Journal articles: 'Poynting flux dominated outflow'

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Gao, Wei-Hong. "SWIFT J164449.3+573451: A PLUNGING EVENT WITH A POYNTING-FLUX-DOMINATED OUTFLOW." Astrophysical Journal 761, no. 2 (December 3, 2012): 113. http://dx.doi.org/10.1088/0004-637x/761/2/113.

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Kirk, John G., and Gwenael Giacinti. "Inductive Acceleration of Ions in Poynting-flux-dominated Outflows." Astrophysical Journal 884, no. 1 (October 11, 2019): 62. http://dx.doi.org/10.3847/1538-4357/ab3c61.

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Zhang, B. B., B. Zhang, A. J. Castro-Tirado, Z. G. Dai, P. H. T. Tam, X. Y. Wang, Y. D. Hu, et al. "Transition from fireball to Poynting-flux-dominated outflow in the three-episode GRB 160625B." Nature Astronomy 2, no. 1 (November 20, 2017): 69–75. http://dx.doi.org/10.1038/s41550-017-0309-8.

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Meng, Yan-Zhi, Jin-Jun Geng, and Xue-Feng Wu. "The photosphere emission spectrum of hybrid relativistic outflow for gamma-ray bursts." Monthly Notices of the Royal Astronomical Society 509, no. 4 (November 3, 2021): 6047–58. http://dx.doi.org/10.1093/mnras/stab3132.

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ABSTRACT The photospheric emission in the prompt phase is the natural prediction of the original fireball model for gamma-ray burst (GRB) due to the large optical depth (τ > 1) at the base of the outflow, which is supported by the quasi-thermal components detected in several Fermi GRBs. However, which radiation mechanism (photosphere or synchrotron) dominates in most GRB spectra is still under hot debate. The shape of the observed photosphere spectrum from a pure hot fireball or a pure Poynting-flux-dominated outflow has been investigated before. In this work, we further study the photosphere spectrum from a hybrid outflow containing both a thermal component and a magnetic component with moderate magnetization (σ0 = LP/LTh ∼ 1 − 10), by invoking the probability photosphere model. The high-energy spectrum from such a hybrid outflow is a power law rather than an exponential cutoff, which is compatible with the observed Band function in a great amount of GRBs. Also, the distribution of the low-energy indices (corresponding to the peak-flux spectra) is found to be quite consistent with the statistical result for the peak-flux spectra of GRBs best-fitted by the Band function, with similar angular profiles of structured jet in our previous works. Finally, the observed distribution of the high-energy indices can be well understood after considering the different magnetic acceleration (due to magnetic reconnection and kink instability) and the angular profiles of dimensionless entropy with the narrower core.

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Zhang, B. B., B. Zhang, A. J. Castro-Tirado, Z. G. Dai, P. H. T. Tam, X. Y. Wang, Y. D. Hu, et al. "Publisher Correction: Transition from fireball to Poynting-flux-dominated outflow in the three-episode GRB 160625B." Nature Astronomy 2, no. 3 (January 31, 2018): 258. http://dx.doi.org/10.1038/s41550-018-0387-2.

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BARKOV, M. V., and S. S. KOMISSAROV. "MAGNETIC ACCELERATION OF ULTRARELATIVISTIC GRB AND AGN JETS." International Journal of Modern Physics D 17, no. 10 (September 2008): 1669–75. http://dx.doi.org/10.1142/s0218271808013285.

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We present numerical simulations of cold, axisymmetric, magnetically driven relativistic outflows. The outflows are initially sub-Alfvénic and Poynting-flux dominated, with total–to–rest-mass energy flux ratio up to μ ~ 620. To study the magnetic acceleration of jets we simulate flows confined within a funnel with a rigid wall of prescribed shape, which we take to be z ∝ ra (in cylindrical coordinates, with a ranging from 1 to 2). This allows us to eliminate the numerical dissipative effects induced by a free boundary with an ambient medium. We find that in all cases they converge to a steady state characterized by a spatially extended acceleration region. For the jet solutions the acceleration process is very efficient — on the outermost scale of the simulation more than half of the Poynting flux has been converted into kinetic energy flux, and the terminal Lorentz factor approached its maximum possible value (Γ∞ ≃ μ). The acceleration is accompanied by the collimation of magnetic field lines in excess of that dictated by the funnel shape. The numerical solutions are generally consistent with the semi-analytic self-similar jets solutions and the spatially extended acceleration observed in some astrophysical relativistic jets. In agreement with previous studies, we also find that the acceleration is significantly less effective for wind solutions suggesting that pulsar winds may remain Poynting dominated when they reach the termination shock.

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Li, Liang. "Multipulse Fermi Gamma-Ray Bursts. I. Evidence of the Transition from Fireball to Poynting-flux-dominated Outflow." Astrophysical Journal Supplement Series 242, no. 2 (May 31, 2019): 16. http://dx.doi.org/10.3847/1538-4365/ab1b78.

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Birn, J., and M. Hesse. "Reconnection in substorms and solar flares: analogies and differences." Annales Geophysicae 27, no. 3 (March 4, 2009): 1067–78. http://dx.doi.org/10.5194/angeo-27-1067-2009.

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Abstract. Magnetic reconnection is the crucial process in the release of magnetic energy associated with magnetospheric substorms and with solar flares. On the basis of three-dimensional resistive MHD simulations we investigate similarities and differences between the two scenarios. We address in particular mechanisms that lead to the onset of reconnection and energy release, transport, and conversion mechanisms. Analogous processes might exist in the motion of field line footpoints on the sun and in magnetic flux addition to the magnetotail. In both cases such processes might lead to a loss of neighboring equilibrium, characterized by the formation of a very thin embedded current sheet, which acts as trigger for reconnection. We find that Joule (or ohmic) dissipation plays only a minor role in the overall energy transfer associated with reconnection. The dominant transfer of released magnetic energy occurs to electromagnetic energy (Poynting) flux and to thermal energy transport as enthalpy flux. The former dominates in low-beta, specifically initially force-free current sheets expected for the solar corona, while the latter dominates in high-beta current sheets, such as the magnetotail. In both cases the outflow from the reconnection site becomes bursty, i.e. spatially and temporally localized, yet carrying most of the outflow energy. Hence an analogy might exist between bursty bulk flows (BBFs) in the magnetotail and pulses of Poynting flux in solar flares. Further similarities might exist in the role of collapsing magnetic flux tubes, as a consequence of reconnection, in the heating and acceleration of charged particles.

