high ( ~ 0.1 M_sun/yr/kpc^2), suggesting that SLSNe form in overdense environments. Their locations trace the UV light of their host galaxies, with a distribution intermediate between that of LGRBs (which are strongly clustered on the brightest regi...

  9. On the nature of Hydrogen-rich Superluminous Supernovae

    CERN Document Server

    Inserra, C; Gall, E E E; Leloudas, G; Chen, T -W; Schulze, S; Jerkstarnd, A; Nicholl, M; Anderson, J P; Arcavi, I; Benetti, S; Cartier, R A; Childress, M; Della Valle, M; Flewelling, H; Fraser, M; Gal-Yam, A; Gutierrez, C P; Hosseinzadeh, G; Howell, D A; Huber, M; Kankare, E; Magnier, E A; Maguire, K; McCully, C; Prajs, S; Primak, N; Scalzo, R; Schmidt, B P; Smith, K W; Tucker, B E; Valenti, S; Wilman, M; Young, D R; Yuan, F

    2016-01-01

    We present observational data for two hydrogen-rich superluminous supernovae (SLSNe), namely SN 2013hx and PS15br. These objects, together with SN 2008es are the only SLSNe showing a distinct, broad H$\\alpha$ feature during the photospheric phase and also do not show any clear sign of interaction between fast moving ejecta and circumstellar shells in their early spectra. Therefore we classify them as SLSN II as distinct from the known class of SLSN IIn. Both transients show a slow decline at later times, and monitoring of SN 2013hx out to 300 days after explosion indicates that the luminosity in this later phase does have a contribution from interaction. We detect strong, multi-component H$\\alpha$ emission at 240 days past maximum which we interpret as an indication of interaction of the ejecta with an asymmetric, clumpy circumstellar material. The spectra and photometric evolution of the two objects are similar to some bright type II (or type IIL) supernovae, although they have much higher luminosity and evo...

  10. A cannonball model of gamma-ray bursts superluminal signatures

    CERN Document Server

    Dar, Arnon; Dar, Arnon; Rujula, Alvaro De

    2000-01-01

    Recent observations suggest that the long-duration gamma ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in supernova explosions. We propose that the result of the event is not just a compact object plus the ejecta: within a day, a fraction of the parent star falls back to produce a thick accretion disk. The subsequent accretion generates jets and constitutes the GRB ``engine'', as in the observed ejection of relativistic ``cannonballs'' of plasma by microquasars and active galactic nuclei. The GRB is produced as the jetted cannonballs exit the supernova shell reheated by the collision, re-emitting their own radiation and boosting the light of the shell. They decelerate by sweeping up interstellar matter, which is accelerated to cosmic-ray energies and emits synchrotron radiation: the afterglow. We emphasize here a smoking-gun signature of this model of GRBs: the superluminal motion of the afterglow, that can be searched for ---the sooner the better--- in the particular...

  11. Spectropolarimetry of superluminous supernovae: insight into their geometry

    CERN Document Server

    Inserra, C; Sim, S A; Smartt, S J

    2016-01-01

    We present the first spectropolarimetric observations of a hydrogen-free superluminous supernova at z=0.1136, namely SN 2015bn. The transient shows significant polarization at both the observed epochs: one 24 days before maximum light in the rest-frame, and the subsequent at 27 days after peak luminosity. Analysis of the Q-U plane suggests the presence of a dominant axis and no physical departure from the main axis at either epoch. The polarization spectrum along the dominant axis is characterized by a strong wavelength dependence and an increase in the signal from the first to the second epoch. We use a Monte Carlo code to demonstrate that these properties are consistent with a simple toy model that adopts an axi-symmetric ellipsoidal configuration for the ejecta. We find that the wavelength dependence of the polarisation is possibly due to a strong wavelength dependence in the line opacity, while the higher level of polarisation at the second epoch is a consequence of the increase in the asphericity of the ...

  12. Astronomy. ASASSN-15lh: A highly super-luminous supernova.

    Science.gov (United States)

    Dong, Subo; Shappee, B J; Prieto, J L; Jha, S W; Stanek, K Z; Holoien, T W-S; Kochanek, C S; Thompson, T A; Morrell, N; Thompson, I B; Basu, U; Beacom, J F; Bersier, D; Brimacombe, J; Brown, J S; Bufano, F; Chen, Ping; Conseil, E; Danilet, A B; Falco, E; Grupe, D; Kiyota, S; Masi, G; Nicholls, B; Olivares E, F; Pignata, G; Pojmanski, G; Simonian, G V; Szczygiel, D M; Woźniak, P R

    2016-01-15

    We report the discovery of ASASSN-15lh (SN 2015L), which we interpret as the most luminous supernova yet found. At redshift z = 0.2326, ASASSN-15lh reached an absolute magnitude of Mu ,AB = -23.5 ± 0.1 and bolometric luminosity Lbol = (2.2 ± 0.2) × 10(45) ergs s(-1), which is more than twice as luminous as any previously known supernova. It has several major features characteristic of the hydrogen-poor super-luminous supernovae (SLSNe-I), whose energy sources and progenitors are currently poorly understood. In contrast to most previously known SLSNe-I that reside in star-forming dwarf galaxies, ASASSN-15lh appears to be hosted by a luminous galaxy (MK ≈ -25.5) with little star formation. In the 4 months since first detection, ASASSN-15lh radiated (1.1 ± 0.2) × 10(52) ergs, challenging the magnetar model for its engine. Copyright © 2016, American Association for the Advancement of Science.

  13. Long-duration superluminous supernovae at late times

    CERN Document Server

    Jerkstrand, A; Inserra, C; Nicholl, M; Chen, T -W; Krühler, T; Sollerman, J; Taubenberger, S; Gal-Yam, A; Kankare, E; Maguire, K; Fraser, M; Valenti, S; Sullivan, M; Cartier, R; Young, D R

    2016-01-01

    We present nebular-phase observations and spectral models of Type Ic superluminous supernovae. LSQ14an and SN 2015bn both display late-time spectra similar to SN 2007bi, and the class shows strong similarity with broad-lined Type Ic SNe such as SN 1998bw. Near-infrared observations of SN 2015bn at +315d show a strong Ca II triplet, O I 9263, O I 1.13 micron and Mg I 1.50 micron, but no strong He, Si, or S emission. The high Ca II NIR/[Ca II] 7291, 7323 ratio of 2 indicates a high electron density of n_e >~ 10^8 cm^{-3}. Spectral models of oxygen-zone emission are investigated to put constraints on the emitting region. Models require M(O) >~ 10 Msun to produce enough [O I] 6300, 6364 luminosity to match observed levels, irrespective of the powering situation and the density. This is an argument against shell collisions from pair-instability pulsations for explaining the powering, as these shells are limited to a few solar masses in published models. The high oxygen-zone mass, supported by high estimated magnes...

  14. The Volumetric Rate of Superluminous Supernovae at z~1

    CERN Document Server

    Prajs, S; Smith, M; Levan, A; Karpenka, N V; Edwards, T D P; Walker, C R; Wolf, W M; Balland, C; Carlberg, R; Howell, A; Lidman, C; Pain, R; Pritchet, C; Ruhlmann-Kleider, V

    2016-01-01

    We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z~1, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically-identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et.al. (2010) and a Monte Carlo approach to calculate the rate based on our SLSN sample. We find that the three identified SLSNe from SNLS give a rate of 91 (+76/-36) SNe/Yr/Gpc^3 at a volume-weighted redshift of z=1.13. This is equivalent to 2.2 (+1.8/-0.9) x10^-4 of the volumetric core collapse supernova rate at the same redshift. When combined with other rate measurements from the literature, we show that the rate of SLSNe increases with redshift in a manner consistent with that of the cosmic star formati...

  15. Rates of Superluminous Supernovae at z~0.2

    CERN Document Server

    Quimby, Robert M; Akerlof, Car; Wheeler, J Craig

    2013-01-01

    We calculate the volumetric rate of superluminous supernovae (SLSNe) based on 5 events discovered with the ROTSE-IIIb telescope. We gather light curves of 19 events from the literature and our own unpublished data and employ crude k-corrections to constrain the pseudo-absolute magnitude distributions in the rest frame ROTSE-IIIb (unfiltered) band pass for both the hydrogen poor (SLSN-I) and hydrogen rich (SLSN-II) populations. We find that the peak magnitudes of the available SLSN-I are narrowly distributed ($M = -21.7 \\pm 0.4$) in our unfiltered band pass and may suggest an even tighter intrinsic distribution when the effects of dust are considered, although the sample may be skewed by selection and publication biases. The presence of OII features near maximum light may uniquely signal a high luminosity event, and we suggest further observational and theoretical work is warranted to assess the possible utility of such SN 2005ap-like SLSN-I as distance indicators. Using the pseudo-absolute magnitude distribut...

  16. What do the remnants of superluminous supernovae look like?

    Science.gov (United States)

    Leloudas, G.

    2016-06-01

    The remnants of core-collapse supernovae often present significant asymmetries while those of thermonuclear supernovae are, more or less, spherically symmetric. As superluminous supernovae (SLSN) do not occur in Milky Way-type galaxies (they prefer metal-poor starburst dwarfs), our chances of studying directly a SLSN remnant are very limited, except perhaps in the Magellanic clouds. Therefore, the only way of probing the SLSN geometry, and thus identifying potential SLSN remnant candidates, is through polarimetry of the explosions themselves. I will present the first polarimetric observations of SLSNe obtained through a dedicated ToO program at the VLT. LSQ14mo is a SLSN-I that showed only a very limited degree of polarisation (P = 0.52%), which corresponds to an upper limit of 10% in the photosphere asphericity. In addition, this signal can be entirely due to interstellar polarisation in the host galaxy. This is perhaps surprising as the leading models for H-poor SLSNe involve a magnetar or CSM interaction, i.e. configurations that are not expected to be spherically symmetric. Observations of a SLSN-II yielded a more significant degree of polarisation, while preliminary analysis for a SLSN-R reveals similarly low levels of asphericity as for LSQ14mo.

  17. SN 2015BN: A Detailed Multi-wavelength View of a Nearby Superluminous Supernova

    Science.gov (United States)

    Nicholl, M.; Berger, E.; Smartt, S. J.; Margutti, R.; Kamble, A.; Alexander, K. D.; Chen, T.-W.; Inserra, C.; Arcavi, I.; Blanchard, P. K.; Cartier, R.; Chambers, K. C.; Childress, M. J.; Chornock, R.; Cowperthwaite, P. S.; Drout, M.; Flewelling, H. A.; Fraser, M.; Gal-Yam, A.; Galbany, L.; Harmanen, J.; Holoien, T. W.-S.; Hosseinzadeh, G.; Howell, D. A.; Huber, M. E.; Jerkstrand, A.; Kankare, E.; Kochanek, C. S.; Lin, Z.-Y.; Lunnan, R.; Magnier, E. A.; Maguire, K.; McCully, C.; McDonald, M.; Metzger, B. D.; Milisavljevic, D.; Mitra, A.; Reynolds, T.; Saario, J.; Shappee, B. J.; Smith, K. W.; Valenti, S.; Villar, V. A.; Waters, C.; Young, D. R.

    2016-07-01

    We present observations of SN 2015bn (=PS15ae = CSS141223-113342+004332 = MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at redshift z = 0.1136. As well as being one of the closest SLSNe I yet discovered, it is intrinsically brighter ({M}U≈ -23.1) and in a fainter galaxy ({M}B≈ -16.0) than other SLSNe at z˜ 0.1. We used this opportunity to collect the most extensive data set for any SLSN I to date, including densely sampled spectroscopy and photometry, from the UV to the NIR, spanning -50 to +250 days from optical maximum. SN 2015bn fades slowly, but exhibits surprising undulations in the light curve on a timescale of 30-50 days, especially in the UV. The spectrum shows extraordinarily slow evolution except for a rapid transformation between +7 and +20-30 days. No narrow emission lines from slow-moving material are observed at any phase. We derive physical properties including the bolometric luminosity, and find slow velocity evolution and non-monotonic temperature and radial evolution. A deep radio limit rules out a healthy off-axis gamma-ray burst, and places constraints on the pre-explosion mass loss. The data can be consistently explained by a ≳ 10 M {}⊙ stripped progenitor exploding with ˜ {10}51 erg kinetic energy, forming a magnetar with a spin-down timescale of ˜20 days (thus avoiding a gamma-ray burst) that reheats the ejecta and drives ionization fronts. The most likely alternative scenario—interaction with ˜20 M {}⊙ of dense, inhomogeneous circumstellar material—can be tested with continuing radio follow-up.

  18. Theoretical Particle Limiting Velocity From The Bicubic Equation: Neutrino Example

    CERN Document Server

    Soln, Josip

    2014-01-01

    There has been a lot of interest in measuring the velocities of massive elementary particles, particularly the neutrinos. Some neutrino experi- ments at first observed superluminal neutrinos, thus violating the velocity of light c as a limiting velocity. But, after eliminating some mistakes, such as, for the OPERA experiments plugging the cable correctly and calibrat- ing the clock correctly, the measured neutrino velocity complied with c. Pursuing the theoretical side of particle limiting velocities, here directly from the special relativistic kinematics, in which all physical quantities are in the overall mathematical consistency with each other, one treats formally the velocity of light c as yet to be deduced particle limiting ve- locity, and derives the bicubic equation for the particle limiting velocity in the arbitrary reference frame.

  19. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Superluminal Motion of Gamma-Ray Bright Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Wehrle, A E; Bloom, S D; Yurchenko, A V; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Wehrle, Ann E; Bloom, Steven D; Yurchenko, Alexei V

    2001-01-01

    We present the results of a program to monitor the structure of the radio emission in 42 $\\gamma$-ray bright blazars (31 quasars and 11 BL Lac objects) with the VLBA at 43, 22, and occasionally 15 and 8.4 GHz, over the period from November 1993 to July 1997. We determine proper motions in 33 sources and find that the apparent superluminal motions in $\\gamma$-ray sources are much faster than for the general population of bright compact radio sources. This follows the strong dependence of the $\\gamma$-ray flux on the level of relativistic beaming for both external-radiation Compton and synchrotron self-Compton emission. There is a positive correlation (correlation coefficient $r$=0.45) between the flux density of the VLBI core and the $\\gamma$-ray flux and a moderate correlation (partial correlation coefficient $r$=0.31) between $\\gamma$-ray apparent luminosity and superluminal velocities of jet components, as expected if the $\\gamma$-ray emission originates in a very compact region of the relativistic jet and ...

  20. Superluminal motions? A bird-eye view of the experimental situation

    CERN Document Server

    Recami, E

    2001-01-01

    In this article (after some brief theoretical considerations) a bird-eye view is presented -with the help of nine figures- of the various experimental sectors of physics in which Superluminal motions seem to appear. In particular, a panorama is presented of the experiments with evanescent waves and/or tunnelling photons, and with the "localized Superluminal solutions" to the Maxwell equations (e.g., with the so-called X-shaped ones). The present paper is sketchy, but is followed by a large enough bibliography to allow the interested reader deepening the preferred topic.

  1. Free Propagation of Wave in Viscoelastic Cables with Small Curvature

    Institute of Scientific and Technical Information of China (English)

    邹宗兰

    2003-01-01

    The coupled longitudinal-transverse waves propagating freely along a viscoelastic cable was studied. The frequency-spectrum equation governing propagating waves and the formulations of the phase velocities and the group velocities characterizing propagating waves were derived. The effects of viscosity parameters on the phase velocities and the group velocities were investigated with numerical simulation. The analyses show that viscosity has a strong influence on the phase velocity and the group velocity of propagating waves and attenuation waves for longitudinal-dominant waves, but the phase velocities of propagating waves of transverse-dominant waves do not change with viscosity.

  2. The volumetric rate of superluminous supernovae at z ˜ 1

    Science.gov (United States)

    Prajs, S.; Sullivan, M.; Smith, M.; Levan, A.; Karpenka, N. V.; Edwards, T. D. P.; Walker, C. R.; Wolf, W. M.; Balland, C.; Carlberg, R.; Howell, D. A.; Lidman, C.; Pain, R.; Pritchet, C.; Ruhlmann-Kleider, V.

    2017-01-01

    We present a measurement of the volumetric rate of superluminous supernovae (SLSNe) at z ˜ 1.0, measured using archival data from the first four years of the Canada-France-Hawaii Telescope Supernova Legacy Survey (SNLS). We develop a method for the photometric classification of SLSNe to construct our sample. Our sample includes two previously spectroscopically identified objects, and a further new candidate selected using our classification technique. We use the point-source recovery efficiencies from Perrett et al. and a Monte Carlo approach to calculate the rate based on our SLSN sample. We find that the three identified SLSNe from SNLS give a rate of 91^{+76}_{-36} SNe yr-1 Gpc-3 at a volume-weighted redshift of z = 1.13. This is equivalent to 2.2^{+1.8}_{-0.9}× 10^{-4} of the volumetric core-collapse supernova rate at the same redshift. When combined with other rate measurements from the literature, we show that the rate of SLSNe increases with redshift in a manner consistent with that of the cosmic star formation history. We also estimate the rate of ultra-long gamma-ray bursts based on the events discovered by the Swift satellite, and show that it is comparable to the rate of SLSNe, providing further evidence of a possible connection between these two classes of events. We also examine the host galaxies of the SLSNe discovered in SNLS, and find them to be consistent with the stellar-mass distribution of other published samples of SLSNe.

  3. 岩石中波传播速度频散与衰减%Velocity dispersion and attenuation of seismic wave propagation in rocks

    Institute of Scientific and Technical Information of China (English)

    王海洋; 孙赞东; Mark CHAPMAN

    2012-01-01

    速度频散与衰减是地震岩石物理领域一个前沿性问题,它不仅是开展频率域储层及流体预测的关键理论基础,同时也是解决不同地球物理测量方法(地面地震、VSP、测井、超声波岩心观测等)之间数据匹配困难的重要手段.笔者在阐述速度频散和衰减现象基本特征的基础上,详细回顾了Biot模型、喷射流模型、BISQ模型、双孔模型、裂缝-孔隙微结构模型和斑块饱和模型等6种主要速度频散与衰减理论模型的研究进程、原理和限制性,利用示意图直观地描述了这些模型的机制,并给出了它们各自的高低频极限、特征频率和适用条件.同时系统回顾并分析了国内外半个多世纪来速度频散与衰减实验测量技术的发展进程和应用现状,并在实验测量数据的基础上给出了自己对地球物理测量手段、岩石物理模型与频率相关性方面的思考和认识,即有必要将单频带的岩石物理模型拓展到全频带,并基于此将不同频带地球物理手段的测量数据联系起来,实现在同一尺度下的综合应用.%A velocity dispersion and attenuation phenomenon is a frontier subject in seismic rock physics. It is not only a key theoretical fundament for reservoir and fluid prediction in the frequency domain but also a crucial technique to solve the data-matching problem of different geophysical measurements, such as surface seismic method, vertical seismic profiling (VSP), well logging, laboratory ultrasonic core observation etc. Based on elaborating characteristics of this phenomenon, we reviewed in detail the progress in development, principles and limitations of six typical velocity dispersion and attenuation models including Biot, Squirt-flow, Biot-Squirt (BISQ), double-porosity, crack-pore microstructure and patchy saturation models, visually depicted mechanisms of these models u-sing schematic diagrams, and at the same time deduced their respective high- and

  4. The superluminal radio source 4c 39. 25 as relativistic jet prototype. El cuasar superluminal 4C 93. 25 como prototipo de jet relativistia

    Energy Technology Data Exchange (ETDEWEB)

    Alberdi, A.; Gomez, J.L.; Marcaide, J.M.

    1993-01-01

    We have developed a numerical code which solves the synchrotron radiation transfer equations to compute the total and polarized emission of bent shocked relativistic jets, and we have applied it to reproduce the compact structure, kinematic evolution of the superluminal radio source 4C 39.25 contains a bent relativistic jet which is misaligned relative to the observer near the core region, leading to a relatively low core brightness. (Author) 12 refs.

  5. Ionization Break-Out from Millisecond Pulsar Wind Nebulae: an X-ray Probe of the Origin of Superluminous Supernovae

    CERN Document Server

    Metzger, Brian D; Hascoet, Romain; Beloborodov, Andrei M

    2013-01-01

    Magnetic spin-down of a millisecond neutron star has been proposed as the power source of hydrogen-poor "superluminous" supernovae (SLSNe-I). However, producing an unambiguous test that can distinguish this model from alternatives, such as circumstellar interaction, has proven challenging. After the supernova explosion, the pulsar wind inflates a hot cavity behind the expanding stellar ejecta: the nascent millisecond pulsar wind nebula. Electron/positron pairs injected by the wind cool through inverse Compton scattering and synchrotron emission, producing a pair cascade and hard X-ray spectrum inside the nebula. These X-rays ionize the inner exposed side of the ejecta, driving an ionization front that propagates outwards with time. Under some conditions this front can breach the ejecta surface within months after the optical supernova peak, allowing ~0.1-1 keV photons to escape the nebula unattenuated with a characteristic luminosity L_X ~ 1e43-1e45 erg/s. This "ionization break-out" may explain the luminous ...

  6. Discussions of the Quantum Superluminality%论量子超光速性

    Institute of Scientific and Technical Information of China (English)

    黄志洵

    2012-01-01

    , the experiments proved that Einstein' s ideas didn' t hold water. In Bell' s opinion, to get rid of the difficulties after the announce- ment of the Aspect' s experiments, it intends to go back to Lorentz and Poincare, and assume that ether existed as a referential system in which matters went faster than light. Bell repeatedly pointed out that be wanted to go back to ether because EPR had predicted there was something faster than light in the back- ground. …… Since 1992, it is reported that there have been many successful faster than light experi-ments. Some of them are based on quantum tunneling effect;some are based on classic physical phenome- na such as evanescent waves, anomalous dispersion. And in 2008, D. Salart et. al. performed a experiment using entangled photons between two villages separated by 18km. In conclusion ,the speed of the influence of quantum entanglement would have to exceed than of light by at least four orders of magnitude, i. e. 10^4c 10^7c. Anyway, this experiment was the summation of discussions about the EPR thesis for a long time. For the past 25 years Quantum Superluminality was one subject of my chief study. In 1985 ,we pro- posed the model of quantum potential barrier equivalent circuit. In 1991, we first indicated that there could be the wave velocity vp 〈 0 and vg 〈 0 in the evanescent waves mode of the waveguide below cut off and the book "An Introduction to the Theory of waveguide Below Cut -off " made me get the First Na- tional Scientific and Technology Book Award of China. Moreover, in 2003 we through an experiment in the coaxial photonic crystal, a superluminal group velocity of ( 1.5 - 2.4) c are observed in the stop - band of frequency. In 2005, we suggested the term of General Information Velocity (GIV) ;and in 2010, we sugges- ted the term of Quantum Superluminality ( QS), and also suggested remodel the existing accelerator to dis- cover the superluminal strange electron. Now,this paper discusses some problems of

  7. Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

    Science.gov (United States)

    Moriya, Takashi J.; Liu, Zheng-Wei; Mackey, Jonathan; Chen, Ting-Wan; Langer, Norbert

    2015-12-01

    We propose that nebular Hα emission, as detected in the Type Ic superluminous supernova iPTF13ehe, stems from matter that is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular Hα luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the Hα luminosity of iPTF13ehe. We find a stripped mass of 0.1-0.9 solar masses, assuming that the supernova luminosity is powered by radioactivity or magnetar spin down. Because a central heating source is required to excite the Hα emission, an interaction-powered model is not favored for iPTF13ehe if the Hα emission is from stripped matter. We derive a companion mass of more than 20 solar masses and a binary separation of less than about 20 companion radii based on the stripping efficiency during the collision, indicating that the supernova progenitor and the companion formed a massive close binary system. If Type Ic superluminous supernovae generally occur in massive close binary systems, the early brightening observed previously in several Type Ic superluminous supernovae may also be due to the collision with a close companion. Observations of nebular hydrogen emission in future Type Ic superluminous supernovae will enable us to test this interpretation.

  8. Infrared spectroscopy of the superluminal Galactic source GRS 1915+105 during the 1994 September outburst

    DEFF Research Database (Denmark)

    CastroTirado, A.J.; Geballe, T.R.; Lund, Niels

    1996-01-01

    We have obtained K-band IR spectra of the superluminal Galactic source GRS 1915+105 on two different dates. The second spectrum, obtained immediately after a bright X-ray outburst in 1994 September, has shown prominent H and He emission lines. The lines are not Doppler shifted, as are those obser...

  9. Superluminal neutrinos and extra dimensions: constraints from the null energy condition

    OpenAIRE

    Gubser, Steven S.

    2011-01-01

    In light of the recent results from the OPERA collaboration, indicating that neutrinos can travel superluminally, I review a simple extra-dimensional strategy for accommodating such behavior; and I also explain why it is hard in this strategy to avoid violating the null energy condition somewhere in the extra dimensions.

  10. NEW SUPERLUMINAL QUASAR-1633+382 AND THE BLAZAR-GAMMA-RAY CONNECTION

    NARCIS (Netherlands)

    BARTHEL, PD; CONWAY, JE; MYERS, ST; PEARSON, TJ; READHEAD, ACS

    1995-01-01

    We report detection of superluminal motion in the core of 4C 38.41, associated with the z = 1.814 quasar 1633+382. The dominant nucleus in the similar to 30 kpc triple morphology of the radio source displays a core-jet structure on the milliarcsecond scale, and a jet component is found moving

  11. Shallow Water Propagation

    Science.gov (United States)

    2014-09-30

    response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and...these modes decay much more slowly than leaky modes as they propagate. The initial focus is on modal phase and group velocity formulas, obtained from...acoustic quantities such as transmission loss and scintillation index. (C) Both physical understanding and reasonable estimates of

  12. Estimación de la velocidad de propagación aórtica basada en el análisis de la onda de pulso radial Velocity estimation of aortic propagation based on radial pulse wave analysis

    Directory of Open Access Journals (Sweden)

    Fernando Clara

    2011-06-01

    specified coefficient in normotensive individuals increased linearly with age, in a similar way to the increase in aortic propagation velocity measured by other methods. The procedure was repeated on another set of 125 individuals with hypertension, without other risk factors, aged between the 3rd and 7th decade. This time we found similar values to normotensive individuals only on the 3th decade, and a pronounced increase on the velocity coefficient at advanced ages was observed. These findings support the feasibility of using this type of signals to indirectly evaluate the propagation velocity together with the increase index, a parameter commonly used in pulse wave analysis.

  13. Far-Ultraviolet to Near-Infrared Spectroscopy of A Nearby Hydrogen Poor Superluminous Supernova Gaia16apd

    CERN Document Server

    Yan, Lin; Gal-Yam, A; Brown, P; Blagorodnova, N; Ofek, E O; Lunnan, R; Cooke, J; Cenko, S B; Jencson, J; Kasliwal, M

    2016-01-01

    We report the first maximum-light far-Ultraviolet to near-infrared spectra (1000A - 1.62um, rest) of a H-poor superluminous supernova, Gaia16apd. At z=0.1018, it is one of the closest and the UV brightest such events, with 17.4 (AB) magnitude in Swift UV band (1928A) at -11days pre-maximum. Assuming an exponential form, we derived the rise time of 33days and the peak bolometric luminosity of 3x10^{44}ergs^-1. At maximum light, the estimated photospheric temperature and velocity are 17,000K and 14,000kms^-1 respectively. The inferred radiative and kinetic energy are roughly 1x10^{51} and 2x10^{52}erg. Gaia16apd is extremely UV luminous, emitting 50% of its total luminosity at 1000 - 2500A. Compared to the UV spectra (normalized at 3100A) of well studied SN1992A (Ia), SN2011fe(Ia), SN1999em (IIP) and SN1993J (IIb), it has orders of magnitude more far-UV emission. This excess is interpreted primarily as a result of weaker metal line blanketing due to much lower abundance of iron-group elements in the outer eject...

  14. Remnant Symmetry, Propagation and Evolution in f(T) Gravity

    CERN Document Server

    Chen, Pisin; Nester, James M; Ong, Yen Chin

    2014-01-01

    It was recently argued that f(T) gravity could inherit "remnant symmetry" from the full Lorentz group, despite the fact that the theory is not locally Lorentz invariant. Confusion has arisen regarding the implication of this result for the previous works, which established that f(T) gravity is pathological due to superluminal propagation, local acausality, and non-unique time evolution. We clarify that the existence of the "remnant group" does not rid the theory of these various problems, but instead strongly supports it.

  15. SN 2012aa: A transient between Type Ibc core-collapse and superluminous supernovae

    Science.gov (United States)

    Roy, R.; Sollerman, J.; Silverman, J. M.; Pastorello, A.; Fransson, C.; Drake, A.; Taddia, F.; Fremling, C.; Kankare, E.; Kumar, B.; Cappellaro, E.; Bose, S.; Benetti, S.; Filippenko, A. V.; Valenti, S.; Nyholm, A.; Ergon, M.; Sutaria, F.; Kumar, B.; Pandey, S. B.; Nicholl, M.; Garcia-Álvarez, D.; Tomasella, L.; Karamehmetoglu, E.; Migotto, K.

    2016-12-01

    Context. Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by 2 mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes ≲-21 are called superluminous SNe (SLSNe). The mechanism that powers the light curves of SLSNe is still not well understood. The proposed scenarios are circumstellar interaction, the emergence of a magnetar after core collapse, or disruption of a massive star through pair production. Aims: There are a few intermediate events which have luminosities between these two classes. They are important for constraining the nature of the progenitors of these two different populations and their environments and powering mechanisms. Here we study one such object, SN 2012aa. Methods: We observed and analysed the evolution of the luminous Type Ic SN 2012aa. The event was discovered by the Lick Observatory Supernova Search in an anonymous galaxy (z ≈ 0.08). The optical photometric and spectroscopic follow-up observations were conducted over a time span of about 120 days. Results: With an absolute V-band peak of - 20 mag, the SN is an intermediate-luminosity transient between regular SNe Ibc and SLSNe. SN 2012aa also exhibits an unusual secondary bump after the maximum in its light curve. For SN 2012aa, we interpret this as a manifestation of SN-shock interaction with the circumstellar medium (CSM). If we assume a 56Ni-powered ejecta, the quasi-bolometric light curve requires roughly 1.3 M⊙ of 56Ni and an ejected mass of 14M⊙. This also implies a high kinetic energy of the explosion, 5.4 × 1051 erg. On the other hand, the unusually broad light curve along with the secondary peak indicate the possibility of interaction with CSM. The third alternative is the presence of a central engine releasing spin energy that eventually powers the light curve over a long time. The host of SN 2012aa is a star-forming Sa/Sb/Sbc galaxy. Conclusions

  16. Neutrino Velocity and Neutrino Oscillations

    CERN Document Server

    Minakata, H

    2012-01-01

    We study distances of propagation and the group velocities of the muon neutrinos in the presence of mixing and oscillations assuming that Lorentz invariance holds. Oscillations lead to distortion of the $\

  17. Light Propagation For Accelerated Observers

    CERN Document Server

    Adewole, A I A

    2001-01-01

    We show that for an observer in translational, rotational or gravitational motion, a linearly polarized plane wave has two modes of propagation in a stationary, homogeneous and isotropic medium according to Hertz's version of Maxwell's theory. The first mode is characterized by polarization at right angles to the direction of propagation and has a phase velocity that is controlled by the material constants of the medium. The second mode is characterized by polarization along the propagation direction and has a phase velocity that is controlled by the motion of the observer. We outline some applications of the second mode in emerging technologies.

  18. Diffusion Simulation of Outer Radiation Belt Electron Dynamics Induced by Superluminous L-O Mode Waves

    Institute of Scientific and Technical Information of China (English)

    XIAO Fu-Liang; HE Zhao-Guo; ZHANG Sai; SU Zhen-Peng; CHEN Liang-Xu

    2011-01-01

    Temporal evolution of outer radiation belt electron dynamics resulting from superluminous L-O mode waves is simulated at L=6.5. Diffusion rates are evaluated and then used as inputs to solve a 2D momentum-pitch-angle diffusion equation, particularly with and without cross diffusion terms. Simulated results demonstrate that phase space density(PSD) of energetic electrons due to L-O mode waves can enhance significantly within 24 h, covering a broader pitch-angle range in the absence of cross terms than that in the presence of cross terms. PSD evolution is also determined by the peak wave frequency, particularly at high kinetic energies. This result indicates that superluminous waves can be a potential candidate responsible for outer radiation belt electron dynamics.

  19. Dynamic evolution of outer radiation belt electrons driven by superluminous R-X mode waves

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    We present initial results on the temporal evolution of the phase space density (PSD) of the outer radiation belt energetic electrons driven by the superluminous R-X mode waves. We calculate diffusion rates in pitch angle and momentum assuming the standard Gaussian distributions in both wave frequency and wave normal angle at the location L=6.5. We solve a 2D momentum-pitch-angle Fokker-Planck equation using those diffusion rates as inputs. Numerical results show that R-X mode can produce significant acceleration of relativistic electrons around geostationary orbit,supporting previous findings that superluminous waves potentially contribute to dramatic variation in the outer radiation belt electron dynamics.

  20. On determination of the geometric cosmological constant from the OPERA experiment of superluminal neutrinos

    OpenAIRE

    Yan, Mu-Lin; Hu, Sen; Huang, Wei; Xiao, Neng-Chao

    2011-01-01

    The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant $\\Lambda_{eff}$ which is the sum of the quantum zero point energy $\\Lambda_{dark energy}$ and the geometric cosmological constant $\\Lambda$. The OPERA experiment can be applied to determine the geometric cosmological constant $\\Lambda$. It is the first time to distingui...

  1. Swift and LT UV and optical observations of type IIn superluminous supernova 2017gir

    Science.gov (United States)

    Cano, Zach; Kuin, Paul; Chandra, Poonam; Ashall, Chris; Malesani, Daniele; Pastorello, Andrea

    2017-09-01

    We observed the field of the type IIn superluminous supernova 2017gir (ATLAS17jsb, Tonry et al. 2017; Lyman et al. 2017, ATel 10674) with Swift via a target-of-opportunity for three epochs (6th, 16th and 19th of September, 2017) in the three UVOT UV filters (w1, m1, w2). The SN is clearly detected in all three filters, and it is seen that its brightness fades over this timescale.

