To see the other types of publications on this topic, follow the link: Electromagnetic ejection.
Journal articles on the topic 'Electromagnetic ejection'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'Electromagnetic ejection.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Muhibbullah, M., and Y. Ikuma. "Photoelectron ejection by electromagnetic wave." Optik 181 (March 2019): 802–9. http://dx.doi.org/10.1016/j.ijleo.2018.12.144.
Full text
2
Ren, Shi-da, Gang Feng, Teng-da LI, and Hui Yang. "Analysis of electromagnetic characteristics of a new electromagnetic ejection device." Journal of Physics: Conference Series 1939, no. 1 (May 1, 2021): 012021. http://dx.doi.org/10.1088/1742-6596/1939/1/012021.
Full text
3
Wang, Xing, Yadong Li, Zhenrui Shi, Baoshan Cao, Yanjie Cao, Hui Zhao, and Xun Gong. "Research on Vehicle-Mounted Electromagnetic Ejection Remote Fire Extinguishing System." Mathematical Problems in Engineering 2022 (August 23, 2022): 1–9. http://dx.doi.org/10.1155/2022/2129942.
Full textAbstract:
This article first introduces the characteristics and disadvantages of traditional remote fire extinguishing technology and proposes a remote fire extinguishing system based on electromagnetic ejection. Based on the finite element analysis method and the grid matrix method, a seven-segment electromagnetic launcher model is designed. As the initial energy source, the capacitor can accelerate a 10 kg fire extinguishing bomb to 113 m/s with a range of 2 km. The results show that the electromagnetic catapult designed in this study can meet the needs of fire extinguishing bombs. This paper also designs the overall structure of the vehicle electromagnetic catapult remote fire extinguishing system, discusses its role in the field of firefighting, and prospects the future work.
4
Naqib, S. H. "On the impossibility of “Photoelectron ejection by electromagnetic wave”." Optik 192 (September 2019): 162934. http://dx.doi.org/10.1016/j.ijleo.2019.162934.
Full text
5
Radice, David, Albino Perego, Kenta Hotokezaka, Steven A. Fromm, Sebastiano Bernuzzi, and Luke F. Roberts. "Binary Neutron Star Mergers: Mass Ejection, Electromagnetic Counterparts, and Nucleosynthesis." Astrophysical Journal 869, no. 2 (December 19, 2018): 130. http://dx.doi.org/10.3847/1538-4357/aaf054.
Full text
6
Lin, Zhiqiang, Guiming Chen, and Hanzeng Liu. "Effectiveness Evaluation of Aircraft Electromagnetic Launch System Based on RIMER." MATEC Web of Conferences 316 (2020): 04002. http://dx.doi.org/10.1051/matecconf/202031604002.
Full textAbstract:
Electromagnetic launching technology is one of the important application technologies in aerospace field in the future. It will change the way of rocket launching and even be applied to aerospace kinetic energy weapon system. Aiming at the characteristics of various bottom indicators, uncertain information probability and expert participation in the effectiveness evaluation system of aircraft electromagnetic ejection system, based on the index hierarchy model, the method of RIMER(rule-base inference methodology using the evidential reasoning) is used to evaluate the effectiveness, which provides some reference for the design and development of aircraft electromagnetic launching system.
7
Shibata, Masaru, and Kenta Hotokezaka. "Merger and Mass Ejection of Neutron Star Binaries." Annual Review of Nuclear and Particle Science 69, no. 1 (October 19, 2019): 41–64. http://dx.doi.org/10.1146/annurev-nucl-101918-023625.
Full textAbstract:
Mergers of binary neutron stars and black hole–neutron star binaries are among the most promising sources for ground-based gravitational-wave (GW) detectors and are also high-energy astrophysical phenomena, as illustrated by the observations of GWs and electromagnetic (EM) waves in the event of GW170817. Mergers of these neutron star binaries are also the most promising sites for r-process nucleosynthesis. Numerical simulation in full general relativity (numerical relativity) is a unique approach to the theoretical prediction of the merger process, GWs emitted, mass ejection process, and resulting EM emission. We summarize the current understanding of the processes of neutron star mergers and subsequent mass ejection based on the results of the latest numerical-relativity simulations. We emphasize that the predictions of the numerical-relativity simulations agree broadly with the optical and IR observations of GW170817.
8
Czechowski, Andrzej, and Jens Kleimann. "Nanodust dynamics during a coronal mass ejection." Annales Geophysicae 35, no. 5 (September 4, 2017): 1033–49. http://dx.doi.org/10.5194/angeo-35-1033-2017.
Full textAbstract:
Abstract. The dynamics of nanometer-sized grains (nanodust) is strongly affected by electromagnetic forces. High-velocity nanodust was proposed as an explanation for the voltage bursts observed by STEREO. A study of nanodust dynamics based on a simple time-stationary model has shown that in the vicinity of the Sun the nanodust is trapped or, outside the trapped region, accelerated to high velocities. We investigate the nanodust dynamics for a time-dependent solar wind and magnetic field configuration in order to find out what happens to nanodust during a coronal mass ejection (CME). The plasma flow and the magnetic field during a CME are obtained by numerical simulations using a 3-D magnetohydrodynamic (MHD) code. The equations of motion for the nanodust particles are solved numerically, assuming that the particles are produced from larger bodies moving in near-circular Keplerian orbits within the circumsolar dust cloud. The charge-to-mass ratios for the nanodust particles are taken to be constant in time. The simulation is restricted to the region within 0.14 AU from the Sun. We find that about 35 % of nanodust particles escape from the computational domain during the CME, reaching very high speeds (up to 1000 km s−1). After the end of the CME the escape continues, but the particle velocities do not exceed 300 km s−1. About 30 % of all particles are trapped in bound non-Keplerian orbits with time-dependent perihelium and aphelium distances. Trapped particles are affected by plasma ion drag, which causes contraction of their orbits.
9
Suga, H., Y. Goto, Y. Igarashi, O. Yamada, T. Nozawa, and Y. Yasumura. "Ventricular suction under zero source pressure for filling." American Journal of Physiology-Heart and Circulatory Physiology 251, no. 1 (July 1, 1986): H47—H55. http://dx.doi.org/10.1152/ajpheart.1986.251.1.h47.
Full textAbstract:
We quantified ventricular suction flow, volume, and pressure under hydrostatically zero source pressure for filling. A large-bore electromagnetic flow probe was placed in the valve-free mitral annulus of the dog heart that had been excised and was cross circulated with the left atrium widely opened. With the heart immersed in a blood pool, ventricular suction flow and transmural pressure were measured. After a rapid ejection flow [peak: 110 +/- 47 (SD) ml . s-1 . 100 g left ventricle-1] during systole, a slow suction flow (peak: 26 +/- 20 ml . s-1 . 100 g-1) occurred during diastole despite the zero source pressure for filling. Peak transmural pressure during ejection was 6 +/- 3 mmHg, and peak negative transmural pressure during suction was 2 +/- 1 mmHg. Suction volume, which was equal to ejection volume in steady state, was 8 +/- 3 ml/100 g left ventricle. Increases in paced heart rate markedly decreased suction volume by curtailing diastolic filling time. Epinephrine, propranolol, calcium, and verapamil variably changed suction volume, and these effects were primarily accounted for by the accompanied heart rate changes.
10
Yatsunskyi, Petro. "THE RESULTS OF RESEARCH PNEUMATIC ELECTROMAGNETIC PULSATOR COMBINED WITH COLLECTOR." Mokslas - Lietuvos ateitis 14 (February 1, 2022): 1–4. http://dx.doi.org/10.3846/mla.2022.15162.