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Deng (邓巍), Wei, Hui Li (李晖), Bing Zhang (张冰), and Shengtai Li (李胜台). "RELATIVISTIC MHD SIMULATIONS OF COLLISION-INDUCED MAGNETIC DISSIPATION IN POYNTING-FLUX-DOMINATED JETS/OUTFLOWS." Astrophysical Journal 805, no. 2 (May 29, 2015): 163. http://dx.doi.org/10.1088/0004-637x/805/2/163.

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Siddique, Iqra, Saeeda Sajjad, and Khadeejah Motiwala. "The Prompt Emission of GRB 130518A and the Study of Its Outflow through Hybrid Jet Models." Astrophysical Journal 938, no. 2 (October 1, 2022): 159. http://dx.doi.org/10.3847/1538-4357/ac8d05.

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Abstract The nature of the prompt emission mechanism in gamma-ray bursts (GRBs) remains uncertain to date. This question is also tied to the composition of the jet: thermal, Poynting flux dominated or hybrid with both types of components. In this work, we aim to study these questions in the context of GRB 130518A. By analysing its prompt emission data from the Fermi Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT), we find that the time-integrated spectrum has a nonthermal component along with a subdominant blackbody component. We use these results to study the properties of the jet in various scenarios through the frameworks developed by Hascoët et al. and Gao & Zhang. Both frameworks exclude the pure fireball model for this GRB. In all other cases, the initial magnetic fraction is greater than the thermal fraction. For small launching radii of the jet, the favored nonthermal emission process is internal shocks. Magnetic reconnection seems likely only for very large initial radii.

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Huarte-Espinosa, Martín, and Adam Frank. "Magnetic towers and binary-formed disks: New results for planetary nebula evolution." Proceedings of the International Astronomical Union 7, S283 (July 2011): 164–67. http://dx.doi.org/10.1017/s1743921312010885.

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AbstractWe present new results of 3-D AMR MHD simulations focusing on two distinct aspects of PPN evolution. We first report new simulations of collimated outflows driven entirely by magnetic fields. These Poynting flux dominated “magnetic towers” hold promise for explaining key properties of PPN flows. Our simulations address magnetic tower evolution and stability. We also present results of a campaign of simulations to explore the development of accretion disks formed via wind capture. Our result focus on the limits of disk formation and the range of disk properties.

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Hardee, Philip E. "The stability of astrophysical jets." Proceedings of the International Astronomical Union 6, S275 (September 2010): 41–49. http://dx.doi.org/10.1017/s1743921310015620.

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AbstractJets are produced by young stellar objects (YSOs), by black hole binary star system “microquasars” (μQSOs), by active galactic nuclei (AGN), are associated with neutron stars and pulsar wind nebulae (PWNe), and are thought responsible for the gamma-ray bursts (GRBs). An understanding of these outflows must include how they are launched and collimated into jets, and how they propagate to large distances. Jets be they Poynting flux and/or kinetic flux dominated are current driven (CD) and/or Kelvin-Helmholtz (KH) velocity shear driven unstable. Here I present some of the work that is leading to a better understanding of the properties required for the observed relative stability of astrophysical jets.

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Gill, Ramandeep, and Jonathan Granot. "Temporal evolution of prompt GRB polarization." Monthly Notices of the Royal Astronomical Society 504, no. 2 (April 12, 2021): 1939–58. http://dx.doi.org/10.1093/mnras/stab1013.

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ABSTRACT The dominant radiation mechanism that produces the prompt emission in gamma-ray bursts (GRBs) remains a major open question. Spectral information alone has proven insufficient in elucidating its nature. Time-resolved linear polarization has the potential to distinguish between popular emission mechanisms, e.g. synchrotron radiation from electrons with a power-law energy distribution or inverse Compton scattering of soft seed thermal photons, which can yield the typical GRB spectrum but produce different levels of polarization. Furthermore, it can be used to learn about the outflow’s composition (i.e. whether it is kinetic-energy-dominated or Poynting-flux-dominated) and angular structure. For synchrotron emission, it is a powerful probe of the magnetic field geometry. Here, we consider synchrotron emission from a thin ultrarelativistic outflow, with bulk Lorentz factor Γ(R) = Γ0(R/R0)−m/2 ≫ 1, that radiates a Band-function spectrum in a single (multiple) pulse(s) over a range of radii, R0 ≤ R ≤ R0 + ΔR. Pulse profiles and polarization evolution at a given energy are presented for a coasting (m = 0) and accelerating (m = −2/3) thin spherical shell and for different viewing angles for a top-hat jet with sharp as well as smooth edges in emissivity. Four different magnetic field configurations are considered, such as a locally ordered field coherent over angular scales θB ≳ 1/Γ, a tangled field (B⊥) in the plane transverse to the radial direction, an ordered field (B∥) aligned in the radial direction, and a globally ordered toroidal field (Btor). All field configurations produce distinct polarization evolution with single (for B⊥ and B∥) and double (for Btor) 90○ changes in the polarization position angle.

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Starling, R. L. C., A. Rowlinson, A. J. van der Horst, and R. A. M. J. Wijers. "LOFAR detectability of prompt low-frequency radio emission during gamma-ray burst X-ray flares." Monthly Notices of the Royal Astronomical Society 494, no. 4 (April 30, 2020): 5787–92. http://dx.doi.org/10.1093/mnras/staa1168.