  2. Properties of Magnetars Mimicking 56Ni-powered Light Curves in Type IC Superluminous Supernovae

    Science.gov (United States)

    Moriya, Takashi J.; Chen, Ting-Wan; Langer, Norbert

    2017-02-01

    Many Type Ic superluminous supernovae have light-curve decline rates after their luminosity peak, which are close to the nuclear decay rate of {}56{Co}, consistent with the interpretation that they are powered by {}56{Ni} and possibly pair-instability supernovae. However, their rise times are typically shorter than those expected from pair-instability supernovae, and Type Ic superluminous supernovae are often suggested to be powered by magnetar spin-down. If magnetar spin-down is actually a major mechanism to power Type Ic superluminous supernovae, it should be able to produce decline rates similar to the {}56{Co} decay rate rather easily. In this study, we investigate the conditions for magnetars under which their spin-down energy input can behave like the {}56{Ni} nuclear decay energy input. We find that an initial magnetic field strength within a certain range is sufficient to keep the magnetar energy deposition within a factor of a few of the {}56{Co} decay energy for several hundreds of days. Magnetar spin-down needs to be by almost pure dipole radiation with the braking index close to three to mimic {}56{Ni} in a wide parameter range. Not only late-phase {}56{Co}-decay-like light curves, but also rise time and peak luminosity of most {}56{Ni}-powered light curves can be reproduced by magnetars. Bolometric light curves for more than 700 days are required to distinguish the two energy sources solely by them. We expect that more slowly declining superluminous supernovae with short rise times should be found if they are mainly powered by magnetar spin-down.

  3. Considerations about the apparent ''superluminal expansions'' observed in astrophysics

    Energy Technology Data Exchange (ETDEWEB)

    Recami, E.; Castellino, A.; Maccarrone, G.D.; Rodono, M.

    1986-06-11

    The orthodox models devised to explain the apparent ''superluminal expansions'' observed in astrophysics - and here briefly summarized and discussed together with the experimental data - do not seem to be too much successful, especially when confronted with the most recent observations, suggesting complicated expansion patterns, even with possible accelerations. At this point it may be, therefore, of some interest to explore the possible alternative models in which actual Superluminal motions take place. To prepare the ground, we start from a variational principle, introduce the elements of a tachyon mechanics within special relativity, and argue about the expected behaviour of tachyonic objects when interacting (gravitationally, for instance) among themselves or with ordinary matter. We then review and develop the simplet ''Superluminal models'', paying particular attention to the observations which they would give rise to. We conclude that some of them appear to be physically acceptable and are statistically favoured with respect to the orthodox ones.

  4. Transverse velocity shifts in protostellar jets: rotation or velocity asymmetries?

    CERN Document Server

    De Colle, Fabio; Riera, Angels

    2016-01-01

    Observations of several protostellar jets show systematic differences in radial velocity transverse to the jet propagation direction, which have been interpreted as evidence of rotation in the jets. In this paper we discuss the origin of these velocity shifts, and show that they could be originated by rotation in the flow, or by side to side asymmetries in the shock velocity, which could be due to asymmetries in the jet ejection velocity/density or in the ambient medium. For typical poloidal jet velocities (~ 100-200 km/s), an asymmetry >~ 10% can produce velocity shifts comparable to those observed. We also present three dimensional numerical simulations of rotating, precessing and asymmetric jets, and show that, even though for a given jet there is a clear degeneracy between these effects, a statistical analysis of jets with different inclination angles can help to distinguish between the alternative origins of transverse velocity shifts. Our analysis indicate that side to side velocities asymmetries could ...

  5. Energy velocity and group velocity

    Institute of Scientific and Technical Information of China (English)

    陈宇

    1995-01-01

    A new Lagrangian method for studying the relationship between the energy velocity and the group velocity is described. It is proved that under the usual quasistatic electric field, the energy velocity is identical to the group velocity for acoustic waves in anisotropic piezoelectric (or non-piezoelectric) media.

  6. Special relativity with an arbitrary limiting velocity of particle

    CERN Document Server

    Parvan, A S

    2012-01-01

    It is shown that a generalized special theory of relativity (GSTR) with an arbitrary limiting velocity of particle different or equal to the speed of light in vacuum can be constructed from the canonical equation of the 4-dimensional hyperboloid of revolution. In particular, when the limiting velocity equals the speed of light, the special theory of relativity (STR), which corresponds to the equation of the equilateral hyperboloid of revolution, is recovered. The (generalized) Lorentz transformations were obtained. It was established that the rest mass of a space-like particle is real. Our results strongly suggest that the muon neutrino in the OPERA experiment is most likely a time-like or a light-like superluminal particle, whose limiting velocity may exceed the speed of light in vacuum, rather than a superluminal space-like particle (tachyon) with a speed limit equal to speed of light for which the rest mass $mc^{2}=117.1^{+11.0}_{-10.5}$ MeV.

  7. Aspects of Quantum Non-Locality I: Superluminal Signalling, Action-at-a-Distance, Non-Separability and Holism

    Science.gov (United States)

    Berkovitz, Joseph

    In this paper and its sequel, I consider the significance of Jarrett's and Shimony's analyses of the so-called factorisability (Bell-locality) condition for clarifying the nature of quantum non-locality. In this paper, I focus on four types of non-locality: superluminal signalling, action-at-a-distance, non-separability and holism. In the second paper, I consider a fifth type of non-locality: superluminal causation according to 'logically weak' concepts of causation, where causal dependence requires neither action nor signalling. In this connection, I pay special attention to the difficulties that superluminal causation raises in relativistic space-time. I conclude by evaluating the relevance of Jarrett's and Shimony's analyses for clarifying the question of the compatibility of quantum non-locality with relativity theory. My main conclusions are, first: these analyses are significant for clarifying the questions of superluminal signalling in quantum phenomena and for the compatibility of these phenomena with relativity. But, second, by contrast: these analyses are not very significant for the study of action-at-a distance, superluminal causation, non-separability and holism in quantum phenomena.

  8. A proposal for a feasible quantum-optical scheme to test for the existence of superluminal signals via quantum mechanical entanglement

    CERN Document Server

    Kalamidas, Demetrios A

    2011-01-01

    Motivated by a proposal from Greenberger [Physica Scripta T76, p.57 (1998) ] for superluminal signaling, and inspired by an experiment from Mandel [Phys. Rev. Lett. 67, p.318 (1991) ] showing interference effects within multi-particle entanglement without coincidence detection, we propose a feasible quantum-optical scheme that purports to manifest the capacity for superluminal transfer of information between distant parties.

  9. On causality, apparent 'superluminality' and reshaping in barrier penetration

    CERN Document Server

    Sokolovski, D

    2010-01-01

    We consider tunnelling of a non-relativistic particle across a potential barrier. It is shown that the barrier acts as an effective beam splitter which builds up the transmitted pulse from the copies of the initial envelope shifted in the coordinate space backwards relative to the free propagation. Although along each pathway causality is explicitly obeyed, in special cases reshaping can result an overall reduction of the initial envelope, accompanied by an arbitrary coordinate shift. In the case of a high barrier the delay amplitude distribution (DAD) mimics a Dirac $\\delta$-function, the transmission amplitude is superoscillatory for finite momenta and tunnelling leads to an accurate advancement of the (reduced) initial envelope by the barrier width. In the case of a wide barrier, initial envelope is accurately translated into the complex coordinate plane. The complex shift, given by the first moment of the DAD, accounts for both the displacement of the maximum of the transmitted probability density and the...

  10. Probes of Lorentz violation in neutrino propagation

    Science.gov (United States)

    Ellis, John; Harries, Nicholas; Meregaglia, Anselmo; Rubbia, André; Sakharov, Alexander S.

    2008-08-01

    It has been suggested that the interactions of energetic particles with the foamy structure of space-time thought to be generated by quantum-gravitational (QG) effects might violate Lorentz invariance, so that they do not propagate at a universal speed of light. We consider the limits that may be set on a linear or quadratic violation of Lorentz invariance in the propagation of energetic neutrinos, v/c=[1±(E/MνQG1)] or [1±(E/MνQG2)2], using data from supernova explosions and the OPERA long-baseline neutrino experiment. Using the SN1987a neutrino data from the Kamioka II, IMB, and Baksan experiments, we set the limits MνQG1>2.7(2.5)×1010GeV for subluminal (superluminal) propagation and MνQG2>4.6(4.1)×104GeV at the 95% confidence level. A future galactic supernova at a distance of 10 kpc would have sensitivity to MνQG1>2(4)×1011GeV for subluminal (superluminal) propagation and MνQG2>2(4)×105GeV. With the current CERN neutrinos to Gran Sasso extraction spill length of 10.5μs and with standard clock synchronization techniques, the sensitivity of the OPERA experiment would reach MνQG1˜7×105GeV (MνQG2˜8×103GeV) after 5 years of nominal running. If the time structure of the super proton synchrotron radio frequency bunches within the extracted CERN neutrinos to Gran Sasso spills could be exploited, these figures would be significantly improved to MνQG1˜5×107GeV (MνQG2˜4×104GeV). These results can be improved further if a similar time resolution can be achieved with neutrino events occurring in the rock upstream of the OPERA detector: we find potential sensitivities to MνQG1˜4×108GeV and MνQG2˜7×105GeV.

  11. Detection of Broad H$\\alpha$ Emission Lines in the Late-time Spectra of a Hydrogen-poor Superluminous Supernova

    CERN Document Server

    Yan, Lin; Ofek, E; Gal-Yam, A; Mazzali, P; Perley, D; Vreeswijk, P; Leloudas, G; de Cia, A; Masci, F; Cenko, S B; Cao, Y; Kulkarni, S R; Nugent, P E; Rebbapragada, Umaa D; Woźniak, P R; Yaron, O

    2015-01-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z=0.3434, with properties similar to SN2007bi. It rises within (83-148)days (rest-frame) to reach a peak bolometric luminosity of 1.3x$10^{44}$erg/s, then decays very slowly at 0.015mag. per day. The measured ejecta velocity is 13000km/s. The inferred explosion characteristics, such as the ejecta mass (67-220$M_\\odot$), the total radiative and kinetic energy ($10^{51}$ & 2x$10^{53}$erg respectively), is typical of SLSN-R events. However, the late-time spectrum taken at +251days reveals a Balmer Halpha emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ~4500km/s and has a ~300km/s blue-ward shift relative to the narrow component. We interpret this broad Halpha emission line as the interaction between the supernova ejecta and a H-rich circumstellar medium (CSM) shell, located at a distance of ~4x$10^{16}$cm from the explosion site. This eje...

  12. More about tunnelling times and superluminal tunnelling (Hartmann effect)

    Energy Technology Data Exchange (ETDEWEB)

    Olkhovsky, V.S. [Ukrainian Akademy of Sciences, Kiev (Ukraine). Inst. for Nuclear Research]|[INFN-Sezione di Catania (Italy); Recami, E. [Bergamo Univ. (Italy). Facolta` di Ingegneria]|[State Univ. at Campinas, Campinas (Brazil); Raciti, F. [Catania Univ. (Italy); Zaichenko, A. [Ukrainian Akademy of Sciences, Kiev (Ukraine). Inst. for Nuclear Reserch

    1995-05-01

    Aims of the present paper are: (i) presenting and analysing the results of various numerical calculations on the penetration and return times <{tau}{sub Pen}>, <{tau}{sub Ret}>, during tunnelling inside a rectangular potential barrier, for various penetration depths x{sub f}; (ii) putting forth and discussing suitable definitions, besides of the mean values, also of the variances (or dispersions) D{sub {tau}T} and D{sub {tau}R} for the time durations of transmission and reflection processes; (iii) mentioning, moreover, that our definition <{tau}{sub T}> for the average transmission time results to constitute an improvement of the ordinary dwell- time formula; (iv) commenting, at last, on the basis of the new numerical results, upon some recent criticism by C.R. Leavens. The paper stresses that numerical evaluations confirm that the approach implied, and implies, the existence of the Hartmann effect: an effect that in these days (due to the theoretical connections between tunnelling and evanescent-wave propagation) is receiving - at Cologne, Berkeley, Florence and Vienna - indirect, but quite interesting, experimental verification.

  13. Attractor scenarios and superluminal signals in k-essence cosmology

    CERN Document Server

    Kang, Jin U; Winitzki, Sergei

    2007-01-01

    Cosmological scenarios with k-essence are invoked in order to explain the observed late-time acceleration of the universe. These scenarios avoid the need for fine-tuned initial conditions (the "coincidence problem") because of the attractor-like dynamics of the k-essence field \\phi. It was recently shown that all k-essence scenarios with Lagrangians p=L(X)/\\phi^2, necessarily involve an epoch where perturbations of \\phi propagate faster than light (the "no-go theorem"). We carry out a comprehensive study of attractor-like cosmological solutions ("trackers") involving a k-essence scalar field \\phi and another matter component. The result of this study is a complete classification of k-essence Lagrangians that admit asymptotically stable tracking solutions, among all Lagrangians of the form p=K(\\phi)L(X) . Using this classification, we select the class of models that describe the late-time acceleration and avoid the coincidence problem through the tracking mechanism. An analogous "no-go theorem" still holds for...

  14. Slowly fading super-luminous supernovae that are not pair-instability explosions

    Science.gov (United States)

    Nicholl, M.; Smartt, S. J.; Jerkstrand, A.; Inserra, C.; McCrum, M.; Kotak, R.; Fraser, M.; Wright, D.; Chen, T.-W.; Smith, K.; Young, D. R.; Sim, S. A.; Valenti, S.; Howell, D. A.; Bresolin, F.; Kudritzki, R. P.; Tonry, J. L.; Huber, M. E.; Rest, A.; Pastorello, A.; Tomasella, L.; Cappellaro, E.; Benetti, S.; Mattila, S.; Kankare, E.; Kangas, T.; Leloudas, G.; Sollerman, J.; Taddia, F.; Berger, E.; Chornock, R.; Narayan, G.; Stubbs, C. W.; Foley, R. J.; Lunnan, R.; Soderberg, A.; Sanders, N.; Milisavljevic, D.; Margutti, R.; Kirshner, R. P.; Elias-Rosa, N.; Morales-Garoffolo, A.; Taubenberger, S.; Botticella, M. T.; Gezari, S.; Urata, Y.; Rodney, S.; Riess, A. G.; Scolnic, D.; Wood-Vasey, W. M.; Burgett, W. S.; Chambers, K.; Flewelling, H. A.; Magnier, E. A.; Kaiser, N.; Metcalfe, N.; Morgan, J.; Price, P. A.; Sweeney, W.; Waters, C.

    2013-10-01

    Super-luminous supernovae that radiate more than 1044 ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of `pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of 56Ni are synthesized; this isotope decays to 56Fe via 56Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10-6 times that of the core-collapse rate.

  15. Slowly fading super-luminous supernovae that are not pair-instability explosions.

    Science.gov (United States)

    Nicholl, M; Smartt, S J; Jerkstrand, A; Inserra, C; McCrum, M; Kotak, R; Fraser, M; Wright, D; Chen, T-W; Smith, K; Young, D R; Sim, S A; Valenti, S; Howell, D A; Bresolin, F; Kudritzki, R P; Tonry, J L; Huber, M E; Rest, A; Pastorello, A; Tomasella, L; Cappellaro, E; Benetti, S; Mattila, S; Kankare, E; Kangas, T; Leloudas, G; Sollerman, J; Taddia, F; Berger, E; Chornock, R; Narayan, G; Stubbs, C W; Foley, R J; Lunnan, R; Soderberg, A; Sanders, N; Milisavljevic, D; Margutti, R; Kirshner, R P; Elias-Rosa, N; Morales-Garoffolo, A; Taubenberger, S; Botticella, M T; Gezari, S; Urata, Y; Rodney, S; Riess, A G; Scolnic, D; Wood-Vasey, W M; Burgett, W S; Chambers, K; Flewelling, H A; Magnier, E A; Kaiser, N; Metcalfe, N; Morgan, J; Price, P A; Sweeney, W; Waters, C

    2013-10-17

    Super-luminous supernovae that radiate more than 10(44) ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-130 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of (56)Ni are synthesized; this isotope decays to (56)Fe via (56)Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae that show relatively fast rise times and blue colours, which are incompatible with pair-instability models. Their late-time light-curve and spectral similarities to supernova 2007bi call the nature of that event into question. Our early spectra closely resemble typical fast-declining super-luminous supernovae, which are not powered by radioactivity. Modelling our observations with 10-16 solar masses of magnetar-energized ejecta demonstrates the possibility of a common explosion mechanism. The lack of unambiguous nearby pair-instability events suggests that their local rate of occurrence is less than 6 × 10(-6) times that of the core-collapse rate.

  16. 超光速佯谬和中微子%Superluminal Paradox and Neutrino

    Institute of Scientific and Technical Information of China (English)

    倪光炯

    2002-01-01

    爱因斯坦的狭义相对论和因果原理意味着任何运动物体的速度不能超过光在真空中的速度.然而,有许多讨论超光速运动粒子的尝试,这些讨论或者是在狭义相对论的框架下进行的,或者是超越了狭义相对论.这些讨论都遇到一系列难以克服的困难,即"超光速佯谬".文中详细分析了这种佯谬,并证明它在与狭义相对论兼容的量子理论中显然是不出现的.在实在世界中,中微子最可能是一种超光速粒子.%Einstein′s theory of special relativity (SR) and the principle of causality imply that the speed of any moving object can not exceed that of light in a vacuum (c). However, there were many attempts in literature discussing the particle moving with speed u>c(called as superluminal particle or tachyon) either in the scheme of SR or beyond it. These theories all encountered a series of insurmountable difficulties which will be named "superluminal paradox"in this paper. We will analyze it in some detail and then prove that the paradox disappears unambiguously in quantum theory, which is compatible with SR. Most likely, the superluminal particle in real world is just a kind of known particle, the neutrino.

  17. Closed timelike curves, superluminal signals, and "free will" in universal quantum mechanics

    CERN Document Server

    Nikolic, H

    2010-01-01

    We explore some implications of the hypothesis that quantum mechanics (QM) is universal, i.e., that QM does not merely describe information accessible to observers, but that it also describes the observers themselves. From that point of view, "free will" (FW) - the ability of experimentalists to make free choices of initial conditions - is merely an illusion. As a consequence, by entangling a part of brain (responsible for the illusion of FW) with a distant particle, one may create nonlocal correlations that can be interpreted as superluminal signals. In addition, if FW is an illusion, then QM on a closed timelike curve can be made consistent even without the Deutch nonlinear consistency constraint.

  18. On determination of the geometric cosmological constant from the OPERA experiment of superluminal neutrinos

    CERN Document Server

    Yan, Mu-Lin; Huang, Wei; Xiao, Neng-Chao

    2011-01-01

    The recent OPERA experiment of superluminal neutrinos has deep consequences in cosmology. In cosmology a fundamental constant is the cosmological constant. From observations one can estimate the effective cosmological constant $\\Lambda_{eff}$ which is the sum of the quantum zero point energy $\\Lambda_{dark energy}$ and the geometric cosmological constant $\\Lambda$. The OPERA experiment can be applied to determine the geometric cosmological constant $\\Lambda$. It is the first time to distinguish the contributions of $\\Lambda$ and $\\Lambda_{dark energy}$ from each other by experiment. The determination is based on an explanation of the OPERA experiment in the framework of Special Relativity with de Sitter space-time symmetry.

  19. PIV uncertainty propagation

    Science.gov (United States)

    Sciacchitano, Andrea; Wieneke, Bernhard

    2016-08-01

    This paper discusses the propagation of the instantaneous uncertainty of PIV measurements to statistical and instantaneous quantities of interest derived from the velocity field. The expression of the uncertainty of vorticity, velocity divergence, mean value and Reynolds stresses is derived. It is shown that the uncertainty of vorticity and velocity divergence requires the knowledge of the spatial correlation between the error of the x and y particle image displacement, which depends upon the measurement spatial resolution. The uncertainty of statistical quantities is often dominated by the random uncertainty due to the finite sample size and decreases with the square root of the effective number of independent samples. Monte Carlo simulations are conducted to assess the accuracy of the uncertainty propagation formulae. Furthermore, three experimental assessments are carried out. In the first experiment, a turntable is used to simulate a rigid rotation flow field. The estimated uncertainty of the vorticity is compared with the actual vorticity error root-mean-square, with differences between the two quantities within 5-10% for different interrogation window sizes and overlap factors. A turbulent jet flow is investigated in the second experimental assessment. The reference velocity, which is used to compute the reference value of the instantaneous flow properties of interest, is obtained with an auxiliary PIV system, which features a higher dynamic range than the measurement system. Finally, the uncertainty quantification of statistical quantities is assessed via PIV measurements in a cavity flow. The comparison between estimated uncertainty and actual error demonstrates the accuracy of the proposed uncertainty propagation methodology.

  20. TSUNAMI WAVE PROPAGATION ALONG WAVEGUIDES

    Directory of Open Access Journals (Sweden)

    Andrei G. Marchuk

    2009-01-01

    Full Text Available This is a study of tsunami wave propagation along the waveguide on a bottom ridge with flat sloping sides, using the wave rays method. During propagation along such waveguide the single tsunami wave transforms into a wave train. The expression for the guiding velocities of the fastest and slowest signals is defined. The tsunami wave behavior above the ocean bottom ridges, which have various model profiles, is investigated numerically with the help of finite difference method. Results of numerical experiments show that the highest waves are detected above a ridge with flat sloping sides. Examples of tsunami propagation along bottom ridges of the Pacific Ocean are presented.

  1. Explosion propagation in inert porous media.

    Science.gov (United States)

    Ciccarelli, G

    2012-02-13

    Porous media are often used in flame arresters because of the high surface area to volume ratio that is required for flame quenching. However, if the flame is not quenched, the flow obstruction within the porous media can promote explosion escalation, which is a well-known phenomenon in obstacle-laden channels. There are many parallels between explosion propagation through porous media and obstacle-laden channels. In both cases, the obstructions play a duel role. On the one hand, the obstruction enhances explosion propagation through an early shear-driven turbulence production mechanism and then later by shock-flame interactions that occur from lead shock reflections. On the other hand, the presence of an obstruction can suppress explosion propagation through momentum and heat losses, which both impede the unburned gas flow and extract energy from the expanding combustion products. In obstacle-laden channels, there are well-defined propagation regimes that are easily distinguished by abrupt changes in velocity. In porous media, the propagation regimes are not as distinguishable. In porous media the entire flamefront is affected, and the effects of heat loss, turbulence and compressibility are smoothly blended over most of the propagation velocity range. At low subsonic propagation speeds, heat loss to the porous media dominates, whereas at higher supersonic speeds turbulence and compressibility are important. This blending of the important phenomena results in no clear transition in propagation mechanism that is characterized by an abrupt change in propagation velocity. This is especially true for propagation velocities above the speed of sound where many experiments performed with fuel-air mixtures show a smooth increase in the propagation velocity with mixture reactivity up to the theoretical detonation wave velocity.

  2. DETECTION OF BROAD Hα EMISSION LINES IN THE LATE-TIME SPECTRA OF A HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Lin; Masci, F. [Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125 (United States); Quimby, R. [Department of Astronomy, San Diego State University, San Diego, CA 92182 (United States); Ofek, E.; Gal-Yam, A.; Vreeswijk, P. M.; Leloudas, G.; Cia, A. de; Yaron, O. [Department of Particle Physics and Astrophysics, Faculty of Physics, The Weizmann Institute of Science, Rehovot 76100 (Israel); Mazzali, P. [Astrophysics Research Institute, Liverpool John Moores University, IC2, Liverpool Science Park, 146 Brownlow Hill, Liverpool L3 5RF (United Kingdom); Perley, D. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Cenko, S. B. [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Cao, Y.; Kulkarni, S. R. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Nugent, P. E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Rebbapragada, Umaa D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Woźniak, P. R., E-mail: lyan@ipac.caltech.edu [Space and Remote Sensing, ISR-2, MS-B244 Los Alamos National Laboratory Los Alamos, NM 87545 (United States)

    2015-12-01

    iPTF13ehe is a hydrogen-poor superluminous supernova (SLSN) at z = 0.3434, with a slow-evolving light curve and spectral features similar to SN2007bi. It rises in 83–148 days to reach a peak bolometric luminosity of ∼1.3 × 10{sup 44} erg s{sup −1}, then decays slowly at 0.015 mag day{sup −1}. The measured ejecta velocity is ∼ 13,000 km s{sup −1}. The inferred explosion characteristics, such as the ejecta mass (70–220 M{sub ⊙}), and the total radiative and kinetic energy (E{sub rad} ∼ 10{sup 51} erg, E{sub kin} ∼ 2 × 10{sup 53} erg), are typical of slow-evolving H-poor SLSN events. However, the late-time spectrum taken at +251 days (rest, post-peak) reveals a Balmer Hα emission feature with broad and narrow components, which has never been detected before among other H-poor SLSNe. The broad component has a velocity width of ∼4500 km s{sup −1} and a ∼300 km s{sup −1} blueward shift relative to the narrow component. We interpret this broad Hα emission with a luminosity of ∼2 × 10{sup 41} erg s{sup −1} as resulting from the interaction between the supernova ejecta and a discrete H-rich shell, located at a distance of ∼4 × 10{sup 16} cm from the explosion site. This interaction causes the rest-frame r-band LC to brighten at late times. The fact that the late-time spectra are not completely absorbed by the shock-ionized H-shell implies that its Thomson scattering optical depth is likely ≤1, thus setting upper limits on the shell mass ≤30 M{sub ⊙}. Of the existing models, a Pulsational Pair Instability supernova model can naturally explain the observed 30 M{sub ⊙} H-shell, ejected from a progenitor star with an initial mass of (95–150) M{sub ⊙} about 40 years ago. We estimate that at least ∼15% of all SLSNe-I may have late-time Balmer emission lines.

  3. The superluminous supernova PS1-11ap: bridging the gap between low and high redshift

    CERN Document Server

    McCrum, M; Kotak, R; Rest, A; Jerkstrand, A; Inserra, C; Rodney, S A; Chen, T -W; Howell, D A; Huber, M E; Pastorello, A; Tonry, J L; Bresolin, F; Kudritzki, R -P; Chornock, R; Berger, E; Smith, K; Botticella, M T; Foley, R J; Fraser, M; Milisavljevic, D; Nicholl, M; Riess, A G; Stubbs, C W; Valenti, S; Wood-Vasey, W M; Wright, D; Young, D R; Drout, M; Czekala, I; Burgett, W S; Chambers, K C; Draper, P; Flewelling, H; Hodapp, K W; Kaiser, N; Magnier, E A; Metcalfe, N; Sweeney, W; Wainscoat, R J

    2013-01-01

    We present optical photometric and spectroscopic coverage of the superluminous supernova (SLSN) PS1-11ap, discovered with the Pan-STARRS1 Medium Deep Survey at z = 0.524. This intrinsically blue transient rose slowly to reach a peak magnitude of M_u = -21.4 mag and bolometric luminosity of 8 x 10^43 ergs^-1 before settling onto a relatively shallow gradient of decline. The observed decline is significantly slower than those of the superluminous type Ic SNe which have been the focus of much recent attention. Spectroscopic similarities with the lower redshift SN2007bi and a decline rate similar to 56Co decay timescale initially indicated that this transient could be a candidate for a pair instability supernova (PISN) explosion. Overall the transient appears quite similar to SN2007bi and the lower redshift object PTF12dam. The extensive data set, from 30 days before peak to 230 days after, allows a detailed and quantitative comparison with published models of PISN explosions. We find that the PS1-11ap data do no...

  4. Slowly fading super-luminous supernovae that are not pair-instability explosions

    CERN Document Server

    Nicholl, M; Jerkstrand, A; Inserra, C; McCrum, M; Kotak, R; Fraser, M; Wright, D; Chen, T -W; Smith, K; Young, D R; Sim, S A; Valenti, S; Howell, D A; Bresolin, F; Kudritzki, R P; Tonry, J L; Huber, M E; Rest, A; Pastorello, A; Tomasella, L; Cappellaro, E; Benetti, S; Mattila, S; Kankare, E; Kangas, T; Leloudas, G; Sollerman, J; Taddia, F; Berger, E; Chornock, R; Narayan, G; Stubbs, C W; Foley, R J; Lunnan, R; Soderberg, A; Sanders, N; Milisavljevic, D; Margutti, R; Kirshner, R P; Elias-Rosa, N; Morales-Garoffolo, A; Taubenberger, S; Botticella, M T; Gezari, S; Urata, Y; Rodney, S; Riess, A G; Scolnic, D; Wood-Vasey, W M; Burgett, W S; Chambers, K; Flewelling, H A; Magnier, E A; Kaiser, N; Metcalfe, N; Morgan, J; Price, P A; Sweeney, W; Waters, C

    2013-01-01

    Super-luminous supernovae that radiate more than 10^44 ergs per second at their peak luminosity have recently been discovered in faint galaxies at redshifts of 0.1-4. Some evolve slowly, resembling models of 'pair-instability' supernovae. Such models involve stars with original masses 140-260 times that of the Sun that now have carbon-oxygen cores of 65-30 solar masses. In these stars, the photons that prevent gravitational collapse are converted to electron-positron pairs, causing rapid contraction and thermonuclear explosions. Many solar masses of 56Ni are synthesized; this isotope decays to 56Fe via 56Co, powering bright light curves. Such massive progenitors are expected to have formed from metal-poor gas in the early Universe. Recently, supernova 2007bi in a galaxy at redshift 0.127 (about 12 billion years after the Big Bang) with a metallicity one-third that of the Sun was observed to look like a fading pair-instability supernova. Here we report observations of two slow-to-fade super-luminous supernovae...

  5. Predictions for signatures of the quark-nova in superluminous supernovae

    CERN Document Server

    Ouyed, Rachid; Jaikumar, Prashanth

    2009-01-01

    [Abridged] Superluminous Supernovae (SN2006gy, SN2005gj, SN2005ap, SN2008fz, SN2003ma) have been a challenge to explain by standard models. We present an alternative scenario involving a quark-nova (QN), an explosive transition of the newly born neutron star to a quark star in which a second explosion (delayed) occurs inside the already expanding ejecta of a normal SN. The reheated SN ejecta can radiate at higher levels for longer periods of time primarily due to reduced adiabatic expansion losses, unlike the standard SN case. Our model is successfully applied to SN2006gy, SN2005gj, SN2005ap, SN2008fz, SN2003ma with encouraging fits to the lightcurves. There are four predictions in our model: (i) superluminous SNe optical lightcurves should show a double-hump with the SN hump at weaker magnitudes occurring days to weeks before the QN; (ii) Two shock breakouts should be observed vis-a-vis one for a normal SN. Depending on the time delay, this would manifest as two distinct spikes in the X-ray region or a broad...

  6. ASASSN-15lh: A Superluminous Ultraviolet Rebrightening Observed by Swift and Hubble

    CERN Document Server

    Brown, Peter J; Cooke, Jeff; Olaes, Melanie; Quimby, Robert M; Baade, Dietrich; Gehrels, Neil; Hoeflich, Peter; Maund, Justyn; Mould, Jeremy; Patat, Ferdinando; Wang, Lifan; Wheeler, J Craig

    2016-01-01

    We present and discuss ultraviolet (UV) and optical photometry from the Ultraviolet/Optical Telescope (UVOT) and X-ray limits from the X-Ray Telescope on Swift and imaging polarimetry and UV/optical spectroscopy with the Hubble Space Telescope (HST) of ASASSN-15lh. It has been classified as a hydrogen-poor superluminous supernova (SLSN I) more luminous than any other supernova observed. From the polarimetry we determine that the explosion was only mildly asymmetric. We find the flux of ASASSN-15lh to increase strongly into the UV, with a UV luminosity a hundred times greater than the hydrogen-rich, UV-bright SLSN II SN~2008es. A late rebrightening -- most prominent at shorter wavelengths -- is seen about two months after the peak brightness, which by itself is as bright as a superluminous supernova. ASASSN-15lh is not detected in the X-rays in individual observations or when the data are summed into two separate bins for the early phase and the rebrightening. The HST UV spectrum during the rebrightening is do...

  7. Two superluminous supernovae from the early universe discovered by the Supernova Legacy Survey

    CERN Document Server

    Howell, D A; Lidman, C; Sullivan, M; Conley, A; Astier, P; Carlberg, C Balland R G; Fouchez, D; Guy, J; Hardin, D; Pain, R; Palanque-Delabrouille, N; Perrett, K; Pritchet, C J; Regnault, N; Rich, J; Ruhlmann-Kleider, V

    2013-01-01

    We present spectra and lightcurves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M_U = -22.7 is one of the most luminous SNe ever observed, and gives a rare glimpse into the restframe ultraviolet where these supernovae put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but based on the supernova spectrum, we estimate it to be at z ~ 1.5. Both supernovae have similar observer-frame griz lightcurves, which map to restframe lightcurves in the U-band and UV, rising in ~ 20 restframe days or longer, and declining over a similar timescale. The lightcurves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra to theoretical models, and identify lines of C II, C III, Fe III, and Mg II in the spectrum of SNLS 06D4eu and SCP 06F6...

  8. Measurement of the velocity of a quantum object: A role of phase and group velocities

    Science.gov (United States)

    Lapinski, Mikaila; Rostovtsev, Yuri V.

    2017-08-01

    We consider the motion of a quantum particle in a free space. Introducing an explicit measurement procedure for velocity, we demonstrate that the measured velocity is related to the group and phase velocities of the corresponding matter waves. We show that for long distances the measured velocity coincides with the matter wave group velocity. We discuss the possibilities to demonstrate these effects for the optical pulses in coherently driven media or for radiation propagating in waveguides.