Full textAbstract:
This article demonstrates the results of experimental research one of the pulsators. Its main difference from others is a pneumatic electromagnetic pulsator in combination with a collector. Therefore, this article describes in detail the process of studying the pulsator. The planned experiment was carried out on by Factorial experiments with multiple factors. The influence of factors (the ripple frequency n, the milk ejection q and the ratio between strokes t/T) on the vacuum pressure in the inter wall chamber of teat cups was studied. The regression equation of the dependence response criterion on factors is modeled. This dependence is demonstrated graphically. Also there is a contour graph which is for more detailed information.
11
Kan, Longxin, Fengxiao Lei, Bo Song, Bin Su, and Yusheng Shi. "Flexible electromagnetic capturer with a rapid ejection feature inspired by a biological ballistic tongue." Bioinspiration & Biomimetics 15, no. 6 (September 14, 2020): 066002. http://dx.doi.org/10.1088/1748-3190/aba444.
Full text
12
Muhibbullah, M., and Y. Ikuma. "Refutation of the short report “On the impossibility of “Photoelectron ejection by electromagnetic wave””." Optik 202 (February 2020): 163734. http://dx.doi.org/10.1016/j.ijleo.2019.163734.
Full text
13
Mandrini, Cristina H. "Magnetic energy release: flares and coronal mass ejections." Proceedings of the International Astronomical Union 5, S264 (August 2009): 257–66. http://dx.doi.org/10.1017/s1743921309992717.
Full textAbstract:
AbstractFree energy stored in the magnetic field is the source that powers solar and stellar activity at all temporal and spatial scales. The energy released during transient atmospheric events is contained in current-carrying magnetic fields that have emerged twisted and may be further stressed via motions in the lower atmospheric layers (i.e. loop-footpoint motions). Magnetic reconnection is thought to be the mechanism through which the stored magnetic energy is transformed into kinetic energy of accelerated particles and mass flows, and radiative energy along the whole electromagnetic spectrum. This mechanism works efficiently at scale lengths much below the spatial resolution of even the highest resolution solar instruments; however, it may imply a large-scale restructuring of the magnetic field inferred indirectly from the combined analysis of observations and models of the magnetic field topology. The aftermath of magnetic energy release includes events ranging from nanoflares, which are below our detection limit, to powerful flares, which may be accompanied by the ejection of large amounts of plasma and magnetic field (so called coronal mass ejections, CMEs), depending on the amount of total available free magnetic energy, the magnetic flux density distribution, the magnetic field configuration, etc. We describe key observational signatures of flares and CMEs on the Sun, their magnetic field topology, and discuss how the combined analysis of solar and interplanetary observations can be used to constrain the flare/CME ejection mechanism.
14
MURPHY, GARETH C., MARK E. DIECKMANN, and LUKE O'C DRURY. "KINETIC PARTICLE-IN-CELL SIMULATIONS OF ASYMMETRIC QUASI-PARALLEL MILDLY RELATIVISTIC PLASMA COLLISIONS: FIELD AND ELECTRON DYNAMICS." International Journal of Modern Physics D 19, no. 06 (June 2010): 707–13. http://dx.doi.org/10.1142/s0218271810016737.
Full textAbstract:
A gamma-ray burst (GRB) is triggered by a stellar implosion and the subsequent ejection of an ultrarelativistic jet. The prompt emissions are attributed to mildly relativistic collisions of plasma clouds within this jet. The resulting internal shocks are instrumental in the generation of the magnetic fields and the energetic electrons, which excite the observed electromagnetic emissions. We use particle-in-cell (PIC) simulations to examine such a shock. The colliding hot magnetized plasma clouds have densities that differ by a factor of 10. Current channels form rapidly in the 3D simulation, which resemble those in a Hammer–Rostoker equilibrium, are observed also in the 2D simulation. The 2D simulation also shows the formation of a shock, which is mediated by a strong electromagnetic wave, and the energy equipartition between electrons and ions.
15
Renzo, M., R. Farmer, S. Justham, Y. Götberg, S. E. de Mink, E. Zapartas, P. Marchant, and N. Smith. "Predictions for the hydrogen-free ejecta of pulsational pair-instability supernovae." Astronomy & Astrophysics 640 (August 2020): A56. http://dx.doi.org/10.1051/0004-6361/202037710.
Full textAbstract:
Present and upcoming time-domain astronomy efforts, in part driven by gravitational-wave follow-up campaigns, will unveil a variety of rare explosive transients in the sky. Here, we focus on pulsational pair-instability evolution, which can result in signatures that are observable with electromagnetic and gravitational waves. We simulated grids of bare helium stars to characterize the resulting black hole (BH) masses together with the ejecta composition, velocity, and thermal state. We find that the stars do not react “elastically” to the thermonuclear ignition in the core: there is not a one-to-one correspondence between pair-instability driven ignition and mass ejections, which causes ambiguity as to what is an observable pulse. In agreement with previous studies, we find that for initial helium core masses of 37.5 M⊙ ≲ MHe, init ≲ 41 M⊙, corresponding to carbon-oxygen core masses 27.5 M⊙ ≲ MCO ≲ 30.1 M⊙, the explosions are not strong enough to affect the surface. With increasing initial helium core mass, they become progressively stronger causing first large radial expansion (41 M⊙ ≲ MHe, init ≲ 42 M⊙, corresponding to 30.1 M⊙ ≲ MCO ≲ 30.8 M⊙) and, finally, also mass ejection episodes (for MHe, init ≳ 42 M⊙, or MCO ≳ 30.8 M⊙). The lowest mass helium core to be fully disrupted in a pair-instability supernova is MHe, init ≃ 80 M⊙, corresponding to MCO ≃ 55 M⊙. Models with MHe, init ≳ 200 M⊙ (MCO ≳ 114 M⊙) reach the photodisintegration regime, resulting in BHs with masses of MBH ≳ 125 M⊙. Although this is currently considered unlikely, if BHs from these models form via (weak) explosions, the previously-ejected material might be hit by the blast wave and convert kinetic energy into observable electromagnetic radiation. We characterize the hydrogen-free circumstellar material from the pulsational pair-instability of helium cores by simply assuming that the ejecta maintain a constant velocity after ejection. We find that our models produce helium-rich ejecta with mass of 10−3 M⊙ ≲ MCSM ≲ 40 M⊙, the larger values corresponding to the more massive progenitor stars. These ejecta are typically launched at a few thousand km s−1 and reach distances of ∼1012 − 1015 cm before the core-collapse of the star. The delays between mass ejection events and the final collapse span a wide and mass-dependent range (from subhour to 104 years), and the shells ejected can also collide with each other, powering supernova impostor events before the final core-collapse. The range of properties we find suggests a possible connection with (some) type Ibn supernovae.
16
Bauswein, A., S. Goriely, and H. T. Janka. "SYSTEMATICS OF DYNAMICAL MASS EJECTION, NUCLEOSYNTHESIS, AND RADIOACTIVELY POWERED ELECTROMAGNETIC SIGNALS FROM NEUTRON-STAR MERGERS." Astrophysical Journal 773, no. 1 (July 29, 2013): 78. http://dx.doi.org/10.1088/0004-637x/773/1/78.
Full text
17
Connerade, J. P., and K. Dietz. "On the simultaneous ejection of several electrons from an atom in a high electromagnetic field." Journal of Physics B: Atomic, Molecular and Optical Physics 25, no. 6 (March 28, 1992): 1185–94. http://dx.doi.org/10.1088/0953-4075/25/6/010.
Full text
18
Afanasenko, G. V., and I. M. Shvedov. "Study of natural and industrial electromagnetic fields for predicting ejection hazatds during mining of carnallite." Soviet Mining Science 27, no. 1 (January 1991): 70–74. http://dx.doi.org/10.1007/bf02499691.
Full text
19
Dupree, Andrea K., Klaus G. Strassmeier, Thomas Calderwood, Thomas Granzer, Michael Weber, Kateryna Kravchenko, Lynn D. Matthews, Miguel Montargès, James Tappin, and William T. Thompson. "The Great Dimming of Betelgeuse: A Surface Mass Ejection and Its Consequences." Astrophysical Journal 936, no. 1 (August 25, 2022): 18. http://dx.doi.org/10.3847/1538-4357/ac7853.