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ABSTRACT The prompt emission in long gamma-ray bursts (GRBs) arises from within relativistic outflows created during the collapse of massive stars, and the mechanism by which radiation is produced may be either magnetically or matter dominated. In this work, we suggest an observational test of a magnetically dominated Poynting flux model that predicts both γ-ray and low-frequency radio pulses. A common feature among early light curves of long GRBs are X-ray flares, which have been shown to arise from sites internal to the jet. Ascribing these events to the prompt emission, we take an established Swift XRT flare sample and apply a magnetically dominated wind model to make predictions for the timing and flux density of corresponding radio pulses in the ∼100–200 MHz band observable with radio facilities such as LOFAR. We find that 44 per cent of the X-ray flares studied would have had detectable radio emission under this model, for typical sensitivities reached using LOFAR’s rapid response mode and assuming negligible absorption and scattering effects in the interstellar and intergalactic medium. We estimate the rate of Swift GRBs displaying X-ray flares with detectable radio pulses, accessible to LOFAR, of order seven per year. We determine that LOFAR triggered observations can play a key role in establishing the long debated mechanism responsible for GRB prompt emission.

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Du, Tan-Tan, Zhao-Yang Peng, Jia-Ming Chen, Ting Li, and Yue Yin. "A Study of the Spectral Properties of Two Gamma-Ray Bursts with the Main Bursts and Postbursts." Astrophysical Journal 940, no. 1 (November 1, 2022): 48. http://dx.doi.org/10.3847/1538-4357/ac94d2.

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Abstract The jet composition in gamma-ray bursts (GRBs) is still an unsolved issue. We try to provide some clues to the issue by analyzing the spectral properties of GRB 160509A and GRB 130427A with a main burst and a postburst. We first perform Bayesian time-resolved spectral analysis and compare the spectral components and spectral properties of the main bursts and postbursts of the two bursts and find that both bursts have the thermal components, and the thermal components are mainly found in the main bursts, while the postbursts are mainly dominated by the nonthermal components. We also find that the low-energy spectral indices of some time bins in the main bursts of these two GRBs exceed the so-called synchronous dead line, and in the postburst, only GRB 160509A has four time bins exceeding the dead line, while none of GRB 130427A exceed the dead line. We then constrain the outflow properties of both bursts and find that the main bursts is consistent with the typical properties of photosphere radiation. Therefore, our results support the transition of the GRB jet component from the fireball to the Poynting-flux-dominated jet. Finally, after analyzing the correlation and parameter evolution of the spectral parameters of the two bursts, we find that the correlations of the spectral parameters have different behaviors in the main bursts and postbursts. The parameter evolution trends of the main bursts and postbursts also show consistent and inconsistent behavior; therefore, we currently cannot determine whether the main bursts and postbursts come from the same origin.

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Sharma, Vidushi, Shabnam Iyyani, Dipankar Bhattacharya, Tanmoy Chattopadhyay, Santosh V. Vadawale, and Varun B. Bhalerao. "Spectropolarimetric analysis of prompt emission of GRB 160325A: jet with evolving environment of internal shocks." Monthly Notices of the Royal Astronomical Society 493, no. 4 (March 4, 2020): 5218–32. http://dx.doi.org/10.1093/mnras/staa570.

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ABSTRACT GRB 160325A is the only bright burst detected by AstroSat CZT Imager in its primary field of view to date. In this work, we present the spectral and polarimetric analysis of the prompt emission of the burst using AstroSat, Fermi, and Niel Gehrels Swift observations. The prompt emission consists of two distinct emission episodes separated by a few seconds of quiescent/ mild activity period. The first emission episode shows a thermal component as well as a low polarization fraction of $PF \lt 37\, {{\ \rm per\ cent}}$ at $1.5\, \sigma$ confidence level. On the other hand, the second emission episode shows a non-thermal spectrum and is found to be highly polarized with $PF \gt 43\, {{\ \rm per\ cent}}$ at 1.5σ confidence level. We also study the afterglow properties of the jet using Swift/XRT data. The observed jet break suggests that the jet is pointed towards the observer and has an opening angle of 1.2° for an assumed redshift, z = 2. With composite modelling of polarization, spectrum of the prompt emission, and the afterglow, we infer that the first episode of emission originates from the photosphere with localized dissipation happening below it, and the second from the optically thin region above the photosphere. The photospheric emission is generated mainly by inverse Compton scattering, whereas the emission in the optically thin region is produced by the synchrotron process. The low radiation efficiency of the burst suggests that the outflow remains baryonic dominated throughout the burst duration with only a subdominant Poynting flux component, and the kinetic energy of the jet is likely dissipated via internal shocks which evolves from an optically thick to optically thin environment within the jet.

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Kirk, John G., and Iwona Mochol. "Waves in Poynting-flux dominated jets." Proceedings of the International Astronomical Union 6, S275 (September 2010): 77–81. http://dx.doi.org/10.1017/s1743921310015668.

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AbstractHigh-energy emission from blazars is thought to arise in a relativistic jet launched by a supermassive black hole. The rapid variability of the emission suggests that structure of length scale smaller than the gravitational radius of the central black hole is imprinted on the jet as it is launched, and modulates the radiation released after it has been accelerated to high Lorentz factor. We describe a mechanism which can account for the acceleration of the jet, and for the rapid variability of the radiation, based on the propagation characteristics of nonlinear waves in charge-starved, polar jets. These exhibit a delayed acceleration phase, that kicks-in when the inertia associated with the wave currents becomes important. The time structure imprinted on the jet at launch modulates the photons produced by the accelerating jet provided that the electromagnetic cascade in the black-hole magnetosphere is not prolific.

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18

Sikora, Marek, Mitchell C. Begelman, Greg M. Madejski, and Jean‐Pierre Lasota. "Are Quasar Jets Dominated by Poynting Flux?" Astrophysical Journal 625, no. 1 (May 20, 2005): 72–77. http://dx.doi.org/10.1086/429314.

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Kirk, J. G., and O. Skjæraasen. "The σ Problem of the Crab Pulsar Wind." Symposium - International Astronomical Union 218 (2004): 171–74. http://dx.doi.org/10.1017/s007418090018088x.