  9. Extensions of Born’s rule to non-linear quantum mechanics, some of which do not imply superluminal communication

    Science.gov (United States)

    Helou, Bassam; Chen, Yanbei

    2017-08-01

    Nonlinear modifications of quantum mechanics have a troubled history. They were initially studied for many promising reasons: resolving the measurement problem, formulating a theory of quantum mechanics and gravity, and understanding the limits of standard quantum mechanics. However, certain non-linear theories have been experimentally tested and failed. More significantly, it has been shown that, in general, deterministic non-linear theories can be used for superluminal communication. We highlight another serious issue: the distribution of measurement results predicted by non-linear quantum mechanics depends on the formulation of quantum mechanics. In other words, Born’s rule cannot be uniquely extended to non-linear quantum mechanics. We present these generalizations of Born’s rule, and then examine whether some exclude superluminal communication. We determine that a large class do not allow for superluminal communication, but many lack a consistent definition. Nonetheless, we find a single extension of Born’s rule with a sound operational definition, and that does not exhibit superluminal communication. The non-linear time-evolution leading to a certain measurement event is driven by the state conditioned on measurements that lie within the past light cone of that event.

  10. Superluminal Radio Features in the M87 Jet and the Site of Flaring TeV Gamma-ray Emission

    CERN Document Server

    Cheung, C C; Stawarz, L

    2007-01-01

    Superluminal motion is a common feature of radio jets in powerful gamma-ray emitting active galactic nuclei. Conventionally, the variable emission is assumed to originate near the central supermassive black-hole where the jet is launched on parsec scales or smaller. Here, we report the discovery of superluminal radio features within a distinct flaring X-ray emitting region in the jet of the nearby radio galaxy M87 with the Very Long Baseline Array. This shows that these two phenomenological hallmarks -- superluminal motion and high-energy variability -- are associated, and we place this activity much further (>=120 pc) from the ``central engine'' in M87 than previously thought in relativistic jet sources. We argue that the recent excess very high-energy TeV emission from M87 reported by the H.E.S.S. experiment originates from this variable superluminal structure, thus providing crucial insight into the production region of gamma-ray emission in more distant blazars.

  11. Longitudinal and transverse velocity fields in parsec-scale jets

    CERN Document Server

    Mertens, Florent

    2015-01-01

    Radio-loud AGN typically manifest powerful relativistic jets extending up to millions of light years and often showing superluminal motions organised in a complex kinematic pattern. A number of physical models are still competing to explain the jet structure and kinematics revealed by radio images using the VLBI technique. Robust measurements of longitudinal and transverse velocity field in the jets would provide crucial information for these models. This is a difficult task, particularly for transversely resolved jets in objects like 3C 273 and M87. To address this task, we have developed a new technique for identifying significant structural patterns (SSP) of smooth, transversely resolved flows and obtaining a velocity field from cross-correlation of these regions in multi-epoch observations. Detection of individual SSP is performed using the wavelet decomposition and multiscale segmentation of the observed structure. The cross-correlation algorithm combines structural information on different scales of the...

  12. Measuring Propagation Speed of Coulomb Fields

    OpenAIRE

    De Sangro, R.; Finocchiaro, G.; Patteri, P.; Piccolo, M.; Pizzella, G.

    2012-01-01

    The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planets motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly movi...

  13. Wave Propagation

    CERN Document Server

    Ferrarese, Giorgio

    2011-01-01

    Lectures: A. Jeffrey: Lectures on nonlinear wave propagation.- Y. Choquet-Bruhat: Ondes asymptotiques.- G. Boillat: Urti.- Seminars: D. Graffi: Sulla teoria dell'ottica non-lineare.- G. Grioli: Sulla propagazione del calore nei mezzi continui.- T. Manacorda: Onde nei solidi con vincoli interni.- T. Ruggeri: "Entropy principle" and main field for a non linear covariant system.- B. Straughan: Singular surfaces in dipolar materials and possible consequences for continuum mechanics

  14. The hydrogen-poor superluminous supernova iPTF 13ajg and its host galaxy in absorption and emission

    Energy Technology Data Exchange (ETDEWEB)

    Vreeswijk, Paul M.; Gal-Yam, Avishay; De Cia, Annalisa; Rubin, Adam; Yaron, Ofer; Tal, David; Ofek, Eran O. [Department of Particle Physics and Astrophysics, Weizmann Institute of Science, Rehovot 7610001 (Israel); Savaglio, Sandra [Max Planck Institute for Extraterrestrial Physics, D-85748 Garching bei München (Germany); Quimby, Robert M. [Kavli Institute for the Physics and Mathematics of the Universe (WPI), Todai Institutes for Advanced Study, The University of Tokyo 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Cenko, S. Bradley; Filippenko, Alexei V.; Clubb, Kelsey I. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Perley, Daniel A.; Cao, Yi [Astronomy Department, California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, CA 91125 (United States); Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos [Department of Astronomy, The Oskar Klein Center, Stockholm University, AlbaNova 10691 Stockholm (Sweden); Arcavi, Iair [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Kasliwal, Mansi M., E-mail: paul.vreeswijk@weizmann.ac.il [The Observatories, Carnegie Institution for Science, 813 Santa Barbara Street, Pasadena, CA 91101 (United States); and others

    2014-12-10

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory, iPTF 13ajg. At a redshift of z = 0.7403, derived from narrow absorption lines, iPTF 13ajg peaked at an absolute magnitude of M {sub u,} {sub AB} = –22.5, one of the most luminous supernovae to date. The observed bolometric peak luminosity of iPTF 13ajg is 3.2 × 10{sup 44} erg s{sup –1}, while the estimated total radiated energy is 1.3 × 10{sup 51} erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the Very Large Telescope. From Voigt profile fitting, we derive the column densities log N(Mg I) =11.94 ± 0.06, log N(Mg II) =14.7 ± 0.3, and log N(Fe II) =14.25 ± 0.10. These column densities, as well as the Mg I and Mg II equivalent widths of a sample of hydrogen-poor SLSNe taken from the literature, are at the low end of those derived for gamma-ray bursts (GRBs) whose progenitors are also thought to be massive stars. This suggests that the environments of hydrogen-poor SLSNe and GRBs are different. From the nondetection of Fe II fine-structure absorption lines, we derive a lower limit on the distance between the supernova and the narrow-line absorbing gas of 50 pc. The neutral gas responsible for the absorption in iPTF 13ajg exhibits a single narrow component with a low velocity width, ΔV = 76 km s{sup –1}, indicating a low-mass host galaxy. No host galaxy emission lines are detected, leading to an upper limit on the unobscured star formation rate (SFR) of SFR{sub [O} {sub II]}<0.07M{sub ⊙}yr{sup −1}. Late-time imaging shows the iPTF 13ajg host galaxy to be faint, with g {sub AB} ≈ 27.0 and R {sub AB} ≥ 26.0 mag, corresponding to M {sub B,} {sub Vega} ≳ –17.7 mag.

  15. 3D Simulations of Relativistic Precessing Jets Probing the Structure of Superluminal Sources

    CERN Document Server

    Aloy, M A; Gómez, J L; Agudo, I; Müller, E; Ibanyez, J M; Aloy, Miguel Angel; Marti, Jose Maria; Gomez, Jose Luis; Agudo, Ivan; Mueller, Ewald; Ibanyez, Jose Maria

    2003-01-01

    We present the results of a three-dimensional, relativistic, hydrodynamic simulation of a precessing jet into which a compact blob of matter is injected. A comparison of synthetic radio maps computed from the hydrodynamic model, taking into account the appropriate light travel time delays, with those obtained from observations of actual superluminal sources shows that the variability of the jet emission is the result of a complex combination of phase motions, viewing angle selection effects, and non-linear interactions between perturbations and the underlying jet and/or the external medium. These results question the hydrodynamic properties inferred from observed apparent motions and radio structures, and reveal that shock-in-jet models may be overly simplistic.

  16. Can pair-instability supernova models match the observations of superluminous supernovae?

    CERN Document Server

    Kozyreva, Alexandra

    2015-01-01

    An increasing number of so-called superluminous supernovae (SLSNe) are discovered. It is believed that at least some of them with slowly fading light curves originate in stellar explosions induced by the pair instability mechanism. Recent stellar evolution models naturally predict pair instability supernovae (PISNe) from very massive stars at wide range of metallicities (up to Z=0.006, Yusof et al. 2013). In the scope of this study we analyse whether PISN models can match the observational properties of SLSNe with various light curve shapes. Specifically, we explore the influence of different degrees of macroscopic chemical mixing in PISN explosive products on the resulting observational properties. We artificially apply mixing to the 250 Msun PISN evolutionary model from Kozyreva et al. (2014) and explore its supernova evolution with the one-dimensional radiation hydrodynamics code STELLA. The greatest success in matching SLSN observations is achieved in the case of an extreme macroscopic mixing, where all r...

  17. Extreme Supernova Models for the Super-luminous Transient ASASSN-15lh

    Science.gov (United States)

    Chatzopoulos, E.; Wheeler, J. C.; Vinko, J.; Nagy, A. P.; Wiggins, B. K.; Even, W. P.

    2016-09-01

    The recent discovery of the unprecedentedly super-luminous transient ASASSN-15lh (or SN 2015L) with its UV-bright secondary peak challenges all the power-input models that have been proposed for super-luminous supernovae. Here we examine some of the few viable interpretations of ASASSN-15lh in the context of a stellar explosion, involving combinations of one or more power inputs. We model the light curve of ASASSN-15lh with a hybrid model that includes contributions from magnetar spin-down energy and hydrogen-poor circumstellar interaction. We also investigate models of pure circumstellar interaction with a massive hydrogen-deficient shell and discuss the lack of interaction features in the observed spectra. We find that, as a supernova, ASASSN-15lh can be best modeled by the energetic core-collapse of an ˜40 M ⊙ star interacting with a hydrogen-poor shell of ˜20 M ⊙. The circumstellar shell and progenitor mass are consistent with a rapidly rotating pulsational pair-instability supernova progenitor as required for strong interaction following the final supernova explosion. Additional energy injection by a magnetar with an initial period of 1-2 ms and magnetic field of 0.1-1 × 1014 G may supply the excess luminosity required to overcome the deficit in single-component models, but this requires more fine-tuning and extreme parameters for the magnetar, as well as the assumption of efficient conversion of magnetar energy into radiation. We thus favor a single-input model where the reverse shock formed in a strong SN ejecta-circumstellar matter interaction following a very powerful core-collapse SN explosion can supply the luminosity needed to reproduce the late-time UV-bright plateau.

  18. A plausible (overlooked) super-luminous supernova in the Sloan digital sky survey stripe 82 data

    Energy Technology Data Exchange (ETDEWEB)

    Kostrzewa-Rutkowska, Zuzanna; Kozłowski, Szymon; Wyrzykowski, Łukasz [Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa (Poland); Djorgovski, S. George; Mahabal, Ashish A. [California Institute of Technology, 1200 E California Blvd., Pasadena, CA 91125 (United States); Glikman, Eilat [Department of Physics and Yale Center for Astronomy and Astrophysics, Yale University, P.O. Box 208121, New Haven, CT 06520-8121 (United States); Koposov, Sergey, E-mail: zkostrzewa@astrouw.edu.pl, E-mail: simkoz@astrouw.edu.pl, E-mail: wyrzykow@astrouw.edu.pl [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)

    2013-12-01

    We present the discovery of a plausible super-luminous supernova (SLSN), found in the archival data of Sloan Digital Sky Survey (SDSS) Stripe 82, called PSN 000123+000504. The supernova (SN) peaked at m {sub g} < 19.4 mag in the second half of 2005 September, but was missed by the real-time SN hunt. The observed part of the light curve (17 epochs) showed that the rise to the maximum took over 30 days, while the decline time lasted at least 70 days (observed frame), closely resembling other SLSNe of SN 2007bi type. The spectrum of the host galaxy reveals a redshift of z = 0.281 and the distance modulus of μ = 40.77 mag. Combining this information with the SDSS photometry, we found the host galaxy to be an LMC-like irregular dwarf galaxy with an absolute magnitude of M{sub B} = –18.2 ± 0.2 mag and an oxygen abundance of 12+log [O/H]=8.3±0.2; hence, the SN peaked at M {sub g} < –21.3 mag. Our SLSN follows the relation for the most energetic/super-luminous SNe exploding in low-metallicity environments, but we found no clear evidence for SLSNe to explode in low-luminosity (dwarf) galaxies only. The available information on the PSN 000123+000504 light curve suggests the magnetar-powered model as a likely scenario of this event. This SLSN is a new addition to a quickly growing family of super-luminous SNe.

  19. FRACTAL KINEMATICS OF CRACK PROPAGATION IN GEOMATERIALS

    Institute of Scientific and Technical Information of China (English)

    谢和平

    1995-01-01

    Experimental results indicate that propagation paths of cracks in geomaterials are often irregular, producing rough fracture surfaces which are fractal. A formula is derived for the fractal kinematics of crack propagation in geomaterials. The formula correlates the dynamic and static fracture toughnesses with crack velocity, crack length and a microstructural parameter, and allows the fractal dimension to be obtained. From the equations for estimating crack velocity and fractal dimension it can be shown that the measured crack velocity, Vo , should be much smaller than the fractal crack velocity, V. It can also be shown that the fractal dimension of the crack propagation path can be calculated directly from Vo and from the fracture toughness.

  20. Local wavefield velocity imaging for damage evaluation

    Science.gov (United States)

    Chia, Chen Ciang; Gan, Chia Sheng; Mustapha, F.

    2017-02-01

    Ultrasonic Propagation Imaging or Acoustic Wavefield Imaging has been widely used to evaluate structural damages and internal features. Inspecting complete wavefield time history for damage identification is tedious and error-prone. A more effective way is by extracting damage-related information into a single image. A wavefield velocity imaging method that maps the local estimates of group or phase velocity is proposed. Actual velocity values rather than arbitrarily-scaled intensities are mapped, enabling damage sizing without the need of supervised training or inspecting wavefield propagation video. Performance of the proposed method was tested by inspecting a 100 mm by 100 mm area of a 2 mm thick stainless steel specimen. Local phase velocity maps of A0 mode showed a half-thickness hole of 2 mm diameter as significant change in local phase velocity from the nominal 2 m/ms. Full width at half maximum of relevant velocity profiles proved the accuracy and consistency of the damage sizing.

  1. The effect of duct surface character on methane explosion propagation

    Institute of Scientific and Technical Information of China (English)

    LIN Bai-quan; YE Qing; JIAN Cong-guang; WU Hai-jin

    2007-01-01

    The effect of duct surface character on methane explosion propagation was experimentally studied and theoretically analyzed. The roughness has effect on methane explosion propagation. The flame propagation velocity and the peak value pressure of methane explosion in rough duct are larger than the parameters in smooth duct. The heat exchange of the surface has effect on methane explosion propagation. The propagation velocity of flame and strength of explosion wave in the duct covered by heat insulation material are larger than those in duct with good heat transmittability.

  2. Investigation into stress wave propagation in metal foams

    Directory of Open Access Journals (Sweden)

    Li Lang

    2015-01-01

    Full Text Available The aim of this study is to investigate stress wave propagation in metal foams under high-speed impact loading. Three-dimensional Voronoi model is established to represent real closed-cell foam. Based on the one-dimensional stress wave theory and Voronoi model, a numerical model is developed to calculate the velocity of elastic wave and shock wave in metal foam. The effects of impact velocity and relative density of metal foam on the stress wave propagation in metal foams are explored respectively. The results show that both elastic wave and shock wave propagate faster in metal foams with larger relative density; with increasing the impact velocity, the shock wave propagation velocity increase, but the elastic wave propagation is not sensitive to the impact velocity.

  3. Flame Propagation Through Concentration Gradient

    Institute of Scientific and Technical Information of China (English)

    JunyaIINO; MitsuakiTANABE; 等

    2000-01-01

    The experiment was carried out in homogeneous propane-air mixture and in several concentration gradient of mixture.Igniter is put on the upper side of the combustion chamber,In concentration gradient experiment.ixture was ignited from lean side.An experimental study was conducted in a combustion chamber.The combustion chamber has glass windows for optical measurements at any side.For the measurement of distribution of fuel concentration,infraed absorption method using 3.39μm He-Ne laser was used,and for the observation of proagating flams,Schlieren method was employed.As a measurment result of flame propagation velocity and flammable limit,for a mixture of an identical local equivalence ratio.flame propagation velocity in concentration gradient is faster than that in homogeneous mixture,and rich flammable limit in concentration gradient shows a tendency to be higher than that in homogeneous mixture.

  4. Wave propagation in ballistic gelatine.

    Science.gov (United States)

    Naarayan, Srinivasan S; Subhash, Ghatu

    2017-01-23

    Wave propagation characteristics in long cylindrical specimens of ballistic gelatine have been investigated using a high speed digital camera and hyper elastic constitutive models. The induced transient deformation is modelled with strain rate dependent Mooney-Rivlin parameters which are determined by modelling the stress-strain response of gelatine at a range of strain rates. The varying velocity of wave propagation through the gelatine cylinder is derived as a function of prestress or stretch in the gelatine specimen. A finite element analysis is conducted using the above constitutive model by suitably defining the impulse imparted by the polymer bar into the gelatine specimen. The model results are found to capture the experimentally observed wave propagation characteristics in gelatine effectively.

  5. Two superluminous supernovae from the early universe discovered by the supernova legacy survey

    Energy Technology Data Exchange (ETDEWEB)

    Howell, D. A. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Kasen, D. [Departments of Physics and Astronomy, University of California, Berkeley, Berkeley, CA 94720-7300 (United States); Lidman, C. [Australian Astronomical Observatory, P.O. Box 915, North Ryde, NSW 1670 (Australia); Sullivan, M. [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309-389 (United States); Astier, P.; Balland, C.; Guy, J.; Hardin, D.; Pain, R.; Regnault, N. [LPNHE, CNRS-IN2P3 and University of Paris VI and VII, F-75005 Paris (France); Carlberg, R. G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H8 (Canada); Fouchez, D. [CPPM, CNRS-IN2P3 and University Aix Marseille II, Case 907, F-13288 Marseille Cedex 9 (France); Palanque-Delabrouille, N.; Rich, J.; Ruhlmann-Kleider, V. [DSM/IRFU/SPP, CEA-Saclay, F-91191 Gif-sur-Yvette (France); Perrett, K. [DRDC Ottawa, 3701 Carling Avenue, Ottawa, ON K1A 0Z4 (Canada); Pritchet, C. J. [Department of Physics and Astronomy, University of Victoria, P.O. Box 3055, Victoria, BC V8W 3P6 (Canada)

    2013-12-20

    We present spectra and light curves of SNLS 06D4eu and SNLS 07D2bv, two hydrogen-free superluminous supernovae (SNe) discovered by the Supernova Legacy Survey. At z = 1.588, SNLS 06D4eu is the highest redshift superluminous SN with a spectrum, at M{sub U} = –22.7 it is one of the most luminous SNe ever observed, and it gives a rare glimpse into the rest-frame ultraviolet where these SNe put out their peak energy. SNLS 07D2bv does not have a host galaxy redshift, but on the basis of the SN spectrum, we estimate it to be at z ∼ 1.5. Both SNe have similar observer-frame griz light curves, which map to rest-frame light curves in the U band and UV, rising in ∼20 rest-frame days or longer and declining over a similar timescale. The light curves peak in the shortest wavelengths first, consistent with an expanding blackbody starting near 15,000 K and steadily declining in temperature. We compare the spectra with theoretical models, and we identify lines of C II, C III, Fe III, and Mg II in the spectra of SNLS 06D4eu and SCP 06F6 and find that they are consistent with an expanding explosion of only a few solar masses of carbon, oxygen, and other trace metals. Thus, the progenitors appear to be related to those suspected for SNe Ic. A high kinetic energy, 10{sup 52} erg, is also favored. Normal mechanisms of powering core-collapse or thermonuclear SNe do not seem to work for these SNe. We consider models powered by {sup 56}Ni decay and interaction with circumstellar material, but we find that the creation and spin-down of a magnetar with a period of 2 ms, a magnetic field of 2 × 10{sup 14} G, and a 3 M {sub ☉} progenitor provides the best fit to the data.

  6. Measuring Propagation Speed of Coulomb Fields

    CERN Document Server

    Calcaterra, A; Finocchiaro, G; Patteri, P; Piccolo, M; Pizzella, G

    2012-01-01

    The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planets motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Li\\'enard-Weichert retarded potential leads to a formula indistinguishable from the one obtained assuming that the electric field propagates with infinite velocity. Feyman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformely moving electron beam. The results we obtain on such a finite lifetime kinema...

  7. Revealing the binary origin of Type Ic superluminous supernovae through nebular hydrogen emission

    CERN Document Server

    Moriya, Takashi J; Mackey, Jonathan; Chen, Ting-Wan; Langer, Norbert

    2015-01-01

    We propose that nebular Halpha emission as detected in the Type Ic superluminous supernova iPTF13ehe stems from matter which is stripped from a companion star when the supernova ejecta collide with it. The temporal evolution, the line broadening, and the overall blueshift of the emission are consistent with this interpretation. We scale the nebular Halpha luminosity predicted for Type Ia supernovae in single-degenerate systems to derive the stripped mass required to explain the Halpha luminosity of iPTF13ehe. We find a stripped mass of 0.1 - 0.9 solar masses, assuming that the supernova luminosity is powered by radioactivity or magnetar spin down. Because a central heating source is required to excite the Halpha emission, an interaction-powered model is not favored for iPTF13ehe. We derive a companion mass of more than 20 solar masses and a binary separation of less than about 20 companion radii based on the stripping efficiency during the collision, indicating that the supernova progenitor and the companion ...

  8. A plausible (overlooked) super-luminous supernova in the SDSS Stripe 82 data

    CERN Document Server

    Kostrzewa-Rutkowska, Zuzanna; Wyrzykowski, Lukasz; Djorgovski, S George; Glikman, Eilat; Mahabal, Ashish A

    2013-01-01

    We present the discovery of a plausible super-luminous supernova (SLSN), found in the archival data of Sloan Digital Sky Survey (SDSS) Stripe 82, called PSN 000123+000504. The supernova peaked at M_g<-21.3 mag in the second half of September 2005, but was missed by the real-time supernova hunt. The observed part of the light curve (17 epochs) showed that the rise to the maximum took over 30 days, while the decline time lasted at least 70 days (observed frame), closely resembling other SLSNe of SN2007bi type. Spectrum of the host galaxy reveals a redshift of z=0.281 and the distance modulus of \\mu=40.77 mag. Combining this information with the SDSS photometry, we found the host galaxy to be an LMC-like irregular dwarf galaxy with the absolute magnitude of M_B=-18.2+/-0.2 mag and the oxygen abundance of 12+log[O/H]=8.3+/-0.2. Our SLSN follows the relation for the most energetic/super-luminous SNe exploding in low-metallicity environments, but we found no clear evidence for SLSNe to explode in low-luminosity ...

  9. On the early-time excess emission in hydrogen-poor superluminous supernovae

    CERN Document Server

    Vreeswijk, Paul M; Gal-Yam, Avishay; De Cia, Annalisa; Perley, Daniel A; Quimby, Robert M; Waldman, Roni; Sullivan, Mark; Yan, Lin; Ofek, Eran O; Fremling, Christoffer; Taddia, Francesco; Sollerman, Jesper; Valenti, Stefano; Arcavi, Iair; Howell, D Andrew; Filippenko, Alexei V; Cenko, S Bradley; Yaron, Ofer; Kasliwal, Mansi M; Cao, Yi; Ben-Ami, Sagi; Horesh, Assaf; Rubin, Adam; Lunnan, Ragnhild; Nugent, Peter E; Laher, Russ; Rebbapragada, Umaa D; Woźniak, Przemysław; Kulkarni, Shrinivas R

    2016-01-01

    We present the light curves of the hydrogen-poor superluminous supernovae (SLSNe-I) PTF12dam and iPTF13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF12dam is very similar in duration (~10 days) and brightness relative to the main peak (2-3 mag fainter) compared to those observed in other SLSNe-I, such as SN2006oz, LSQ14bdq and DES14X3taz. In contrast, the long-duration (>30 days) early excess emission in iPTF13dcc, whose brightness competes with that of the main peak, appears to be of a different nature. We construct bolometric light curves for both targets, and fit a variety of light-curve models to both the early bump and main peak in an attempt to understand the nature of these explosions. Even though the slope of the late-time light-curve decline in both SLSNe is suggestively close to that expected from the radioactive decay of $^{56}$Ni and $^{56}$Co, the amount of nickel req...

  10. Superluminal non-ballistic jet swing in the quasar NRAO 150 revealed by mm-VLBI

    CERN Document Server

    Agudo, I; Krichbaum, T P; Marscher, A P; Gonidakis, I; Diamond, P J; Perucho, M; Alef, W; Graham, D A; Witzel, A; Zensus, J A; Bremer, M; Acosta-Pulido, J A; Barrena, R

    2007-01-01

    NRAO 150 -a compact and bright radio to mm source showing core/jet structure- has been recently identified as a quasar at redshift z=1.52 through a near-IR spectral observation. To study the jet kinematics on the smallest accessible scales and to compute the first estimates of its basic physical properties, we have analysed the ultra-high-resolution images from a new monitoring program at 86 GHz and 43 GHz with the GMVA and the VLBA, respectively. An additional archival and calibration VLBA data set, covering from 1997 to 2007, has been used. Our data shows an extreme projected counter-clock-wise jet position angle swing at an angular rate of up to ~11 deg./yr within the inner ~31 pc of the jet, which is associated with a non-ballistic superluminal motion of the jet within this region. The results suggest that the magnetic field could play an important role in the dynamics of the jet in NRAO 150, which is supported by the large values of the magnetic field strength obtained from our first estimates. The extre...

  11. An extreme ultraviolet excess in the superluminous supernova Gaia16apd reveals a powerful central engine

    CERN Document Server

    Nicholl, M; Margutti, R; Blanchard, P K; Milisavljevic, D; Challis, P; Metzger, B D; Chornock, R

    2016-01-01

    Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below $\\sim 3000$ \\AA. Yan et al (2016) have recently presented HST UV spectra and attributed the UV flux to low metallicity and hence reduced line blanketing. Here we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite a typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by $\\sim 10$-15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV cont...

  12. Gaia16apd -- a link between fast-and slowly-declining type I superluminous supernovae

    CERN Document Server

    Kangas, T; Mattila, S; Lundqvist, P; Fraser, M; Hardy, L K; Stritzinger, M D; Cappellaro, E; Elias-Rosa, N; Harmanen, J; Hsiao, E Y; Kankare, E; Nielsen, M B; Reynolds, T M; Rhodes, L; Somero, A; Wyrzykowski, L

    2016-01-01

    We present ultraviolet, optical and infrared photometry and optical spectroscopy of the type Ic superluminous supernova (SLSN) Gaia16apd, covering its evolution from 27 d before the $g$-band peak to the nebular phase, including the latest spectrum ever obtained for a fast-declining type Ic SLSN at 150.9 d. Gaia16apd is one of the closest SLSNe known ($z = 0.102\\pm0.001$), with detailed optical and \\emph{Swift} ultraviolet (UV) band observations covering the peak. Gaia16apd is a spectroscopically typical type Ic SLSN, exhibiting the characteristic blue early spectra with O {\\sc ii} absorption, and reaches a peak $M_{g} = -21.8 \\pm 0.1$ mag. However, photometrically it exhibits an evolution intermediate between the fast- and slowly-declining type Ic SLSNe, with an early evolution closer to the fast-declining events. It is unusually UV-bright even for a SLSN, reaching a non-$K$-corrected $M_{uvm2} \\simeq -23.2$ mag, the only other type Ic SLSN with similar UV brightness being SN 2010gx. This event highlights the...

  13. Studies of the Jet in BL Lacertae. II. Superluminal Alfv\\'en Waves

    CERN Document Server

    Cohen, M H; Arshakian, T G; Clausen-Brown, E; Homan, D C; Hovatta, T; Kovalev, Y Y; Lister, M L; Pushkarev, A B; Richards, J L; Savolainen, T

    2014-01-01

    Ridge lines on the pc-scale jet of the active galactic nucleus BL Lac display transverse patterns that move superluminally downstream. The patterns are not ballistic, but are analogous to waves on a whip. Their apparent speeds $\\beta_\\mathrm{app}$ (units of $c$) range from 4.2 to 13.5, corresponding to $\\beta_\\mathrm{wave}^\\mathrm{gal}= 0.981 - 0.998$ in the galaxy frame. We show that the magnetic field in the jet is well-ordered with a strong transverse component, and assume that it is helical and that the transverse patterns are longitudinal Alfv\\'en waves. The wave-induced transverse speed of the jet is non-relativistic ($\\beta_\\mathrm{tr}^\\mathrm{gal}\\sim 0.09$) and in agreement with our assumption of low-amplitude waves. In 2010 the wave activity subsided and the jet displayed a mild wiggle that had a complex oscillatory behavior. The waves are excited by changes in the position angle of the recollimation shock, in analogy to exciting a wave on a whip by shaking it. Simple models of the system are presen...

  14. H i Absorption in the Steep-Spectrum Superluminal Quasar 3C 216.

    Science.gov (United States)

    Pihlström; Vermeulen; Taylor; Conway

    1999-11-01

    The search for H i absorption in strong compact steep-spectrum sources is a natural way to probe the neutral gas contents in young radio sources. In turn, this may provide information about the evolution of powerful radio sources. The recently improved capabilities of the Westerbork Synthesis Radio Telescope have made it possible to detect a 0.31% (19 mJy) deep neutral atomic hydrogen absorption line associated with the steep-spectrum superluminal quasar 3C 216. The redshift (z=0.67) of the source shifts the frequency of the 21 cm line down to the ultra-high-frequency (UHF) band (850 MHz). The exact location of the H i-absorbing gas remains to be determined by spectral line VLBI observations at 850 MHz. We cannot exclude that the gas might be extended on galactic scales, but we think it is more likely to be located in the central kiloparsec. Constraints from the lack of X-ray absorption probably rule out obscuration of the core region, and we argue that the most plausible site for the H i absorption is in the jet-cloud interaction observed in this source.

  15. Polarimetry of the Superluminous Supernova LSQ14mo: No Evidence for Significant Deviations from Spherical Symmetry

    Science.gov (United States)

    Leloudas, Giorgos; Patat, Ferdinando; Maund, Justyn R.; Hsiao, Eric; Malesani, Daniele; Schulze, Steve; Contreras, Carlos; de Ugarte Postigo, Antonio; Sollerman, Jesper; Stritzinger, Maximilian D.; Taddia, Francesco; Wheeler, J. Craig; Gorosabel, Javier

    2015-12-01

    We present the first polarimetric observations of a Type I superluminous supernova (SLSN). LSQ14mo was observed with VLT/FORS2 at five different epochs in the V band, with the observations starting before maximum light and spanning 26 days in the rest frame (z = 0.256). During this period, we do not detect any statistically significant evolution (\\lt 2σ ) in the Stokes parameters. The average values we obtain, corrected for interstellar polarization in the Galaxy, are Q = -0.01% (±0.15%) and U = -0.50% (±0.14%). This low polarization can be entirely due to interstellar polarization in the SN host galaxy. We conclude that, at least during the period of observations and at the optical depths probed, the photosphere of LSQ14mo does not present significant asymmetries, unlike most lower-luminosity hydrogen-poor SNe Ib/c. Alternatively, it is possible that we may have observed LSQ14mo from a special viewing angle. Supporting spectroscopy and photometry confirm that LSQ14mo is a typical SLSN I. Further studies of the polarization of Type I SLSNe are required to determine whether the low levels of polarization are a characteristic of the entire class and to also study the implications for the proposed explosion models.

  16. Host-Galaxy Properties of 32 Low-Redshift Superluminous Supernovae from the Palomar Transient Factory

    CERN Document Server

    Perley, Daniel A; Yan, Lin; Vreeswijk, Paul; De Cia, Annalisa; Lunnan, Ragnhild; Gal-Yam, Avishay; Yaron, Ofer; Filippenko, Alexei V; Graham, Melissa L; Nugent, Peter E

    2016-01-01

    We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013, and derive measurements of their luminosities, star-formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe are found almost exclusively in low-mass (M 0.5 Z_sun. Extremely low metallicities are not required, and indeed provide no further increase in the relative SLSN rate. Several SLSN-I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star-formation histories. Type-II (hydrogen-rich) SLSNe are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is a Type I SLSN in a massive, luminous infrared galaxy at re...

  17. SN 2012aa - a transient between Type Ibc core-collapse and superluminous supernovae

    CERN Document Server

    Roy, R; Silverman, J M; Pastorello, A; Fransson, C; Drake, A; Taddia, F; Fremling, C; Kankare, E; Kumar, B; Cappellaro, E; Bose, S; Benetti, S; Filippenko, A V; Valenti, S; Nyholm, A; Ergon, M; Sutaria, F; Kumar, B; Pandey, S B; Nicholl, M; Garcia-Alvarez, D; Tomasella, L; Karamehmetoglu, E; Migotto, K

    2016-01-01

    Context: Research on supernovae (SNe) over the past decade has confirmed that there is a distinct class of events which are much more luminous (by $\\sim2$ mag) than canonical core-collapse SNe (CCSNe). These events with visual peak magnitudes $\\lesssim-21$ are called superluminous SNe (SLSNe). Aims: There are a few intermediate events which have luminosities between these two classes. Here we study one such object, SN 2012aa. Methods: The optical photometric and spectroscopic follow-up observations of the event were conducted over a time span of about 120 days. Results: With V_abs at peak ~-20 mag, the SN is an intermediate-luminosity transient between regular SNe Ibc and SLSNe. It also exhibits an unusual secondary bump after the maximum in its light curve. We interpret this as a manifestation of SN-shock interaction with the CSM. If we would assume a $^{56}$Ni-powered ejecta, the bolometric light curve requires roughly 1.3 M_sun of $^{56}$Ni and an ejected mass of ~14 M_sun. This would also imply a high kin...

