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Sample records for magnetized relativistic jets

  1. Asymptotic theory of relativistic, magnetized jets

    SciTech Connect

    Lyubarsky, Yuri

    2011-01-15

    The structure of a relativistically hot, strongly magnetized jet is investigated at large distances from the source. Asymptotic equations are derived describing collimation and acceleration of the externally confined jet. Conditions are found for the transformation of the thermal energy into the fluid kinetic energy or into the Poynting flux. Simple scalings are presented for the jet collimation angle and Lorentz factors.

  2. Asymptotic theory of relativistic, magnetized jets.

    PubMed

    Lyubarsky, Yuri

    2011-01-01

    The structure of a relativistically hot, strongly magnetized jet is investigated at large distances from the source. Asymptotic equations are derived describing collimation and acceleration of the externally confined jet. Conditions are found for the transformation of the thermal energy into the fluid kinetic energy or into the Poynting flux. Simple scalings are presented for the jet collimation angle and Lorentz factors.

  3. RECOLLIMATION SHOCKS IN MAGNETIZED RELATIVISTIC JETS

    SciTech Connect

    Mizuno, Yosuke; Rezzolla, Luciano; Gómez, Jose L.; Nishikawa, Ken-Ichi; Meli, Athina; Hardee, Philip E.

    2015-08-10

    We have performed two-dimensional special-relativistic magnetohydrodynamic simulations of non-equilibrium over-pressured relativistic jets in cylindrical geometry. Multiple stationary recollimation shock and rarefaction structures are produced along the jet by the nonlinear interaction of shocks and rarefaction waves excited at the interface between the jet and the surrounding ambient medium. Although initially the jet is kinematically dominated, we have considered axial, toroidal, and helical magnetic fields to investigate the effects of different magnetic-field topologies and strengths on the recollimation structures. We find that an axial field introduces a larger effective gas pressure and leads to stronger recollimation shocks and rarefactions, resulting in larger flow variations. The jet boost grows quadratically with the initial magnetic field. On the other hand, a toroidal field leads to weaker recollimation shocks and rarefactions, significantly modifying the jet structure after the first recollimation rarefaction and shock. The jet boost decreases systematically. For a helical field, instead, the behavior depends on the magnetic pitch, with a phenomenology that ranges between the one seen for axial and toroidal magnetic fields, respectively. In general, however, a helical magnetic field yields a more complex shock and rarefaction substructure close to the inlet that significantly modifies the jet structure. The differences in shock structure resulting from different field configurations and strengths may have observable consequences for disturbances propagating through a stationary recollimation shock.

  4. Magnetic Field Structure in Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Jermak, Helen; Mundell, Carole; Steele, Iain; Harrison, Richard; Kobayashi, Shiho; Lindfors, Elina; Nilsson, Kari; Barres de Almeida, Ulisses

    2013-12-01

    Relativistic jets are ubiquitous when considering an accreting black hole. Two of the most extreme examples of these systems are blazars and gamma-ray bursts (GRBs), the jets of which are thought to be threaded with a magnetic field of unknown structure. The systems are made up of a black hole accreting matter and producing, as a result, relativistic jets of plasma from the poles of the black hole. Both systems are viewed as point sources from Earth, making it impossible to spatially resolve the jet. In order to explore the structure of the magnetic field within the jet we take polarisation measurements with the RINGO polarimeters on the world's largest fully autonomous, robotic optical telescope: The Liverpool Telescope. Using the polarisation degree and angle measured by the RINGO polarimeters it is possible to distinguish between global magnetic fields created in the central engine and random tangled magnetic fields produced locally in shocks. We also monitor blazar sources regularly during quiescence with periods of flaring monitored more intensively. Reported here are the early polarisation results for GRBs 060418 and 090102, along with future prospects for the Liverpool Telescope and the RINGO polarimeters.

  5. Short and long term simulations of relativistic, magnetized jets

    NASA Astrophysics Data System (ADS)

    Aloy, M. A.