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The conversion of the Crab pulsar wind from one dominated by Poynting flux close to the star to one dominated by particle-borne energy at the termination shock is considered. The idea put forth by Coroniti (1990) and criticized by Lyubarsky & Kirk (2001) that reconnection in a striped wind is responsible, is generalized to include faster prescriptions for the a priori unknown dissipation rate. Strong acceleration of the wind is confirmed, and the higher dissipation rates imply complete conversion of Poynting flux into particle-borne flux within the unshocked wind.

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CAREY, C. S., C. R. SOVINEC, S. HEINZ, and J. E. EVERETT. "MAGNETIC COLLIMATION AND MAGNETOHYDRODYNAMIC KINK INSTABILITY DRIVEN BY DIFFERENTIAL ROTATION." International Journal of Modern Physics D 17, no. 10 (September 2008): 1707–13. http://dx.doi.org/10.1142/s0218271808013327.

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We investigate the launching and stability of extragalactic jets through magnetohydrodynamic simulations of jet evolution. In these simulations, a small scale equilibrium magnetic corona is twisted by a differentially rotating accretion disk. Two-dimensional calculations show the formation of a collimated outflow. This outflow is divided into two regions by the Alfvén surface: a magnetically dominated Poynting region, and a kinetically dominated region. Three-dimensional calculations show that the outflow is unstable to the m = 1 kink instability, and that the growth rate of the kink instability decreases as the rotation rate of the accretion disk increases.

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Kadowaki, Luis H. S., Elisabete M. de Gouveia Dal Pino, Tania E. Medina-Torrejón, Yosuke Mizuno, and Pankaj Kushwaha. "Fast Magnetic Reconnection Structures in Poynting Flux-dominated Jets." Astrophysical Journal 912, no. 2 (May 1, 2021): 109. http://dx.doi.org/10.3847/1538-4357/abee7a.

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LEE, HYUN KYU. "POYNTING FLUX DOMINATED ACCRETION FLOW: A TWO-DIMENSIONAL MODEL." Modern Physics Letters A 21, no. 03 (January 30, 2006): 181–96. http://dx.doi.org/10.1142/s0217732306019220.

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The dynamics of the accretion flow onto a black hole driven by Poynting flux is discussed in a simplified model of a two-dimensional accretion disk on equatorial plane. In an axisymmetric, stationary and force-free magnetosphere, the accretion flow is described by the three accretion equations obtained from the conservation of stress–energy tensor and one stream equation for a force-free magnetosphere. It is found that the angular velocity of the magnetic surface can be obtained by the dynamics of the accreting matter, [Formula: see text]. The effect of the magnetic field on the accretion flow is discussed in detail using the paraboloidal type configuration suggested by Blandford in 1976. In numerical analysis, it is demonstrated that the angular velocity of the disk, ΩD, deviates from the Keplerian angular velocity and the dynamics of the accretion disk is found to depend strongly on the ratio of the accretion rate to the magnetic field strength.

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Bégué, D., and A. Pe’er. "POYNTING-FLUX-DOMINATED JETS CHALLENGED BY THEIR PHOTOSPHERIC EMISSION." Astrophysical Journal 802, no. 2 (April 2, 2015): 134. http://dx.doi.org/10.1088/0004-637x/802/2/134.

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Huarte-Espinosa, M., A. Frank, E. G. Blackman, A. Ciardi, P. Hartigan, S. V. Lebedev, and J. P. Chittenden. "Comparing Poynting flux dominated magnetic tower jets with kinetic-energy dominated jets." High Energy Density Physics 9, no. 2 (June 2013): 264–68. http://dx.doi.org/10.1016/j.hedp.2013.01.010.

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Giannios, D., and H. C. Spruit. "The role of kink instability in Poynting-flux dominated jets." Astronomy & Astrophysics 450, no. 3 (April 19, 2006): 887–98. http://dx.doi.org/10.1051/0004-6361:20054107.

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Paesold, G., E. G. Blackman, and P. Messmer. "On particle acceleration and trapping by Poynting flux dominated flows." Plasma Physics and Controlled Fusion 47, no. 11 (October 10, 2005): 1925–47. http://dx.doi.org/10.1088/0741-3335/47/11/005.

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Melatos, A. "Theory of Pulsar Winds." Symposium - International Astronomical Union 218 (2004): 143–50. http://dx.doi.org/10.1017/s0074180900180830.

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Recent progress in the theory of pulsar wind electrodynamics is reviewed, with emphasis on the following open questions, (i) Is the bipolar, jet-torus geometry imprinted by collimation or injection? (ii) what is the magnetic field geometry as a function of latitude, and is it stable? (iii) How rapidly does the postshock flow fluctuate, e.g. in the near infrared? (iv) The σ paradox: is Poynting flux converted gradually to kinetic energy flux as the wind expands, as in a linear accelerator, or is the conversion lossy, due to reconnection or parametric instabilities in a wave-like outflow?

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Kuijpers, Jan. "Equatorial Pulsar Winds." Publications of the Astronomical Society of Australia 18, no. 4 (2001): 407–14. http://dx.doi.org/10.1071/as01048.

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AbstractAtraditional problem in pulsar wind physics has been the nature of the pulsar wind.Ontheoretical grounds, the wind is expected to be dominated by Poynting flux associated with the outgoing magnetic field lines anchored on the polar caps of the rotating neutron star, while observations of the Crab Nebula demonstrate that the wind must be dominated by kinetic energy before the termination shock. Here we suggest a new approach to this old problem by studying the distributed currents rather than the singular sheet currents which have been the object of study in most work.We find that, at a distance well in between the light cylinder and the termination shock, current starvation sets in, and electric fields develop along the magnetic field lines which cause the current to dissipate and convert at least half of the Poynting flux into kinetic energy flux in a relatively thin shell. In the shell, at least half of the current closes across the magnetic field lines, the pitch of the spiralling magnetic field lines jumps downward strongly, and the outer pattern of magnetic field lines slips over the inner pattern.

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Hanami, Hitoshi. "Gamma Ray Bursts as Death of Magnetized Neutron Stars." International Astronomical Union Colloquium 160 (1996): 361–62. http://dx.doi.org/10.1017/s0252921100041907.