  18. Polarimetry of the superluminous supernova LSQ14mo: no evidence for significant deviations from spherical symmetry

    CERN Document Server

    Leloudas, Giorgos; Maund, Justyn R; Hsiao, Eric; Malesani, Daniele; Schulze, Steve; Contreras, Carlos; Postigo, Antonio de Ugarte; Sollerman, Jesper; Stritzinger, Maximilian D; Taddia, Francesco; Wheeler, J Craig; Gorosabel, Javier

    2015-01-01

    We present the first polarimetric observations of a Type I superluminous supernova (SLSN). LSQ14mo was observed with VLT/FORS2 at 5 different epochs in the V band, observations starting before maximum light and spanning 26 days in the rest-frame (z=0.256). During this period, we do not detect any statistically significant evolution (< 2$\\sigma$) in the Stokes parameters. The average values we obtain, corrected for interstellar polarisation in the Galaxy, are Q = -0.01% ($\\pm$ 0.15%) and U = - 0.50% ($\\pm$ 0.14%). This low polarisation can be entirely due to interstellar polarisation in the SN host galaxy. We conclude that, at least during the period of observations and at the optical depths probed, the photosphere of LSQ14mo does not present significant asymmetries, unlike most lower-luminosity hydrogen-poor SNe Ib/c. Alternatively, it is possible that we may have observed LSQ14mo from a special viewing angle. Supporting spectroscopy and photometry confirm that LSQ14mo is a typical SLSN I. Further studies ...

  19. Constraining the ellipticity of strongly magnetized neutron stars powering superluminous supernovae

    Science.gov (United States)

    Moriya, Takashi J.; Tauris, Thomas M.

    2016-07-01

    Superluminous supernovae (SLSNe) have been suggested to be powered by strongly magnetized, rapidly rotating neutron stars which are often called magnetars. In this process, rotational energy of the magnetar is radiated via magnetic dipole radiation and heats the supernova ejecta. However, if magnetars are highly distorted in their geometric shape, rotational energy is mainly lost as gravitational wave radiation and thus such magnetars cannot power SLSNe. By simply comparing electromagnetic and gravitational wave emission time-scales, we constrain upper limits to the ellipticity of magnetars by assuming that they power the observed SLSNe. We find that their ellipticity typically needs to be less than about a few 10-3. This indicates that the toroidal magnetic field strengths in these magnetars are typically less than a few 1016 G so that their distortions remain small. Because light-curve modelling of SLSNe shows that their dipole magnetic field strengths are of the order of 1014 G, the ratio of poloidal to toroidal magnetic field strengths is found to be larger than ˜0.01 in magnetars powering SLSNe.

  20. Constraining the ellipticity of strongly-magnetized neutron stars powering superluminous supernovae

    CERN Document Server

    Moriya, Takashi J

    2016-01-01

    Superluminous supernovae (SLSNe) have been suggested to be powered by strongly-magnetized, rapidly-rotating neutron stars which are often called magnetars. In this process, rotational energy of the magnetar is radiated via magnetic dipole radiation and heats the supernova ejecta. However, if magnetars are highly distorted in their geometric shape, rotational energy is mainly lost as gravitational wave radiation and thus such magnetars cannot power SLSNe. By simply comparing electromagnetic and gravitational wave emission timescales, we constrain upper limits to the ellipticity of magnetars by assuming that they power the observed SLSNe. We find that their ellipticity typically needs to be less than about a few 1e-3. This indicates that the toroidal magnetic field strengths in these magnetars are typically less than a few 1e16 G so that their distortions remain small. Because light-curve modeling of SLSNe shows that their dipole magnetic field strengths are of the order of 1e14 G, the ratio of poloidal to toro...

  1. A Triple-energy-source Model for Superluminous Supernova iPTF13ehe

    Science.gov (United States)

    Wang, S. Q.; Liu, L. D.; Dai, Z. G.; Wang, L. J.; Wu, X. F.

    2016-09-01

    Almost all superluminous supernovae (SLSNe) whose peak magnitudes are ≲ -21 mag can be explained by the 56Ni-powered model, the magnetar-powered (highly magnetized pulsar) model, or the ejecta-circumstellar medium (CSM) interaction model. Recently, iPTF13ehe challenged these energy-source models, because the spectral analysis shows that ˜ 2.5{M}⊙ of 56Ni have been synthesized, but are inadequate to power the peak bolometric emission of iPTF13ehe, while the rebrightening of the late-time light curve (LC) and the Hα emission lines indicate that the ejecta-CSM interaction must play a key role in powering the late-time LC. Here we propose a triple-energy-source model, in which a magnetar together with some amount (≲ 2.5{M}⊙ ) of 56Ni may power the early LC of iPTF13ehe, while the late-time rebrightening can be quantitatively explained by an ejecta-CSM interaction. Furthermore, we suggest that iPTF13ehe is a genuine core-collapse supernova rather than a pulsational pair-instability supernova candidate. Further studies on similar SLSNe in the future would eventually shed light on their explosion and energy-source mechanisms.

  2. DES13S2cmm: The First Superluminous Supernova from the Dark Energy Survey

    CERN Document Server

    Papadopoulos, A; Sullivan, M; Nichol, R C; Barbary, K; Biswas, R; Brown, P J; Covarrubias, R A; Finley, D A; Fischer, J A; Foley, R F; Goldstein, D; Gupta, R R; Kessler, R; Kovacs, E; Kuhlmann, S E; Lidman, C; March, M; Nugent, P E; Sako, M; Smith, R C; Spinka, H; Wester, W; Abbott, T M C; Abdalla, F; Allam, S S; Banerji, M; Bernstein, J P; Bernstein, R A; Carnero, A; da Costa, L N; DePoy, D L; Desai, S; Diehl, H T; Eifler, T; Evrard, A E; Flaugher, B; Frieman, J A; Gerdes, D; Gruen, D; Honscheid, K; James, D; Kuehn, K; Kuropatkin, N; Lahav, O; Maia, M A G; Makler, M; Marshall, J L; Merritt, K W; Miller, C J; Miquel, R; Ogando, R; Plazas, A A; Roe, N A; Romer, A K; Rykoff, E; Sanchez, E; Santiago, B X; Scarpine, V; Schubnell, M; Sevilla, I; Santos, M Soares-; Suchyta, E; Swanson, M; Tarle, G; Thaler, J; Tucker, D L; Wechsler, R H; Zuntz, J

    2015-01-01

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 +/- 0.001 based on the host-galaxy emission lines) and likely spectral type (type I). Using this redshift, we find M_U_peak = -21.05 +0.10 -0.09 for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low metallicity (sub-solar), low stellar-mass host galaxy (log(M/M_sun) = 9.3 +/- 0.3); consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to fourteen similarly well-observed SLSNe-I in the literature and find it possesses one of the slowest declining tails (beyond +30 days rest frame past peak), and is the faintest at peak. Moreover, we find the b...

  3. Comments on Musha's theorem that an evanescent photon in the microtubule is a superluminal particle.

    Science.gov (United States)

    Hari, Syamala D

    2014-07-01

    Takaaki Musha's research of high performance quantum computation in living systems is motivated by the theories of Penrose and Hameroff that microtubules in the brain function as quantum computers, and by those of Jibu and Yasue that the quantum states of microtubules depend upon boson condensates of evanescent photons. His work is based on the assumption that the evanescent photons described by Jibu et al. are superluminal and that they are tachyons defined and discussed by well-known physicists such as Sudarshan, Feinberg and Recami. Musha gives a brief justification for the assumption and sometimes calls it a theorem. However, the assumption is not valid because Jibu et al. stated that the evanescent photons have transmission speed smaller than that of light and that their mass is real and momentum is imaginary whereas a tachyon's mass is imaginary and momentum is real. We show here that Musha's proof of the "theorem" has errors and hence his theorem/assumption is not valid. This article is not meant to further discuss any biological aspects of the brain but only to comment on the consistency of the quantum-physical aspects of earlier work by Musha et al.

  4. SN 2015bn: a detailed multi-wavelength view of a nearby superluminous supernova

    CERN Document Server

    Nicholl, M; Smartt, S J; Margutti, R; Kamble, A; Alexander, K D; Chen, T -W; Inserra, C; Arcavi, I; Blanchard, P K; Cartier, R; Chambers, K C; Childress, M J; Chornock, R; Cowperthwaite, P S; Drout, M; Flewelling, H A; Fraser, M; Gal-Yam, A; Galbany, L; Harmanen, J; Holoien, T W -S; Hosseinzadeh, G; Howell, D A; Huber, M E; Jerkstrand, A; Kankare, E; Kochanek, C S; Lin, Z -Y; Lunnan, R; Magnier, E A; Maguire, K; McCully, C; McDonald, M; Metzger, B D; Milisavljevic, D; Mitra, A; Reynolds, T; Saario, J; Shappee, B J; Smith, K W; Valenti, S; Villar, V A; Waters, C; Young, D R

    2016-01-01

    We present observations of SN 2015bn (= PS15ae = CSS141223-113342+004332 = MLS150211-113342+004333), a Type I superluminous supernova (SLSN) at $z=0.1136$. As well as being one of the closest SLSNe, it is intrinsically brighter ($M_U\\approx-23.1$) and in a fainter host ($M_B\\approx-16.0$) than other SLSNe at $z\\sim0.1$. We collected the most extensive dataset for an SLSN I to date, including spectroscopy and UV to NIR photometry from $-$50 to +250 d from maximum light. SN 2015bn is a slowly-declining SLSN, but exhibits surprising undulations in the light curve on a timescale of 30-50 d, which are more pronounced in the UV. The spectrum resembles other SLSNe, but our well-sampled data reveal extraordinarily slow evolution except for a rapid transformation between +7 and +30 d. We detect weak features that we tentatively suggest may be hydrogen and helium. At late times, blue colours and a trio of lines around 6000 \\AA\\ seem to distinguish slowly-declining SLSNe from faster ones. We derive physical properties i...

  5. Experimental demonstration of a new radiation mechanism: emission by an oscillating, accelerated, superluminal polarization current

    CERN Document Server

    Ardavan, A; Ardavan, H; Fopma, J; Halliday, D; Hayes, W

    2004-01-01

    We describe the experimental implementation of a superluminal ({\\it i.e.} faster than light {\\it in vacuo}) polarization current distribution that both oscillates and undergoes centripetal acceleration. Theoretical treatments lead one to expect that the radiation emitted from each volume element of such a polarization current will comprise a \\v{C}erenkov-like envelope with two sheets that meet along a cusp. The emission from the experimental machine is in good agreement with these expectations, the combined effect of the volume elements leading to tightly-defined beams of a well-defined geometry, determined by the source speed and trajectory. In addition, over a restricted range of angles, we detect the presence of cusps in the emitted radiation. These are due to the detection over a short time period (in the laboratory frame) of radiation emitted over a considerably longer period of source time. Consequently, the intensity of the radiation at these angles was observed to decline more slowly with increasing d...

  6. Signal velocity in oscillator arrays

    Science.gov (United States)

    Cantos, C. E.; Veerman, J. J. P.; Hammond, D. K.

    2016-09-01

    We investigate a system of coupled oscillators on the circle, which arises from a simple model for behavior of large numbers of autonomous vehicles where the acceleration of each vehicle depends on the relative positions and velocities between itself and a set of local neighbors. After describing necessary and sufficient conditions for asymptotic stability, we derive expressions for the phase velocity of propagation of disturbances in velocity through this system. We show that the high frequencies exhibit damping, which implies existence of well-defined signal velocitiesc+ > 0 and c- < 0 such that low frequency disturbances travel through the flock as f+(x - c+t) in the direction of increasing agent numbers and f-(x - c-t) in the other.

  7. Premixed flame propagation in vertical tubes

    CERN Document Server

    Kazakov, Kirill A

    2015-01-01

    Analytical treatment of premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations describing quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds, and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by the gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are ide...

  8. THE HOST GALAXY OF THE SUPER-LUMINOUS SN 2010gx AND LIMITS ON EXPLOSIVE {sup 56}Ni PRODUCTION

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Ting-Wan; Smartt, Stephen J.; Kotak, Rubina; McCrum, Matt; Fraser, Morgan [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Bresolin, Fabio; Kudritzki, Rolf-Peter [Institute for Astronomy, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Pastorello, Andrea [INAF-Osservatorio Astronomico di Padova, vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Valenti, Stefano [Las Cumbres Observatory Global Telescope Network, Inc., Santa Barbara, CA 93117 (United States)

    2013-02-01

    Super-luminous supernovae have a tendency to occur in faint host galaxies which are likely to have low mass and low metallicity. While these extremely luminous explosions have been observed from z = 0.1 to 1.55, the closest explosions allow more detailed investigations of their host galaxies. We present a detailed analysis of the host galaxy of SN 2010gx (z = 0.23), one of the best studied super-luminous type Ic supernovae. The host is a dwarf galaxy (M{sub g} = -17.42 {+-} 0.17) with a high specific star formation rate. It has a remarkably low metallicity of 12 + log (O/H) = 7.5 {+-} 0.1 dex as determined from the detection of the [O III] {lambda}4363 line. This is the first reliable metallicity determination of a super-luminous stripped-envelope supernova host. We collected deep multi-epoch imaging with Gemini + GMOS between 240 and 560 days after explosion to search for any sign of radioactive {sup 56}Ni, which might provide further insights on the explosion mechanism and the progenitor's nature. We reach griz magnitudes of m{sub AB} {approx} 26, but do not detect SN 2010gx at these epochs. The limit implies that any {sup 56}Ni production was similar to or below that of SN 1998bw (a luminous type Ic SN that produced around 0.4 M{sub Sun} of {sup 56}Ni). The low volumetric rates of these supernovae ({approx}10{sup -4} of the core-collapse population) could be qualitatively matched if the explosion mechanism requires a combination of low-metallicity (below 0.2 Z{sub Sun }), high progenitor mass (>60 M{sub Sun }) and high rotation rate (fastest 10% of rotators).

  9. Wave Propagation in Modified Gravity

    CERN Document Server

    Lindroos, Jan Ø; Mota, David F

    2015-01-01

    We investigate the propagation of scalar waves induced by matter sources in the context of scalar-tensor theories of gravity which include screening mechanisms for the scalar degree of freedom. The usual approach when studying these theories in the non-linear regime of cosmological perturbations is based on the assumption that scalar waves travel at the speed of light. Within General Relativity such approximation is good and leads to no loss of accuracy in the estimation of observables. We find, however, that mass terms and non-linearities in the equations of motion lead to propagation and dispersion velocities significantly different from the speed of light. As the group velocity is the one associated to the propagation of signals, a reduction of its value has direct impact on the behavior and dynamics of nonlinear structures within modified gravity theories with screening. For instance, the internal dynamics of galaxies and satellites submerged in large dark matter halos could be affected by the fact that t...

  10. Wave equations for pulse propagation

    Energy Technology Data Exchange (ETDEWEB)

    Shore, B.W.

    1987-06-24

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity. The memo discusses various ways of characterizing the polarization characteristics of plane waves, that is, of parameterizing a transverse unit vector, such as the Jones vector, the Stokes vector, and the Poincare sphere. It discusses the connection between macroscopically defined quantities, such as the intensity or, more generally, the Stokes parameters, and microscopic field amplitudes. The material presented here is a portion of a more extensive treatment of propagation to be presented separately. The equations presented here have been described in various books and articles. They are collected here as a summary and review of theory needed when treating pulse propagation.

  11. The superluminous supernova PS1-11ap: bridging the gap between low and high redshift

    Science.gov (United States)

    McCrum, M.; Smartt, S. J.; Kotak, R.; Rest, A.; Jerkstrand, A.; Inserra, C.; Rodney, S. A.; Chen, T.-W.; Howell, D. A.; Huber, M. E.; Pastorello, A.; Tonry, J. L.; Bresolin, F.; Kudritzki, R.-P.; Chornock, R.; Berger, E.; Smith, K.; Botticella, M. T.; Foley, R. J.; Fraser, M.; Milisavljevic, D.; Nicholl, M.; Riess, A. G.; Stubbs, C. W.; Valenti, S.; Wood-Vasey, W. M.; Wright, D.; Young, D. R.; Drout, M.; Czekala, I.; Burgett, W. S.; Chambers, K. C.; Draper, P.; Flewelling, H.; Hodapp, K. W.; Kaiser, N.; Magnier, E. A.; Metcalfe, N.; Price, P. A.; Sweeney, W.; Wainscoat, R. J.

    2014-01-01

    We present optical photometric and spectroscopic coverage of the superluminous supernova (SLSN) PS1-11ap, discovered with the Pan-STARRS1 Medium Deep Survey at z = 0.524. This intrinsically blue transient rose slowly to reach a peak magnitude of Mu = -21.4 mag and bolometric luminosity of 8 × 1043 erg s-1 before settling on to a relatively shallow gradient of decline. The observed decline is significantly slower than those of the SLSNe-Ic which have been the focus of much recent attention. Spectroscopic similarities with the lower redshift SN2007bi and a decline rate similar to 56Co decay time-scale initially indicated that this transient could be a candidate for a pair instability supernova (PISN) explosion. Overall the transient appears quite similar to SN2007bi and the lower redshift object PTF12dam. The extensive data set, from 30 d before peak to 230 d after, allows a detailed and quantitative comparison with published models of PISN explosions. We find that the PS1-11ap data do not match these model explosion parameters well, supporting the recent claim that these SNe are not pair instability explosions. We show that PS1-11ap has many features in common with the faster declining SLSNe-Ic, and the light-curve evolution can also be quantitatively explained by the magnetar spin-down model. At a redshift of z = 0.524, the observer-frame optical coverage provides comprehensive rest-frame UV data and allows us to compare it with the SLSNe recently found at high redshifts between z = 2 and 4. While these high-z explosions are still plausible PISN candidates, they match the photometric evolution of PS1-11ap and hence could be counterparts to this lower redshift transient.

  12. The unexpected, long-lasting, UV rebrightening of the superluminous supernova ASASSN-15lh

    Science.gov (United States)

    Godoy-Rivera, D.; Stanek, K. Z.; Kochanek, C. S.; Chen, Ping; Dong, Subo; Prieto, J. L.; Shappee, B. J.; Jha, S. W.; Foley, R. J.; Pan, Y.-C.; Holoien, T. W.-S.; Thompson, Todd. A.; Grupe, D.; Beacom, J. F.

    2017-04-01

    Given its peak luminosity and early-time spectra, ASASSN-15lh was classified as the most luminous supernova ever discovered. Here, we report a UV rebrightening of ASASSN-15lh observed with Swift during our follow-up campaign. The rebrightening began at t ≃ 90 d (observer frame) after the primary peak and was followed by a ∼120-d long plateau in the bolometric luminosity, before starting to fade again at t ≃ 210 d. ASASSN-15lh rebrightened in the Swift UV bands by ΔmUVW2 ≃ -1.75 mag, ΔmUVM2 ≃ -1.25 mag and ΔmUVW1 ≃ -0.8 mag, but did not rebrighten in the optical bands. Throughout its initial decline, subsequent rebrightening and renewed decline, the spectra did not show evidence of interactions between the ejecta and circumstellar medium such as narrow emission lines. There are hints of weak Hα emission at late-times, but Margutti et al. have shown that it is narrow line emission consistent with star formation in the host nucleus. By fitting a blackbody, we find that during the rebrightening, the effective photospheric temperature increased from TBB ≃ 11 000 K to TBB ≃ 18 000 K. Over the ∼ 550 d since its detection, ASASSN-15lh has radiated ∼1.7 -1.9 × 1052 erg. Although its physical nature remains uncertain, the evolution of ASASSN-15lh's photospheric radius, its radiated energy and the implied event rate, are all more similar to those of H-poor superluminous supernovae than to tidal disruption events.

  13. On the Early-Time Excess Emission in Hydrogen-Poor Superluminous Supernovae

    Science.gov (United States)

    Vreeswijk, Paul M.; Leloudas, Giorgos; Gal-Yam, Avishay; De Cia, Annalisa; Perley, Daniel A.; Quimby, Robert M.; Waldman, Roni; Sullivan, Mark; Yan, Lin; Ofek, Eran O.; hide

    2017-01-01

    We present the light curves of the hydrogen-poor super-luminous supernovae (SLSNe I) PTF 12dam and iPTF 13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF 12dam is very similar in duration (approximately 10 days) and brightness relative to the main peak (23 mag fainter) compared to that observed in other SLSNe I. In contrast, the long-duration (greater than 30 days) early excess emission in iPTF 13dcc, whose brightness competes with that of the main peak, appears to be of a different nature. We construct bolometric light curves for both targets, and fit a variety of light-curve models to both the early bump and main peak in an attempt to understand the nature of these explosions. Even though the slope of the late-time decline in the light curves of both SLSNe is suggestively close to that expected from the radioactive decay of 56Ni and 56Co, the amount of nickel required to power the full light curves is too large considering the estimated ejecta mass. The magnetar model including an increasing escape fraction provides a reasonable description of the PTF 12dam observations. However, neither the basic nor the double-peaked magnetar model is capable of reproducing the light curve of iPTF 13dcc. A model combining a shock breakout in an extended envelope with late-time magnetar energy injection provides a reasonable fit to the iPTF 13dcc observations. Finally, we find that the light curves of both PTF 12dam and iPTF 13dcc can be adequately fit with the model involving interaction with the circumstellar medium.

  14. An Ultraviolet Excess in the Superluminous Supernova Gaia16apd Reveals a Powerful Central Engine

    Science.gov (United States)

    Nicholl, M.; Berger, E.; Margutti, R.; Blanchard, P. K.; Milisavljevic, D.; Challis, P.; Metzger, B. D.; Chornock, R.

    2017-01-01

    Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below ∼3000 Å. Yan et al. have recently presented HST UV spectra and attributed the UV flux to low iron-group abundance in the outer ejecta, and hence reduced line blanketing. Here, we present UV and optical light curves over a longer baseline in time, revealing a rapid decline at UV wavelengths despite a typical optical evolution. Combining the published UV spectra with our own optical data, we demonstrate that Gaia16apd has a much hotter continuum than virtually any SLSN at maximum light, but it cools rapidly thereafter and is indistinguishable from the others by ∼10–15 days after peak. Comparing the equivalent widths of UV absorption lines with those of other events, we show that the excess UV continuum is a result of a more powerful central power source, rather than a lack of UV absorption relative to other SLSNe or an additional component from interaction with the surrounding medium. These findings strongly support the central-engine hypothesis for hydrogen-poor SLSNe. An explosion ejecting Mej = 4.8(0.2/κ) M⊙, where κ is the opacity in cm2 g‑1, and forming a magnetar with spin period P = 2 ms, and B = 2 × 1014 G (lower than other SLSNe with comparable rise times) can consistently explain the light curve evolution and high temperature at peak. The host metallicity, Z = 0.18 Z⊙, is comparable to other SLSNe.

  15. ANALYTICAL LIGHT CURVE MODELS OF SUPERLUMINOUS SUPERNOVAE: {chi}{sup 2}-MINIMIZATION OF PARAMETER FITS

    Energy Technology Data Exchange (ETDEWEB)

    Chatzopoulos, E.; Wheeler, J. Craig; Vinko, J. [Department of Astronomy, University of Texas at Austin, Austin, TX (United States); Horvath, Z. L.; Nagy, A., E-mail: manolis@astro.as.utexas.edu [Department of Optics and Quantum Electronics, University of Szeged (Hungary)

    2013-08-10

    We present fits of generalized semi-analytic supernova (SN) light curve (LC) models for a variety of power inputs including {sup 56}Ni and {sup 56}Co radioactive decay, magnetar spin-down, and forward and reverse shock heating due to supernova ejecta-circumstellar matter (CSM) interaction. We apply our models to the observed LCs of the H-rich superluminous supernovae (SLSN-II) SN 2006gy, SN 2006tf, SN 2008am, SN 2008es, CSS100217, the H-poor SLSN-I SN 2005ap, SCP06F6, SN 2007bi, SN 2010gx, and SN 2010kd, as well as to the interacting SN 2008iy and PTF 09uj. Our goal is to determine the dominant mechanism that powers the LCs of these extraordinary events and the physical conditions involved in each case. We also present a comparison of our semi-analytical results with recent results from numerical radiation hydrodynamics calculations in the particular case of SN 2006gy in order to explore the strengths and weaknesses of our models. We find that CS shock heating produced by ejecta-CSM interaction provides a better fit to the LCs of most of the events we examine. We discuss the possibility that collision of supernova ejecta with hydrogen-deficient CSM accounts for some of the hydrogen-deficient SLSNe (SLSN-I) and may be a plausible explanation for the explosion mechanism of SN 2007bi, the pair-instability supernova candidate. We characterize and discuss issues of parameter degeneracy.

  16. SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. Q.; Wang, L. J.; Dai, Z. G. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Wu, X. F., E-mail: dzg@nju.edu.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2015-01-20

    Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required.

  17. Host-galaxy Properties of 32 Low-redshift Superluminous Supernovae from the Palomar Transient Factory

    Science.gov (United States)

    Perley, D. A.; Quimby, R. M.; Yan, L.; Vreeswijk, P. M.; De Cia, A.; Lunnan, R.; Gal-Yam, A.; Yaron, O.; Filippenko, A. V.; Graham, M. L.; Laher, R.; Nugent, P. E.

    2016-10-01

    We present ultraviolet through near-infrared photometry and spectroscopy of the host galaxies of all superluminous supernovae (SLSNe) discovered by the Palomar Transient Factory prior to 2013 and derive measurements of their luminosities, star formation rates, stellar masses, and gas-phase metallicities. We find that Type I (hydrogen-poor) SLSNe (SLSNe I) are found almost exclusively in low-mass ({M}* \\lt 2× {10}9 {M}ȯ ) and metal-poor (12 + log10[O/H] \\lt 8.4) galaxies. We compare the mass and metallicity distributions of our sample to nearby galaxy catalogs in detail and conclude that the rate of SLSNe I as a fraction of all SNe is heavily suppressed in galaxies with metallicities ≳ 0.5 {Z}ȯ . Extremely low metallicities are not required and indeed provide no further increase in the relative SLSN rate. Several SLSN I hosts are undergoing vigorous starbursts, but this may simply be a side effect of metallicity dependence: dwarf galaxies tend to have bursty star formation histories. Type II (hydrogen-rich) SLSNe (SLSNe II) are found over the entire range of galaxy masses and metallicities, and their integrated properties do not suggest a strong preference for (or against) low-mass/low-metallicity galaxies. Two hosts exhibit unusual properties: PTF 10uhf is an SLSN I in a massive, luminous infrared galaxy at redshift z = 0.29, while PTF 10tpz is an SLSN II located in the nucleus of an early-type host at z = 0.04.

  18. The Unexpected, Long-Lasting, UV Rebrightening of the Super-Luminous Supernova ASASSN-15lh

    Science.gov (United States)

    Godoy-Rivera, D.; Stanek, K. Z.; Kochanek, C. S.; Chen, Ping; Dong, Subo; Prieto, J. L.; Shappee, B. J.; Jha, S. W.; Foley, R. J.; Pan, Y.-C.; Holoien, T. W.-S.; Thompson, Todd. A.; Grupe, D.; Beacom, J. F.

    2017-01-01

    Given its peak luminosity and early-time spectra, ASASSN-15lh was classified as the most luminous supernova (SN) ever discovered (Dong et al. 2016).. Here we report a UV rebrightening of ASASSN-15lh observed with Swift during our follow-up campaign. The rebrightening began at t ≃ 90 days (observer frame) after the primary peak and was followed by a ˜120-day long plateau in the bolometric luminosity, before starting to fade again at t ≃ 210 days. ASASSN-15lh rebrightened in the Swift UV bands by ΔmUVW2 ≃ -1.75 mag, ΔmUVM2 ≃ -1.25 mag, and ΔmUVW1 ≃ -0.8 mag, but did not rebrighten in the optical bands. Throughout its initial decline, subsequent rebrightening, and renewed decline, the spectra did not show evidence of interactions between the ejecta and circumstellar medium (CSM) such as narrow emission lines. There are hints of weak Hα emission at late-times, but Margutti et al. (2016) have shown that it is narrow line emission consistent with star formation in the host nucleus. By fitting a blackbody we find that during the rebrightening the effective photospheric temperature increased from TBB ≃ 11000 K to TBB ≃ 18000 K. Over the ˜ 550 days since its detection, ASASSN-15lh has radiated ˜1.7 - -1.9 × 1052 ergs. Although its physical nature remains uncertain, the evolution of ASASSN-15lh's photospheric radius, its radiated energy, and the implied event rate, are all more similar to those of H-poor superluminous supernovae (SLSNe-I) than to tidal disruption events (TDEs).

  19. A numerical simulation of nonlinear propagation of gravity wave packet in three-dimension compressible atmosphere

    Institute of Scientific and Technical Information of China (English)

    WU; Shaoping(吴少平); YI; Fan(易帆)

    2002-01-01

    By using FICE scheme, a numerical simulation of nonlinear propagation of gravity wave packet in three-dimension compressible atmosphere is presented. The whole nonlinear propagation process of the gravity wave packet is shown; the basic characteristics of nonlinear propagation and the influence of the ambient winds on the propagation are analyzed. The results show that FICE scheme can be extended in three-dimension by which the calculation is steady and kept for a long time; the increase of wave amplitude is faster than the exponential increase according to the linear gravity theory; nonlinear propagation makes the horizontal perturbation velocity increase greatly which can lead to enhancement of the local ambient winds; the propagation path and the propagation velocity of energy are different from the results expected by the linear gravity waves theory, the nonlinearity causes the change in propagation characteristics of gravity wave; the ambient winds alter the propagation path and group velocity of gravity wave.

  20. Wave equations for pulse propagation

    Science.gov (United States)

    Shore, B. W.

    1987-06-01

    Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity.

  1. Universal power law for front propagation in all fiber resonators.

    Science.gov (United States)

    Coulibaly, S; Taki, M; Tlidi, M

    2014-01-13

    We consider a bistable system consisting of all fiber cavity driven by an external injected continuous wave. We report on front propagation in a high finesse cavity. We study the asymptotic behavior of the front velocity. We show that the front velocity is affected by the distance from the critical point associated with bistability. We provide a scaling low governing its evolution near the up-switching point of the bistable curve. We show also that the velocity of front propagation obeys a generic power law when the front velocity approaches asymptotically its linear growing value.

  2. Superluminous supernova 2015bn in the nebular phase: evidence for the engine-powered explosion of a stripped massive star

    CERN Document Server

    Nicholl, M; Margutti, R; Chornock, R; Blanchard, P K; Jerkstrand, A; Smartt, S J; Arcavi, I; Challis, P; Chambers, K C; Chen, T -W; Cowperthwaite, P S; Gal-Yam, A; Hosseinzadeh, G; Howell, D A; Inserra, C; Kankare, E; Magnier, E A; Maguire, K; Mazzali, P A; McCully, C; Milisavljevic, D; Smith, K W; Taubenberger, S; Valenti, S; Wainscoat, R J; Yaron, O; Young, D R

    2016-01-01

    We present nebular-phase imaging and spectroscopy for the hydrogen-poor superluminous supernova SN 2015bn, at redshift z=0.1136, spanning +250-400 d after maximum light. The light curve exhibits a steepening in the decline rate from 1.4 mag/(100 d) to 1.7 mag/(100 d), suggestive of a significant decrease in the opacity. This change is accompanied by a transition from a blue continuum superposed with photospheric absorption lines to a nebular spectrum dominated by emission lines of oxygen, calcium and magnesium. There are no obvious signatures of circumstellar interaction or large nickel mass. We show that the spectrum at +400 d is virtually identical to a number of energetic Type Ic supernovae such as SN 1997dq, SN 2012au, and SN 1998bw, indicating similar core conditions and strengthening the link between `hypernovae'/long gamma-ray bursts and superluminous supernovae. A single explosion mechanism may unify these events that span absolute magnitudes of -22 < M_B < -17. Both the light curve and spectrum...

  3. Spectroscopy of superluminous supernova host galaxies. A preference of hydrogen-poor events for extreme emission line galaxies

    CERN Document Server

    Leloudas, G; Kruehler, T; Gorosabel, J; Christensen, L; Mehner, A; Postigo, A de Ugarte; Amorin, R; Thoene, C C; Anderson, J P; Bauer, F E; Gallazzi, A; Helminiak, K G; Hjorth, J; Ibar, E; Malesani, D; Morell, N; Vinko, J; Wheeler, J C

    2014-01-01

    Superluminous supernovae (SLSNe) were only discovered recently due to their preference for occurring in faint dwarf galaxies. Understanding why stellar evolution yields different types of stellar explosions in these environments is fundamental in order to both uncover the elusive progenitors of SLSNe and to study star formation in dwarf galaxies. In this paper, we present the first results of our project to study SUperluminous Supernova Host galaxIES (SUSHIES), focusing on the sample for which we have obtained spectroscopy. We show that SLSNe-I and SLSNe-R (hydrogen-poor) often (~50% in our sample) occur in a class of galaxies that is known as Extreme Emission Line Galaxies (EELGs). The probability of this happening by chance is negligible and we therefore conclude that the extreme environmental conditions and the SLSN phenomenon are related. In contrast, SLSNe-II (hydrogen-rich) occur in more massive, more metal-rich galaxies with softer radiation fields. Therefore, if SLSNe-II constitute a uniform class, th...

  4. An Infinitesimally Superluminal Neutrino is Left-Handed, Conserves Lepton Number and Solves the Autobahn Paradox (Illustrative Discussion)

    CERN Document Server

    Jentschura, U D

    2012-01-01

    Consider a gedanken experiment in which a massive left-handed neutrino, traveling on an autobahn at a speed of v=0.999c is overtaken by a tuned-up Cagiva V-Raptor 1000 traveling at a speed of 0.999999c. The biker, looking back, would see a right-handed neutrino. Unless one invokes exotic mechanisms like a sterile neutrino, this "autobahn paradox" implies that a massive subluminal (tardyonic) neutrino necessarily has to be a Majorana particle, i.e, equal to its own antiparticle. In turn, this would require us to assign the same lepton number to charged leptons and antileptons, essentially voiding the concept of lepton number. By contrast, an infinitesimally superluminal (tachyonic) neutrino is not equal to its own antiparticle and allows us to assign proper lepton number, just as if the neutrino were a Weyl particle. Furthermore, if Lorentz symmetry holds, then an infinitesimally tachyonic neutrino remains superluminal upon Lorentz transformation, which implies that it is impossible to overtake it in a gedanke...