    2004-12-01

    We will present a series of numerical simulations addressed to understand the morphology and dynamics of relativistic, magnetized, axisymmetric jets. Some of the simulations have been specifically set up to follow the long term evolution of extragalactic jets under idealized conditions. The simulations have been done with an extension of the GENESIS code (Aloy et al 1999a} suitable for relativistic magnetohydrodynamcs applications. The code is based on a Godunov-type scheme whose building block is a method of lines. The numerical algorithm can provide up to third order of accuracy and makes use of a constrained transport method in order to keep the divergence--free condition of the magnetic field.

  6. Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Hededal, C.; Mizuno, Yosuke; Fishman, G. Jerry; Hartmann, D. H.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), supernova remnants, and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that particle acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration' is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different spectral properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations of relativistic jets and try to make a connection with observations.

  7. Simulations and analytic models of relativistic magnetized jets

    NASA Astrophysics Data System (ADS)

    Tchekhovskoi, Alexandre Dmitrievich

    Astrophysical jets are tightly collimated streams that are often observed to move at velocities close to the speed of light. While many such systems are known, understanding and explaining how jets collimate and accelerate has been a long-standing challenge and is currently an area of active research. Finding analytic solutions for jets is extremely hard because the equations that describe the jets are highly nonlinear and difficult to solve analytically. Only in the last few years has it become possible to simulate ultrarelativistic jets computationally, which has led to unprecedented insights into their structure. We now think that many relativistic jets are produced by magnetic fields twisted by the rotation of a central compact object, which can be a black hole or a neutron star. In this thesis I present numerical and analytical studies of relativistic jets. In Chapter 2, I start with a discussion of a simple, idealized model that has the bare minimum of ingredients needed for the production of jets: regular magnetic field, spinning central compact object, and externally imposed collimation. The model assumes that magnetic field in the jet is so strong that plasma inertia is negligible and can be ignored. The simplicity of this model allows for a fully analytic description and an intuitive understanding of the results. Despite being simple, this model possesses non-trivial properties and has important applications to various astrophysical systems --- compact object binaries, gamma-ray bursts, and active galactic nuclei. Chapters 3 -- 7 add an extra level of realism (and sophistication) into jet models: they account for mass inertia of the jet fluid and study its effects on the jet structure. Chapter 4 discusses the effect of jet confinement on the acceleration of the jet. Chapter 5 shows that deconfinement can also have a dramatic effect on the jet. Chapter 6 studies how the structure of the jet changes if the central object driving the jet is a black hole

  8. Radiation from Relativistic Jets in Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Hardee, P.; Niemiec, J.; Nordlund, A.; Frederiksen, J.; Mizuno, Y.; Sol, H.; Fishman, G. J.

    2008-01-01

    Using our new 3-D relativistic electromagnetic particle (REMP) code parallelized with MPI, we have investigated long-term particle acceleration associated with an relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. The simulations have been performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks. The acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value. Behind the bow shock in the jet shock strong electromagnetic fields are generated. These fields may lead to the afterglow emission. We have calculated the time evolution of the spectrum from two electrons propagating in a uniform parallel magnetic field to verify the technique.

  9. Magnetically driven relativistic jets and winds: Exact solutions

    NASA Technical Reports Server (NTRS)

    Contopoulos, J.

    1994-01-01

    We present self-consistent solutions of the full set of ideal MHD equations which describe steady-state relativistic cold outflows from thin accretion disks. The magnetic field forms a spiral which is anchored in the disk, rotates with it, and accelerates the flow out of the disk plane. The collimation at large distances depends on the total amount of electric current that flows along the jet. We considered various distributions of electric current and derived the result that in straight jets which extend to infinite distances, a strong electric current flows along their axis of symmetry. The asymptotic flow velocities are of the order of the initial rotational velocity at the base of the flow (a few tenths of the speed of light). The solutions are applied to both galactic (small-scale) and extragalactic (large-scale) jets.