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AbstractWe propose magnetic cannon ball mechanism in which the collapse of a magnetosphere onto a black hole can generate strong outward Poynting flux which can drive a baryon-free fireball. This process can occur at the final collapsing phase of a neutron star with strong magnetic field. The magnetic cannon ball can drive a relativistic outflow without the rotation of the central object. This baryon-free process can explain gamma-ray bursts as the final phase of dead pulsars.

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Lee, Hyun Kyu. "Dynamics of Accretion Flows Dominated by the Poynting Flux onto Black Holes." Progress of Theoretical Physics Supplement 155 (2004): 369–70. http://dx.doi.org/10.1143/ptps.155.369.

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Lee, Hyun Kyu, and Hui-Kyung Kim. "Poynting Flux Dominated Black Hole-Accretion Disk System as GRB Power House." Symposium - International Astronomical Union 214 (2003): 323–30. http://dx.doi.org/10.1017/s0074180900194665.

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We investigate a black hole-accretion disk system which is dominated by Poynting flux to see whether it can be a possible power house for GRBs. For a set of GRBs for which the isotropic energy and Td are known, the effect of the disk mass and the magnetic field are discussed quantitatively using a simplified model. It is demonstrated explicitly that there is a lower limit on the angular momentum parameter for a given GRB energy. It is found that the most energetic GRBs can only accommodate relatively rapid-rotating black holes at the center.

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Semper, Bill. "Computation of outflow flux for convection-dominated transport equations." Communications in Numerical Methods in Engineering 9, no. 8 (August 1993): 639–47. http://dx.doi.org/10.1002/cnm.1640090803.

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ARKA, IOANNA, and JOHN G. KIRK. "LINEARLY POLARIZED SUPERLUMINAL WAVES IN PULSAR WINDS." International Journal of Modern Physics: Conference Series 08 (January 2012): 96–101. http://dx.doi.org/10.1142/s2010194512004461.

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Pulsar winds are the ideal environment for the study of non-linear electromagnetic waves. It is generally thought that a pulsar launches a striped wind, a magnetohydrodynamic entropy wave, where plasma sheets carried along with the flow separate regions of alternating magnetic field. But when the density drops below a critical value, or equivalently for distances from the pulsar greater than a critical radius, a strong superluminal wave can also propagate. In this contribution we discuss the conversion of the equatorial striped wind into a linearly polarized superluminal wave, and we argue that this mode is important for the conversion of Poynting flux to kinetic energy flux before the outflow reaches the termination shock.

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MURPHY, G. C., R. OUYED, and G. PELLETIER. "3D RESISTIVE MHD SIMULATIONS OF MAGNETIC RECONNECTION AND THE TEARING MODE INSTABILITY IN CURRENT SHEETS." International Journal of Modern Physics D 17, no. 10 (September 2008): 1715–21. http://dx.doi.org/10.1142/s0218271808013339.

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Magnetic reconnection plays a critical role in many astrophysical processes where high energy emission is observed, e.g. particle acceleration, relativistic accretion powered outflows, pulsar winds and probably in dissipation of Poynting flux in GRBs. The magnetic field acts as a reservoir of energy and can dissipate its energy to thermal and kinetic energy via the tearing mode instability. We have performed 3D nonlinear MHD simulations of the tearing mode instability in a current sheet. Results from a temporal stability analysis in both the linear regime and weakly nonlinear (Rutherford) regime are compared to the numerical simulations. We observe magnetic island formation, island merging and oscillation once the instability has saturated. The growth in the linear regime is exponential in agreement with linear theory. In the second, Rutherford regime the island width grows linearly with time. We find that thermal energy produced in the current sheet strongly dominates the kinetic energy. Finally preliminary analysis indicates a P(k) 4.8 power law for the power spectral density which suggests that the tearing mode vortices play a role in setting up an energy cascade.

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Machida, Masahiro N., and Shantanu Basu. "Different modes of star formation – II. Gas accretion phase of initially subcritical star-forming clouds." Monthly Notices of the Royal Astronomical Society 494, no. 1 (March 13, 2020): 827–45. http://dx.doi.org/10.1093/mnras/staa672.

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ABSTRACT The accretion phase of star formation is investigated in magnetically dominated clouds that have an initial subcritical mass-to-flux ratio. We employ non-ideal magnetohydrodynamic simulations that include ambipolar diffusion and ohmic dissipation. During the early prestellar phase, the mass-to-flux ratio rises towards the critical value for collapse, and during this time the angular momentum of the cloud core is reduced significantly by magnetic braking. Once a protostar is formed in the core, the accretion phase is characterized by the presence of a small amount of angular momentum but a large amount of magnetic flux in the near-protostellar environment. The low angular momentum leads to a very small (or even non-existent) disc and weak outflow, while the large magnetic flux can lead to an interchange instability that rapidly removes flux from the central region. The effective magnetic braking in the early collapse phase can even lead to a counterrotating disc and outflow, in which the rotation direction of the disc and outflow is opposite to that of the infalling envelope. The solutions with a counterrotating disc, tiny disc, or non-existent disc (direct collapse) are unique outcomes that are realized in collapse from magnetically dominated clouds with an initial subcritical mass-to-flux ratio.

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Kirk, J. G., and O. Skjaraasen. "Dissipation in Poynting‐Flux–dominated Flows: The σ‐Problem of the Crab Pulsar Wind." Astrophysical Journal 591, no. 1 (July 2003): 366–79. http://dx.doi.org/10.1086/375215.

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Romero, Gustavo, and Eduardo Gutiérrez. "The Origin of Matter at the Base of Relativistic Jets in Active Galactic Nuclei." Universe 6, no. 7 (July 18, 2020): 99. http://dx.doi.org/10.3390/universe6070099.