  5. Optimization of directional elastic energy propagation

    DEFF Research Database (Denmark)

    Andreassen, Erik; Chang, Hannah R.; Ruzzene, Massimo;

    2016-01-01

    The aim of this paper is to demonstrate how topology optimization can be used to design a periodically perforated plate, in order to obtain a tailored anisotropic group velocity profile. The main method is demonstrated on both low and high frequency bending wave propagation in an aluminum plate, ...

  6. Domain Wall Propagation through Spin Wave Emission

    NARCIS (Netherlands)

    Wang, X.S.; Yan, P.; Shen, Y.H.; Bauer, G.E.W.; Wang, X.R.

    2012-01-01

    We theoretically study field-induced domain wall motion in an electrically insulating ferromagnet with hard- and easy-axis anisotropies. Domain walls can propagate along a dissipationless wire through spin wave emission locked into the known soliton velocity at low fields. In the presence of damping

  7. Wave propagation in spatially modulated tubes

    CERN Document Server

    Ziepke, A; Engel, H

    2016-01-01

    We investigate wave propagation in rotationally symmetric tubes with a periodic spatial modulation of cross section. Using an asymptotic perturbation analysis, the governing quasi two-dimensional reaction-diffusion equation can be reduced into a one-dimensional reaction-diffusion-advection equation. Assuming a weak perturbation by the advection term and using projection method, in a second step, an equation of motion for traveling waves within such tubes can be derived. Both methods predict properly the nonlinear dependence of the propagation velocity on the ratio of the modulation period of the geometry to the intrinsic width of the front, or pulse. As a main feature, we can observe finite intervals of propagation failure of waves induced by the tube's modulation. In addition, using the Fick-Jacobs approach for the highly diffusive limit we show that wave velocities within tubes are governed by an effective diffusion coefficient. Furthermore, we discuss the effects of a single bottleneck on the period of pul...

  8. Gap junction channels and cardiac impulse propagation.

    Science.gov (United States)

    Desplantez, Thomas; Dupont, Emmanuel; Severs, Nicholas J; Weingart, Robert

    2007-08-01

    The role of gap junction channels on cardiac impulse propagation is complex. This review focuses on the differential expression of connexins in the heart and the biophysical properties of gap junction channels under normal and disease conditions. Structural determinants of impulse propagation have been gained from biochemical and immunocytochemical studies performed on tissue extracts and intact cardiac tissue. These have defined the distinctive connexin coexpression patterns and relative levels in different cardiac tissues. Functional determinants of impulse propagation have emerged from electrophysiological experiments carried out on cell pairs. The static properties (channel number and conductance) limit the current flow between adjacent cardiomyocytes and thus set the basic conduction velocity. The dynamic properties (voltage-sensitive gating and kinetics of channels) are responsible for a modulation of the conduction velocity during propagated action potentials. The effect is moderate and depends on the type of Cx and channel. For homomeric-homotypic channels, the influence is small to medium; for homomeric-heterotypic channels, it is medium to strong. Since no data are currently available on heteromeric channels, their influence on impulse propagation is speculative. The modulation by gap junction channels is most prominent in tissues at the boundaries between cardiac tissues such as sinoatrial node-atrial muscle, atrioventricular node-His bundle, His bundle-bundle branch and Purkinje fibers-ventricular muscle. The data predict facilitation of orthodromic propagation.

  9. Measurements of anisotropic sound propagation in glass wool

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    2000-01-01

    The attenuation coefficient and phase velocity of plane sound waves propagating in three perpendicular directions in glass wool were measured in the frequency range 50–10 000 Hz. For glass wool of mass density 14 kg/m3 at the frequency 1000 Hz, the attenuation constant for propagation perpendicular...

  10. Quantum transport velocity in strongly scattering media

    NARCIS (Netherlands)

    Malfliet, R

    1998-01-01

    Based on the Kadanoff-Baym equations of quantum transport: theory, an approach is proposed which goes beyond the usual quasiparticle approximation. It allows one to deduct the correct transport velocity for propagation in strongly scattering media, a quantity of great importance for localization phe

  11. Performance of a vector velocity estimator

    DEFF Research Database (Denmark)

    Munk, Peter; Jensen, Jørgen Arendt

    1998-01-01

    It is a well-known limitation of all commercially available scanners that only the velocity component along the propagation direction of the emitted pulse is measured, when evaluating blood velocities with ultrasound. Proposals for solving this limitation using several transducers or speckle...... tracking can be found in the literature, but no method with a satisfactory performance has been found that can be used in a commercial implementation. A method for estimation of the velocity vector is presented. Here an oscillation transverse to the ultrasound beam is generated, so that a transverse motion...

  12. Superluminous Supernovae as Standardizable Candles and High-redshift Distance Probes

    Science.gov (United States)

    Inserra, C.; Smartt, S. J.

    2014-12-01

    We investigate the use of type Ic superluminous supernovae (SLSN Ic) as standardizable candles and distance indicators. Their appeal as cosmological probes stems from their remarkable peak luminosities, hot blackbody temperatures, and bright rest-frame ultraviolet emission. We present a sample of 16 published SLSN, from redshifts 0.1 to 1.2, and calculate accurate K corrections to determine uniform magnitudes in 2 synthetic rest-frame filter bandpasses with central wavelengths at 400 nm and 520 nm. At 400 nm, we find an encouragingly low scatter in their uncorrected, raw mean magnitudes with M(400) = -21.86 ± 0.35 mag for the full sample of 16 objects. We investigate the correlation between their decline rates and peak magnitude and find that the brighter events appear to decline more slowly. In a manner similar to the Phillips relation for type Ia SNe (SNe Ia), we define a ΔM 20 decline relation. This correlates peak magnitude and decline over 20 days and can reduce the scatter in standardized peak magnitudes to ±0.22 mag. We further show that M(400) appears to have a strong color dependence. Redder objects are fainter and also become redder faster. Using this peak magnitudecolor evolution relation, a surprisingly low scatter of between ±0.08 mag and ±0.13 mag can be found in peak magnitudes, depending on sample selection. However, we caution that only 8 to 10 objects currently have enough data to test this peak magnitudecolor evolution relation. We conclude that SLSN Ic are promising distance indicators in the high-redshift universe in regimes beyond those possible with SNe Ia. Although the empirical relationships are encouraging, the unknown progenitor systems, how they may evolve with redshift, and the uncertain explosion physics are of some concern. The two major measurement uncertainties are the limited numbers of low-redshift, well-studied objects available to test these relationships and internal dust extinction in the host galaxies.

  13. DES13S2cmm: the first superluminous supernova from the Dark Energy Survey

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, A.; D’Andrea, C. B.; Sullivan, M; Nichol, R. C.; Barbary, K.; Biswas, R.; Brown, P. J.; Covarrubias, R. A.; Finley, D. A.; Fischer, J. A.; Gupta, R. R.; Kovacs, E.; Kuhlmann, S. E.; Spinka, H.; Bernstein, J. P.

    2015-05-11

    We present DES13S2cmm, the first spectroscopically-confirmed superluminous supernova (SLSN) from the Dark Energy Survey (DES). We briefly discuss the data and search algorithm used to find this event in the first year of DES operations, and outline the spectroscopic data obtained from the European Southern Observatory (ESO) Very Large Telescope to confirm its redshift (z = 0.663 +/- 0.001 based on the host-galaxy emission lines) and likely spectral type (Type I). Using this redshift, we find M-U(peak) = -21.05(-0.09)(+0.10) for the peak, rest-frame U-band absolute magnitude, and find DES13S2cmm to be located in a faint, low-metallicity (subsolar), low stellar-mass host galaxy (log (M/M-circle dot) = 9.3 +/- 0.3), consistent with what is seen for other SLSNe-I. We compare the bolometric light curve of DES13S2cmm to 14 similarly well-observed SLSNe-I in the literature and find that it possesses one of the slowest declining tails (beyond +30 d rest-frame past peak), and is the faintest at peak. Moreover, we find the bolometric light curves of all SLSNe-I studied herein possess a dispersion of only 0.2-0.3 mag between +25 and +30 d after peak (rest frame) depending on redshift range studied; this could be important for 'standardizing' such supernovae, as is done with the more common Type Ia. We fit the bolometric light curve of DES13S2cmm with two competing models for SLSNe-I-the radioactive decay of Ni-56, and a magnetar - and find that while the magnetar is formally a better fit, neither model provides a compelling match to the data. Although we are unable to conclusively differentiate between these two physical models for this particular SLSN-I, further DES observations of more SLSNe-I should break this degeneracy, especially if the light curves of SLSNe-I can be observed beyond 100 d in the rest frame of the supernova.

  14. Finite element modeling of impulsive excitation and shear wave propagation in an incompressible, transversely isotropic medium.

    Science.gov (United States)

    Rouze, Ned C; Wang, Michael H; Palmeri, Mark L; Nightingale, Kathy R

    2013-11-15

    Elastic properties of materials can be measured by observing shear wave propagation following localized, impulsive excitations and relating the propagation velocity to a model of the material. However, characterization of anisotropic materials is difficult because of the number of elasticity constants in the material model and the complex dependence of propagation velocity relative to the excitation axis, material symmetries, and propagation directions. In this study, we develop a model of wave propagation following impulsive excitation in an incompressible, transversely isotropic (TI) material such as muscle. Wave motion is described in terms of three propagation modes identified by their polarization relative to the material symmetry axis and propagation direction. Phase velocities for these propagation modes are expressed in terms of five elasticity constants needed to describe a general TI material, and also in terms of three constants after the application of two constraints that hold in the limit of an incompressible material. Group propagation velocities are derived from the phase velocities to describe the propagation of wave packets away from the excitation region following localized excitation. The theoretical model is compared to the results of finite element (FE) simulations performed using a nearly incompressible material model with the five elasticity constants chosen to preserve the essential properties of the material in the incompressible limit. Propagation velocities calculated from the FE displacement data show complex structure that agrees quantitatively with the theoretical model and demonstrates the possibility of measuring all three elasticity constants needed to characterize an incompressible, TI material.

  15. Viscothermal wave propagation

    NARCIS (Netherlands)

    Nijhof, Marten Jozef Johannes

    2010-01-01

    In this work, the accuracy, efficiency and range of applicability of various (approximate) models for viscothermal wave propagation are investigated. Models for viscothermal wave propagation describe thewave behavior of fluids including viscous and thermal effects. Cases where viscothermal effects a

  16. Peculiar velocities in dynamic spacetimes

    CERN Document Server

    Bini, Donato

    2014-01-01

    We investigate the asymptotic behavior of peculiar velocities in certain physically significant time-dependent gravitational fields. Previous studies of the motion of free test particles have focused on the \\emph{collapse scenario}, according to which a double-jet pattern with Lorentz factor $\\gamma \\to \\infty$ develops asymptotically along the direction of complete gravitational collapse. In the present work, we identify a second \\emph{wave scenario}, in which a single-jet pattern with Lorentz factor $\\gamma \\to \\infty$ develops asymptotically along the direction of wave propagation. The possibility of a connection between the two scenarios for the formation of cosmic jets is critically examined.

  17. Wave propagation in thermoelastic saturated porous medium

    Indian Academy of Sciences (India)

    M D Sharma

    2008-12-01

    Biot ’s theory for wave propagation in saturated porous solid is modified to study the propagation of thermoelastic waves in poroelastic medium. Propagation of plane harmonic waves is considered in isotropic poroelastic medium. Relations are derived among the wave-induced temperature in the medium and the displacements of fluid and solid particles. Christoffel equations obtained are modified with the thermal as well as thermoelastic coupling parameters. These equations explain the existence and propagation of four waves in the medium. Three of the waves are attenuating longitudinal waves and one is a non-attenuating transverse wave. Thermal properties of the medium have no effect on the transverse wave. The velocities and attenuation of the longitudinal waves are computed for a numerical model of liquid-saturated sandstone. Their variations with thermal as well as poroelastic parameters are exhibited through numerical examples.

  18. Magnetoelastic contribution in domain wall propagation of micrometric wires.

    Science.gov (United States)

    Zhukov, A; Blanco, J M; Ipatov, M; Zhukova, V

    2012-09-01

    We report on studies of domain wall propagation of magnetically-bistable Fe-Co-rich microwires paying attention on the effect of applied and internal stresses. We measured magnetic domain propagation in various magnetic Fe-Co-rich amorphous microwires with metallic nucleus diameters (from 2.8 microm to 18 microm) using Sixtus Tonks-like experiments. We found that application of applied stresses and increasing of internal stresses result in decreasing of domain wall (DW) velocity. We assume that in order to achieve higher DW propagation velocity at the same magnetic field and enhanced DW mobility, special attention should be paid to the decrease of magnetoelastic energy.

  19. La velocidad de propagación del flujo M color es un marcador sensible de disfunción diastólica en miocardiopatía chagásica Color M flow velocity propagation is a sensible diastolic disfunction marker in Chagas cardiomyopathy

    Directory of Open Access Journals (Sweden)

    Carlos A Luengas

    2008-12-01

    ,007; p=0,02. Hubo incremento de la relación E/e del anillo mitral sólo en el grupo III (p=0,00. Se registró disminución de las velocidades e y s del anillo mitral y e del anillo tricúspide, y prolongación del tiempo de contracción isovolumétrica del ventrículo derecho a partir del grupo II. La velocidad de propagación del flujo M color mitral, tuvo una disminución constante a partir del grupo I (p=0,01; p=0,005; p=0,0002. El índice de Tei no mostró cambios significativos entre los grupos. Conclusión: la disminución de la velocidad del flujo M color por debajo de 72 cm/s fue la variable más sensible para detectar disfunción diastólica ventricular izquierda en pacientes con miocardiopatía chagásica.Introduction and Objectives: Chagasic myocardiopathy is a severe health problem in Latin America. It is the first cause of dilated cardiopathy of infectious origin in Colombia.The changes described in the evaluation of the diastolic function of patients with cardiopathy are precocious and generally precede symptoms and changes in systolic function. The objective of this study is to understand the behavior of the different variables, to evaluate the diastolic function in patients at different stages of Chagas disease, and to establish whether there are early alterations that can be predictive of the progression rate of the disease. Methods: We evaluated systolic and diastolic ventricular functions in 600 patients distributed as follows: 165 (27.5% asymptomatic patients, seronegative for Chagas disease (group 0; 277 (46.2% seropositive asymptomatic patients (group I; 116 (19.3% seropositive with right bundle branch block (group II; and 42 (7% seropositive with heart failure (group III. Mitral, tricuspid and pulmonary vein flows, Doppler of mitral and tricuspid rings, color-M mode Doppler flow propagation velocity and Tei index were measured. For the descriptive analysis, the type of variable was taken into account. To establish the frequencies behavior, the

  20. PS1-10afx AT z = 1.388: PAN-STARRS1 DISCOVERY OF A NEW TYPE OF SUPERLUMINOUS SUPERNOVA

    Energy Technology Data Exchange (ETDEWEB)

    Chornock, R.; Berger, E.; Milisavljevic, D.; Lunnan, R.; Foley, R. J.; Soderberg, A. M.; Challis, P.; Czekala, I.; Drout, M.; Fong, W.; Kirshner, R. P.; McLeod, B.; Marion, G. H.; Narayan, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Smartt, S. J. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast, BT7 1NN (United Kingdom); Burgasser, A. J. [Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093 (United States); Chomiuk, L. [Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824 (United States); Huber, M. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Leibler, C., E-mail: rchornock@cfa.harvard.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95060 (United States); and others

    2013-04-20

    We present the Pan-STARRS1 discovery of PS1-10afx, a unique hydrogen-deficient superluminous supernova (SLSN) at redshift z = 1.388. The light curve peaked at z{sub P1} = 21.7 mag, making PS1-10afx comparable to the most luminous known SNe, with M{sub u} = -22.3 mag. Our extensive optical and near-infrared observations indicate that the bolometric light curve of PS1-10afx rose on the unusually fast timescale of {approx}12 days to the extraordinary peak luminosity of 4.1 Multiplication-Sign 10{sup 44} erg s{sup -1} (M{sub bol} = -22.8 mag) and subsequently faded rapidly. Equally important, the spectral energy distribution is unusually red for an SLSN, with a color temperature of {approx}6800 K near maximum light, in contrast to previous hydrogen-poor SLSNe, which are bright in the ultraviolet (UV). The spectra more closely resemble those of a normal SN Ic than any known SLSN, with a photospheric velocity of {approx}11, 000 km s{sup -1} and evidence for line blanketing in the rest-frame UV. Despite the fast rise, these parameters imply a very large emitting radius ({approx}> 5 Multiplication-Sign 10{sup 15} cm). We demonstrate that no existing theoretical model can satisfactorily explain this combination of properties: (1) a nickel-powered light curve cannot match the combination of high peak luminosity with the fast timescale; (2) models powered by the spindown energy of a rapidly rotating magnetar predict significantly hotter and faster ejecta; and (3) models invoking shock breakout through a dense circumstellar medium cannot explain the observed spectra or color evolution. The host galaxy is well detected in pre-explosion imaging with a luminosity near L*, a star formation rate of {approx}15 M{sub Sun} yr{sup -1}, and is fairly massive ({approx}2 Multiplication-Sign 10{sup 10} M{sub Sun }), with a stellar population age of {approx}10{sup 8} yr, also in contrast to the young dwarf hosts of known hydrogen-poor SLSNe. PS1-10afx is distinct from known examples of

  1. Wave Propagation in an Ion Beam-Plasma System

    DEFF Research Database (Denmark)

    Jensen, T. D.; Michelsen, Poul; Juul Rasmussen, Jens

    1979-01-01

    The spatial evolution of a velocity- or density-modulated ion beam is calculated for stable and unstable ion beam plasma systems, using the linearized Vlasov-Poisson equations. The propagation properties are found to be strongly dependent on the form of modulation. In the case of velocity...

  2. Perfect Derived Propagators

    CERN Document Server

    Schulte, Christian

    2008-01-01

    When implementing a propagator for a constraint, one must decide about variants: When implementing min, should one also implement max? Should one implement linear equations both with and without coefficients? Constraint variants are ubiquitous: implementing them requires considerable (if not prohibitive) effort and decreases maintainability, but will deliver better performance. This paper shows how to use variable views, previously introduced for an implementation architecture, to derive perfect propagator variants. A model for views and derived propagators is introduced. Derived propagators are proved to be indeed perfect in that they inherit essential properties such as correctness and domain and bounds consistency. Techniques for systematically deriving propagators such as transformation, generalization, specialization, and channeling are developed for several variable domains. We evaluate the massive impact of derived propagators. Without derived propagators, Gecode would require 140000 rather than 40000 ...

  3. Detonation propagation in a high loss configuration

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, Scott I [Los Alamos National Laboratory; Shepherd, Joseph E [CALTECH

    2009-01-01

    This work presents an experimental study of detonation wave propagation in tubes with inner diameters (ID) comparable to the mixture cell size. Propane-oxygen mixtures were used in two test section tubes with inner diameters of 1.27 mm and 6.35 mm. For both test sections, the initial pressure of stoichiometric mixtures was varied to determine the effect on detonation propagation. For the 6.35 mm tube, the equivalence ratio {phi} (where the mixture was {phi} C{sub 3}H{sub 8} + 50{sub 2}) was also varied. Detonations were found to propagate in mixtures with cell sizes as large as five times the diameter of the tube. However, under these conditions, significant losses were observed, resulting in wave propagation velocities as slow as 40% of the CJ velocity U{sub CJ}. A review of relevant literature is presented, followed by experimental details and data. Observed velocity deficits are predicted using models that account for boundary layer growth inside detonation waves.

  4. Comments on the compatibility of thermodynamic equilibrium conditions with lattice propagators

    Science.gov (United States)

    Canfora, Fabrizio; Giacomini, Alex; Pais, Pablo; Rosa, Luigi; Zerwekh, Alfonso

    2016-08-01

    In this paper the compatibility is analyzed of the non-perturbative equations of state of quarks and gluons arising from the lattice with some natural requirements for self-gravitating objects at equilibrium: the existence of an equation of state (namely, the possibility to define the pressure as a function of the energy density), the absence of superluminal propagation and Le Chatelier's principle. It is discussed under which conditions it is possible to extract an equation of state (in the above sense) from the non-perturbative propagators arising from the fits of the latest lattice data. In the quark case, there is a small but non-vanishing range of temperatures in which it is not possible to define a single-valued functional relation between density and pressure. Interestingly enough, a small change of the parameters appearing in the fit of the lattice quark propagator (of around 10 %) could guarantee the fulfillment of all the three conditions (keeping alive, at the same time, the violation of positivity of the spectral representation, which is the expected signal of confinement). As far as gluons are concerned, the analysis shows very similar results. Whether or not the non-perturbative quark and gluon propagators satisfy these conditions can have a strong impact on the estimate of the maximal mass of quark stars.

  5. Comments on the compatibility of thermodynamic equilibrium conditions with lattice propagators

    Energy Technology Data Exchange (ETDEWEB)

    Canfora, Fabrizio [Centro de Estudios Cientificos (CECs), Valdivia (Chile); Giacomini, Alex [Universidad Austral de Chile, Instituto de Ciencias Fisicas y Matematicas, Valdivia (Chile); Pais, Pablo [Centro de Estudios Cientificos (CECs), Valdivia (Chile); Universite Libre de Bruxelles and International Solvay Institutes, Physique Theorique et Mathematique, Brussels (Belgium); Rosa, Luigi [Universita di Napoli Federico II, Complesso Universitario di Monte S. Angelo, Dipartimento di Fisica, Naples (Italy); Complesso Universitario di Monte S. Angelo, Naples (Italy); INFN, Sezione di Napoli, Naples (Italy); Zerwekh, Alfonso [Universidad Tecnica Federico Santa Maria, Departamento de Fisica and Centro Cientifico-Tecnologico de Valparaiso, Valparaiso (Chile)

    2016-08-15

    In this paper the compatibility is analyzed of the non-perturbative equations of state of quarks and gluons arising from the lattice with some natural requirements for self-gravitating objects at equilibrium: the existence of an equation of state (namely, the possibility to define the pressure as a function of the energy density), the absence of superluminal propagation and Le Chatelier's principle. It is discussed under which conditions it is possible to extract an equation of state (in the above sense) from the non-perturbative propagators arising from the fits of the latest lattice data. In the quark case, there is a small but non-vanishing range of temperatures in which it is not possible to define a single-valued functional relation between density and pressure. Interestingly enough, a small change of the parameters appearing in the fit of the lattice quark propagator (of around 10 %) could guarantee the fulfillment of all the three conditions (keeping alive, at the same time, the violation of positivity of the spectral representation, which is the expected signal of confinement). As far as gluons are concerned, the analysis shows very similar results. Whether or not the non-perturbative quark and gluon propagators satisfy these conditions can have a strong impact on the estimate of the maximal mass of quark stars. (orig.)

  6. Do not mess with time: Probing faster than light travel and chronology protection with superluminal warp drives

    CERN Document Server

    Liberati, Stefano

    2016-01-01

    While General Relativity ranks undoubtedly among the best physics theories ever developed, it is also among those with the most striking implications. In particular, General Relativity admits solutions which allow faster than light motion and consequently time travel. Here we shall consider a "pre-emptive" chronology protection mechanism that destabilises superluminal warp drives via quantum matter back-reaction and hence forbids even the conceptual possibility to use these solutions for building a time machine. This result will be considered both in standard quantum field theory in curved spacetime as well as in the case of a quantum field theory with Lorentz invariance breakdown at high energies. Some lessons and future perspectives will be finally discuss.

  7. Velocity anticipation in the optimal velocity model

    Institute of Scientific and Technical Information of China (English)

    DONG Li-yun; WENG Xu-dan; LI Qing-ding

    2009-01-01

    In this paper,the velocity anticipation in the optimal velocity model (OVM) is investigated.The driver adjusts the velocity of his vehicle by the desired headway,which depends on both instantaneous headway and relative velocity.The effect of relative velocity is measured by a sensitivity function.A specific form of the sensitivity function is supposed and the involved parameters are determined by the both numerical simulation and empirical data.It is shown that inclusion of velocity anticipation enhances the stability of traffic flow.Numerical simulations show a good agreement with empirical data.This model provides a better description of real traffic,including the acceleration process from standing states and the deceleration process approaching a stopped car.

  8. Quench propagation analysis in adiabatic superconducting windings

    Energy Technology Data Exchange (ETDEWEB)

    Ishiyama, A.; Matsumura, H.; Takita, W. (Dept. of Electrical Engineering, Waseda Univ., Tokyo (JP)); Iwasa, Y (Massachusetts Inst. of Tech., Cambridge, MA (United States). Francis Bitter National Magnet Lab.)

    1991-03-01

    This paper reports the basic postulate of the author's quench simulation code, developed to analyze normal-zone propagation in adiabatic magnets which is the code's computation may be immensely simplified without sacrifice in accuracy by aggregating all thermal properties of the winding affecting normal-zone propagation into a single parameter of the transverse quench velocity. In order to verify this postulate, a finite element method (FEM) analysis has been applied to solve the temporal and spatial evolution of temperature within a section of an adiabatic magnet winding.

  9. Anisotropy and sound propagation in glass wool

    DEFF Research Database (Denmark)

    Tarnow, Viggo

    1999-01-01

    Sound propagation in glass wool is studied theoretically and experimentally. Theoretical computation of attenuation and phase velocity for plane, harmonic waves will be presented. Glass wool is a highly anisotropic material, and sound waves propagating in different directions in the material...... by regarding it as a continuous medium described by its elastic moduli and mass density. The computed attenuation of sound waves, for frequencies 50–5000 Hz, will be compared with experimental results for glass wool with fiber diameters of 6.8 micrometers, mass density of 15 and 30 kg/m3, and elastic moduli...... of 2000 and 16 000 Pa (sound wave vector perpendicular to fibers)....

  10. Behavior of ultrasounds crossing perfluorocarbon liquids and random propagation times.

    Science.gov (United States)

    Lacaze, Bernard

    2015-12-01

    Random propagation times are able to model waves attenuation and velocity. It is true for electromagnetic waves (light, radar, guided propagation) and also for acoustics and ultrasounds (acoustics for high frequencies). About the latter, it can be shown that stable probability laws are well-fitted for frequencies up to dozens of megahertz in numerous cases. Nowadays, medical applications are performed using propagation through perfluorocarbon (PFC). Experiments were done to measure attenuations and phase changes. Using these results, this paper addresses the question to know if stable probability laws can be used to characterize the propagation of ultrasounds through PFC liquids.

  11. The Wheeler Propagator

    OpenAIRE

    Bollini, C. G.; Rocca, M. C.

    1998-01-01

    We study the half advanced and half retarded Wheeler Green function and its relation to Feynman propagators. First for massless equation. Then, for Klein-Gordon equations with arbitrary mass parameters; real, imaginary or complex. In all cases the Wheeler propagator lacks an on-shell free propagation. The Wheeler function has support inside the light-cone (whatever the mass). The associated vacuum is symmetric with respect to annihilation and creation operators. We show with some examples tha...

  12. Premixed flame propagation in vertical tubes

    Science.gov (United States)

    Kazakov, Kirill A.

    2016-04-01

    Analytical treatment of the premixed flame propagation in vertical tubes with smooth walls is given. Using the on-shell flame description, equations for a quasi-steady flame with a small but finite front thickness are obtained and solved numerically. It is found that near the limits of inflammability, solutions describing upward flame propagation come in pairs having close propagation speeds and that the effect of gravity is to reverse the burnt gas velocity profile generated by the flame. On the basis of these results, a theory of partial flame propagation driven by a strong gravitational field is developed. A complete explanation is given of the intricate observed behavior of limit flames, including dependence of the inflammability range on the size of the combustion domain, the large distances of partial flame propagation, and the progression of flame extinction. The role of the finite front-thickness effects is discussed in detail. Also, various mechanisms governing flame acceleration in smooth tubes are identified. Acceleration of methane-air flames in open tubes is shown to be a combined effect of the hydrostatic pressure difference produced by the ambient cold air and the difference of dynamic gas pressure at the tube ends. On the other hand, a strong spontaneous acceleration of the fast methane-oxygen flames at the initial stage of their evolution in open-closed tubes is conditioned by metastability of the quasi-steady propagation regimes. An extensive comparison of the obtained results with the experimental data is made.

  13. Crack propagation in fracture mechanical graded structures

    Directory of Open Access Journals (Sweden)

    B. Schramm

    2015-10-01

    Full Text Available The focus of manufacturing is more and more on innovative and application-oriented products considering lightweight construction. Hence, especially functional graded materials come to the fore. Due to the application-matched functional material gradation different local demands such as absorbability, abrasion and fatigue of structures are met. However, the material gradation can also have a remarkable influence on the crack propagation behavior. Therefore, this paper examines how the crack propagation behavior changes when a crack grows through regions which are characterized by different fracture mechanical material properties (e.g. different threshold values KI,th, different fracture toughness KIC. In particular, the emphasis of this paper is on the beginning of stable crack propagation, the crack velocity, the crack propagation direction as well as on the occurrence of unstable crack growth under static as well as cyclic loading. In this context, the developed TSSR-concept is presented which allows the prediction of crack propagation in fracture mechanical graded structures considering the loading situation (Mode I, Mode II and plane Mixed Mode and the material gradation. In addition, results of experimental investigations for a mode I loading situation and numerical simulations of crack growth in such graded structures confirm the theoretical findings and clarify the influence of the material gradation on the crack propagation behavior.

  14. Neutrino and the Possibility of Superluminal Phenomenon%中微子和超光速现象的可能性

    Institute of Scientific and Technical Information of China (English)

    韩锋

    2012-01-01

    If the rest mass of the neutrino is not zero, it is required that neutrino be superluminal in order to explain the two - component neutrino theory of parity non - conservation. In the light of this, the paper discusses the superluminal phenomenon under the guidance of the theory of relativity and also the possibility of the existence of tachyon.%如果中微子静止质量不为零,那么为了解释宇称不守恒的二分量中微子理论就要求中微子是超光速的。讨论了在相对论框架内对这种超光速现象的理解,以及存在"快子"的可能性。

  15. Propagating Disturbances in Coronal Loops: A Detailed Analysis of Propagation Speeds

    CERN Document Server

    Kiddie, G; Del Zanna, G; McIntosh, S W; Whittaker, I

    2012-01-01

    Quasi-periodic disturbances have been observed in the outer solar atmosphere for many years now. Although first interpreted as upflows (Schrijver et al. (1999)), they have been widely regarded as slow magnetoacoustic waves, due to observed velocities and periods. However, recent observations have questioned this interpretation, as periodic disturbances in Doppler velocity, line width and profile asymmetry were found to be in phase with the intensity oscillations (De Pontieu et al. (2010),Tian1 et al. (2011))}, suggesting the disturbances could be quasi-periodic upflows. Here we conduct a detailed analysis of the velocities of these disturbances across several wavelengths using the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We analysed 41 examples, including both sunspot and non sunspot regions of the Sun. We found that the velocities of propagating disturbances (PDs) located at sunspots are more likely to be temperature dependent, whereas the velocities of PDs at non sun...

  16. An Empirical Study of Infrasonic Propagation

    Energy Technology Data Exchange (ETDEWEB)

    J. Paul Mutschlecner; Rodney W. Whitaker; Lawrence H. Auer

    1999-10-01

    Observations of atmospheric nuclear tests carried out at the Nevada Test Site from 1951 to 1958 provided data for an empirical investigation of how infrasonic signals are propagated to distances of about 250 km. Those observations and the analysis documented in this report involved signal amplitudes and average velocities and included three classes of signals: stratospheric, thermospheric, and tropospheric/surface. The authors' analysis showed that stratospheric winds have a dominant effect upon stratospheric signal amplitudes. The report outlines a method for normalizing stratospheric signal amplitudes for the effects of upper atmospheric winds and presents equations for predicting or normalizing amplitude and average velocity for the three types of signals.

  17. Love Wave Propagation in Poro elasticity

    Directory of Open Access Journals (Sweden)

    Y.V. Rama Rao

    1978-10-01

    Full Text Available It is observed that on similar reasons as in classical theory of elasticity, SH wave propagation in a semi infinite poroelastic body is not possible and is possible when there is a layer of another poro elastic medium over it i.e., Love waves. Two particular cases are considered in one of which phase velocity can be determined for a given wave length. In the same case, equation for phase velocity is of the same form as that of the classical theory of Elasticity.

  18. Photon trajectories, anomalous velocities, and weak measurements: A classical interpretation

    CERN Document Server

    Bliokh, Konstantin Y; Nori, Franco

    2013-01-01

    Recently, Kocsis et al. reported the observation of "average trajectories of single photons" in a two-slit interference experiment [Science 332, 1170 (2011)]. This was possible by using the quantum weak-measurements method, which implies averaging over many events, i.e., in fact, a multi-photon limit of classical optics. We give a classical-optics interpretation to this experiment and other related problems. It appears that weak measurements of the local momentum of photons made by Kocsis et al. represent measurements of the Poynting vector in an optical field. We consider both the real and imaginary parts of the local momentum, and show that their measurements have been realized in classical optics using small probe particles. We also examine the appearance of "anomalous" values of the local momentum: either negative (backflow) or exceeding the wavenumber (superluminal propagation). These features appear to be closely related to vortices and evanescent waves. Finally, we revisit a number of older works and f...

  19. High velocity collisions of nanoparticles

    Science.gov (United States)

    Johnson, Donald F.; Mattson, William D.

    2017-01-01

    Nanoparticles (NPs) are a unique class of material with highly functionalizable surfaces and exciting applications. With a large surface-to-volume ratio and potentially high surface tension, shocked nanoparticles might display unique materials behavior. Using density functional theory, we have simulated high-velocity NP collisions under a variety of conditions. NPs composed of diamond-C, cubic-BN, and diamond-Si were considered with particle sizes up to 3.5 nm diameter. Additional simulations involved NPs that were destabilized by incorporating internal strain. The initial spherical NP structures were carved out of bulk crystals while the NPs with internal strain were constructed as a dense core (compressive strain) encompassed by a thin shell (tensile strain). Both on-axis and off-axis collisions were simulated at 10 km/s relative velocity. The amount of internal strain was artificially increased by creating a dense inner core with bond lengths compressed up to 8%. Collision dynamics, shock propagation, and fragmentation will be analyzed, but the simulation are ongoing and results are not finalized. The effect of material properties, internal strain, and collision velocity will be discussed.