Full textAbstract:
Abstract The bright supergiant, Betelgeuse (Alpha Orionis, HD 39801), underwent a historic optical dimming during 2020 January 27–February 13. Many imaging and spectroscopic observations across the electromagnetic spectrum were obtained prior to, during, and subsequent to this dimming event. These observations of Betelgeuse reveal that a substantial surface mass ejection (SME) occurred and moved out through the extended atmosphere of the supergiant. A photospheric shock occurred in 2019 January–March, progressed through the extended atmosphere of the star during the following 11 months and led to dust production in the atmosphere. Resulting from the substantial mass outflow, the stellar photosphere was left with lower temperatures and the chromosphere with a lower density. The mass ejected could represent a significant fraction of the total annual mass-loss rate from the star suggesting that episodic mass-loss events can contribute an amount comparable to that of the stellar wind. Following the SME, Betelgeuse was left with a cooler average photosphere, an unusual short photometric oscillation, reduced velocity excursions, and the disappearance of the ∼400 day pulsation in the optical and radial velocity for more than two years following the Great Dimming.
20
Dmytriv, V. T., I. V. Dmytriv, and P. P. Yatsunskyi. "EXPERIMENTAL PULSE GENERATOR COMBINED WITH THE MILKING MACHINE COLLECTOR." INMATEH Agricultural Engineering 59, no. 3 (December 20, 2019): 219–26. http://dx.doi.org/10.35633/inmateh-59-24.
Full textAbstract:
Factors affecting the milk ejection intensity and power consumption of the pulse generator combined with the milking machine collector have been analyzed. The main factors and limits of their variation, as well as the results of experimental studies are given. The matrices of a multivariate planned experimental study of a pulse generator with a combined collector (pneumatic-electromagnetic pulsator-collector) have been developed. According to the results of experimental studies, the coded and natural values of the regression equation are derived. The equations characterize the dependence of the milk ejection intensity on the pulsation frequency, the ratio between the strokes and the vacuum pressure in the under teats space of the teat cup. The dependence of the power consumption of the pulse generator on the pulse rate and the ratio between the strokes are derived. Graphical models of interpretation of regression dependencies according to the experimental data are constructed. Student's t-test, Fisher and Cochran criteria are calculated. These indicators show the adequacy and reproducibility of the models obtained during the studies using an experimental pulse generator combined with a milking machine collector.
21
Falayi, E. O., A. B. Rabiu, O. S. Bolaji, and R. S. Fayose. "Response of ionospheric disturbance dynamo and electromagnetic induction during geomagnetic storm." Canadian Journal of Physics 93, no. 10 (October 2015): 1156–63. http://dx.doi.org/10.1139/cjp-2014-0461.
Full textAbstract:
During geomagnetic storms, the direct penetration of magnetospheric convection electric field and the ionospheric disturbance dynamo (IDD) take place in the ionosphere. In this paper, we studied variability of IDD and electromagnetic induction (EMI) at different latitudinal sectors during the geomagnetic storms on 7 and 8 September 2002 and 20 and 21 November 2003 with high solar wind speed due to coronal mass ejection. This investigation employs geomagnetic field components (H and Z), the geomagnetic indices (Dst, AL, and AU), solar wind speed (Vx), and interplanetary magnetic field (Bz). It was observed that the H component of geomagnetic field decreases across latitudes, and varies with Vx, Bz, Dst, AL, and AU indices throughout the difference phases of the storm. Our result demonstrated the dominance of the IDD during the nighttime compared to the daytime. This implies that neutral dynamic wind is greater at night than during the day. Higher ratio ΔZ/ΔH is observed at nighttime because of the reduction on the E region conductivity, which allowed F region electric fields to dominate.
22
Rosswog, Stephan. "The dynamic ejecta of compact object mergers and eccentric collisions." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 371, no. 1992 (June 13, 2013): 20120272. http://dx.doi.org/10.1098/rsta.2012.0272.
Full textAbstract:
Compact object mergers eject neutron-rich matter in a number of ways: by the dynamical ejection mediated by gravitational torques, as neutrino-driven winds, and probably also a good fraction of the resulting accretion disc finally becomes unbound by a combination of viscous and nuclear processes. If compact binary mergers indeed produce gamma-ray bursts, there should also be an interaction region where an ultra-relativistic outflow interacts with the neutrino-driven wind and produces moderately relativistic ejecta. Each type of ejecta has different physical properties, and therefore plays a different role for nucleosynthesis and for the electromagnetic (EM) transients that go along with compact object encounters. Here, we focus on the dynamic ejecta and present results for over 30 hydrodynamical simulations of both gravitational wave-driven mergers and parabolic encounters as they may occur in globular clusters. We find that mergers eject approximately 1 per cent of a Solar mass of extremely neutron-rich material. The exact amount, as well as the ejection velocity, depends on the involved masses with asymmetric systems ejecting more material at higher velocities. This material undergoes a robust r-process and both ejecta amount and abundance pattern are consistent with neutron star mergers being a major source of the ‘heavy’ ( A >130) r-process isotopes. Parabolic collisions, especially those between neutron stars and black holes, eject substantially larger amounts of mass, and therefore cannot occur frequently without overproducing gala- ctic r-process matter. We also discuss the EM transients that are powered by radioactive decays within the ejecta (‘macronovae’), and the radio flares that emerge when the ejecta dissipate their large kinetic energies in the ambient medium.
23
Coughlin, Michael W., Tim Dietrich, Sarah Antier, Mattia Bulla, Francois Foucart, Kenta Hotokezaka, Geert Raaijmakers, Tanja Hinderer, and Samaya Nissanke. "Implications of the search for optical counterparts during the first six months of the Advanced LIGO’s and Advanced Virgo’s third observing run: possible limits on the ejecta mass and binary properties." Monthly Notices of the Royal Astronomical Society 492, no. 1 (December 10, 2019): 863–76. http://dx.doi.org/10.1093/mnras/stz3457.
Full textAbstract:
ABSTRACT GW170817 showed that neutron star mergers not only emit gravitational waves but also can release electromagnetic signatures in multiple wavelengths. Within the first half of the third observing run of the Advanced LIGO and Virgo detectors, there have been a number of gravitational wave candidates of compact binary systems for which at least one component is potentially a neutron star. In this article, we look at the candidates S190425z, S190426c, S190510g, S190901ap, and S190910h, predicted to have potentially a non-zero remnant mass, in more detail. All these triggers have been followed up with extensive campaigns by the astronomical community doing electromagnetic searches for their optical counterparts; however, according to the released classification, there is a high probability that some of these events might not be of extraterrestrial origin. Assuming that the triggers are caused by a compact binary coalescence and that the individual source locations have been covered during the EM follow-up campaigns, we employ three different kilonova models and apply them to derive possible constraints on the matter ejection consistent with the publicly available gravitational-wave trigger information and the lack of a kilonova detection. These upper bounds on the ejecta mass can be related to limits on the maximum mass of the binary neutron star candidate S190425z and to constraints on the mass-ratio, spin, and NS compactness for the potential black hole–neutron star candidate S190426c. Our results show that deeper electromagnetic observations for future gravitational wave events near the horizon limit of the advanced detectors are essential.
24
Talpeanu, D. C., E. Chané, S. Poedts, E. D’Huys, M. Mierla, I. Roussev, and S. Hosteaux. "Numerical simulations of shear-induced consecutive coronal mass ejections." Astronomy & Astrophysics 637 (May 2020): A77. http://dx.doi.org/10.1051/0004-6361/202037477.