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The generation of relativistic jets in active sources such as blazars is a complex problem with many aspects, most of them still not fully understood. Relativistic jets are likely produced by the accretion of matter and magnetic fields onto spinning black holes. Ergospheric dragging effects launch a Poynting-dominated outflow in the polar directions of these systems. Observations with very high resolution of the jet in the nearby radio galaxy M87 and evidence of extremely fast variability in the non-thermal radiation of several other objects indicate that charged particles produce synchrotron emission and gamma rays very close to the base of the jet. How these particles are injected into the magnetically shielded outflow is a mystery. Here we explore the effects of various processes in the hot accretion inflow close to the black hole that might result in the copious production of neutral particles which, through annihilation and decay in the jet’s funnel, might load the outflow with mass and charged particles on scales of a few Schwarzschild radii.

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LOVELACE, R. V. E., and G. S. BISNOVATYI-KOGAN. "LARGE-SCALE MAGNETIC FIELD IN ACCRETION DISKS AND RELATIVISTIC POYNTING-FLUX JETS." International Journal of Modern Physics: Conference Series 08 (January 2012): 277–86. http://dx.doi.org/10.1142/s2010194512004710.

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In earlier works we pointed out that the disk's surface layers are non-turbulent and thus highly conducting (or non-diffusive) because of hydrodynamic and/or magnetorotational (MRI) instabilities are suppressed high in the disk where the magnetic and radiation pressures are larger than the plasma thermal pressure. We have derived equations for the vertical profiles of stationary accretion flows (with radial and azimuthal components), and the profiles of the large-scale, magnetic field taking into account the turbulent viscosity and diffusivity and the fact that the turbulence vanishes at the surface of the disk. Our recent analysis in Ref. 1 shows that the inward or outward advection of the large-scale magnetic field depends on the ratio [Formula: see text] of the accretion power going into magnetic disk winds to the viscous power dissipation and the plasma-β which is the ratio of the midplane plasma pressure to the magnetic pressure. Recent radio emission, polarization, and Faraday rotation maps of the radio jet of the galaxy 3C303 have been obtained in Ref. 2 and show that one component of this jet has a galactic-scale electric current of ~ 3 × 1018 A flowing along the jet axis. We show that this current can be used to calculate the electromagnetic energy flow in this magnetically dominated jet.

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Medina-Torrejón, Tania E., Elisabete M. de Gouveia Dal Pino, Luis H. S. Kadowaki, Grzegorz Kowal, Chandra B. Singh, and Yosuke Mizuno. "Particle Acceleration by Relativistic Magnetic Reconnection Driven by Kink Instability Turbulence in Poynting Flux–Dominated Jets." Astrophysical Journal 908, no. 2 (February 1, 2021): 193. http://dx.doi.org/10.3847/1538-4357/abd6c2.

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Li, Bin, Huigen Yang, Jicheng Sun, Zejun Hu, Jianjun Liu, Xiangcai Chen, Yongfu Wang, et al. "Cluster Observation of Ion Outflow in Middle Altitude LLBL/Cusp from Different Origins." Magnetochemistry 9, no. 2 (January 20, 2023): 39. http://dx.doi.org/10.3390/magnetochemistry9020039.

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The ionosphere is the ionized part of the upper atmosphere that is caused mainly by photoionization by solar extreme ultraviolet (EUV) emission and the atmospheric photochemistry process. The ionospheric ions escape from the ionosphere and populate the Earth’s magnetosphere. In this case study, ion outflows from two different origins were obtained by spacecraft Cluster C1 in the magnetospheric cusp region. One of the outflows was from the reflection of the dispersed solar wind particles. The other was the ionospheric outflow passing through the low latitude boundary layer of the cusp (LLBL/cusp), which was energized by downward Poynting flux. Similar to the reflected solar wind particles, outflowing ionospheric cold ions could also extend to the high-latitude region with magnetic field line convection, which mixed it up with solar wind particles. Based on the Cluster observation in the cusp region, two different origins of the outflowing particles were determined, and their unique mechanisms of formation were discussed. Results suggest that the strong electric field associated with solar wind particle precipitation may additionally accelerate the cold ionospheric ion flow in the LLBL/cusp.

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An, Xin, Anton Artemyev, Vassilis Angelopoulos, Andrei Runov, San Lu, and Philip Pritchett. "Suppression of reconnection in polarized, thin magnetotail current sheets: 2D simulations and implications." Physics of Plasmas 29, no. 9 (September 2022): 092901. http://dx.doi.org/10.1063/5.0088064.

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Many in situ spacecraft observations have demonstrated that magnetic reconnection in the Earth's magnetotail is largely controlled by the pre-reconnection current sheet configuration. One of the most important thin current sheet characteristics is the preponderance of electron currents driven by strong polarized electric fields, which are commonly observed in the Earth's magnetotail well before the reconnection. We use particle-in-cell simulations to investigate magnetic reconnection in the 2D magnetotail current sheet with a finite magnetic field component normal to the current sheet and with the current sheet polarization. Under the same external driving conditions, reconnection in a polarized current sheet is shown to occur at a lower rate than in a nonpolarized current sheet. The reconnection rate in a polarized current sheet decreases linearly as the electron current's contribution to the cross-tail current increases. In simulations with lower background temperature, the reconnection electric field is higher. We demonstrate that after reconnection in such a polarized current sheet, the outflow energy flux is mostly in the form of ion enthalpy flux, followed by electron enthalpy flux, Poynting flux, ion kinetic energy flux, and electron kinetic energy flux. These findings are consistent with spacecraft observations. Because current sheet polarization is not uniform along the magnetotail, our results suggest that it may slow down reconnection in the most polarized near-Earth magnetotail and thereby move the location of reconnection onset downtail.

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Howson, T. A., I. De Moortel, and L. E. Fyfe. "The effects of driving time scales on heating in a coronal arcade." Astronomy & Astrophysics 643 (November 2020): A85. http://dx.doi.org/10.1051/0004-6361/202038869.