  20. Velocity-selected molecular pulses produced by an electric guide

    CERN Document Server

    Sommer, Christian; Chervenkov, Sotir; van Buuren, Laurens D; Zeppenfeld, Martin; Pinkse, Pepijn W H; Rempe, Gerhard

    2010-01-01

    Electrostatic velocity filtering is a technique for the production of continuous guided beams of slow polar molecules from a thermal gas. We extended this technique to produce pulses of slow molecules with a narrow velocity distribution around a tunable velocity. The pulses are generated by sequentially switching the voltages on adjacent segments of an electric quadrupole guide synchronously with the molecules propagating at the desired velocity. This technique is demonstrated for deuterated ammonia (ND$_{3}$), delivering pulses with a velocity in the range of $20-100\\,\\rm{m/s}$ and a relative velocity spread of $(16\\pm 2)\\,%$ at FWHM. At velocities around $60\\,\\rm{m/s}$, the pulses contain up to $10^6$ molecules each. The data are well reproduced by Monte-Carlo simulations, which provide useful insight into the mechanisms of velocity selection.

  1. Equation of state and sound velocity of hadronic gas with hard-core interaction

    CERN Document Server

    Satarov, L M; Mishustin, I N

    2014-01-01

    Thermodynamic properties of hot and dense hadronic systems with a hard-sphere interaction are calculated in the Boltzmann approximation. Two parametrizations of pressure as a function of density are considered: the first one, used in the excluded volume model and the second one, suggested earlier by Carnahan and Starling. The results are given for one-component systems containing only nucleons or pions, as well as for chemically equilibrated mixtures of pions, nucleons and delta resonances. It is shown that the Carnahan-Starling approach can be used in a much broader range of hadronic densities as compared to the excluded volume model. In this case superluminal sound velocities appear only at very high densities, in the region where the deconfinement effects should be already important.

  2. Multi-Epoch VLBA Observations of EGRET-Detected Quasars and BL Lac Objects Connection between Superluminal Ejections and Gamma-Ray Flares in Blazars

    CERN Document Server

    Jorstad, S G; Mattox, J R; Aller, M F; Aller, H D; Wehrle, A E; Bloom, S D; Jorstad, Svetlana G; Marscher, Alan P; Mattox, John R; Aller, Margo F; Aller, Hugh D; Wehrle, Ann E; Bloom, Steven D

    2001-01-01

    We examine the coincidence of times of high $\\gamma$-ray flux and ejections of superluminal components from the core in EGRET blazars based on a VLBA monitoring program at 22 and 43 GHz from November 1993 to July 1997. In 23 cases of $\\gamma$-ray flares for which sufficient VLBA data exist, 16 of the flares (in 14 objects) fall within 3$\\sigma$ and 9 of these within 1$\\sigma$ uncertainties of the extrapolated epoch of zero separation from the core of a superluminal radio component. In each of two sources (0528+134 and 1730-130) two successive $\\gamma$-ray flares were followed by the appearance of new superluminal components. We carried out statistical simulations which show that if the number of coincidences $\\ge$ 7 the radio and $\\gamma$-ray events are associated with each other at >99.999% confidence. Our analysis of the observed behavior, including variability of the polarized radio flux, of the sources before, during, and after the $\\gamma$-ray flares suggests that the $\\gamma$-ray events occur in the sup...

  3. Shallow-Water Propagation

    Science.gov (United States)

    2016-06-07

    Shallow- Water Propagation William L. Siegmann Rensselaer Polytechnic Institute 110 Eighth Street Troy, New York 12180-3590 phone: (518) 276...ocean_acoustics LONG-TERM GOALS Develop methods for propagation and coherence calculations in complex shallow- water environments, determine...intensity and coherence. APPROACH (A) Develop high accuracy PE techniques for applications to shallow- water sediments, accounting for

  4. B2 1144+35 A Giant Low Power Radio Galaxy with Superluminal Motion

    CERN Document Server

    Giovannini, G; Arbizzani, E; Bondi, M; Cotton, W D; Feretti, L; Lara, L; Venturi, T

    1999-01-01

    We report on centimeter VLA and VLBI observations of the giant, low power radio galaxy 1144+35. These observations are sensitive to structures on scales from less than 1 parsec to greater than 1 megaparsec. Diffuse steep spectrum lobes on the megaparsec scale are consistent with an age of $\\sim$ 10$^8$ years. On the parsec scale, a complex jet component is seen to move away from the center of activity with an apparent velocity 2.7 h$^{-1}_{50}$ c. It shows a central spine -- shear layer morphology. A faint parsec scale counterjet is detected and an intrinsic jet velocity of 0.95 c and angle to the line of sight of 25$^\\circ$ are derived, consistent with an intrinsically symmetric ejection. The central spine in the parsec scale jet is expected to move at a higher velocity and a Lorentz factor $\\gamma$ $\\sim$ 15 has been estimated near the core.The age of this inner VLBI structure is $\\sim$ 300 years. Assuming a constant angle to the line-of-sight, the jet velocity is found to decrease from 0.95 c at 20 mas (32...

  5. Solitary wave propagation through two-dimensional treelike structures.

    Science.gov (United States)

    Falls, William J; Sen, Surajit

    2014-02-01

    It is well known that a velocity perturbation can travel through a mass spring chain with strongly nonlinear interactions as a solitary and antisolitary wave pair. In recent years, nonlinear wave propagation in 2D structures have also been explored. Here we first consider the propagation of such a velocity perturbation for cases where the system has a 2D "Y"-shaped structure. Here each of the three pieces that make up the "Y" are made of a small mass spring chain. In addition, we consider a case where multiple "Y"-shaped structures are used to generate a "tree." We explore the early time dynamical behavior associated with the propagation of a velocity perturbation initiated at the trunk and at the extremities for both cases. We are looking for the energy transmission properties from one branch to another of these "Y"-shaped structures. Our dynamical simulations suggest the following broad observations: (i) for strongly nonlinear interactions, mechanical energy propagation resembles pulse propagation with the energy propagation being dispersive in the linear case; (ii) for strong nonlinear interactions, the tree-like structure acts as an energy gate showing preference for large perturbations in the system while the behavior of the linear case shows no such preference, thereby suggesting that such structures can possibly act as switches that activate at sufficiently high energies. The study aspires to develop insights into the nature of nonlinear wave propagation through a network of linear chains.

  6. Measuring propagation speed of Coulomb fields

    Energy Technology Data Exchange (ETDEWEB)

    Sangro, R. de; Finocchiaro, G.; Patteri, P.; Piccolo, M.; Pizzella, G. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Frascati (Italy)

    2015-03-01

    The problem of gravity propagation has been subject of discussion for quite a long time: Newton, Laplace and, in relatively more modern times, Eddington pointed out that, if gravity propagated with finite velocity, planet motion around the sun would become unstable due to a torque originating from time lag of the gravitational interactions. Such an odd behavior can be found also in electromagnetism, when one computes the propagation of the electric fields generated by a set of uniformly moving charges. As a matter of fact the Lienard-Weichert retarded potential leads to the same formula as the one obtained assuming that the electric field propagate with infinite velocity. The Feynman explanation for this apparent paradox was based on the fact that uniform motions last indefinitely. To verify such an explanation, we performed an experiment to measure the time/space evolution of the electric field generated by an uniformly moving electron beam. The results we obtain, on a finite lifetime kinematical state, are compatible with an electric field rigidly carried by the beam itself. (orig.)

  7. On the compatibility of thermodynamic equilibrium conditions with the non-perturbative lattice propagators

    CERN Document Server

    Canfora, Fabrizio; Pais, Pablo; Rosa, Luigi; Zerwekh, Alfonso

    2016-01-01

    In this paper it is analyzed the compatibility of the non-perturbative equations of state of quarks and gluons arising from the lattice with some natural requirements for self gravitating objects at equilibrium: the existence of an equation of state (namely, the possibility to define the pressure as a function of the energy density), the absence of superluminal propagation and Le Chatelier's principle. It is discussed under which conditions it is possible to extract an equation of state (in the above sense) from the non-perturbative propagators arising from the fits of the last lattice data. In particular, in the quarks case, there is a small but non vanishing range of temperatures in which it is not possible to define a single-valued functional relation between density and pressure. Interestingly enough, a small change of the parameters appearing in the fit of the lattice quark propagator (of around 10\\%) can guarantee the fulfillment of all the three conditions (keeping alive, at the same time, the violatio...

  8. Fatigue Performance of Composite Laminates After Low-velocity Impact

    Directory of Open Access Journals (Sweden)

    LIANG Xiao-lin

    2016-12-01

    Full Text Available Compression-compression fatigue tests were carried out on T300/5405 composite laminates after low-velocity impact, compression performance of the laminates with different impact damages was studied together with its fatigue life and damage propagation under different stress levels, then the effects of impact energy, stress level and damage propagation on fatigue life of laminates were discussed. The results indicate that impact damage can greatly reduce the residual strength of laminates; under low fatigue load levels, the higher impact energy is, the shorter the fatigue life of laminates with impact damage will be; damage propagation undergoes two stages during the fatigue test, namely the steady propagation and the rapid propagation, accounting for 80% and 20% of the overall fatigue life, respectively; damage propagation rate decreases with the reduction of stress level.

  9. Interaction-powered supernovae: rise-time versus peak-luminosity correlation and the shock-breakout velocity

    Energy Technology Data Exchange (ETDEWEB)

    Ofek, Eran O.; Arcavi, Iair; Tal, David; Gal-Yam, Avishay; Ben-Ami, Sagi; De Cia, Annalisa; Yaron, Ofer [Benoziyo Center for Astrophysics, Weizmann Institute of Science, 76100 Rehovot (Israel); Sullivan, Mark [School of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ (United Kingdom); Kulkarni, Shrinivas R.; Cao, Yi [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Nugent, Peter E. [Computational Cosmology Center, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Bersier, David [Astrophysics Research Institute, Liverpool John Moores University, Liverpool L3 5RF (United Kingdom); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, Mail Code 661, Greenbelt, MD 20771 (United States); Filippenko, Alexei V. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Fransson, Claes [Department of Astronomy, The Oskar Klein Centre, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Kasliwal, Mansi M. [Observatories of the Carnegie Institution for Science, 813 Santa Barbara St, Pasadena, CA 91101 (United States); Laher, Russ; Surace, Jason [Spitzer Science Center, MS 314-6, California Institute of Technology, Pasadena, CA 91125 (United States); Quimby, Robert [Kavli IPMU (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa-shi, Chiba 277-8583 (Japan)

    2014-06-20

    Interaction of supernova (SN) ejecta with the optically thick circumstellar medium (CSM) of a progenitor star can result in a bright, long-lived shock-breakout event. Candidates for such SNe include Type IIn and superluminous SNe. If some of these SNe are powered by interaction, then there should be a specific relation between their peak luminosity, bolometric light-curve rise time, and shock-breakout velocity. Given that the shock velocity during shock breakout is not measured, we expect a correlation, with a significant spread, between the rise time and the peak luminosity of these SNe. Here, we present a sample of 15 SNe IIn for which we have good constraints on their rise time and peak luminosity from observations obtained using the Palomar Transient Factory. We report on a possible correlation between the R-band rise time and peak luminosity of these SNe, with a false-alarm probability of 3%. Assuming that these SNe are powered by interaction, combining these observables and theory allows us to deduce lower limits on the shock-breakout velocity. The lower limits on the shock velocity we find are consistent with what is expected for SNe (i.e., ∼10{sup 4} km s{sup –1}). This supports the suggestion that the early-time light curves of SNe IIn are caused by shock breakout in a dense CSM. We note that such a correlation can arise from other physical mechanisms. Performing such a test on other classes of SNe (e.g., superluminous SNe) can be used to rule out the interaction model for a class of events.

  10. Wave velocities in a pre-stressed anisotropic elastic medium

    Indian Academy of Sciences (India)

    M D Sharma; Neetu Garg

    2006-04-01

    Modified Christoffel equations are derived for three-dimensional wave propagation in a general anisotropic medium under initial stress.The three roots of a cubic equation define the phase velocities of three quasi-waves in the medium.Analytical expressions are used to calculate the directional derivatives of phase velocities.These derivatives are,further,used to calculate the group velocities and ray directions of the three quasi-waves in a pre-stressed anisotropic medium.Effect of initial stress on wave propagation is observed through the deviations in phase velocity,group velocity and ray direction for each of the quasi-waves.The variations of these deviations with the phase direction are plotted for a numerical model of general anisotropic medium with triclinic/ monoclinic/orthorhombic symmetry.

  11. High-velocity clouds

    NARCIS (Netherlands)

    Wakker, BP; vanWoerden, H

    1997-01-01

    High-velocity clouds (HVCs) consist of neutral hydrogen (HI) at velocities incompatible with a simple model of differential galactic rotation; in practice one uses \\v(LSR)\\ greater than or equal to 90 km/s to define HVCs. This review describes the main features of the sky and velocity distributions,

  12. Transverse Spectral Velocity Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2014-01-01

    A transverse oscillation (TO)-based method for calculating the velocity spectrum for fully transverse flow is described. Current methods yield the mean velocity at one position, whereas the new method reveals the transverse velocity spectrum as a function of time at one spatial location. A convex...

  13. Tunable THz Generation by the Interaction of a Super-luminous Laser Pulse with Biased Semiconductor Plasma

    Science.gov (United States)

    Papadopoulos, K.; Zigler, A.

    2006-01-01

    Terahertz (THz) radiation is electromagnetic radiation in the range between several hundred and a few thousand GHz. It covers the gap between fast-wave electronics (millimeter waves) and optics (infrared). This spectral region offers enormous potential for detection of explosives and chemical/biological agents, non-destructive testing of non-metallic structural materials and coatings of aircraft structures, medical imaging, bio-sensing of DNA stretching modes and high-altitude secure communications. The development of these applications has been hindered by the lack of powerful, tunable THz sources with controlled waveform. The need for such sources is accentuated by the strong, but selective absorption of THz radiation during transmission through air with high vapor content. The majority of the current experimental work relies on time-domain spectroscopy using fast electrically biased photoconductive sources in conjunction with femto-second mode-locked Ti:Sapphire lasers. These sources known as Large Aperture Photoconductive Antennas (LAPA) have very limited tunability, relatively low upper bound of power and no bandwidth control. The paper presents a novel source of THz radiation known as Miniature Photoconductive Capacitor Array (MPCA). Experiments demonstrated tunability between .1 - 2 THz, control of the relative bandwidth Δf/f between .5-.01, and controlled pulse length and pulse waveform (temporal shape, chirp, pulse-to-pulse modulation etc.). Direct scaling from the current device indicates efficiency in excess of 30% at 1 THz with 1/f2 scaling at higher frequencies, peak power of 100 kW and average power between .1-1 W. The physics underlying the MPCA is the interaction of a super-luminous ionization front generated by the oblique incidence of a Ti:Sapphire laser pulse on a semiconductor crystal (ZnSe) biased with an alternating electrostatic field, similar to that of a frozen wave generator. It is shown theoretically and experimentally that the

  14. Gear Crack Propagation Investigation

    Science.gov (United States)

    1995-01-01

    Reduced weight is a major design goal in aircraft power transmissions. Some gear designs incorporate thin rims to help meet this goal. Thin rims, however, may lead to bending fatigue cracks. These cracks may propagate through a gear tooth or into the gear rim. A crack that propagates through a tooth would probably not be catastrophic, and ample warning of a failure could be possible. On the other hand, a crack that propagates through the rim would be catastrophic. Such cracks could lead to disengagement of a rotor or propeller from an engine, loss of an aircraft, and fatalities. To help create and validate tools for the gear designer, the NASA Lewis Research Center performed in-house analytical and experimental studies to investigate the effect of rim thickness on gear-tooth crack propagation. Our goal was to determine whether cracks grew through gear teeth (benign failure mode) or through gear rims (catastrophic failure mode) for various rim thicknesses. In addition, we investigated the effect of rim thickness on crack propagation life. A finite-element-based computer program simulated gear-tooth crack propagation. The analysis used principles of linear elastic fracture mechanics, and quarter-point, triangular elements were used at the crack tip to represent the stress singularity. The program had an automated crack propagation option in which cracks were grown numerically via an automated remeshing scheme. Crack-tip stress-intensity factors were estimated to determine crack-propagation direction. Also, various fatigue crack growth models were used to estimate crack-propagation life. Experiments were performed in Lewis' Spur Gear Fatigue Rig to validate predicted crack propagation results. Gears with various backup ratios were tested to validate crack-path predictions. Also, test gears were installed with special crack-propagation gages in the tooth fillet region to measure bending-fatigue crack growth. From both predictions and tests, gears with backup ratios

  15. The Wheeler Propagator

    CERN Document Server

    Bollini, C G

    1998-01-01

    We study the half advanced and half retarded Wheeler Green function and its relation to Feynman propagators. First for massless equation. Then, for Klein-Gordon equations with arbitrary mass parameters; real, imaginary or complex. In all cases the Wheeler propagator lacks an on-shell free propagation. The Wheeler function has support inside the light-cone (whatever the mass). The associated vacuum is symmetric with respect to annihilation and creation operators. We show with some examples that perturbative unitarity holds, whatever the mass (real or complex). Some possible applications are discussed.

  16. Propagation of Weak Pressure Waves against Two Parallel Subsonic Streams

    Institute of Scientific and Technical Information of China (English)

    Makiko YONAMINE; Takanori USHIJIMA; Yoshiaki MIYAZATO; Mitsuharu MASUDA; Hiroshi KATANODA; Kazuyasu MATSUO

    2006-01-01

    In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation,and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves.The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.

  17. Correction of edge-flame propagation speed in a counterflow, annular slot burner

    KAUST Repository

    Tran, Vu Manh

    2015-10-22

    To characterize the propagation modes of flames, flame propagation speed must be accurately calculated. The impact of propagating edge-flames on the flow fields of unburned gases is limited experimentally. Thus, few studies have evaluated true propagation speeds by subtracting the flow velocities of unburned gases from flame displacement speeds. Here, we present a counterflow, annular slot burner that provides an ideal one-dimensional strain rate and lengthwise zero flow velocity that allowed us to study the fundamental behaviors of edge-flames. In addition, our burner has easy optical access for detailed laser diagnostics. Flame displacement speeds were measured using a high-speed camera and related flow fields of unburned gases were visualized by particle image velocimetry. These techniques allowed us to identify significant modifications to the flow fields of unburned gases caused by thermal expansion of the propagating edges, which enabled us to calculate true flame propagation speeds that took into account the flow velocities of unburned gases.

  18. Slow wave propagation in soft adhesive interfaces.

    Science.gov (United States)

    Viswanathan, Koushik; Sundaram, Narayan K; Chandrasekar, Srinivasan

    2016-11-16

    Stick-slip in sliding of soft adhesive surfaces has long been associated with the propagation of Schallamach waves, a type of slow surface wave. Recently it was demonstrated using in situ experiments that two other kinds of slow waves-separation pulses and slip pulses-also mediate stick-slip (Viswanathan et al., Soft Matter, 2016, 12, 5265-5275). While separation pulses, like Schallamach waves, involve local interface detachment, slip pulses are moving stress fronts with no detachment. Here, we present a theoretical analysis of the propagation of these three waves in a linear elastodynamics framework. Different boundary conditions apply depending on whether or not local interface detachment occurs. It is shown that the interface dynamics accompanying slow waves is governed by a system of integral equations. Closed-form analytical expressions are obtained for the interfacial pressure, shear stress, displacements and velocities. Separation pulses and Schallamach waves emerge naturally as wave solutions of the integral equations, with oppositely oriented directions of propagation. Wave propagation is found to be stable in the stress regime where linearized elasticity is a physically valid approximation. Interestingly, the analysis reveals that slow traveling wave solutions are not possible in a Coulomb friction framework for slip pulses. The theory provides a unified picture of stick-slip dynamics and slow wave propagation in adhesive contacts, consistent with experimental observations.

  19. Geotail observations of FTE velocities

    Directory of Open Access Journals (Sweden)

    G. I. Korotova

    2009-01-01

    Full Text Available We discuss the plasma velocity signatures expected in association with flux transfer events (FTEs. Events moving faster than or opposite the ambient media should generate bipolar inward/outward (outward/inward flow perturbations normal to the nominal magnetopause in the magnetosphere (magnetosheath. Flow perturbations directly upstream and downstream from the events should be in the direction of event motion. Flows on the flanks should be in the direction opposite the motion of events moving at subsonic and subAlfvénic speeds relative to the ambient plasma. Events moving with the ambient flow should generate no flow perturbations in the ambient plasma. Alfvén waves propagating parallel (antiparallel to the axial magnetic field of FTEs may generate anticorrelated (correlated magnetic field and flow perturbations within the core region of FTEs. We present case studies illustrating many of these signatures. In the examples considered, Alfvén waves propagate along event axes away from the inferred reconnection site. A statistical study of FTEs observed by Geotail over a 3.5-year period reveals that FTEs within the magnetosphere invariably move faster than the ambient flow, while those in the magnetosheath move both faster and slower than the ambient flow.

  20. Stable Propagating Waves and Wake Fields in Relativistic Electromagnetic Plasma

    Institute of Scientific and Technical Information of China (English)

    DUAN Yi-Shi; XIE Bai-Song; TIAN Miao; YIN Xin-Tao; ZHANG Xin-Hui

    2008-01-01

    Stable propagating waves and wake fields in relativistic electromagnetic plasma are investigated. The incident electromagnetic field has a finite initial constant amplitude meanwhile the longitudinal momentum of electrons is taken into account in the problem. It is found that in the moving frame with transverse wave group velocity the stable propagating transverse electromagnetic waves and longitudinal plasma wake fields can exist in the appropriate regime of plasma.

  1. Orbit Propagation and Determination of Low Earth Orbit Satellites

    OpenAIRE

    Ho-Nien Shou

    2014-01-01

    This paper represents orbit propagation and determination of low Earth orbit (LEO) satellites. Satellite global positioning system (GPS) configured receiver provides position and velocity measures by navigating filter to get the coordinates of the orbit propagation (OP). The main contradictions in real-time orbit which is determined by the problem are orbit positioning accuracy and the amount of calculating two indicators. This paper is dedicated to solving the problem of tradeoffs. To plan t...

  2. Azimuthal Spoke Propagation in Hall Effect Thrusters

    Science.gov (United States)

    Sekerak, Michael J.; Longmier, Benjamin W.; Gallimore, Alec D.; Brown, Daniel L.; Hofer, Richard R.; Polk, James E.

    2013-01-01

    Spokes are azimuthally propagating perturbations in the plasma discharge of Hall Effect Thrusters (HETs) that travel in the E x B direction and have been observed in many different systems. The propagation of azimuthal spokes are investigated in a 6 kW HET known as the H6 using ultra-fast imaging and azimuthally spaced probes. A spoke surface is a 2-D plot of azimuthal light intensity evolution over time calculated from 87,500 frames/s videos. The spoke velocity has been determined using three methods with similar results: manual fitting of diagonal lines on the spoke surface, linear cross-correlation between azimuthal locations and an approximated dispersion relation. The spoke velocity for three discharge voltages (300, 400 and 450 V) and three anode mass flow rates (14.7, 19.5 and 25.2 mg/s) yielded spoke velocities between 1500 and 2200 m/s across a range of normalized magnetic field settings. The spoke velocity was inversely dependent on magnetic field strength for low B-field settings and asymptoted at B-field higher values. The velocities and frequencies are compared to standard drifts and plasma waves such as E x B drift, electrostatic ion cyclotron, magnetosonic and various drift waves. The empirically approximated dispersion relation yielded a characteristic velocity that matched the ion acoustic speed for 5 eV electrons that exist in the near-anode and near-field plume regions of the discharge channel based on internal measurements. Thruster performance has been linked to operating mode where thrust-to-power is maximized when azimuthal spokes are present so investigating the underlying mechanism of spokes will benefit thruster operation.

  3. Time-domain nature of group delay

    Institute of Scientific and Technical Information of China (English)

    王建武; 冯正和

    2015-01-01

    The characteristic of group delay is analyzed based on an electronic circuit, and its time-domain nature is studied with time-domain simulation and experiment. The time-domain simulations and experimental results show that group delay is the delay of the energy center of the amplitude-modulated pulse, rather than the propagation delay of the electromagnetic field. As group velocity originates from the definition of group delay and group delay is different from the propagation delay, the superluminality or negativity of group velocity does not mean the superluminal or negative propagation of the electromagnetic field.

  4. LSQ14bdq: A Type Ic super-luminous supernova with a double-peaked light curve

    CERN Document Server

    Nicholl, M; Jerkstrand, A; Sim, S A; Inserra, C; Anderson, J P; Baltay, C; Benetti, S; Chambers, K; Chen, T -W; Elias-Rosa, N; Feindt, U; Flewelling, H A; Fraser, M; Gal-Yam, A; Galbany, L; Huber, M E; Kangas, T; Kankare, E; Kotak, R; Krühler, T; Maguire, K; McKinnon, R; Rabinowitz, D; Rostami, S; Schulze, S; Smith, K W; Sullivan, M; Tonry, J L; Valenti, S; Young, D R

    2015-01-01

    We present data for LSQ14bdq, a hydrogen-poor super-luminous supernova (SLSN) discovered by the La Silla QUEST survey and classified by the Public ESO Spectroscopic Survey of Transient Objects. The spectrum and light curve are very similar to slow-declining SLSNe such as PTF12dam. However, detections within $\\sim1$ day after explosion show a bright and relatively fast initial peak, lasting for $\\sim15$ days, prior to the usual slow rise to maximum light. The broader, main peak can be fit with either central engine or circumstellar interaction models. We discuss the implications of the precursor peak in the context of these models. It is too bright and narrow to be explained as a normal \\Ni-powered SN, and we suggest that interaction models may struggle to fit the precursor and main peak simultaneously. We propose that the initial peak is from the post-shock cooling of an extended stellar envelope, and reheating by a central engine drives the second peak. In this picture, we show that an explosion energy of $\\...

  5. Selecting superluminous supernovae in faint galaxies from the first year of the Pan-STARRS1 Medium Deep Survey

    CERN Document Server

    McCrum, M; Rest, A; Smith, K; Kotak, R; Rodney, S A; Young, D R; Chornock, R; Berger, E; Foley, R J; Fraser, M; Wright, D; Scolnic, D; Tonry, J L; Urata, Y; Huang, K; Pastorello, A; Botticella, M T; Valenti, S; Mattila, S; Kankare, E; Farrow, D J; Huber, M E; Stubbs, C W; Kirshner, R P; Bresolin, F; Burgett, W S; Chambers, K C; Draper, P W; Flewelling, H; Jedicke, R; Kaiser, N; Magnier, E A; Metcalfe, N; Morgan, J S; Price, P A; Sweeney, W; Wainscoat, R J; Waters, C

    2014-01-01

    The Pan-STARRS1 (PS1) survey has obtained imaging in 5 bands (grizy_P1) over 10 Medium Deep Survey (MDS) fields covering a total of 70 square degrees. This paper describes the search for apparently hostless supernovae (SNe) within the first year of PS1 MDS data with an aim of discovering new superluminous supernovae (SLSNe). A total of 249 hostless transients were discovered down to a limiting magnitude of M_AB ~ 23.5, of which 75 were classified as Type Ia SNe. There were 58 SNe with complete light curves that are likely core-collapse SNe (CCSNe) or SLSNe and 13 of these have had spectra taken. Of these 13 hostless, non-Type Ia SNe, 9 were SLSNe of Type I at redshifts between 0.5-1.4. Thus one can maximise the discovery rate of Type I SLSNe by concentrating on hostless transients and removing normal SNe Ia. We present data for three new possible SLSNe; PS1-10pm (z = 1.206), PS1-10ahf (z = 1.16) and PS1-11acn (z ~ 0.61), and estimate the rate of SLSNe-I to be between 0.6pm0.3 * 10^-4 and 1.0pm0.3 * 10^-4 of t...

  6. The hydrogen-poor superluminous supernova iPTF13ajg and its host galaxy in absorption and emission

    CERN Document Server

    Vreeswijk, Paul M; Gal-Yam, Avishay; De Cia, Annalisa; Quimby, Robert M; Sullivan, Mark; Cenko, S Bradley; Perley, Daniel A; Filippenko, Alexei V; Clubb, Kelsey I; Taddia, Francesco; Sollerman, Jesper; Leloudas, Giorgos; Arcavi, Iair; Rubin, Adam; Kasliwal, Mansi M; Cao, Yi; Yaron, Ofer; Tal, David; Ofek, Eran O; Capone, John; Kutyrev, Alexander S; Toy, Vicki; Nugent, Peter E; Laher, Russ; Surace, Jason; Kulkarni, Shrinivas R

    2014-01-01

    We present imaging and spectroscopy of a hydrogen-poor superluminous supernova (SLSN) discovered by the intermediate Palomar Transient Factory: iPTF13ajg. At a redshift of z=0.7403, derived from narrow absorption lines, iPTF13ajg peaked at an absolute magnitude M(u,AB)=-22.5, one of the most luminous supernovae to date. The uBgRiz light curves, obtained with the P48, P60, NOT, DCT, and Keck telescopes, and the nine-epoch spectral sequence secured with the Keck and the VLT (covering 3 rest-frame months), are tied together photometrically to provide an estimate of the flux evolution as a function of time and wavelength. The observed bolometric peak luminosity of iPTF13ajg is 3.2x10^44 erg/s, while the estimated total radiated energy is 1.3x10^51 erg. We detect narrow absorption lines of Mg I, Mg II, and Fe II, associated with the cold interstellar medium in the host galaxy, at two different epochs with X-shooter at the VLT. From Voigt-profile fitting, we derive the column densities log N(Mg I)=11.94+-0.06, log ...

  7. PS1-14bj: A Hydrogen-Poor Superluminous Supernova With a Long Rise and Slow Decay

    CERN Document Server

    Lunnan, R; Berger, E; Milisavljevic, D; Jones, D O; Rest, A; Fong, W; Fransson, C; Margutti, R; Drout, M R; Blanchard, P K; Challis, P; Cowperthwaite, P S; Foley, R J; Kirshner, R P; Morell, N; Riess, A G; Roth, K C; Scolnic, D; Smartt, S J; Smith, K W; Villar, V A; Chambers, K C; Draper, P W; Huber, M E; Kaiser, N; Kudritzki, R -P; Magnier, E A; Metcalfe, N; Waters, C

    2016-01-01

    We present photometry and spectroscopy of PS1-14bj, a hydrogen-poor superluminous supernova (SLSN) at redshift $z=0.5215$ discovered in the last months of the Pan-STARRS1 Medium Deep Survey. PS1-14bj stands out by its extremely slow evolution, with an observed rise to maximum light $\\gtrsim 125$ days in the rest frame, and exponential decline out to $\\sim 250$ days past peak at a measured rate of $9.75\\times 10^{-3}$ mag day$^{-1}$, consistent with fully-trapped $^{56}$Co decay. This is the longest rise time measured in a SLSN to date, and the first SLSN to show a rise time consistent with pair-instability supernova (PISN) models. Compared to other slowly-evolving SLSNe, it is spectroscopically similar to the prototype SN 2007bi at maximum light, though somewhat lower in luminosity ($L_{\\rm peak} \\simeq 4.4 \\times 10^{43}~{\\rm erg~s}^{-1}$) and with a flatter peak than previous events. In addition to its slow evolution, PS1-14bj shows a number of peculiar properties, including a near-constant color temperatur...

  8. DES14X3taz: A Type I Superluminous Supernova Showing a Luminous, Rapidly Cooling Initial Pre-Peak Bump

    CERN Document Server

    Smith, M; D'Andrea, C B; Castander, F J; Casas, R; Prajs, S; Papadopoulos, A; Nichol, R C; Karpenka, N V; Bernard, S R; Brown, P; Cartier, R; Cooke, J; Curtin, C; Davis, T M; Finley, D A; Foley, R J; Gal-Yam, A; Goldstein, D A; González-Gaitán, S; Gupta, R R; Howell, D A; Inserra, C; Kessler, R; Lidman, C; Marriner, J; Nugent, P; Pritchard, T A; Sako, M; Smartt, S; Smith, R C; Spinka, H; Wolf, R C; Zentano, A; Abbott, T M C; Benoit-Lévy, A; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; Cunha, C E; da Costa, L N; Desai, S; Diehl, H T; Doel, P; Estrada, J; Evrard, A E; Flaugher, B; Fosalba, P; Frieman, J; Gerdes, D W; Gruen, D; Gruendl, R A; James, D J; Kuehn, K; Kuropatkin, N; Lahav, O; Li, T S; Marshall, J L; Martini, P; Miller, C J; Miquel, R; Ogando, R; Plazas, A A; Romer, A K; Roodman, A; Rykoff, E S; Sanchez, E; Scarpine, V; Schubnell, M; Sevilla-Noarbe, I; Soares-Santos, M; Sobreira, F; Suchyta, E; Swanson, M E C; Tarle, G; Thomas, R C; Walker, A R; Wester, W

    2015-01-01

    We present DES14X3taz, a new hydrogen-poor super luminous supernova (SLSN-I) discovered by the Dark Energy Survey (DES) supernova program, with additional photometric data provided by the Survey Using DECam for Superluminous Supernovae (SUDSS). Spectra obtained using OSIRIS on the Gran Telescopio CANARIAS (GTC) show DES14X3taz is a SLSN-I at z=0.608. Multi-color photometry reveals a double-peaked light curve: a blue and relatively bright initial peak that fades rapidly prior to the slower rise of the main light curve. Our multi-color photometry allows us, for the first time, to show that the initial peak cools from 22,000K to 8,000K over 15 rest-frame days, and is faster and brighter than any published core-collapse supernova, reaching 30% of the bolometric luminosity of the main peak. No physical Ni-powered model can fit this initial peak. We show that a shock-cooling model followed by a magnetar driving the second phase of the light curve can adequately explain the light curve of DES14X3taz, with the coolin...