Full textAbstract:
Context. It is widely accepted that photospheric shearing motions play an important role in triggering the initiation of coronal mass ejections (CMEs). Even so, there are events for which the source signatures are difficult to locate, while the CMEs can be clearly observed in coronagraph data. These events are therefore called ‘stealth’ CMEs. They are of particular interest to space weather forecasters, since eruptions are usually discarded from arrival predictions if they appear to be backsided, which means not presenting any clear low-coronal signatures on the visible solar disc. Such assumptions are not valid for stealth CMEs since they can originate from the front side of the Sun and be Earth-directed, but they remain undetected and can therefore trigger unpredicted geomagnetic storms. Aims. We numerically model and investigate the effects of shearing motion variations onto the resulting eruptions and we focus in particular on obtaining a stealth CME in the trailing current sheet of a previous ejection. Methods. We used the 2.5D magnetohydrodynamics package of the code MPI-AMRVAC to numerically simulate consecutive CMEs by imposing shearing motions onto the inner boundary, which represents, in our case, the low corona. The initial magnetic configuration consists of a triple arcade structure embedded into a bimodal solar wind, and the sheared polarity inversion line is found in the southern loop system. The mesh was continuously adapted through a refinement method that applies to current carrying structures, allowing us to easily track the CMEs in high resolution, without resolving the grid in the entire domain. We also compared the obtained eruptions with the observed directions of propagation, determined using a forward modelling reconstruction technique based on a graduated cylindrical shell geometry, of an initial multiple coronal mass ejection (MCME) event that occurred in September 2009. We further analysed the simulated ejections by tracking the centre of their flux ropes in latitude and their total speed. Radial Poynting flux computation was employed as well to follow the evolution of electromagnetic energy introduced into the system. Results. Changes within 1% in the shearing speed result in three different scenarios for the second CME, although the preceding eruption seems insusceptible to such small variations. Depending on the applied shearing speed, we thus obtain a failed eruption, a stealth, or a CME driven by the imposed shear, as the second ejection. The dynamics of all eruptions are compared with the observed directions of propagation of an MCME event and a good correlation is achieved. The Poynting flux analysis reveals the temporal variation of the important steps of eruptions. Conclusions. For the first time, a stealth CME is simulated in the aftermath of a first eruption, originating from an asymmetric streamer configuration, through changes in the applied shearing speed, indicating it is not necessary for a closed streamer to exist high in the corona for such an event to occur. We also emphasise the high sensitivity of the corona to small changes in motions at the photosphere, or in our simulations, at the low corona.
25
Altyntsev, Alexander, Sergey Lesovoi, Mariia Globa, Aleksey Gubin, Aleksey Kochanov, Victor Grechnev, Evgeniy Ivanov, et al. "Multiwave Siberian Radioheliograph." Solnechno-Zemnaya Fizika 6, no. 2 (June 27, 2020): 37–50. http://dx.doi.org/10.12737/szf-62202003.
Full textAbstract:
The article discusses characteristics, fundamental and applied tasks of the Siberian Radioheliograph that is developed at the ISTP SB RAS Radio Astrophysical Observatory and spectropolarimetric complex that measures the total flux of solar radio emission. The multi-wave mapping of the Sun in the microwave range is a powerful and relatively inexpensive, in comparison with space technologies, means of observing solar activity processes and diagnosing plasma parameters. All-weather monitoring of electromagnetic solar emission (in the range from meter to millimeter waves, including measurements of the solar activity index at 2.8 GHz), and at the location of other diverse diagnostic facilities of the Heliogeophysical Complex, is of particular value. Radioheliograph data is necessary to develop and implement methods of short-term forecast of solar flares, measurements of kinematics and characteristics of coronal mass ejection plasma, forecast of characteristics of fast solar wind streams.
26
Altyntsev, Alexander, Sergey Lesovoi, Mariia Globa, Aleksey Gubin, Aleksey Kochanov, Victor Grechnev, Evgeniy Ivanov, et al. "Multiwave Siberian Radioheliograph." Solar-Terrestrial Physics 6, no. 2 (June 27, 2020): 30–40. http://dx.doi.org/10.12737/stp-62202003.
Full textAbstract:
The article discusses characteristics, fundamental and applied tasks of the Siberian Radioheliograph that is developed at the ISTP SB RAS Radio Astrophysical Observatory and spectropolarimetric complex that measures the total flux of solar radio emission. The multi-wave mapping of the Sun in the microwave range is a powerful and relatively inexpensive, in comparison with space technologies, means of observing solar activity processes and diagnosing plasma parameters. All-weather monitoring of electromagnetic solar emission (in the range from meter to millimeter waves, including measurements of the solar activity index at 2.8 GHz), and at the location of other diverse diagnostic facilities of the Heliogeophysical Complex, is of particular value. Radioheliograph data is necessary to develop and implement methods of short-term forecast of solar flares, measurements of kinematics and characteristics of coronal mass ejection plasma, forecast of characteristics of fast solar wind streams.
27
Dean, Coleman, Rodrigo Fernández, and Brian D. Metzger. "Resolving the Fastest Ejecta from Binary Neutron Star Mergers: Implications for Electromagnetic Counterparts." Astrophysical Journal 921, no. 2 (November 1, 2021): 161. http://dx.doi.org/10.3847/1538-4357/ac1f20.
Full textAbstract:
Abstract We examine the effect of spatial resolution on initial mass ejection in grid-based hydrodynamic simulations of binary neutron star mergers. The subset of the dynamical ejecta with velocities greater than ∼0.6c can generate an ultraviolet precursor to the kilonova on approximately hour timescales and contribute to a years long nonthermal afterglow. Previous work has found differing amounts of this fast ejecta, by one to two orders of magnitude, when using particle-based or grid-based hydrodynamic methods. Here, we carry out a numerical experiment that models the merger as an axisymmetric collision in a corotating frame, accounting for Newtonian self-gravity, inertial forces, and gravitational wave losses. The lower computational cost allows us to reach spatial resolutions as high as 4 m, or ∼3 × 10−4 of the stellar radius. We find that fast ejecta production converges to within 10% for a cell size of 20 m. This suggests that fast ejecta quantities found in existing grid-based merger simulations are unlikely to increase to the level needed to match particle-based results upon further resolution increases. The resulting neutron-powered precursors are in principle detectable out to distances ≲200 Mpc with upcoming facilities.We also find that head-on collisions at the freefall speed, relevant for eccentric mergers, yield fast and slow ejecta quantities of order 10−2 M ⊙, with a kilonova signature distinct from that of quasi-circular mergers.
28
Glanz, Hila, and Hagai B. Perets. "Simulations of common envelope evolution in triple systems: circumstellar case." Monthly Notices of the Royal Astronomical Society 500, no. 2 (October 21, 2020): 1921–32. http://dx.doi.org/10.1093/mnras/staa3242.
Full textAbstract:
ABSTRACT The dynamical evolution of triple stellar systems could induce the formation of compact binaries and binary mergers. Common envelope (CE) evolution, which plays a major role in the evolution of compact binary systems, can similarly play a key role in the evolution of triples. Here, we use hydrodynamical simulations coupled with few-body dynamics to provide the first detailed models of the triple common envelope (TCE) evolution. We focus on the circumstellar case, where the envelope of an evolved giant engulfs a compact binary orbiting the giant, which then in-spirals into the core of the evolved star. Through our exploratory modelling, we find several possible outcomes of such TCE: the merger of the binary inside the third star’s envelope; the disruption of the in-spiralling binary following its plunge, leading to a chaotic triple dynamics of the stellar core and the two components of the former disrupted binary. The chaotic evolution typically leads to the in-spiral and merger of at least one of the former binary components with the core, and sometimes to the ejection of the second, or alternatively its further now-binary CE evolution. The in-spiral in TCE leads to overall slower in-spiral, larger mass ejection, and the production of more aspherical remnant, compared with a corresponding binary case of similar masses, due to the energy/momentum extraction from the inner-binary. We expect TCE to play a key role in producing various types of stellar-mergers and unique compact binary systems, and potentially induce transient electromagnetic and gravitational wave sources.