  10. 3D RMHD Simulations of Magnetized Spine-Sheath Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Mizuno, Yosuke; Hardee, Philip; Nishikawa, Ken-Ichi

    2008-01-01

    We have performed numerical simulations of weakly and strongly magnetized relativistic jets embedded in a weakly and strongly magnetized stationary or mildly relativistic (0.5c) sheath flow using the RAISHIN code. In the numerical simulations a jet with Lorentz factor gamma=2.5 is processed to break the initial equilibrium configuration. Results of the numerical simulations are compared to theoretical predictions from a normal mode analysis of the linearized RMHD equations describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized sheath flow. The prediction of increased stability of a weakly-magnetized system with mildly relativistic sheath flow to Kelvin-Helmholtz instabilities and the stabilization of a strongly magnetized system with mildly relativistic sheath flow is confirmed by the numerical simulations.

  11. 3D RMHD Simulations of Magnetized Spine-sheath Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Mizuno, Yosuke; Hardee, Phillip; Ken-Ichi, Nishikawa

    2008-01-01

    We have performed numerical simulations of weakly and strongly magnetized relativistic jets embedded in a weakly and strongly magnetized stationary or mildly relativistic'(0.5c) sheath flow using the RAISHIN code. In the numerical simulations a jet with Lorentz factor gamma=2.5 is processed to break the initial equilibrium configuration. Results of the numerical simulations are compared to theoretical predictions from a normal mode analysis of the linearized RMHD equations describing a uniform axially magnetized cylindrical relativistic jet embedded in a uniform axially magnetized sheath flow. The prediction of increased stability of a weakly-magnetized system with mildly relativistic sheath flow to Kelvin-Helmholtz instabilities and the stabilization of a strongly-magnetized system with mildly relativistic sheath flow is confirmed by the numerical simulations.

  12. 3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

    2006-01-01

    Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

  13. 3-D RPIC Simulations of Relativistic Jets: Particle Acceleration, Magnetic Field Generation, and Emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Hededal, C. B.; Fishman, G. J.

    2006-01-01

    Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets into ambient plasmas show that acceleration occurs in relativistic shocks. The Weibel instability created in shocks is responsible for particle acceleration, and generation and amplification of highly inhomogeneous, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection in relativistic jets. The "jitter" radiation from deflected electrons has different properties than the synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understand the complex time evolution and spectral structure in relativistic jets and gamma-ray bursts. We will present recent PIC simulations which show particle acceleration and magnetic field generation. We will also calculate associated self-consistent emission from relativistic shocks.

  14. Radiation from Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Hardee, P.; Sol, H.; Medvedev, M.; Zhang, B.; Nordlund, A.; Frederiksen, J. T.; Fishman, G. J.; Preece, R.

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  15. Particle-in-cell Simulations of Global Relativistic Jets with Helical Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Duţan, Ioana; Nishikawa, Ken-Ichi; Mizuno, Yosuke; Niemiec, Jacek; Kobzar, Oleh; Pohl, Martin; Gómez, Jose L.; Pe'er, Asaf; Frederiksen, Jacob T.; Nordlund, Åke; Meli, Athina; Sol, Helene; Hardee, Philip E.; Hartmann, Dieter H.

    We study the interaction of relativistic jets with their environment, using 3-dimen- sional relativistic particle-in-cell simulations for two cases of jet composition: (i) electron-proton (e - - p +) and (ii) electron-positron (e +/-) plasmas containing helical magnetic fields. We have performed simulations of ``global'' jets containing helical magnetic fields in order to examine how helical magnetic fields affect kinetic instabilities such as the Weibel instability, the kinetic Kelvin-Helmholtz instability and the Mushroom instability. We have found that these kinetic instabilities are suppressed and new types of instabilities can grow. For the e - - p + jet, a recollimation-like instability occurs and jet electrons are strongly perturbed, whereas for the e +/- jet, a recollimation-like instability occurs at early times followed by kinetic instability and the general structure is similar to a simulation without a helical magnetic field. We plan to perform further simulations using much larger systems to confirm these new findings.