  9. Environmental fifth-force hypothesis for the OPERA superluminal neutrino phenomenology: constraints from orbital motions around the Earth

    CERN Document Server

    Iorio, Lorenzo

    2011-01-01

    It has been recently suggested by Dvali and Vikman [arXiv:1109.5685] that the superluminal neutrino phenomenology of the OPERA experiment may be due to an environmental feature of the Earth, naturally yielding a long-range fifth force of gravitational origin. Its scale length l should not be smaller than one Earth's radius Re, while its upper bound is expected to be slightly smaller than the Earth-Moon distance (60 Re). We analytically work out some orbital effects of a Yukawa-type fifth force for a test particle moving in the modified field of a central body. Our results are quite general since they are not restricted to any particular size of l; moreover, they are valid for an arbitrary orbital configuration of the particle, i.e. for any value of its eccentricity e. We find that the dimensionless strength coupling parameter a is constrained to |a| <= 5\\times10-10 for 1 Re <= l <= 4 Re by the laser data of the Earth's artificial satellite LAGEOS II. The Moon perigee allows to obtain |a| <= 3\\time...

  10. Superluminal energy transmission in the Goos-Hanchen shift of total reflection

    Science.gov (United States)

    Wang, Zhong-Yue

    2011-04-01

    The dispersion relation ω2 = β2c2 - τ2c2 of surface electromagnetic waves is corresponding to that E2 = p2c2 - m02c4 of a tachyon where the coefficient of proportionality is the squared Planck constant ℏ2. Then we prove the energy flow velocity of the Goos-Hanchen shift in vacuum is cn sin θi > c as well according to electrodynamics. These two different ways lead to a same conclusion that energy transport in the Goos-Hanchen effect of total reflection is faster than light.

  11. The Propagation Characteristics of the Electron Beam with Initial Modulation

    Institute of Scientific and Technical Information of China (English)

    Zhang Jun(张军); Zhong Huihuang(钟辉煌)

    2003-01-01

    The propagation characteristics of the beam under various initial conditions are investigated by means of PIC method. The influences of density modulation and velocity modulation on the propagation characteristics are discussed and compared. The results reveal that by changing the amplitude of the two kinds of modulations and the phase difference between them, the distribution property of the first harmonic of the current density can be adapted along the beam propagating path, which is a feasible method to enhance the beam-wave interaction efficiency in Cerenkov HPM devices.

  12. Surface plasmon polariton propagation in organic nanofiber based plasmonic waveguides

    DEFF Research Database (Denmark)

    Leißner, Till; Lemke, Christoph; Jauernik, Stephan

    2013-01-01

    Plasmonic wave packet propagation is monitored in dielectric-loaded surface plasmon polariton waveguides realized from para-hexaphenylene nanofibers deposited onto a 60 nm thick gold film. Using interferometric time resolved two-photon photoemission electron microscopy we are able to determine...... phase and group velocity of the surface plasmon polariton (SPP) waveguiding mode (0.967c and 0.85c at λLaser = 812nm) as well as the effective propagation length (39 μm) along the fiber-gold interface. We furthermore observe that the propagation properties of the SPP waveguiding mode are governed...

  13. Velocity selective optical pumping

    OpenAIRE

    Aminoff, C. G.; Pinard, M.

    1982-01-01

    We consider optical pumping with a quasi monochromatic tunable light beam, in the low intensity limit where a rate equation regime is obtained The velocity selective optical pumping (V.S.O.P.) introduces a correlation between atomic velocity and internal variables in the ground (or metastable) state. The aim of this article is to evaluate these atomic observables (orientation, alignment, population) as a function of velocity, using a phenomenological description of the relaxation effect of co...

  14. Propagation of gravitational waves in the nonperturbative spinor vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Dzhunushaliev, Vladimir [Al-Farabi Kazakh National University, Department of Theoretical and Nuclear Physics, Almaty (Kazakhstan); Al-Farabi Kazakh National University, Institute of Experimental and Theoretical Physics, Almaty (Kazakhstan); Eurasian National University, Institute for Basic Research, Astana (Kazakhstan); Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, Bishkek (Kyrgyzstan); Folomeev, Vladimir [Institute of Physicotechnical Problems and Material Science of the NAS of the Kyrgyz Republic, Bishkek (Kyrgyzstan)

    2014-09-15

    The propagation of gravitational waves on the background of a nonperturbative vacuum of a spinor field is considered. It is shown that there are several distinctive features in comparison with the propagation of plane gravitational waves through empty space: there exists a fixed phase difference between the h{sub yy,zz} and h{sub yz} components of the wave; the phase and group velocities of gravitational waves are not equal to the velocity of light; the group velocity is always less than the velocity of light; under some conditions the gravitational waves are either damped or absent; for given frequency, there exist two waves with different wave vectors. We also discuss the possibility of an experimental verification of the obtained effects as a tool to investigate nonperturbative quantum field theories. (orig.)

  15. Propagation of internal waves up continental slope and shelf

    Institute of Scientific and Technical Information of China (English)

    DAI Dejun; WANG Wei; QIAO Fangli; YUAN Yeli; XIANG Wenxi

    2008-01-01

    In a two-dimensional and linear framework, a transformation was developed to derive eigensolutions of internal waves over a subcriticai hyperbolic slope and to approximate the continental slope and shelf. The transformation converts a hyperbolic slope in physical space into a fiat bottom in transform space while the governing equations of internal waves remain hyperbolic. The eigensolutions are further used to study the evolution of linear internal waves as it propagates to subcritical continental slope and shelf. The stream function, velocity, and vertical shear of velocity induced by internal wave at the hyperbolic slope are analytically expressed by superposition of the obtained eigensolutions. The velocity and velocity shear increase as the internal wave propagates to a hyperbolic slope. They become very large especially when the slope of internal wave rays approaches the topographic slope, which is consistent with the previous studies.

  16. Weak Equivalence Principle and Propagation of the Wave Function in Quantum Mechanics

    CERN Document Server

    de Matos, Clovis Jacinto

    2010-01-01

    The propagation of the wave function of a particle is characterised by a group and a phase velocity. The group velocity is associated with the particle's classical velocity, which is always smaller than the speed of light, and the phase velocity is associated with the propagation speed of the wave function phase and is treated as being unphysical, since its value is always greater than the speed of light. Here we show, using Sciama's Machian formulation of rest mass energy, that this physical interpretation, for the group and the phase velocity of the wave function, is only valid if the weak equivalence principle strictly holds for the propagating particle, except for the photon. In case this constraint is released the phase velocity of the wave function could acquire a physical meaning in quantum condensates.

  17. Wave propagation in spatially modulated tubes.

    Science.gov (United States)

    Ziepke, A; Martens, S; Engel, H

    2016-09-07

    We investigate wave propagation in rotationally symmetric tubes with a periodic spatial modulation of cross section. Using an asymptotic perturbation analysis, the governing quasi-two-dimensional reaction-diffusion equation can be reduced into a one-dimensional reaction-diffusion-advection equation. Assuming a weak perturbation by the advection term and using projection method, in a second step, an equation of motion for traveling waves within such tubes can be derived. Both methods predict properly the nonlinear dependence of the propagation velocity on the ratio of the modulation period of the geometry to the intrinsic width of the front, or pulse. As a main feature, we observe finite intervals of propagation failure of waves induced by the tube's modulation and derive an analytically tractable condition for their occurrence. For the highly diffusive limit, using the Fick-Jacobs approach, we show that wave velocities within modulated tubes are governed by an effective diffusion coefficient. Furthermore, we discuss the effects of a single bottleneck on the period of pulse trains. We observe period changes by integer fractions dependent on the bottleneck width and the period of the entering pulse train.

  18. Wave propagation in spatially modulated tubes

    Science.gov (United States)

    Ziepke, A.; Martens, S.; Engel, H.

    2016-09-01

    We investigate wave propagation in rotationally symmetric tubes with a periodic spatial modulation of cross section. Using an asymptotic perturbation analysis, the governing quasi-two-dimensional reaction-diffusion equation can be reduced into a one-dimensional reaction-diffusion-advection equation. Assuming a weak perturbation by the advection term and using projection method, in a second step, an equation of motion for traveling waves within such tubes can be derived. Both methods predict properly the nonlinear dependence of the propagation velocity on the ratio of the modulation period of the geometry to the intrinsic width of the front, or pulse. As a main feature, we observe finite intervals of propagation failure of waves induced by the tube's modulation and derive an analytically tractable condition for their occurrence. For the highly diffusive limit, using the Fick-Jacobs approach, we show that wave velocities within modulated tubes are governed by an effective diffusion coefficient. Furthermore, we discuss the effects of a single bottleneck on the period of pulse trains. We observe period changes by integer fractions dependent on the bottleneck width and the period of the entering pulse train.

  19. The role of drop velocity in statistical spray description

    Science.gov (United States)

    Groeneweg, J. F.; El-Wakil, M. M.; Myers, P. S.; Uyehara, O. A.

    1978-01-01

    The justification for describing a spray by treating drop velocity as a random variable on an equal statistical basis with drop size was studied experimentally. A double-exposure technique using fluorescent drop photography was used to make size and velocity measurements at selected locations in a steady ethanol spray formed by a swirl atomizer. The size-velocity data were categorized to construct bivariate spray density functions to describe the spray immediately after formation and during downstream propagation. It was found that a statistical treatment of drop velocity was supported by the data. Spray density function shapes and modal characteristics depended strongly on position and the amount of droplet-gas interaction that had occurred. Bimodal density functions were formed by environmental interaction during downstream propagation. Large differences were also found between spatial mass density and mass flux size distributions at the same location.

  20. Velocity dispersion and attenuation of P waves in partially-saturated rocks:Wave propagation equations in double-porosity medium%非饱和岩石中的纵波频散与衰减:双重孔隙介质波传播方程

    Institute of Scientific and Technical Information of China (English)

    巴晶; Carcione J M; 曹宏; 杜启振; 袁振宇; 卢明辉

    2012-01-01

    The dynamic process of P-wave-induced local fluid flow in partially-saturated rocks is described by introducing Rayleigh's theory into poroelastic equations. The wave propagation equations in double-porosity medium (Biot-Rayleigh Equations) are derived from Hamilton's principle of classic mechanics. This thoery benefits from concise mathematical expressions and fewer coefficients. All relevant coefficients in expressions can be determined by measuring rock fundamental properties, so that the Biot-Rayleigh equations are physically realizable. Comparisons with the former theories in literature have preliminarily proved the validity of this theory. An analysis on the sandstone reservoirs of the three districts shows: seismic-band P waves are sensitive to gas in reservoir, but are not so efficient to quantitatively indicate gassaturation, and P-wave dispersion and attenuation are more significant in seismic band for lower porosity sandstones; the CH4-saturated and CO2-saturated reservoirs share the same 3rd type of AVO characteristics and can hardly be discriminated based on the traditional pre-stack analysis; the theory successfully predicts the trends and the multi-frequency-band experimental observed characteristics of P wave velocity variation in relation to water saturation and frequency.%本文采用Rayleigh理论描述纵波激励下非饱和岩石中气泡的局域流体流动,从经典力学的哈密顿原理导出了双重孔隙介质中的波传播方程,即Biot-Rayleigh方程.方程的格式简洁,参数少,所有相关参数物理可测,因此,方程具有较好的物理可实现性.基于相同的岩石与前人理论对比,初步验证了本理论的有效性.对三个地区的砂岩储层进行了分析,结果显示:地震频段内纵波对储层是否含气非常敏感,但对含气饱和度指示性不佳,且随着孔隙度降低,纵波频散与衰减在中低频段更为显著;含甲烷与含二氧化碳的砂岩储层均呈第三类AVO响应特

  1. Hierarchical Affinity Propagation

    CERN Document Server

    Givoni, Inmar; Frey, Brendan J

    2012-01-01

    Affinity propagation is an exemplar-based clustering algorithm that finds a set of data-points that best exemplify the data, and associates each datapoint with one exemplar. We extend affinity propagation in a principled way to solve the hierarchical clustering problem, which arises in a variety of domains including biology, sensor networks and decision making in operational research. We derive an inference algorithm that operates by propagating information up and down the hierarchy, and is efficient despite the high-order potentials required for the graphical model formulation. We demonstrate that our method outperforms greedy techniques that cluster one layer at a time. We show that on an artificial dataset designed to mimic the HIV-strain mutation dynamics, our method outperforms related methods. For real HIV sequences, where the ground truth is not available, we show our method achieves better results, in terms of the underlying objective function, and show the results correspond meaningfully to geographi...

  2. The discrete regime of flame propagation

    Science.gov (United States)

    Tang, Francois-David; Goroshin, Samuel; Higgins, Andrew

    The propagation of laminar dust flames in iron dust clouds was studied in a low-gravity envi-ronment on-board a parabolic flight aircraft. The elimination of buoyancy-induced convection and particle settling permitted measurements of fundamental combustion parameters such as the burning velocity and the flame quenching distance over a wide range of particle sizes and in different gaseous mixtures. The discrete regime of flame propagation was observed by substitut-ing nitrogen present in air with xenon, an inert gas with a significantly lower heat conductivity. Flame propagation in the discrete regime is controlled by the heat transfer between neighbor-ing particles, rather than by the particle burning rate used by traditional continuum models of heterogeneous flames. The propagation mechanism of discrete flames depends on the spa-tial distribution of particles, and thus such flames are strongly influenced by local fluctuations in the fuel concentration. Constant pressure laminar dust flames were observed inside 70 cm long, 5 cm diameter Pyrex tubes. Equally-spaced plate assemblies forming rectangular chan-nels were placed inside each tube to determine the quenching distance defined as the minimum channel width through which a flame can successfully propagate. High-speed video cameras were used to measure the flame speed and a fiber optic spectrometer was used to measure the flame temperature. Experimental results were compared with predictions obtained from a numerical model of a three-dimensional flame developed to capture both the discrete nature and the random distribution of particles in the flame. Though good qualitative agreement was obtained between model predictions and experimental observations, residual g-jitters and the short reduced-gravity periods prevented further investigations of propagation limits in the dis-crete regime. The full exploration of the discrete flame phenomenon would require high-quality, long duration reduced gravity environment

  3. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  4. Estimation of vector velocity

    DEFF Research Database (Denmark)

    2000-01-01

    Using a pulsed ultrasound field, the two-dimensional velocity vector can be determined with the invention. The method uses a transversally modulated ultrasound field for probing the moving medium under investigation. A modified autocorrelation approach is used in the velocity estimation. The new...

  5. Two parameters describing a superluminal neutrino%二参量描述的超光速中微子述的超光速中微子

    Institute of Scientific and Technical Information of China (English)

    倪光炯; 张操

    2002-01-01

    Based on the experimental data that the mass-square of neutrino might be negative, a quantum theory for superluminal neutrino is proposed. Two Weyl equations coupled together via a mass term respecting the maximum parity violation lead to a new equation which describes the superluminal motion of neutrino with permanent helicity. Various strange features of subluminal and superluminal particles can be ascribed to the relative variation of two contradictory fields superposing coherently inside the particle with the change of its speed u in the whole range (0<u<∞). Being compatible with the theory of special relativity, this theory may have various applications.%根据中微子质量平方是负值的实验数据,提出了一个关于超光速中微子的量子理论.用一个和最大宇称破坏相关的质量项将两个Weyl方程耦合在一起,得到一个描述具有永久螺旋度且超光速运动的中微子的新方程.超光速粒子的速度在 (0,∞)范围内变化,其内部相干迭加的两个矛盾场的相对变化导致亚光速粒子和超光速粒子的各种奇异特性.这个理论和狭义相对论是兼容的,因而可以有多方面的应用.

  6. Propagation behavior of acoustic wave in wood

    Institute of Scientific and Technical Information of China (English)

    Huadong Xu; Guoqi Xu; Lihai Wang; Lei Yu

    2014-01-01

    We used acoustic tests on a quarter-sawn poplar timbers to study the effects of wood anisotropy and cavity defects on acoustic wave velocity and travel path, and we investigated acoustic wave propagation behavior in wood. The timber specimens were first tested in unmodified condition and then tested after introduction of cavity defects of varying sizes to quantify the transmitting time of acoustic waves in laboratory conditions. Two-dimensional acoustic wave contour maps on the radial section of specimens were then simulated and analyzed based on the experimental data. We tested the relationship between wood grain and acoustic wave velocity as waves passed in various directions through wood. Wood anisotropy has significant effects on both velocity and travel path of acoustic waves, and the velocity of waves passing longitudinally through timbers exceeded the radial velocity. Moreover, cavity defects altered acoustic wave time contours on radial sections of timbers. Acous-tic wave transits from an excitation point to the region behind a cavity in defective wood more slowly than in intact wood.

  7. Solitary Wave Propagation Influenced by Submerged Breakwater

    Institute of Scientific and Technical Information of China (English)

    王锦; 左其华; 王登婷

    2013-01-01

    The form of Boussinesq equation derived by Nwogu (1993) using velocity at an arbitrary distance and surface elevation as variables is used to simulate wave surface elevation changes. In the numerical experiment, water depth was divided into five layers with six layer interfaces to simulate velocity at each layer interface. Besides, a physical experiment was carried out to validate numerical model and study solitary wave propagation.“Water column collapsing”method (WCCM) was used to generate solitary wave. A series of wave gauges around an impervious breakwater were set-up in the flume to measure the solitary wave shoaling, run-up, and breaking processes. The results show that the measured data and simulated data are in good agreement. Moreover, simulated and measured surface elevations were analyzed by the wavelet transform method. It shows that different wave frequencies stratified in the wavelet amplitude spectrum. Finally, horizontal and vertical velocities of each layer interface were analyzed in the process of solitary wave propagation through submerged breakwater.

  8. Propagation of waves

    CERN Document Server

    David, P

    2013-01-01

    Propagation of Waves focuses on the wave propagation around the earth, which is influenced by its curvature, surface irregularities, and by passage through atmospheric layers that may be refracting, absorbing, or ionized. This book begins by outlining the behavior of waves in the various media and at their interfaces, which simplifies the basic phenomena, such as absorption, refraction, reflection, and interference. Applications to the case of the terrestrial sphere are also discussed as a natural generalization. Following the deliberation on the diffraction of the "ground? wave around the ear

  9. Spin-velocity correlations of optically pumped atoms

    Science.gov (United States)

    Marsland, R., III; McGuyer, B. H.; Olsen, B. A.; Happer, W.

    2012-08-01

    We present efficient theoretical tools for describing the optical pumping of atoms by light propagating at arbitrary directions with respect to an external magnetic field, at buffer-gas pressures that are small enough for velocity-selective optical pumping (VSOP) but large enough to cause substantial collisional relaxation of the velocities and the spin. These are the conditions for the sodium atoms at an altitude of about 100 km that are used as guidestars for adaptive optics in modern ground-based telescopes to correct for aberrations due to atmospheric turbulence. We use spin and velocity relaxation modes to describe the distribution of atoms in spin space (including both populations and coherences) and velocity space. Cusp kernels are used to describe velocity-changing collisions. Optical pumping operators are represented as a sum of poles in the complex velocity plane. Signals simulated with these methods are in excellent agreement with previous experiments and with preliminary experiments in our laboratory.

  10. Moisture content effect on ultrasonic velocity in Goupia glabra

    Directory of Open Access Journals (Sweden)

    Fabiana Goia Rosa de Oliveira

    2005-03-01

    Full Text Available This paper discusses the application of ultrasound waves on a Brazilian hardwood, Goupia glabra, to evaluate the sensitivity of the ultrasonic technique to the moisture content in wood. The velocity of ultrasonic wave is sensitive to the material's quality-determining factors; hence, this technique is an important industrial tool to improve the quality control of processes. The nature of the response of velocity of sound to changes in moisture content led us to conclude that moisture gradients during drying exert a dominating effect. The ultrasonic velocity was measured both parallel and perpendicular to the fibers of Goupia glabra during drying from green to 6% moisture content. The results of this study showed that velocity of ultrasonic waves is sensitive to changes in moisture content of lumber during drying. The velocity under dry conditions was always higher than the velocity under more humid conditions, in both directions of propagation.

  11. Urban traffic congestion propagation and bottleneck identification

    Institute of Scientific and Technical Information of China (English)

    LONG JianCheng; GAO ZiYou; REN HuaLing; LIAN AiPing

    2008-01-01

    Bottlenecks in urban traffic network are sticking points in restricting network col-lectivity traffic efficiency.To identify network bottlenecks effectively is a founda-tional work for improving network traffic condition and preventing traffic conges-tion.In this paper,a congestion propagation model of urban network traffic is proposed based on the cell transmission model (CTM).The proposed model in-cludes a link model,which describes flow propagation on links,and a node model,which represents link-to-link flow propagation.A new method of estimating average journey velocity (AJV) of both link and network is developed to identify network congestion bottlenecks.A numerical example is studied in Sioux Falls urban traffic network.The proposed model is employed in simulating network traffic propaga-tion and congestion bottleneck identification under different traffic demands.The simulation results show that continual increase of traffic demand is an immediate factor in network congestion bottleneck emergence and increase as well as re-ducing network collectivity capability.Whether a particular link will become a bot-tleneck is mainly determined by its position in network,its traffic flow (attributed to different OD pairs) component,and network traffic demand.

  12. Low Frequency Sound Propagation in Lipid Membranes

    CERN Document Server

    Mosgaard, Lars D; Heimburg, Thomas

    2012-01-01

    In the recent years we have shown that cylindrical biological membranes such as nerve axons under physiological conditions are able to support stable electromechanical pulses called solitons. These pulses share many similarities with the nervous impulse, e.g., the propagation velocity as well as the measured reversible heat production and changes in thickness and length that cannot be explained with traditional nerve models. A necessary condition for solitary pulse propagation is the simultaneous existence of nonlinearity and dispersion, i.e., the dependence of the speed of sound on density and frequency. A prerequisite for the nonlinearity is the presence of a chain melting transition close to physiological temperatures. The transition causes a density dependence of the elastic constants which can easily be determined by experiment. The frequency dependence is more difficult to determine. The typical time scale of a nerve pulse is 1 ms, corresponding to a characteristic frequency in the range up to one kHz. ...

  13. PS1-10bzj: A FAST, HYDROGEN-POOR SUPERLUMINOUS SUPERNOVA IN A METAL-POOR HOST GALAXY

    Energy Technology Data Exchange (ETDEWEB)

    Lunnan, R.; Chornock, R.; Berger, E.; Milisavljevic, D.; Drout, M.; Sanders, N. E.; Challis, P. M.; Czekala, I.; Foley, R. J.; Fong, W.; Kirshner, R. P.; Leibler, C.; Marion, G. H.; Narayan, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Huber, M. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); McCrum, M.; Smartt, S. J. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Rest, A. [Space Telescope Science Institute, 3700 San Martin Dr., Baltimore, MD 21218 (United States); Roth, K. C. [Gemini Observatory, 670 N. Aohoku Place, Hilo, HI 96720 (United States); Scolnic, D., E-mail: rlunnan@cfa.harvard.edu [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); and others

    2013-07-10

    We present observations and analysis of PS1-10bzj, a superluminous supernova (SLSN) discovered in the Pan-STARRS Medium Deep Survey at a redshift z = 0.650. Spectroscopically, PS1-10bzj is similar to the hydrogen-poor SLSNe 2005ap and SCP 06F6, though with a steeper rise and lower peak luminosity (M{sub bol} {approx_equal} -21.4 mag) than previous events. We construct a bolometric light curve, and show that while PS1-10bzj's energetics were less extreme than previous events, its luminosity still cannot be explained by radioactive nickel decay alone. We explore both a magnetar spin-down and circumstellar interaction scenario and find that either can fit the data. PS1-10bzj is located in the Extended Chandra Deep Field South and the host galaxy is imaged in a number of surveys, including with the Hubble Space Telescope. The host is a compact dwarf galaxy (M{sub B} Almost-Equal-To -18 mag, diameter {approx}< 800 pc), with a low stellar mass (M{sub *} Almost-Equal-To 2.4 Multiplication-Sign 10{sup 7} M{sub Sun }), young stellar population ({tau}{sub *} Almost-Equal-To 5 Myr), and a star formation rate of {approx}2-3 M{sub Sun} yr{sup -1}. The specific star formation rate is the highest seen in an SLSN host so far ({approx}100 Gyr{sup -1}). We detect the [O III] {lambda}4363 line, and find a low metallicity: 12 + (O/H) = 7.8 {+-} 0.2 ({approx_equal} 0.1 Z{sub Sun }). Together, this indicates that at least some of the progenitors of SLSNe come from young, low-metallicity populations.

  14. Taking stock of superluminous supernovae and long gamma-ray burst host galaxy comparison using a complete sample of LGRBs

    Science.gov (United States)

    Japelj, J.; Vergani, S. D.; Salvaterra, R.; Hunt, L. K.; Mannucci, F.

    2016-10-01

    Long gamma-ray bursts (LGRBs) and superluminous supernovae (SLSNe) are both explosive transients with very massive progenitor stars. Clues about the nature of the progenitors can be found by investigating environments in which such transients occur. While studies of LGRB host galaxies have a long history, dedicated observational campaigns have only recently resulted in a high enough number of photometrically and spectroscopically observed SLSN hosts to allow statistically significant analysis of their properties. In this paper we make a comparison of the host galaxies of hydrogen-poor (H-poor) SLSNe and the Swift/BAT6 sample of LGRBs. In contrast to previous studies, we use a complete sample of LGRBs and we pay special attention to the comparison methodology and the selection of SLSN sample whose data have been compiled from the available literature. At intermediate redshifts (0.3 < z < 0.7) the two classes of transients select galaxies whose properties (stellar mass, luminosity, star formation rate, specific star formation rate and metallicity) do not differ significantly. Moreover, the host galaxies of both classes of objects follow the fundamental metallicity relation and the fundamental plane of metallicity. In contrast to previous studies we show that at intermediate redshifts the emission line equivalent widths of the two populations are essentially the same and that the previous claims regarding the higher fraction of SLSN hosts among the extreme emission line galaxies with respect to LGRBs are mostly due to a larger fraction of strong-line emitters among SLSN hosts at z < 0.3, where samples of LGRB hosts are small and poorly defined.

  15. Hydrogen-poor superluminous supernovae and long-duration gamma-ray bursts have similar host galaxies

    Energy Technology Data Exchange (ETDEWEB)

    Lunnan, R.; Chornock, R.; Berger, E.; Laskar, T.; Fong, W.; Sanders, N. E.; Challis, P. M.; Drout, M. R.; Foley, R. J.; Kirshner, R. P.; Leibler, C.; Marion, G. H.; Milisavljevic, D.; Narayan, G. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Rest, A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Huber, M. E. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); McCrum, M.; Smartt, S. J.; Smith, K. W. [Astrophysics Research Centre, School of Mathematics and Physics, Queen' s University Belfast, Belfast BT7 1NN (United Kingdom); Scolnic, D., E-mail: rlunnan@cfa.harvard.edu [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); and others

    2014-06-01

    We present optical spectroscopy and optical/near-IR photometry of 31 host galaxies of hydrogen-poor superluminous supernovae (SLSNe), including 15 events from the Pan-STARRS1 Medium Deep Survey. Our sample spans the redshift range 0.1 ≲ z ≲ 1.6, and is the first comprehensive host galaxy study of this specific subclass of cosmic explosions. Combining the multi-band photometry and emission-line measurements, we determine the luminosities, stellar masses, star formation rates, and metallicities. We find that, as a whole, the hosts of SLSNe are a low-luminosity ((M{sub B} ) ≈ –17.3 mag), low stellar mass ((M {sub *}) ≈ 2 × 10{sup 8} M {sub ☉}) population, with a high median specific star formation rate ((sSFR) ≈ 2 Gyr{sup –1}). The median metallicity of our spectroscopic sample is low, 12 + log (O/H) ≈ 8.35 ≈ 0.45 Z {sub ☉}, although at least one host galaxy has solar metallicity. The host galaxies of H-poor SLSNe are statistically distinct from the hosts of GOODS core-collapse SNe (which cover a similar redshift range), but resemble the host galaxies of long-duration gamma-ray bursts (LGRBs) in terms of stellar mass, SFR, sSFR, and metallicity. This result indicates that the environmental causes leading to massive stars forming either SLSNe or LGRBs are similar, and in particular that SLSNe are more effectively formed in low metallicity environments. We speculate that the key ingredient is large core angular momentum, leading to a rapidly spinning magnetar in SLSNe and an accreting black hole in LGRBs.

  16. DROMO propagator revisited

    Science.gov (United States)

    Urrutxua, Hodei; Sanjurjo-Rivo, Manuel; Peláez, Jesús

    2016-01-01

    In the year 2000 an in-house orbital propagator called DROMO (Peláez et al. in Celest Mech Dyn Astron 97:131-150, 2007. doi: 10.1007/s10569-006-9056-3) was developed by the Space Dynamics Group of the Technical University of Madrid, based in a set of redundant variables including Euler-Rodrigues parameters. An original deduction of the DROMO propagator is carried out, underlining its close relation with the ideal frame concept introduced by Hansen (Abh der Math-Phys Cl der Kon Sachs Ges der Wissensch 5:41-218, 1857). Based on the very same concept, Deprit (J Res Natl Bur Stand Sect B Math Sci 79B(1-2):1-15, 1975) proposed a formulation for orbit propagation. In this paper, similarities and differences with the theory carried out by Deprit are analyzed. Simultaneously, some improvements are introduced in the formulation, that lead to a more synthetic and better performing propagator. Also, the long-term effect of the oblateness of the primary is studied in terms of DROMO variables, and new numerical results are presented to evaluate the performance of the method.

  17. Propagation of elastic waves through textured polycrystals: application to ice.

    Science.gov (United States)

    Maurel, Agnès; Lund, Fernando; Montagnat, Maurine

    2015-05-08

    The propagation of elastic waves in polycrystals is revisited, with an emphasis on configurations relevant to the study of ice. Randomly oriented hexagonal single crystals are considered with specific, non-uniform, probability distributions for their major axis. Three typical textures or fabrics (i.e. preferred grain orientations) are studied in detail: one cluster fabric and two girdle fabrics, as found in ice recovered from deep ice cores. After computing the averaged elasticity tensor for the considered textures, wave propagation is studied using a wave equation with elastic constants c=〈c〉+δc that are equal to an average plus deviations, presumed small, from that average. This allows for the use of the Voigt average in the wave equation, and velocities are obtained solving the appropriate Christoffel equation. The velocity for vertical propagation, as appropriate to interpret sonic logging measurements, is analysed in more details. Our formulae are shown to be accurate at the 0.5% level and they provide a rationale for previous empirical fits to wave propagation velocities with a quantitative agreement at the 0.07-0.7% level. We conclude that, within the formalism presented here, it is appropriate to use, with confidence, velocity measurements to characterize ice fabrics.

  18. Directional bending wave propagation in periodically perforated plates

    DEFF Research Database (Denmark)

    Andreassen, Erik; Manktelow, Kevin; Ruzzene, Massimo

    2015-01-01

    We report on the investigation of wave propagation in a periodically perforated plate. A unit cell with double-C perforations is selected as a test article suitable to investigate two-dimensional dispersion characteristics, group velocities, and internal resonances. A numerical model, formulated ...

  19. Azimuthal Spoke Propagation in Hall Effect Thrusters

    Science.gov (United States)

    2013-10-01

    to bk. The cross-correlation function is17 Rjk = lim T→∞ 1 T ∫ T 0 bj (t) bk (t + τ)dt (2) Signal delays for non -frequency dispersive propagation can...During the neutral replenishment period within the discharge channel, slight perturbations or azimuthal non - uniformities in electron density, electron...electron thermal velocity is the average of an assumed Maxwellian distribution37 vthe = √ 8qTe/(πme) with Te in eV. The region from 0.16 < z/Lchnl

  20. Tsunami Propagation Models Based on First Principles

    Science.gov (United States)

    2012-11-21

    obstacle and strike land in the shadow regions. Since v h according to Eq. (9), the velocity decreases nearer the coast as the depth decreases. The wave...Earth by the two locations is, from spherical trigonometry ,  1cos sin sin cos cos coss d s d d sθ λ λ λ λ φ φ      (37) The linear...speed of propagation, bending of tsunamis around obstacles and depth of the ocean, among others. Two-dimensional models on flat and spherical ocean

  1. Surface wave propagation in a fluid-saturated incompressible porous medium

    Indian Academy of Sciences (India)

    Rajneesh Kumar; B S Hundal

    2007-06-01

    A study of surface wave propagation in a fluid-saturated incompressible porous half-space lying under a uniform layer of liquid is presented. The dispersion relation connecting the phase velocity with wave number is derived. The variation of phase velocity and attenuation coefficients with wave number is presented graphically and discussed. As a particular case, the propagation of Rayleigh type surface waves at the free surface of an incompressible porous half-space is also deduced and discussed.

  2. The wave phase velocity in superconducting transmission lines near T{sub c}

    Energy Technology Data Exchange (ETDEWEB)

    Kuzhakhmetov, A.R.; Lobov, G.D.; Shtykov, V.V.; Zhgoon, S.A. [Moscow Power Engineering Inst. (Russian Federation). Radio Engineering Dept.

    1998-06-01

    A peculiarity in behavior of electromagnetic waves phase velocity ({nu}{sub ph}), propagating in superconducting planar transmission lines, in the vicinity of the transition temperature (T{sub c}) was observed in experiment and deduced theoretically. (orig.) 5 refs.

  3. Impulse propagation in a conducting medium with arbitrary thermal conductivity

    Energy Technology Data Exchange (ETDEWEB)

    Myasnikov, S.P.

    1977-07-01

    An examination is made of impulse propagation in a conducting medium that accounts for its thermal conductivity. Such a medium, even with an infinitely large electric conductivity, will have a weak dispersion. Following dispersion through a sufficiently large time interval, out of the entire set of planar waves comprising a wave packet, only the low-frequency components were shown to remain (these are the components that are propagated at a velocity of c/sub s/) along with the high-frequency components that are propagated at the speed of c/sub T/. Consequently, the initial derangement is converted into two separate waves of a bell-shaped form that run to various sides at a phase velocity equal to the adiabatic speed of sound c/sub s/. 6 references.

  4. On the propagation of a coupled saturation and pressure front

    Energy Technology Data Exchange (ETDEWEB)

    Vasco, D. W.