29
Margutti, Raffaella, and Ryan Chornock. "First Multimessenger Observations of a Neutron Star Merger." Annual Review of Astronomy and Astrophysics 59, no. 1 (September 8, 2021): 155–202. http://dx.doi.org/10.1146/annurev-astro-112420-030742.
Full textAbstract:
We describe the first observations of the same celestial object with gravitational waves and light. ▪ GW170817 was the first detection of a neutron star merger with gravitational waves. ▪ The detection of a spatially coincident weak burst of gamma-rays (GRB 170817A) 1.7 s after the merger constituted the first electromagnetic detection of a gravitational wave source and established a connection between at least some cosmic short gamma-ray bursts (SGRBs) and binary neutron star mergers. ▪ A fast-evolving optical and near-infrared transient (AT 2017gfo) associated with the event can be interpreted as resulting from the ejection of ∼0.05 M⊙ of material enriched in r-process elements, finally establishing binary neutron star mergers as at least one source of r-process nucleosynthesis. ▪ Radio and X-ray observations revealed a long-rising source that peaked ∼160,d after the merger. Combined with the apparent superluminal motion of the associated very long baseline interferometry source, these observations show that the merger produced a relativistic structured jet whose core was oriented ≈20 deg from the line of sight and with properties similar to SGRBs. The jet structure likely results from interaction between the jet and the merger ejecta. ▪ The electromagnetic and gravitational wave information can be combined to produce constraints on the expansion rate of the Universe and the equation of state of dense nuclear matter. These multimessenger endeavors will be a major emphasis of future work.
30
Yatsunskyi, Petro. "The pressure oscillation in the inter-wall chamber of the teat cup." Ukrainian Journal of Mechanical Engineering and Materials Science 7, no. 3-4 (2021): 11–19. http://dx.doi.org/10.23939/ujmems2021.03-04.011.
Full textAbstract:
Factors influencing the vacuum gauge pressure in the inter-wall chamber of milking teat cups of a milking machine with a pneumo- and electromagnetic pulse generator with a combined collector are analyzed. The main factors of research and the limits of their variation are formed, the matrix of multifactor planned experiment is developed, and also results of experimental researches are received. According to the results of experimental studies, the regression equations in coded and real or natural values are derived, which characterize the dependence of pressure oscillation in the inter-wall chamber of milking teat cups on the pulsation frequency, milk ejection intensity and the ratio between strokes. A graphical model of interpretation of regression dependence based on experimental data is built. Student's t-test, Fisher's and Cochran’s criteria are calculated, which show the adequacy and reproducibility of the obtained model of the technological process using of the experimental pulse generator with combined collector of the milking machine.
31
Robinson, Timothy, Samuel Giltrap, Samuel Eardley, Fabrizio Consoli, Riccardo De Angelis, Francesco Ingenito, Nicholas Stuart, Claudio Verona, and Roland A. Smith. "Electro-optic analysis of the influence of target geometry on electromagnetic pulses generated by petawatt laser-matter interactions." EPJ Web of Conferences 167 (2018): 03007. http://dx.doi.org/10.1051/epjconf/201816703007.
Full textAbstract:
We present an analysis of strong laser-driven electromagnetic pulses using novel electro-optic diagnostic techniques. A range of targets were considered, including thin plastic foils (20-550 nm) and mass-limited, optically-levitated micro-targets. Results from foils indicate a dependence of EMP on target thickness, with larger peak electric fields observed with thinner targets. Spectral analysis suggests high repeatability between shots, with identified spectral features consistently detected with <1 MHz standard deviations of the peak position. This deviation is reduced for shots taken on the same day, suggesting that local conditions, such as movement of metal objects within the target chamber, are more likely to lead to minor spectral modifications, highlighting the role of the local environment in determining the details of EMP production. Levitated targets are electrically isolated from their environment, hence these targets should be unable to draw a neutralization current from the earth following ejection of hot electrons from the plasma, in contrast to predictions for pin-mounted foils in the Poyé EMP generation model. With levitated targets, no EMP was measurable above the noise threshold of any diagnostic, despite observation of protons accelerated to >30 MeV energies, suggesting the discharge current contribution to EMP is dominant.
32
Falayi, E. O., J. O. Adepitan, and O. A. Oyebanjo. "Geomagnetic field H, Z, and electromagnetic induction features of coronal mass ejections in association with geomagnetic storm at African longitudes." Canadian Journal of Physics 96, no. 6 (June 2018): 654–63. http://dx.doi.org/10.1139/cjp-2017-0460.
Full textAbstract:
The largest geomagnetic disturbance caused by a coronal mass ejection (CME) of solar cycle 24 recorded on both 17 March and 22 June 2015 with minimum disturbance storm time values of −223 and −195 nT, respectively, was investigated. This study examines the effect of CME on Earth’s geomagnetic field, which includes the time derivatives of horizontal (H) and vertical (Z) components of the geomagnetic field and the rate of induction ΔZ/ΔH at African longitudes (AAE, MBO, HBK, HER, and TAM). The results demonstrated enhancement of dH/dt and dZ/dt in the daytime over the equatorial zone (AAE and MBO) and mid-latitudes (TAM, HER, and HBK) on 17 March 2015. Nighttime enhancement was observed on 22 June 2015 over the equatorial zones and mid-latitudes. Wavelet spectrum approach is used to investigate ΔZ/ΔH variation observed at AAE, MBO, HBK, HER, and TAM. The CME may have influence on time derivatives of geomagnetic field H, Z, and electromagnetic induction at the African longitudes, which may be associated with perturbations in electric fields and currents in the equatorial and low-latitude magnetic field linked with the changes in magnetospheric convection.
33
Poklonskiy, Eugen, and Stanislav Totkal. "Superradiation of Mobile Oscillators." 3, no. 3 (September 2, 2022): 14–18. http://dx.doi.org/10.26565/2312-4334-2022-3-02.
Full textAbstract:
The paper considers the development of the process of superradiance of radiating oscillators interacting with each other by means of an electromagnetic field. The interaction of oscillators occurs both with the nearest neighbors and with all other oscillators in the system. In this case, the possibility of longitudinal motion of oscillators along the system, due to the action of the Lorentz force, is taken into account. It is shown that, regardless of the motion of the oscillators, for example, due to their different masses, the maximum attainable amplitude of the generation field changes little. However, the radiation efficiency depends on how this field is distributed in the longitudinal direction. In the case of a shift of the field maximum towards the ends of the system, the radiation efficiency can noticeably increase. In addition, the direction of the phase velocity of the external initiating field is important, which accelerates the process of phase synchronization of the oscillators. This can also affect the ejection of particles outside the initial region, and here the total number of ejected particles and their speed turn out to be important. It is discussed how the density of oscillators and the size of the region occupied by oscillators will change.
34
Zhang, Hongye, Tianhui Yang, Wenxin Li, Ying Xin, Chao Li, Matteo F. Iacchetti, Alexander C. Smith, and Markus Mueller. "Origin of the anomalous electromechanical interaction between a moving magnetic dipole and a closed superconducting loop." Superconductor Science and Technology 35, no. 4 (February 25, 2022): 045009. http://dx.doi.org/10.1088/1361-6668/ac53dc.