  16. Relativistic jets shine through shocks or magnetic reconnection?

    NASA Astrophysics Data System (ADS)

    Sironi, Lorenzo; Petropoulou, Maria; Giannios, Dimitrios

    2015-06-01

    Observations of gamma-ray-bursts and jets from active galactic nuclei reveal that the jet flow is characterized by a high radiative efficiency and that the dissipative mechanism must be a powerful accelerator of non-thermal particles. Shocks and magnetic reconnection have long been considered as possible candidates for powering the jet emission. Recent progress via fully-kinetic particle-in-cell simulations allows us to revisit this issue on firm physical grounds. We show that shock models are unlikely to account for the jet emission. In fact, when shocks are efficient at dissipating energy, they typically do not accelerate particles far beyond the thermal energy, and vice versa. In contrast, we show that magnetic reconnection can deposit more than 50 per cent of the dissipated energy into non-thermal leptons as long as the energy density of the magnetic field in the bulk flow is larger than the rest-mass energy density. The emitting region, i.e. the reconnection downstream, is characterized by a rough energy equipartition between magnetic fields and radiating particles, which naturally accounts for a commonly observed property of blazar jets.

  17. Particle Acceleration, Magnetic Field Generation and Emission from Relativistic Jets and Supernova Remnants

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hartmann, D. H.; Hardee, P.; Hededal, C.; Mizunno, Y.; Fishman, G. J.

    2006-01-01

    We performed numerical simulations of particle acceleration, magnetic field generation, and emission from shocks in order to understand the observed emission from relativistic jets and supernova remnants. The investigation involves the study of collisionless shocks, where the Weibel instability is responsible for particle acceleration as well as magnetic field generation. A 3-D relativistic particle-in-cell (RPIC) code has been used to investigate the shock processes in electron-positron plasmas. The evolution of theWeibe1 instability and its associated magnetic field generation and particle acceleration are studied with two different jet velocities (0 = 2,5 - slow, fast) corresponding to either outflows in supernova remnants or relativistic jets, such as those found in AGNs and microquasars. Slow jets have intrinsically different structures in both the generated magnetic fields and the accelerated particle spectrum. In particular, the jet head has a very weak magnetic field and the ambient electrons are strongly accelerated and dragged by the jet particles. The simulation results exhibit jitter radiation from inhomogeneous magnetic fields, generated by the Weibel instability, which has different spectral properties than standard synchrotron emission in a homogeneous magnetic field.

  18. Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Pair Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Mizuno, Y.

    2005-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created by relativistic pair jets are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. Simulations show that the Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  19. Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Pair Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Mizuno, Y.

    2005-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created by relativistic pair jets are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. Simulations show that the Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  20. Particle acceleration, magnetic field generation, and emission in relativistic pair jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Kouveliotou, C.; Fishman, G. J.; Mizuno, Y.

    2005-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Recent simulations show that the Weibel instability created by relativistic pair jets is responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet propagating through an ambient plasma with and without initial magnetic fields. The growth rates of the Weibel instability depends on the distribution of pair jets. The Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. This instability is also responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The jitter radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  1. Particle acceleration magnetic field generation, and emission in Relativistic pair jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Ramirez-Ruiz, E.; Hardee, P.; Hededal, C.; Kouveliotou, C.; Fishman, G. J.

    2005-01-01

    Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) are responsible for particle acceleration in relativistic pair jets. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic pair jet propagating through a pair plasma. Simulations show that the Weibel instability created in the collisionless shock accelerates particles perpendicular and parallel to the jet propagation direction. Simulation results show that this instability generates and amplifies highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The "jitter' I radiation from deflected electrons can have different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. The growth rate of the Weibel instability and the resulting particle acceleration depend on the magnetic field strength and orientation, and on the initial particle distribution function. In this presentation we explore some of the dependencies of the Weibel instability and resulting particle acceleration on the magnetic field strength and orientation, and the particle distribution function.