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Context. The relative importance of alternating current (AC) and direct current (DC) heating mechanisms in maintaining the temperature of the solar corona is not well constrained. Aims. We aim to investigate the effects of the characteristic time scales of photospheric driving on the injection and dissipation of magnetic and kinetic energy within a coronal arcade. Methods. We conducted three-dimensional magnetohydrodynamic simulations of complex foot point driving imposed on a potential coronal arcade. We modified the typical time scales associated with the velocity driver to understand the efficiency of heating obtained using AC and DC drivers. We considered the implications for the injected Poynting flux and the spatial and temporal nature of the energy release in dissipative regimes. Results. For the same driver amplitude and complexity, long time scale velocity motions are able to inject a much greater Poynting flux of energy into the corona. Consequently, in non-ideal regimes, slow stressing motions result in a greater increase in plasma temperature than for wave-like driving. In dissipative simulations, Ohmic heating is found to be much more significant than viscous heating. For all drivers in our parameter space, energy dissipation is greatest close to the base of the arcade, where the magnetic field strength is strongest, and at separatrix surfaces, where the field connectivity changes. Across all simulations, the background field is stressed with random foot point motions (in a manner more typical of DC heating studies), and, even for short time scale driving, the injected Poynting flux is large given the small amplitude flows considered. For long time scale driving, the rate of energy injection was comparable to the expected requirements in active regions. The heating rates were found to scale with the perturbed magnetic field strength and not the total field strength. Conclusions. Alongside recent studies that show that power within the corona is dominated by low frequency motions, our results suggest that, in the closed corona, DC heating is more significant than AC heating.

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Lu, Yingchao, Fan Guo, Patrick Kilian, Hui Li, Chengkun Huang, and Edison Liang. "Studying particle acceleration from driven magnetic reconnection at the termination shock of a relativistic striped wind using particle-in-cell simulations." EPJ Web of Conferences 235 (2020): 07003. http://dx.doi.org/10.1051/epjconf/202023507003.

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A rotating pulsar creates a surrounding pulsar wind nebula (PWN) by steadily releasing an energetic wind into the interior of the expanding shockwave of supernova remnant or interstellar medium. At the termination shock of a PWN, the Poynting-flux- dominated relativistic striped wind is compressed. Magnetic reconnection is driven by the compression and converts magnetic energy into particle kinetic energy and accelerating particles to high energies. We carrying out particle-in-cell (PIC) simulations to study the shock structure as well as the energy conversion and particle acceleration mechanism. By analyzing particle trajectories, we find that many particles are accelerated by Fermi-type mechanism. The maximum energy for electrons and positrons can reach hundreds of TeV.

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Krumpen, T., M. Janout, K. I. Hodges, R. Gerdes, F. Girard-Ardhuin, J. A. Hölemann, and S. Willmes. "Variability and trends in Laptev Sea ice outflow between 1992–2011." Cryosphere Discussions 6, no. 4 (July 27, 2012): 2891–930. http://dx.doi.org/10.5194/tcd-6-2891-2012.

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Abstract. Variability and trends in seasonal and interannual ice area export out of the Laptev Sea between 1992 and 2011 are investigated using satellite-based sea ice drift and concentration data. We found an average winter (October to May) ice area transport across the northern and eastern Laptev Sea boundaries (NB and EB) of 3.48 × 105 km2. The average transport across the NB (2.87 × 105 km2) is thereby higher than across the EB (0.61 × 105 km2), with a less pronounced seasonal cycle. The total Laptev Sea ice area flux significantly increased over the last decades (0.85 × 105 km2/decade, p > 0.95), dominated by increasing export through the EB (0.55 × 105 km2/decade, p > 0.90), while the increase in export across the NB is small (0.3 × 105 km2/decade) and statistically not significant. The strong coupling between across-boundary SLP gradient and ice drift velocity indicates that monthly variations in ice area flux are primarily controlled by changes in geostrophic wind velocities, although the Laptev Sea ice circulation shows no clear relationship with large-scale atmospheric indices. Also there is no evidence of increasing wind velocities that could explain the overall positive trends in ice export. Following Spreenet al. (2011), we therefore assume that changes in ice flux rates may be related to changes in the ice cover such as thinning and/or a decrease in concentration. The use of a back-propagation method revealed that most of the ice that is incorporated into the Transpolar Drift is formed during freeze-up and originates from the central and western part of the Laptev Sea, while the exchange with the East Siberian Sea is dominated by ice coming from the Central and South-Eastern Laptev Sea. Furthermore, our results imply that the late winter (February to May) ice area flux may at least partially control the summer sea ice extent in the Laptev Sea.

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Rowlinson, A., K. Gourdji, K. van der Meulen, Z. S. Meyers, T. W. Shimwell, S. ter Veen, R. A. M. J. Wijers, et al. "LOFAR early-time search for coherent radio emission from GRB 180706A." Monthly Notices of the Royal Astronomical Society 490, no. 3 (October 21, 2019): 3483–92. http://dx.doi.org/10.1093/mnras/stz2866.

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ABSTRACT The nature of the central engines of gamma-ray bursts (GRBs) and the composition of their relativistic jets are still under debate. If the jets are Poynting flux dominated rather than baryon dominated, a coherent radio flare from magnetic reconnection events might be expected with the prompt gamma-ray emission. There are two competing models for the central engines of GRBs; a black hole or a newly formed millisecond magnetar. If the central engine is a magnetar it is predicted to produce coherent radio emission as persistent or flaring activity. In this paper, we present the deepest limits to date for this emission following LOFAR rapid response observations of GRB 180706A. No emission is detected to a 3σ limit of 1.7 mJy beam−1 at 144 MHz in a 2-h LOFAR observation starting 4.5 min after the gamma-ray trigger. A forced source extraction at the position of GRB 180706A provides a marginally positive (1σ) peak flux density of 1.1 ± 0.9 mJy. The data were time sliced into different sets of snapshot durations to search for FRB like emission. No short duration emission was detected at the location of the GRB. We compare these results to theoretical models and discuss the implications of a non-detection.

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46

Bhatta, Gopal. "Blazar Jets as Possible Sources of Ultra-High Energy Photons: A Short Review." Universe 8, no. 10 (October 1, 2022): 513. http://dx.doi.org/10.3390/universe8100513.