Full textAbstract:
Abstract Lenz’s law states that ‘the current induced in a circuit due to a change in a magnetic field is directed to oppose the change in flux and to exert a mechanical force which opposes the motion’. This statement has been widely adopted to predict many effects in electromagnetism. However, multiple recent experimental measurements have shown that the interactions between a moving permanent magnet (PM) and a closed superconducting loop can disobey the fundamental statement of Lenz’s law: during the entire process of a PM threading a high temperature superconducting (HTS) coil, the current induced in the HTS coil keeps the same direction, and thus the mechanical force exerted on the PM does not always oppose its movement. The seeming ‘Lenz’s law-violated phenomenon’, namely the anomalous electromechanical interaction between a moving PM and a closed superconducting loop, can bring about numerous potential applications in the domains of superconducting magnetic energy storage, electromagnetic ejection, and flux pumps, etc. However, the cause of this anomalous phenomenon remains controversial. By representing the PM as a magnetic dipole, taking the perfect conductor approximation for the closed superconducting loop, this paper has theoretically studied the anomalous electromechanical effect with rigorous mathematical formulae derivation. The proposed analytical equations have been verified by numerical modelling and experimental measurements, which further confirms the effectiveness of the perfect conductor approximation in ease of calculation. Results have shown that both the induced electromotive force and the intrinsic properties of the conductive loop (resistance-dominant or inductance-dominant) determine together the electromechanical performance of the studied energy conversion system, and the nearly zero resistivity of superconductors is the dominant cause of the anomalous phenomenon. This paper has illuminated the origin of the anomalous electromechanical interaction between a moving magnetic dipole and a closed superconducting loop, provided an efficient and reliable tool to predict the electromechanical performance of the studied energy conversion system, and is believed to deepen people’s understanding of the interactions between magnetic field sources and superconductors.
35
Pinsky, M. R., G. M. Matuschak, L. Bernardi, and M. Klain. "Hemodynamic effects of cardiac cycle-specific increases in intrathoracic pressure." Journal of Applied Physiology 60, no. 2 (February 1, 1986): 604–12. http://dx.doi.org/10.1152/jappl.1986.60.2.604.
Full textAbstract:
Changes in intrathoracic pressure (ITP) can influence cardiac performance by affecting ventricular loading conditions. Because both systemic venous return and factors determining left ventricular (LV) ejection may vary over the cardiac cycle, phasic increases in ITP may differentially affect preload or afterload if delivered at specific points within the cardiac cycle. We studied the hemodynamic effects of cardiac cycle-specific increases in ITP (pulses) delivered by a high-frequency jet ventilator in an acute closed-chested canine model (n = 11), using electromagnetic flow probes to measure biventricular stroke volume. Measurements were taken during a control condition after the induction of acute ventricular failure (AVF) by propranolol hydrochloride and volume infusion. ITP was independently varied without changing lung volume by the inflation of thoracoabdominal binders. Although synchronous pulses had minimal hemodynamic effects in unbound controls, binding pulses timed to occur in early diastole resulted in decreases in LV filling pressure and left ventricular stroke volume (SVlv) (P less than 0.05). In the AVF condition, pulses increased LV performance, evidenced by increases in SVlv (P less than 0.01), despite decreases in LV filling pressure (P less than 0.05). This effect is maximized by binding and by timing the pulses to occur in systole. We conclude that cardiac cycle-specific increases in ITP can significantly affect cardiac performance. These effects appear to be related to the ability of such timed pulses to selectively affect LV preload and afterload.
36
Fernández, Rodrigo, Francois Foucart, and Jonas Lippuner. "The landscape of disc outflows from black hole–neutron star mergers." Monthly Notices of the Royal Astronomical Society 497, no. 3 (July 28, 2020): 3221–33. http://dx.doi.org/10.1093/mnras/staa2209.
Full textAbstract:
ABSTRACT We investigate mass ejection from accretion discs formed in mergers of black holes (BHs) and neutron stars (NSs). The third observing run of the LIGO/Virgo interferometers provided BH–NS candidate events that yielded no electromagnetic (EM) counterparts. The broad range of disc configurations expected from BH–NS mergers motivates a thorough exploration of parameter space to improve EM signal predictions. Here we conduct 27 high-resolution, axisymmetric, long-term hydrodynamic simulations of the viscous evolution of BH accretion discs that include neutrino emission/absorption effects and post-processing with a nuclear reaction network. In the absence of magnetic fields, these simulations provide a lower limit to the fraction of the initial disc mass ejected. We find a nearly linear inverse dependence of this fraction on disc compactness (BH mass over initial disc radius). The dependence is related to the fraction of the disc mass accreted before the ouflow is launched, which depends on the disc position relative to the innermost stable circular orbit. We also characterize a trend of decreasing ejected fraction and decreasing lanthanide/actinide content with increasing disc mass at fixed BH mass. This trend results from a longer time to reach weak freezout and an increasingly dominant role of neutrino absorption at higher disc masses. We estimate the radioactive luminosity from the disc outflow alone available to power kilonovae over the range of configurations studied, finding a spread of two orders of magnitude. For most of the BH–NS parameter space, the disc outflow contribution is well below the kilonova mass upper limits for GW190814.
37
Souza, Vitor Moura, Margarete Oliveira Domingues, Odim Mendes, and Aylton Pagamisse. "PLASMA STRUCTURE EXTRACTION FROM LASCO IMAGES BY THE DUAL-TREE COMPLEX WAVELET TRANSFORM." Revista Brasileira de Geofísica 33, no. 1 (November 19, 2015): 45. http://dx.doi.org/10.22564/rbgf.v33i1.600.
Full textAbstract:
ABSTRACT. Images of the Sun obtained in distinct electromagnetic ranges can be very useful to investigate electrodynamical processes that occur in this star. This work analyzes the application of a two-dimensional version of the Dual-Tree Complex Wavelet Transform (DTCWT) to highlight physical features in the Large Angle and Spectrometric Coronograph images. The importance of those features is that they are related with coronal ejections of magnetized solar plasma, which can produce geomagnetic disturbances at the Earth. The DTCWT is a laborious improvement of the well-known Discrete Wavelet Transform (DWT) with additional properties of shift invariance, ability to analyze multiple directions for multidimensional signals, and computationally efficient algorithms. The multilevel decomposition of an image with the DTCWT generates complex wavelet coefficients, which are manipulated for providing a proper visualization of the plasma structures, highlighting features, and helping further analyses. The methodology implemented here is of interest to space weather laboratories and has been shown to be a very useful tool to a better identification and characterization of the features related to magnetized plasma phenomena in the solar corona.Keywords: coronal mass ejection, solar plasma, solar corona images, complex wavelet transform, space weather.RESUMO. Imagens do Sol obtidas em diferentes intervalos do espectro eletromagnético podem ser bem úteis na investigação de processos eletrodinâmicos que ocorrem nesta estrela. Este trabalho analisa a aplicação de uma versão bidimensional da Transformada Wavelet Complexa de dupla árvore (DTCWT) para destacar características físicas nas imagens do Coronógrafo Espectométrico de Ângulo Largo (LASCO). A importância dessas características é que elas estão relacionadas a ejeções coronais de plasma solar magnetizado, que podem produzir perturbações geomagnéticas na Terra. A DTCWT é um aprimoramento laborioso da bem conhecida Transformada Wavelet Discreta (DWT), com propriedades adicionais de: (i) invariância a deslocamentos, (ii) habilidade em analisar múltiplas direções para sinais multidimensionais, e (iii) algoritmo computacionalmente eficiente. A decomposição multinível de uma imagem com a DTCWT gera coeficientes wavelets complexos, que são manipulados para prover uma visualização adequada das estruturas de plasmas, destacando características, e ajudando nas análises posteriores. De interesse dos laboratórios de Clima Espacial, a metodologia implementada aqui mostrou-se ser muito útil para uma melhor identificação e caracterização dos fenômenos de plasmas magnetizados na coroa solar.Palavras-chave: ejeção de massa coronal, plasma solar, imagens da coroa solar, transformada wavelet complexa, clima espacial.
38
Fernández, Rodrigo, Ben Margalit, and Brian D. Metzger. "Nuclear-dominated accretion flows in two dimensions – II. Ejecta dynamics and nucleosynthesis for CO and ONe white dwarfs." Monthly Notices of the Royal Astronomical Society 488, no. 1 (June 27, 2019): 259–79. http://dx.doi.org/10.1093/mnras/stz1701.