    2010-12-01

    Using an asymptotic technique, valid for a medium with smoothly varying heterogeneity, I derive an expression for the velocity of a propagating, coupled saturation and pressure front. Due to the nonlinearity of the governing equations, the velocity of the propagating front depends upon the magnitude of the saturation and pressure changes across the front in addition to the properties of the medium. Thus, the expression must be evaluated in conjunction with numerical reservoir simulation. The propagation of the two-phase front is governed by the background saturation distribution, the saturation-dependent component of the fluid mobility, the porosity, the permeability, the capillary pressure function, the medium compressibility, and the ratio of the slopes of the relative permeability curves. Numerical simulation of water injection into a porous layer saturated with a nonaqueous phase liquid indicates that two modes of propagation are important. The fastest mode of propagation is a pressure-dominated disturbance that travels through the saturated layer. This is followed, much later, by a coupled mode with a large saturation change. These two modes are also observed in a simulation using a heterogeneous porous layer. A comparison between the propagation times estimated from the results of the numerical simulation and predictions from the asymptotic expression indicates overall agreement.

  5. Extreme Velocity Wind Sensor

    Science.gov (United States)

    Perotti, Jose; Voska, Ned (Technical Monitor)

    2002-01-01

    This presentation provides an overview of the development of new hurricane wind sensor (Extreme Velocity Wind Sensor) for the Kennedy Space Center (KSC) which is designed to withstand winds of up to three hundred miles an hour. The proposed Extreme Velocity Wind Sensor contains no moveable components that would be exposed to extreme wind conditions. Topics covered include: need for new hurricane wind sensor, conceptual design, software applications, computational fluid dynamic simulations of design concept, preliminary performance tests, and project status.

  6. Effect of Microscopic Noise on Front Propagation

    Science.gov (United States)

    Brunet, Éric; Derrida, Bernard

    2001-04-01

    We study the effect of the noise due to microscopic fluctuations on the position of a one dimensional front propagating from a stable to an unstable region in the "linearly marginal stability case." By simulating a very simple system for which the effective number N of particles can be as large as N=10150, we measure the N dependence of the diffusion constant DN of the front and the shift of its velocity vN. Our results indicate that DN˜(log N)-3. They also confirm our recent claim that the shift of velocity scales like vmin-vN≃K(log N)-2 and indicate that the numerical value of K is very close to the analytical expression Kapprox obtained in our previous work using a simple cut-off approximation.

  7. Propagating Instabilities in Solids

    Science.gov (United States)

    Kyriakides, Stelios

    1998-03-01

    Instability is one of the factors which limit the extent to which solids can be loaded or deformed and plays a pivotal role in the design of many structures. Such instabilities often result in localized deformation which precipitates catastrophic failure. Some materials have the capacity to recover their stiffness following a certain amount of localized deformation. This local recovery in stiffness arrests further local deformation and spreading of the instability to neighboring material becomes preferred. Under displacement controlled loading the propagation of the transition fronts can be achieved in a steady-state manner at a constant stress level known as the propagation stress. The stresses in the transition fronts joining the highly deformed zone to the intact material overcome the instability nucleation stresses and, as a result, the propagation stress is usually much lower than the stress required to nucleate the instability. The classical example of this class of material instabilities is L/"uders bands which tend to affect mild steels and other metals. Recent work has demonstrated that propagating instabilities occur in several other materials. Experimental and analytical results from four examples will be used to illustrate this point: First the evolution of L=FCders bands in mild steel strips will be revisited. The second example involves the evolution of stress induced phase transformations (austenite to martensite phases and the reverse) in a shape memory alloy under displacement controlled stretching. The third example is the crushing behavior of cellular materials such as honeycombs and foams made from metals and polymers. The fourth example involves the axial broadening/propagation of kink bands in aligned fiber/matrix composites under compression. The microstructure and, as a result, the micromechanisms governing the onset, localization, local arrest and propagation of instabilities in each of the four materials are vastly different. Despite this

  8. Calculation of the conduction velocity of short nerve fibres

    NARCIS (Netherlands)

    van der Vliet, G.H.; Holsheimer, J.

    1980-01-01

    The conduction velocity v of a nerve fibre is calculated from the time delay Δ of a propagating action potential between two recording sites along the fibre. However, the conventional method of determining Δ cannot be applied to short nerve fibres. Therefore several linear signal analysis methods

  9. Combined imaging and velocity estimation by Joint Migration Inversion

    NARCIS (Netherlands)

    Staal, X.R.

    2015-01-01

    Seismic imaging projects aim to reveal the structure of the earths crust from seismic data. These projects typically include three separate processing steps, being: • attenuation of multiple reflections in the seismic data. • estimating seismic wave propagation velocities from the seismic data. • ma

  10. Lower bound on the electroweak wall velocity from hydrodynamic instability

    Energy Technology Data Exchange (ETDEWEB)

    Mégevand, Ariel; Membiela, Federico Agustín; Sánchez, Alejandro D. [IFIMAR (CONICET-UNMdP), Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Deán Funes (7600) 3350 Mar del Plata (Argentina)

    2015-03-27

    The subsonic expansion of bubbles in a strongly first-order electroweak phase transition is a convenient scenario for electroweak baryogenesis. For most extensions of the Standard Model, stationary subsonic solutions (i.e., deflagrations) exist for the propagation of phase transition fronts. However, deflagrations are known to be hydrodynamically unstable for wall velocities below a certain critical value. We calculate this critical velocity for several extensions of the Standard Model and compare with an estimation of the wall velocity. In general, we find a region in parameter space which gives stable deflagrations as well as favorable conditions for electroweak baryogenesis.

  11. Effect of Fermion Velocity on Phase Structure of QED3

    Science.gov (United States)

    Li, Jian-Feng; Feng, Hong-Tao; Zong, Hong-Shi

    2016-11-01

    Dynamical chiral symmetry breaking (DCSB) in thermal QED3 with fermion velocity is studied in the framework of Dyson-Schwinger equations. By adopting instantaneous approximation and neglecting the transverse component of gauge boson propagator at finite temperature, we numerically solve the fermion self-energy equation in the rainbow approximation. It is found that both DCSB and fermion chiral condensate are suppressed by fermion velocity. Moreover, the critical temperature decreases as fermion velocity increases. Supported in part by the National Natural Science Foundation of China under Grant No. 11535005 and the Natural Science Foundation of Jiangsu Province under Grant No. BK20130387

  12. Demonstration of sub-luminal propagation of single-cycle terahertz pulses for particle acceleration

    CERN Document Server

    Walsh, D A; Snedden, E W; Cliffe, M J; Graham, D M; Jamison, S P

    2016-01-01

    The sub-luminal phase velocity of electromagnetic waves in free space is generally unobtainable, being closely linked to forbidden faster than light group velocities. The requirement of effective sub-luminal phase-velocity in laser-driven particle acceleration schemes imposes a fundamental limit on the total acceleration achievable in free-space, and necessitates the use of dielectric structures and waveguides for extending the field-particle interaction. Here we demonstrate a new travelling-source and free space propagation approach to overcoming the sub-luminal propagation limits. The approach exploits the relative ease of generating ultrafast optical sources with slow group velocity propagation, and a group-to-phase front conversion through non-linear optical interaction near a material-vacuum boundary. The concept is demonstrated with two terahertz generation processes, non-linear optical rectification and current-surge rectification. The phase velocity is tunable, both above and below vacuum speed of lig...

  13. Comparative studies of methods of obtaining AGW's propagation properties

    Science.gov (United States)

    Lue, H. Y.; Kuo, F. S.

    2012-03-01

    Three among the existing methods of obtaining the properties (intrinsic period, wavelength, propagation direction) of atmospheric gravity waves (AGWs) were compared and studied by numerical method to simulate radar data. Three-dimensional fluctuation velocity satisfying dispersion equation and polarization relation of atmospheric gravity wave were generated, then the numerical data were analysed by these methods to obtain the properties of waves. We found that, hodograph analysis was accurate for a monochromatic wave in obtaining its wave period and propagation direction, but the analysis became erratic for the case of multiple waves' superposition. The error was especially large when data consisted of both upward propagating waves and downward propagating waves. The hodograph method became meaningful again if all the component waves propagated in the same direction and the resulting period was dominantly decided by the lowest frequency wave. Stokes parameters method would obtain statistically meaningful values of wave period and azimuth if the spreading of the azimuths among the component waves did not exceed 90° and the resulting period and azimuth were dominated by the lowest frequency wave component as well, irrespective of the vertical sense of propagation. Another method called phase and group velocity tracing technique was reconfirmed to be meaningful in measuring the characteristic wave period and vertical group and phase velocities of a wave packet: the characteristic wave period and vertical wavelength was dominated by the wave with the highest frequency among the component waves in the wave packet. Based on these numerical results, a composite procedure of data analysis for wave propagation was proposed and an example of real data analysis was presented.

  14. Vegetative propagation of jojoba

    Energy Technology Data Exchange (ETDEWEB)

    Low, C.B.; Hackett, W.P.

    1981-03-01

    Development of jojoba as an economically viable crop requires improved methods of propagation and culture. Rooting experiments were performed on cutting material collected from wild jojoba plants. A striking seasonal fluctuation in rooting potential was found. Jojoba plants can be successfully propagated from stem cuttings made during spring, summer, and, to some extent, fall. Variability among jojoba plants may also play a role in rooting potential, although it is not as important as season. In general, the use of auxin (4,000 ppm indolebutyric acid) on jojoba cuttings during periods of high rooting potential promotes adventitious root formation, but during periods of low rooting potential it has no effect or is even slightly inhibitory. In the greenhouse, cutting-grown plants apparently reproductively matured sooner than those grown from seed. If this observation holds true for plants transplanted into the field, earlier fruit production by cutting--grown plants would mean earlier return of initial planting and maintenance costs.

  15. Propagation of Tau aggregates.

    Science.gov (United States)

    Goedert, Michel; Spillantini, Maria Grazia

    2017-05-30

    Since 2009, evidence has accumulated to suggest that Tau aggregates form first in a small number of brain cells, from where they propagate to other regions, resulting in neurodegeneration and disease. Propagation of Tau aggregates is often called prion-like, which refers to the capacity of an assembled protein to induce the same abnormal conformation in a protein of the same kind, initiating a self-amplifying cascade. In addition, prion-like encompasses the release of protein aggregates from brain cells and their uptake by neighbouring cells. In mice, the intracerebral injection of Tau inclusions induced the ordered assembly of monomeric Tau, followed by its spreading to distant brain regions. Short fibrils constituted the major species of seed-competent Tau. The existence of several human Tauopathies with distinct fibril morphologies has led to the suggestion that different molecular conformers (or strains) of aggregated Tau exist.

  16. Stochastic wave propagation

    CERN Document Server

    Sobczyk, K

    1985-01-01

    This is a concise, unified exposition of the existing methods of analysis of linear stochastic waves with particular reference to the most recent results. Both scalar and vector waves are considered. Principal attention is concentrated on wave propagation in stochastic media and wave scattering at stochastic surfaces. However, discussion extends also to various mathematical aspects of stochastic wave equations and problems of modelling stochastic media.

  17. Bidirectional beam propagation method

    Science.gov (United States)

    Kaczmarski, P.; Lagasse, P. E.

    1988-05-01

    A bidirectional extension of the beam propagation method (BPM) to optical waveguides with a longitudinal discontinuity is presented. The algorithm is verified by computing a reflection of the TE(0) mode from a semiconductor laser facet. The bidirectional BPM is applicable to other configurations such as totally reflecting waveguide mirrors, an abruption transition in a waveguide, or a waveguide with many discontinuities generating multiple reflections. The method can also be adapted to TM polarization.

  18. Gauge engineering and propagators

    Directory of Open Access Journals (Sweden)

    Maas Axel

    2017-01-01

    The dependence of the propagators on the choice of these complete gauge-fixings will then be investigated using lattice gauge theory for Yang-Mills theory. It is found that the implications for the infrared, and to some extent mid-momentum behavior, can be substantial. In going beyond the Yang-Mills case it turns out that the influence of matter can generally not be neglected. This will be briefly discussed for various types of matter.

  19. Critical velocity of sandwich cylindrical shell under moving internal pressure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Critical velocity of an infinite long sandwich shell under moving internal pres-sure is studied using the sandwich shell theory and elastodynamics theory. Propagation of axisymmetric free harmonic waves in the sandwich shell is studied using the sandwich shell theory by considering compressibility and transverse shear deformation of the core, and transverse shear deformation of face sheets. Based on the elastodynamics theory, displacement components expanded by Legendre polynomials, and position-dependent elastic constants and densities are introduced into the equations of motion. Critical ve-locity is the minimum phase velocity on the desperation relation curve obtained by using the two methods. Numerical examples and the finite element (FE) simulations are pre-sented. The results show that the two critical velocities agree well with each other, and two desperation relation curves agree well with each other when the wave number κ is relatively small. However, two limit phase velocities approach to the shear wave velocities of the face sheet and the core respectively when k limits to infinite. The two methods are efficient in the investigation of wave propagation in a sandwich cylindrical shell when κ is relatively small. The critical velocity predicted in the FE simulations agrees with theoretical prediction.

  20. Subluminal velocity of OAM-carrying beam

    CERN Document Server

    Bareza, Nestor D

    2015-01-01

    We report a consequence of the orbital angular momentum (OAM) of a beam to its group velocity. We calculate the group velocity $v_g$ of Laguerre-Gauss beam ($\\emph{LG}$) with $\\ell$ and at $p=0$. The $v_g$ reduction of $\\emph{LG}$ beam even in free space is observed to have dependence on both orbital or winding number $\\ell$ and the beam's divergence $\\theta_0$. We found that light possessing higher $\\ell$ travels relatively slower than that with lower $\\ell$ values. This suggests that light of different OAM separate in the temporal domain along propagation and it is an added effect to the dispersion due to field confinement. Our results are useful for treating information embedded in light with OAM from astronomical sources and/or data transmission in free space.

  1. Commwarrior worm propagation model for smart phone networks

    Institute of Scientific and Technical Information of China (English)

    XIA Wei; LI Zhao-hui; CHEN Zeng-qiang; YUAN Zhu-zhi

    2008-01-01

    Commwarrior worm is capable of spreading through both Bluetooth and multimedia messaging service (MMS) in smart phone networks. According to the propagation characteristics of Bluetooth and MMS, we built the susceptible- exposed-infected-recovered-dormancy (SEIRD) model for the Bluetooth and MMS hybrid spread mode and performed the stability analysis. The simulation results show good correlation with our theoretical analysis and demonstrate the effectiveness of this dynamic propagation model. On the basis of the SEIRD model, we further discuss at length the influence of the propagation parameters such as user gather density in groups, moving velocity of smart phone, the time for worm to replicate itself, and other interrelated parameters on the propagation of the virus. On the basis of these analytical and simulation results, some feasible control strategies will be proposed to restrain the spread of mobile worm such as commwarrior on smart phone network.

  2. Cardiac Shear Wave Velocity Detection in the Porcine Heart.

    Science.gov (United States)

    Vos, Hendrik J; van Dalen, Bas M; Heinonen, Ilkka; Bosch, Johan G; Sorop, Oana; Duncker, Dirk J; van der Steen, Antonius F W; de Jong, Nico

    2017-04-01

    Cardiac muscle stiffness can potentially be estimated non-invasively with shear wave elastography. Shear waves are present on the septal wall after mitral and aortic valve closure, thus providing an opportunity to assess stiffness in early systole and early diastole. We report on the shear wave recordings of 22 minipigs with high-frame-rate echocardiography. The waves were captured with 4000 frames/s using a programmable commercial ultrasound machine. The wave pattern was extracted from the data through a local tissue velocity estimator based on one-lag autocorrelation. The wave propagation velocity was determined with a normalized Radon transform, resulting in median wave propagation velocities of 2.2 m/s after mitral valve closure and 4.2 m/s after aortic valve closure. Overall the velocities ranged between 0.8 and 6.3 m/s in a 95% confidence interval. By dispersion analysis we found that the propagation velocity only mildly increased with shear wave frequency.

  3. Velocities in Solar Pores

    Science.gov (United States)

    Balasubramaniam, K. S.; Keil, S. L.; Smaldone, L. A.

    1996-05-01

    We investigate the three dimensional structure of solar pores and their surroundings using high spatial and spectral resolution data. We present evidence that surface velocities decrease around pores with a corresponding increase in the line-of-sight (LOS) velocities. LOS velocities in pores increase with the strength of the magnetic field. Surface velocities show convergence toward a weak downflow which appear to trace boundaries resembling meso-granular and super granular flows. The observed magnetic fields in the pores appear near these boundaries. We analyze the vertical velocity structure in pores and show that they generally have downflows decreasing exponentially with height, with a scale height of about 90 km. Evidence is also presented for the expanding nature of flux tubes. Finally we describe a phenomenological model for pores. This work was supported by AFOSR Task 2311G3. LAS was partially supported by the Progetto Nazionale Astrofisica e Fisica Cosmica of MURST and Scambi Internazionali of the Universita degli Studi di Napoli Frederico II. National Solar Observatory, NOAO, is operated for the National Science Foundation by AURA, Inc.

  4. Counterposition and negative phase velocity in uniformly moving dissipative materials

    Energy Technology Data Exchange (ETDEWEB)

    Mackay, Tom G [School of Mathematics and Maxwell Institute for Mathematical Sciences, University of Edinburgh, Edinburgh EH9 3JZ (United Kingdom); Lakhtakia, Akhlesh [NanoMM-Nanoengineered Metamaterials Group, Department of Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802-6812 (United States)], E-mail: T.Mackay@ed.ac.uk, E-mail: akhlesh@psu.edu

    2009-10-16

    We considered the phenomena of counterposition and negative phase velocity, which are relevant to certain metamaterials and certain astrophysical scenarios. The Lorentz transformations of electric and magnetic fields were implemented to study (i) the refraction of linearly polarized plane waves into a half-space occupied by a uniformly moving material and (ii) the traversal of linearly polarized Gaussian beams through a uniformly moving slab. Motion was taken to occur tangentially to the interface(s) and in the plane of incidence. The moving materials were assumed to be isotropic, homogeneous and dissipative dielectric materials from the perspective of a co-moving observer. Two different moving materials were considered: from the perspective of a co-moving observer, material A supports planewave propagation with only positive phase velocity, whereas material B supports planewave propagation with both positive and negative phase velocity, depending on the polarization state. For both materials A and B, the sense of the phase velocity and whether or not counterposition occurred, as perceived by a non-co-moving observer, could be altered by varying the observer's velocity. Furthermore, the lateral position of a beam upon propagating through a uniformly moving slab made of material A, as perceived by a non-co-moving observer, could be controlled by varying the observer's velocity. In particular, at certain velocities, the transmitted beam emerged from the slab laterally displaced in the direction opposite to the direction of incident beam. The transmittances of a uniformly moving slab made of material B were very small and the energy density of the transmitted beam was largely concentrated in the direction normal to the slab, regardless of the observer's velocity.

  5. Leading-Edge Velocities and Lifted Methane Jet Flame Stability

    Directory of Open Access Journals (Sweden)

    W. Wang

    2010-01-01

    Full Text Available Current interest exists in understanding reaction-zone dynamics and mechanisms with respect to how they counterpropagate against incoming reactants. Images of flame position and flow-field morphology are presented from flame chemiluminescence and particle image velocimetry (PIV measurements. In the present study, PIV experiments were carried out to measure the methane jet lifted-flame flow-field velocities in the vicinity of the flame leading edge. Specifically, velocity fields within the high-temperature zone were examined in detail, which complements previous studies, whose prime focus is the flow-field upstream of the high-temperature boundary. PIV data is used not only to determine the velocities, but, along with chemiluminescence images, to also indicate the approximate location of the reaction zone (further supported by/through the leading-edge flame velocity distributions. The velocity results indirectly support the concept that the flame is anchored primarily through the mechanism of partially premixed flame propagation.

  6. Wave velocity characteristic for Kenaf natural fibre under impact damage

    Science.gov (United States)

    Zaleha, M.; Mahzan, S.; Fitri, Muhamad; Kamarudin, K. A.; Eliza, Y.; Tobi, A. L. Mohd

    2017-01-01

    This paper aims to determining the wave velocity characteristics for kenaf fibre reinforced composite (KFC) and it includes both experimental and simulation results. Lead zirconate titanate (PZT) sensor were proposed to be positioned to corresponding locations on the panel. In order to demonstrate the wave velocity, an impacts was introduced onto the panel. It is based on a classical sensor triangulation methodology, combines with experimental strain wave velocity analysis. Then the simulation was designed to replicate panel used in the experimental impacts test. This simulation was carried out using ABAQUS. It was shown that the wave velocity propagates faster in the finite element simulation. Although the experimental strain wave velocity and finite element simulation results do not match exactly, the shape of both waves is similar.

  7. Seismic wave propagation modeling in porous media for various frequencies: A case study in carbonate rock

    Science.gov (United States)

    Nurhandoko, Bagus Endar B.; Wardaya, Pongga Dikdya; Adler, John; Siahaan, Kisko R.

    2012-06-01

    Seismic wave parameter plays very important role to characterize reservoir properties whereas pore parameter is one of the most important parameter of reservoir. Therefore, wave propagation phenomena in pore media is important to be studied. By referring this study, in-direct pore measurement method based on seismic wave propagation can be developed. Porosity play important role in reservoir, because the porosity can be as compartment of fluid. Many type of porosity like primary as well as secondary porosity. Carbonate rock consist many type of porosity, i.e.: inter granular porosity, moldic porosity and also fracture porosity. The complexity of pore type in carbonate rocks make the wave propagation in these rocks is more complex than sand reservoir. We have studied numerically wave propagation in carbonate rock by finite difference modeling in time-space domain. The medium of wave propagation was modeled by base on the result of pattern recognition using artificial neural network. The image of thin slice of carbonate rock is then translated into the velocity matrix. Each mineral contents including pore of thin slice image are translated to velocity since mineral has unique velocity. After matrix velocity model has been developed, the seismic wave is propagated numerically in this model. The phenomena diffraction is clearly shown while wave propagates in this complex carbonate medium. The seismic wave is modeled in various frequencies. The result shows dispersive phenomena where high frequency wave tends to propagate in matrix instead pores. In the other hand, the low frequency waves tend to propagate through pore space even though the velocity of pore is very low. Therefore, this dispersive phenomena of seismic wave propagation can be the future indirect measurement technology for predicting the existence or intensity of pore space in reservoir rock. It will be very useful for the future reservoir characterization.

  8. Rapid high-amplitude circumferential slow wave propagation during normal gastric pacemaking and dysrhythmias.

    Science.gov (United States)

    O'Grady, G; Du, P; Paskaranandavadivel, N; Angeli, T R; Lammers, W J E P; Asirvatham, S J; Windsor, J A; Farrugia, G; Pullan, A J; Cheng, L K

    2012-07-01

    Gastric slow waves propagate aborally as rings of excitation. Circumferential propagation does not normally occur, except at the pacemaker region. We hypothesized that (i) the unexplained high-velocity, high-amplitude activity associated with the pacemaker region is a consequence of circumferential propagation; (ii) rapid, high-amplitude circumferential propagation emerges during gastric dysrhythmias; (iii) the driving network conductance might switch between interstitial cells of Cajal myenteric plexus (ICC-MP) and circular interstitial cells of Cajal intramuscular (ICC-IM) during circumferential propagation; and (iv) extracellular amplitudes and velocities are correlated. An experimental-theoretical study was performed. High-resolution gastric mapping was performed in pigs during normal activation, pacing, and dysrhythmia. Activation profiles, velocities, and amplitudes were quantified. ICC pathways were theoretically evaluated in a bidomain model. Extracellular potentials were modeled as a function of membrane potentials. High-velocity, high-amplitude activation was only recorded in the pacemaker region when circumferential conduction occurred. Circumferential propagation accompanied dysrhythmia in 8/8 experiments was faster than longitudinal propagation (8.9 vs 6.9 mm s(-1) ; P = 0.004) and of higher amplitude (739 vs 528 μV; P = 0.007). Simulations predicted that ICC-MP could be the driving network during longitudinal propagation, whereas during ectopic pacemaking, ICC-IM could outpace and activate ICC-MP in the circumferential axis. Experimental and modeling data demonstrated a linear relationship between velocities and amplitudes (P propagation. Rapid circumferential propagation also emerges during a range of gastric dysrhythmias, elevating extracellular amplitudes and organizing transverse wavefronts. One possible explanation for these findings is bidirectional coupling between ICC-MP and circular ICC-IM networks. © 2012 Blackwell Publishing Ltd.

  9. Quantitative velocity modulation spectroscopy

    Science.gov (United States)

    Hodges, James N.; McCall, Benjamin J.

    2016-05-01

    Velocity Modulation Spectroscopy (VMS) is arguably the most important development in the 20th century for spectroscopic study of molecular ions. For decades, interpretation of VMS lineshapes has presented challenges due to the intrinsic covariance of fit parameters including velocity modulation amplitude, linewidth, and intensity. This limitation has stifled the growth of this technique into the quantitative realm. In this work, we show that subtle changes in the lineshape can be used to help address this complexity. This allows for determination of the linewidth, intensity relative to other transitions, velocity modulation amplitude, and electric field strength in the positive column of a glow discharge. Additionally, we explain the large homogeneous component of the linewidth that has been previously described. Using this component, the ion mobility can be determined.

  10. Propagation law of impact elastic wave based on specific materials

    Directory of Open Access Journals (Sweden)

    Chunmin CHEN

    2017-02-01

    Full Text Available In order to explore the propagation law of the impact elastic wave on the platform, the experimental platform is built by using the specific isotropic materials and anisotropic materials. The glass cloth epoxy laminated plate is used for anisotropic material, and an organic glass plate is used for isotropic material. The PVDF sensors adhered on the specific materials are utilized to collect data, and the elastic wave propagation law of different thick plates and laminated plates under impact conditions is analyzed. The Experimental results show that in anisotropic material, transverse wave propagation speed along the fiber arrangement direction is the fastest, while longitudinal wave propagation speed is the slowest. The longitudinal wave propagation speed in anisotropic laminates is much slower than that in the laminated thick plates. In the test channel arranged along a particular angle away from the central region of the material, transverse wave propagation speed is larger. Based on the experimental results, this paper proposes a material combination mode which is advantageous to elastic wave propagation and diffusion in shock-isolating materials. It is proposed to design a composite material with high acoustic velocity by adding regularly arranged fibrous materials. The overall design of the barrier material is a layered structure and a certain number of 90°zigzag structure.

  11. Wave propagation in elastic solids

    CERN Document Server

    Achenbach, Jan

    1984-01-01

    The propagation of mechanical disturbances in solids is of interest in many branches of the physical scienses and engineering. This book aims to present an account of the theory of wave propagation in elastic solids. The material is arranged to present an exposition of the basic concepts of mechanical wave propagation within a one-dimensional setting and a discussion of formal aspects of elastodynamic theory in three dimensions, followed by chapters expounding on typical wave propagation phenomena, such as radiation, reflection, refraction, propagation in waveguides, and diffraction. The treat

  12. The Prescribed Velocity Method

    DEFF Research Database (Denmark)

    Nielsen, Peter Vilhelm

    The- velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactory...... description of this momentum flow. The Prescribed Velocity Method is a practical method for the description of an Air Terminal Device which will save grid points close to the opening and ensure the right level of the momentum flow....

  13. Cirrus Crystal Terminal Velocities.

    Science.gov (United States)

    Heymsfield, Andrew J.; Iaquinta, Jean

    2000-04-01

    Cirrus crystal terminal velocities are of primary importance in determining the rate of transport of condensate from upper- to middle-tropospheric levels and profoundly influence the earth's radiation balance through their effect on the rate of buildup or decay of cirrus clouds. In this study, laboratory and field-based cirrus crystal drag coefficient data, as well as analytical descriptions of cirrus crystal shapes, are used to derive more physically based expressions for the velocities of cirrus crystals than have been available in the past.Polycrystals-often bullet rosettes-are shown to be the dominant crystal types in synoptically generated cirrus, with columns present in varying but relatively large percentages, depending on the cloud. The two critical parameters needed to calculate terminal velocity are the drag coefficient and the ratio of mass to cross-sectional area normal to their fall direction. Using measurements and calculations, it is shown that drag coefficients from theory and laboratory studies are applicable to crystals of the types found in cirrus. The ratio of the mass to area, which is shown to be relatively independent of the number of bullets in the rosette, is derived from an analytic model that represents bullet rosettes containing one to eight bullets in 19 primary geometric configurations. The ratio is also derived for columns. Using this information, a general set of equations is developed to calculate the terminal velocities and masses in terms of the aspect ratio (width divided by length), ice density, and rosette maximum dimension. Simple expressions for terminal velocity and mass as a function of bullet rosette maximum dimension are developed by incorporating new information on bullet aspect ratios.The general terminal velocity and mass relations are then applied to a case from the First International Satellite Cloud Climatology Project (ISCCP) Research Experiment (FIRE) 2, when size spectra from a balloon-borne ice crystal

  14. Front propagation in A+B→2A reaction under subdiffusion

    Science.gov (United States)

    Froemberg, D.; Schmidt-Martens, H.; Sokolov, I. M.; Sagués, F.

    2008-07-01

    We consider an irreversible autocatalytic conversion reaction A+B→2A under subdiffusion described by continuous-time random walks. The reactants’ transformations take place independently of their motion and are described by constant rates. The analog of this reaction in the case of normal diffusion is described by the Fisher-Kolmogorov-Petrovskii-Piskunov equation leading to the existence of a nonzero minimal front propagation velocity, which is really attained by the front in its stable motion. We show that for subdiffusion, this minimal propagation velocity is zero, which suggests propagation failure.

  15. Temporal scaling in information propagation.

    Science.gov (United States)

    Huang, Junming; Li, Chao; Wang, Wen-Qiang; Shen, Hua-Wei; Li, Guojie; Cheng, Xue-Qi

    2014-06-18

    For the study of information propagation, one fundamental problem is uncovering universal laws governing the dynamics of information propagation. This problem, from the microscopic perspective, is formulated as estimating the propagation probability that a piece of information propagates from one individual to another. Such a propagation probability generally depends on two major classes of factors: the intrinsic attractiveness of information and the interactions between individuals. Despite the fact that the temporal effect of attractiveness is widely studied, temporal laws underlying individual interactions remain unclear, causing inaccurate prediction of information propagation on evolving social networks. In this report, we empirically study the dynamics of information propagation, using the dataset from a population-scale social media website. We discover a temporal scaling in information propagation: the probability a message propagates between two individuals decays with the length of time latency since their latest interaction, obeying a power-law rule. Leveraging the scaling law, we further propose a temporal model to estimate future propagation probabilities between individuals, reducing the error rate of information propagation prediction from 6.7% to 2.6% and improving viral marketing with 9.7% incremental customers.

  16. Temporal scaling in information propagation

    Science.gov (United States)

    Huang, Junming; Li, Chao; Wang, Wen-Qiang; Shen, Hua-Wei; Li, Guojie; Cheng, Xue-Qi

    2014-06-01

    For the study of information propagation, one fundamental problem is uncovering universal laws governing the dynamics of information propagation. This problem, from the microscopic perspective, is formulated as estimating the propagation probability that a piece of information propagates from one individual to another. Such a propagation probability generally depends on two major classes of factors: the intrinsic attractiveness of information and the interactions between individuals. Despite the fact that the temporal effect of attractiveness is widely studied, temporal laws underlying individual interactions remain unclear, causing inaccurate prediction of information propagation on evolving social networks. In this report, we empirically study the dynamics of information propagation, using the dataset from a population-scale social media website. We discover a temporal scaling in information propagation: the probability a message propagates between two individuals decays with the length of time latency since their latest interaction, obeying a power-law rule. Leveraging the scaling law, we further propose a temporal model to estimate future propagation probabilities between individuals, reducing the error rate of information propagation prediction from 6.7% to 2.6% and improving viral marketing with 9.7% incremental customers.

  17. Validity of Parametrized Quark Propagator

    Institute of Scientific and Technical Information of China (English)

    ZHUJi-Zhen; ZHOULi-Juan; MAWei-Xing

    2005-01-01

    Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the “rainbow”approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions A/(p2), Bl(p2) and effective mass M$(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.

  18. Validity of Parametrized Quark Propagator

    Institute of Scientific and Technical Information of China (English)

    ZHU Ji-Zhen; ZHOU Li-Juan; MA Wei-Xing

    2005-01-01

    Based on an extensively study of the Dyson-Schwinger equations for a fully dressed quark propagator in the "rainbow" approximation, a parametrized fully dressed quark propagator is proposed in this paper. The parametrized propagator describes a confining quark propagator in hadron since it is analytic everywhere in complex p2-plane and has no Lemmann representation. The validity of the new propagator is discussed by comparing its predictions on selfenergy functions Af(p2), Bf(p2) and effective mass Mf(p2) of quark with flavor f to their corresponding theoretical results produced by Dyson-Schwinger equations. Our comparison shows that the parametrized quark propagator is a good approximation to the fully dressed quark propagator given by the solutions of Dyson-Schwinger equations in the rainbow approximation and is convenient to use in any theoretical calculations.

  19. Ionospheric Radio Propagation

    Science.gov (United States)

    1948-06-25

    applies Chapter 2 presents in simple form the mathe - principles which have been found to work in prac- matical theory underlying the propagation of...6.17, which was described under sec- L713 412 812.111 410.511171IS1&41&716.3 A& tion 6.5 above, and read the value of the muf for muFi .-f------ - 01...twepse, 71. mathe 1measuring virtual 6elghts, is world contour charts. 57; zero distance, 73. Se .1.. Contour chairt MCNiII, A. 0., 106 G Median value

  20. Sequential Back—Propagation

    Institute of Scientific and Technical Information of China (English)

    王晖; 刘大有; 等

    1994-01-01

    In this paper we consider the problem of sequential processing and present a sequential model based on the back-propagation algorithm.This model is intended to deal with intrinsically sequential problems,such as word recognition,speech recognition,natural language understanding.This model can be used to train a network to learn the sequence of input patterns,in a fixed order or a random order.Besides,this model is open- and partial-associative,characterized as “resognizing while accumulating”, which, as we argue, is mental cognition process oriented.