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In this paper, I present a qualitative discussion on the prospect of production of ultra-high photons in blazars. The sources are a subclass of active galactic nuclei which host supermassive black holes and fire relativistic jets into the intergalactic medium. The kpc-scale jets are believed to be dominated by Poynting flux and constitute one of the most efficient cosmic particle accelerators, that potentially are capable of accelerating the particles up to EeV energies. Recent IceCube detection of astrophysical neutrino emissions, in coincidence with the enhanced gamma-ray from Tev blazar TXS 0506 + 056, further supports hadronic models of blazar emissions in which particle acceleration processes, such as relativistic shocks, magnetic re-connection, and relativistic turbulence, could energize hadrons, e.g., protons, up to energies equivalent to billions of Lorentz factors. The ensuing photo-pionic processes may then result in gamma-rays accompanied by neutrino flux. Furthermore, the fact that blazars are the dominant source of observed TeV emission encourages search for signatures of acceleration scenarios that would lead to the creation of ultra-high-energy photons.

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47

Jardine, M. "Three-dimensional steady-state magnetic reconnection." Journal of Plasma Physics 51, no. 3 (June 1994): 399–422. http://dx.doi.org/10.1017/s0022377800017657.

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A family of three-dimensional models of reconnection is presented in which the different members of the family are characterized by the vorticity with which plasma flows towards the reconnection site. The nature of this inflow also determines the size and speed of the outflow jet that carries reconnected field lines away from the reconnection site, and the shape of the MHD shocks that bound it. Flows with positive vorticity are of a flux pile-up type, for which the outflow jet is fastest and narrowest. Among those with negative vorticity is the three-dimensional analogue of Petschek reconnection. Not all combinations of vorticity and reconnection rate are possible; for those solutions with negative vorticity, there is a maximum reconnection rate. As the magnetic Reynolds number Rme or the current density is increased, this maximum is reduced and the possible types of solution become more polarized towards the two extremes of flux pile-up and slow compression regimes. Given a distribution of vorticities and inflow speeds, these models give the corresponding distribution of possible steady-state reconnection rates. As an illustrative example, we take Gaussian distributions of both to show that the resulting distribution is dominated by the flux pile-up regime.

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48

Krumpen, T., M. Janout, K. I. Hodges, R. Gerdes, F. Girard-Ardhuin, J. A. Hölemann, and S. Willmes. "Variability and trends in Laptev Sea ice outflow between 1992–2011." Cryosphere 7, no. 1 (February 28, 2013): 349–63. http://dx.doi.org/10.5194/tc-7-349-2013.

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Abstract. Variability and trends in seasonal and interannual ice area export out of the Laptev Sea between 1992 and 2011 are investigated using satellite-based sea ice drift and concentration data. We found an average total winter (October to May) ice area transport across the northern and eastern Laptev Sea boundaries (NB and EB) of 3.48 × 105 km2. The average transport across the NB (2.87 × 105 km2) is thereby higher than across the EB (0.61 × 105 km2), with a less pronounced seasonal cycle. The total Laptev Sea ice area flux significantly increased over the last decades (0.85 × 105 km2 decade−1, p > 0.95), dominated by increasing export through the EB (0.55 × 105 km2 decade−1, p > 0.90), while the increase in export across the NB is smaller (0.3 × 105 km2 decade−1) and statistically not significant. The strong coupling between across-boundary SLP gradient and ice drift velocity indicates that monthly variations in ice area flux are primarily controlled by changes in geostrophic wind velocities, although the Laptev Sea ice circulation shows no clear relationship with large-scale atmospheric indices. Also there is no evidence of increasing wind velocities that could explain the overall positive trends in ice export. The increased transport rates are rather the consequence of a changing ice cover such as thinning and/or a decrease in concentration. The use of a back-propagation method revealed that most of the ice that is incorporated into the Transpolar Drift is formed during freeze-up and originates from the central and western part of the Laptev Sea, while the exchange with the East Siberian Sea is dominated by ice coming from the central and southeastern Laptev Sea. Furthermore, our results imply that years of high ice export in late winter (February to May) have a thinning effect on the ice cover, which in turn preconditions the occurence of negative sea ice extent anomalies in summer.

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Nakamura, Masanori, and David L. Meier. "Poynting Flux–dominated Jets in Decreasing‐Density Atmospheres. I. The Nonrelativistic Current‐driven Kink Instability and the Formation of “Wiggled” Structures." Astrophysical Journal 617, no. 1 (December 10, 2004): 123–54. http://dx.doi.org/10.1086/425337.

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Chatterjee, K., and R. Narayan. "Flux Eruption Events Drive Angular Momentum Transport in Magnetically Arrested Accretion Flows." Astrophysical Journal 941, no. 1 (December 1, 2022): 30. http://dx.doi.org/10.3847/1538-4357/ac9d97.

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Abstract We evolve two high-resolution general relativistic magnetohydrodynamic simulations of advection-dominated accretion flows around nonspinning black holes (BHs), each over a duration ∼3 × 105 GM BH/c 3. One model captures the evolution of a weakly magnetized (SANE) disk and the other that of a magnetically arrested disk (MAD). Magnetic flux eruptions in the MAD model push out gas from the disk and launch strong winds with outflow efficiencies at times reaching 10% of the incoming accretion power. Despite the substantial power in these winds, average mass outflow rates remain low out to a radius ∼100GM BH/c 2, only reaching ∼60%–80% of the horizon accretion rate. The average outward angular momentum transport is primarily radial in both modes of accretion, but with a clear distinction: magnetic flux eruption–driven disk winds cause a strong vertical flow of angular momentum in the MAD model, while for the SANE model, the magnetorotational instability (MRI) moves angular momentum mostly equatorially through the disk. Further, we find that the MAD state is highly transitory and nonaxisymmetric, with the accretion mode often changing to a SANE-like state following an eruption before reattaining magnetic flux saturation with time. The Reynolds stress changes directions during such transitions, with the MAD (SANE) state showing an inward (outward) stress, possibly pointing to intermittent MRI-driven accretion in MADs. Pinning down the nature of flux eruptions using next-generation telescopes will be crucial in understanding the flow of mass, magnetic flux, and angular momentum in sub-Eddington accreting BHs like M87* and Sagittarius A*.

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Journal articles on the topic 'Poynting flux dominated outflow'

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