Full textAbstract:
ABSTRACT We study mass ejection from accretion discs formed in the merger of a white dwarf with a neutron star or black hole. These discs are mostly radiatively inefficient and support nuclear fusion reactions, with ensuing outflows and electromagnetic transients. Here we perform time-dependent, axisymmetric hydrodynamic simulations of these discs including a physical equation of state, viscous angular momentum transport, a coupled 19-isotope nuclear network, and self-gravity. We find no detonations in any of the configurations studied. Our global models extend from the central object to radii much larger than the disc. We evolve these global models for several orbits, as well as alternate versions with an excised inner boundary to much longer times. We obtain robust outflows, with a broad velocity distribution in the range 102–104 km s−1. The outflow composition is mostly that of the initial white dwarf, with burning products mixed in at the ${\lesssim } 10\rm {-}30{{\ \rm per\ cent}}$ level by mass, including up to ∼10−2 M⊙ of 56Ni. These heavier elements (plus 4He) are ejected within ≲ 40° of the rotation axis, and should have higher average velocities than the lighter elements that make up the white dwarf. These results are in broad agreement with previous one- and two-dimensional studies, and point to these systems as progenitors of rapidly rising (∼ few day) transients. If accretion on to the central BH/NS powers a relativistic jet, these events could be accompanied by high-energy transients with peak luminosities ∼1047–1050 erg s−1 and peak durations of up to several minutes, possibly accounting for events like CDF-S XT2.
39
SODHA, MAHENDRA SINGH, and MOHAMMAD FAISAL. "Filamentation instability in a collisional magnetoplasma with thermal conduction." Journal of Plasma Physics 75, no. 4 (August 2009): 563–73. http://dx.doi.org/10.1017/s0022377809007831.
Full textAbstract:
AbstractThis paper presents an analysis of the spatial growth of a transverse instability, corresponding to the propagation of an electromagnetic beam, with uniform irradiance along the wavefront in a collisional plasma, along the direction of a static magnetic field; expressions have been derived for the rate of growth, the maximum value of the rate of growth and the corresponding value of the wave number of the instability. The instability arises on account of the ejection of electrons from regions where the irradiance of the perturbation is large. The energy balance of the electrons taking into account ohmic heating and the power loss of electrons on account of (i) collisions with ions and neutral species and (ii) thermal conduction has been taken into account for the evaluation of the perturbation in electron temperature, which determines the subsequent growth of the instability. Further, the relationship between the electron density and temperature, as obtained from the kinetic theory, has been used. The filamentation instability becomes enhanced with the increase of the static magnetic field for the extraordinary mode while the reverse is true for the ordinary mode. Dependence of growth rate on irradiance of the main beam, magnetic field and a parameter proportional to the ratio of power loss of electrons by conduction to that by collisions has been numerically studied and illustrated by figures. The dependence of the maximum growth rate and the corresponding optimum value of the wave number of the instability on the irradiance of the main beam has also been studied. The paper concludes with a discussion of the numerical results, so obtained.
40
SIVERSKY, TARAS V., and VALENTINA V. ZHARKOVA. "Particle acceleration in a reconnecting current sheet: PIC simulation." Journal of Plasma Physics 75, no. 5 (October 2009): 619–36. http://dx.doi.org/10.1017/s0022377809008009.
Full textAbstract:
AbstractThe acceleration of protons and electrons in a reconnecting current sheet (RCS) is simulated with a particle-in-cell (PIC) 2D3V (two-dimensional in space and three-dimensional in velocity space) code for the proton-to-electron mass ratio of 100. The electromagnetic configuration forming the RCS incorporates all three components of the magnetic field (including the guiding field) and a drifted electric field. PIC simulations reveal that there is a polarization electric field that appears during acceleration owing to a separation of electrons from protons towards the midplane of the RCS. If the plasma density is low, the polarization field is weak and the particle trajectories in the PIC simulations are similar to those in the test particle (TP) approach. For the higher plasma density the polarization field is stronger and it affects the trajectories of protons by increasing their orbits during acceleration. This field also leads to a less asymmetrical abundance of ejected protons towards the midplane in comparison with the TP approach. For a given magnetic topology electrons in PIC simulations are ejected to the same semispace as protons, in contrast to the TP results. This happens because the polarization field extends far beyond the thickness of a current sheet. This field decelerates the electrons, which are initially ejected into the semispace opposite to the protons, returns them back to the RCS, and, eventually, leads to the electron ejection into the same semispace as protons. The energy distribution of the ejected electrons is rather wide and single-peaked, in contrast to the two-peak narrow-energy distribution obtained in the TP approach. In the case of a strong guiding field, the mean energy of the ejected electrons is found to be smaller than it is predicted analytically and by the TP simulations. The beam of accelerated electrons is also found to generate turbulent electric field in the form of Langmuir waves.
41
Komossa, S. "Electromagnetic Signatures of Recoiling Black Holes." Proceedings of the International Astronomical Union 5, S267 (August 2009): 451–57. http://dx.doi.org/10.1017/s174392131000699x.
Full textAbstract:
AbstractRecent numerical relativity simulations predict that coalescing supermassive black holes (SMBHs) can receive kick velocities up to several thousands of kilometers per second due to anisotropic emission of gravitational waves, leading to long-lived oscillations of the SMBHs in galaxy cores and even SMBH ejections from their host galaxies. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically offset from their host galaxies. The presence of these “kicks” and “superkicks” has a wide range of exciting astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy growth at the epoch of structure formation, modes of feedback, unified models of AGN, and the number of obscured AGN. SMBH recoil oscillations beyond the torus scale can be on the order of a quasar lifetime, thus potentially affecting a large fraction of the quasar population. We discuss how this might explain the long-standing puzzle of a deficiency of obscured type 2 quasars at high luminosities. Observational signatures of recoiling SMBHs are discussed and results from follow-up studies of the candidate recoiling SMBH SDSSJ0927+2943 are presented.
42
Xia, Shengguo, Pengfei Wu, Yan Xiong, Jinghan Xu, Jinghui Ruan, Zengji Wang, Lixue Chen, and Chengxian Li. "Simulation on Side-Ejecting Characteristics of Metal Liquid Film in Electromagnetic Launcher." IEEE Transactions on Plasma Science 48, no. 11 (November 2020): 4006–13. http://dx.doi.org/10.1109/tps.2020.3027719.
Full text
43
Komossa, S. "Recoiling Black Holes: Electromagnetic Signatures, Candidates, and Astrophysical Implications." Advances in Astronomy 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/364973.
Full textAbstract:
Supermassive black holes (SMBHs) may not always reside right at the centers of their host galaxies. This is a prediction of numerical relativity simulations, which imply that the newly formed single SMBH, after binary coalescence in a galaxy merger, can receive kick velocities up to several 1000 km/s due to anisotropic emission of gravitational waves. Long-lived oscillations of the SMBHs in galaxy cores, and in rare cases even SMBH ejections from their host galaxies, are the consequence. Observationally, accreting recoiling SMBHs would appear as quasars spatially and/or kinematically offset from their host galaxies. The presence of the “kicks” has a wide range of astrophysical implications which only now are beginning to be explored, including consequences for black hole and galaxy assembly at the epoch of structure formation, black hole feeding, and unified models of active galactic nuclei (AGN). Here, we review the observational signatures of recoiling SMBHs and the properties of the first candidates which have emerged, including follow-up studies of the candidate recoiling SMBH of SDSSJ092712.65+294344.0.
44
Cheng, Zhi. "Cherenkov Radiation of Gravitational Waves." Advances in Geoscience 3, no. 1 (December 27, 2019): 28. http://dx.doi.org/10.18686/ag.v3i1.2009.
Full textAbstract:
<p align="justify">If the velocity of gravitational waves is less than the speed of light, the velocity of mass motion may exceed the velocity of gravitational waves. This will cause Cherenkov-like radiation similar to electromagnetic interaction. The Cherenkov-like radiation of gravitational waves will produce a relatively specific observable effect. Due to the concentrated release of energy, the easiest to observe is that a large number of photons are radiated from the Cherenkov-like radiation source to form optical effects of high intensity and relatively special shapes. The speed of gravitational waves is less than the speed of light, because the compression of space and time by very large masses causes the gravitational waves to travel less in the masses than the speed of light. The mass of the material itself is not affected by this space-time compression. Thus, under certain conditions, the velocity of the mass of matter exceeds the velocity of the gravitational wave, forming a Cherenkov-like effect. A typical example is the aura of special structures formed by the supernova explosion. Among them, the supernova 1987A has been in existence for more than 30 years. After several years of the explosion, through the observation of the high-resolution Hubble telescope, it was found that the supernova 1987A showed two distinct auras in its explosion direction. There are many explanations for how these halos are formed. This paper points out that the formation of the two halos of the supernova 1987A is related to the propagation of gravitational waves in the mass of matter. Due to the very high mass density of the supernova explosion area, the space-time compression effect is very obvious, which will cause the gravitational wave to have a wave speed less than the speed of light. The material ejected by the supernova after exploding is close to the speed of light, and it is easy to exceed the velocity of gravitational waves propagating in the cosmic fluid around the supernova explosion, which will form the shock wave effect of gravitational waves. The Cherenkov effect of gravitational waves can also be used to explain the origin of high-intensity photon radiation in some galaxy centers. When the black hole in the center of the galaxy attracts the outer mass, the closer it is to the central black hole, the faster it moves. In the right position, the mass moves faster than the gravitational wave. The Cherenkov-like radiation of gravitational waves will be product. In addition, if there is a white hole, the energy is continuously released from the source of the white hole, which will also cause the mass ejection speed to exceed the speed of the gravitational wave, and thus produces the Cherenkov-like effect. Since the dynamic mechanism of the black hole and the white hole are different, by observing the Cherenkov-like effect of the center of the galaxy, it can effectively distinguish whether the center of the galaxy is a white hole or a black hole.</p>
45
Igarashi, Y., and H. Suga. "Assessment of slope of end-systolic pressure-volume line of in situ dog heart." American Journal of Physiology-Heart and Circulatory Physiology 250, no. 4 (April 1, 1986): H685—H692. http://dx.doi.org/10.1152/ajpheart.1986.250.4.h685.
Full textAbstract:
The purpose of this study was to establish a new method of assessment of the slope (Emax) of the end-systolic pressure-volume line (ESPVL) of the in situ heart. In anesthetized open-chest dogs, an isovolumic contraction was produced by an aortic occlusion after steady-state ejecting contractions in the left ventricle. We plotted ventricular pressure measured with a catheter-tip manometer against time integral of aortic flow measured with an electromagnetic flowmeter of the last ejecting and the first isovolumic contraction, assuming the same end-diastolic volume. ESPVL was drawn from the peak isovolumic pressure-volume point tangential to the left upper corner of the +/- 3.0 (SE) mmHg/ml (n = 9 dogs) in control run and was increased by 59 +/- 19% under isoproterenol and decreased by 47 +/- 9% after propranolol. Emax was little changed by atrial pacing. We conclude that Emax by this aortic occlusion method is useful for assessment of left ventricular contractility of the in situ dog heart.
46
Carfora, Luca. "Montecarlo simulation of the High Energy Particle Detector on board the satellite CSES." EPJ Web of Conferences 209 (2019): 01050. http://dx.doi.org/10.1051/epjconf/201920901050.
Full textAbstract:
The High-Energy Particle Detector (HEPD) is an instrument devoted to the measurement of cosmic particles from few MeV up to hundreds of MeV. The HEPD will contribute to the China Seismo-Electromagnetic Satellite mission by measuring the precipitation of trapped particles and by studying the solar-terrestrial environment especially during impulsive events like coronal mass ejections and solar energetic particle emissions. A Monte Carlo software was realized to study the performance of HEPD, such as its particle discrimination capability, the energy threshold for trigger and the maximum energy detectable in full containment. This contribution reports the main features of the HEPD Monte Carlo simulation and some results of the detector performance based on it. A comparison with beam tests was carried out, showing a good agreement with the simulation.
47
Haruki, T., J. I. Sakai, and S. Saito. "Electromagnetic wave emission during collision between a current sheet and a fast magnetosonic shock associated with coronal mass ejections." Astronomy & Astrophysics 455, no. 3 (August 16, 2006): 1099–103. http://dx.doi.org/10.1051/0004-6361:20065416.
Full text
48
Strachan, L., Y. K. Ko, J. D. Moses, J. M. Laming, F. Auchere, R. Casini, S. Fineschi, et al. "Waves and Magnetism in the Solar Atmosphere (WAMIS)." Proceedings of the International Astronomical Union 10, S305 (December 2014): 121–26. http://dx.doi.org/10.1017/s1743921315004639.
Full textAbstract:
AbstractMagnetic fields in the solar atmosphere provide the energy for most varieties of solar activity, including high-energy electromagnetic radiation, solar energetic particles, flares, and coronal mass ejections, as well as powering the solar wind. Despite the fundamental role of magnetic fields in solar and heliospheric physics, there exist only very limited measurements of the field above the base of the corona. What is needed are direct measurements of not only the strength and orientation of the magnetic field but also the signatures of wave motions in order to better understand coronal structure, solar activity, and the role of MHD waves in heating and accelerating the solar wind. Fortunately, the remote sensing instrumentation used to make magnetic field measurements is also well suited to measure the Doppler signature of waves in the solar structures. We present here a mission concept for the Waves And Magnetism In the Solar Atmosphere (WAMIS) experiment which is proposed for a NASA long-duration balloon flight.
49
Dröge, Wolfgang. "Particle Acceleration by Waves and Fields." Highlights of Astronomy 11, no. 2 (1998): 865–68. http://dx.doi.org/10.1017/s1539299600018967.
Full textAbstract:
The acceleration of electrons and charged nuclei to high energies is a phenomenon occuring at many sites throughout the universe, including the galaxy, pulsars, quasars, and around black holes. In the heliosphere, large solar flares and the often associated coronal mass ejections (CMEs) are the most energetic natural particle accelerators, occasionally accelerating protons to GeV and electrons to tens of MeV energies. The observation of these particles offers the unique opportunity to study fundamental processes in astrophysics. Particles that escape into interplanetary space can be observed in situ with particle detectors on spacecraft. In particular, particle spectra can be diagnostic of flare acceleration processes. On the other hand, energetic processes on the sun can be studied indirectly, via observations of the electromagnetic emissions (radio, X-ray, gamma-ray) produced by the particles in their interactions with the solar atmosphere. The purpose of this article is to give a brief overview on current models on particle acceleration and the present status of observations of solar energetic particles.
50
Akasofu, Syun-Ichi. "The electric current approach in the solar–terrestrial relationship." Annales Geophysicae 35, no. 4 (August 21, 2017): 965–78. http://dx.doi.org/10.5194/angeo-35-965-2017.
Full textAbstract:
Abstract. The sequence of phenomena consisting of solar flares, coronal mass ejections (CMEs), auroral substorms, and geomagnetic storms is mostly a manifestation of electromagnetic energy dissipation. Thus, first of all, it is natural to consider each of them in terms of a sequence of power supply (dynamo), power transmission (electric currents/circuits), and dissipation (mostly observed phenomena), i.e., as an input–output process and the electric current line approach. Secondly, extending this concept, it is attempted in this paper to consider the whole solar–terrestrial relationship in terms of electric currents. This approach enables us to follow through not only the sequence in solar flares, auroral substorms, and geomagnetic storms but also to connect all phenomena naturally as a continuous flow of magnetic energy (V[B2∕8π]) from the sun across the magnetopause. This consideration gives some insight into all the processes involved equally well compared with the magnetic field line approach, which has been adopted almost exclusively in the past.