  2. Relativistic MHD simulations of core-collapse GRB jets: 3D instabilities and magnetic dissipation

    NASA Astrophysics Data System (ADS)

    Bromberg, Omer; Tchekhovskoy, Alexander

    2016-02-01

    Relativistic jets are associated with extreme astrophysical phenomena, like the core collapse of massive stars in gamma-ray bursts (GRBs) and the accretion on to supermassive black holes in active galactic nuclei. It is generally accepted that these jets are powered electromagnetically, by the magnetized rotation of a central compact object (black hole or neutron star). However, how the jets produce the observed emission and survive the propagation for many orders of magnitude in distance without being disrupted by current-driven instabilities is the subject of active debate. We carry out time-dependent 3D relativistic magnetohydrodynamic (MHD) simulations of relativistic, Poynting-flux-dominated jets. The jets are launched self-consistently by the rotation of a strongly magnetized central object. This determines the natural degree of azimuthal magnetic field winding, a crucial factor that controls jet stability. We find that the jets are susceptible to two types of instability: (i) a global, external kink mode that grows on long time-scales. It bodily twists the jet, reducing its propagation velocity. We show analytically that in flat density profiles, like the ones associated with galactic cores, the external mode grows and may stall the jet. In the steep profiles of stellar envelopes the external kink weakens as the jet propagates outward. (ii) a local, internal kink mode that grows over short time-scales and causes small-angle magnetic reconnection and conversion of about half of the jet electromagnetic energy flux into heat. We suggest that internal kink instability is the main dissipation mechanism responsible for powering GRB prompt emission.

  3. Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Pair Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K. I.; Hardee, P.; Hededal, C. B.; Richardson, G.; Sol, H.; Preece, R.; Fishman, G. J.

    2004-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating into an ambient plasma. We find that the growth times depend on the Lorenz factors of jets. The jets with larger Lorenz factors grow slower. Simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. The small scale magnetic field structure generated by the Weibel instability is appropriate to the generation of "jitter" radiation from deflected electrons (positrons) as opposed to synchrotron radiation. The jitter radiation resulting from small scale magnetic field structures may be important for understanding the complex time structure and spectral evolution observed in gamma-ray bursts or other astrophysical sources containing relativistic jets and relativistic collisionless shocks.

  4. 3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

  5. 3-D RPIC simulations of relativistic jets: Particle acceleration, magnetic field generation, and emission

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2006-01-01

    Nonthermal radiation observed from astrophysical systems containing (relativistic) jets and shocks, e.g., supernova remnants, active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Fermi acceleration is the mechanism usually assumed for the acceleration of particles in astrophysical environments. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet, rather than by the scattering of particles back and forth across the shock as in Fermi acceleration. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the .shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. We will review recent PIC simulations which show particle acceleration in jets.

  6. Differentially rotating relativistic magnetic jets. Asymptotic trans-field force-balance including differential rotation.

    NASA Astrophysics Data System (ADS)

    Fendt, C.

    1997-07-01

    Highly collimated jets are observed in various astronomical objects, as active galactic nuclei, galactic high energy sources, and also young stellar objects. There is observational indication that these jets originate in accretion disks, and that magnetic fields play an important role for the jet collimation and plasma acceleration. The rapid disk rotation close to the central object leads to relativistic rotational velocities of the magnetic field lines. The structure of these axisymmetric magnetic flux surfaces follows from the trans-field force-balance described by the Grad-Schlueter-Shafranov equation. In this paper, we investigate the asymptotic field structure of differentially rotating magnetic jets, widening the study by Appl & Camenzind (1993A&A...270...71A, 1993A&A...274..699A). In general, our results show that, with the same current distribution, differentially rotating jets are collimated to smaller jet radii as compared with jets with rigidly rotating field. Differentially rotating jets need a stronger net poloidal current in order to collimate to the same asymptotic radius. Current-free solutions are not possible for differentially rotating disk-jet magnetospheres with cylindrical asymptotics. We present a simple analytical relation between the poloidal current distribution and magnetic field rotation law. A general relation is derived for the current strength for jets with maximum differential rotation and minimum differential rotation. Analytical solutions are also given in the case of a field rotation leading to a degeneration of the light cylinder. By linking the asymptotic solution to a Keplerian accretion disk, 'total expansion rates' for the jets, and also the flux distribution at the foot points of the flux surfaces are derived. Large poloidal currents imply a strong opening of flux surfaces, a stronger gradient of field rotation leads to smaller expansion rates. There is indication that AGN jet expansion rates are less than in the case of

  7. Particle Acceleration, Magnetic Field Generation, and Associated Emission in Collisionless Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron)jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  8. Particle Acceleration, Magnetic Field Generation and Associated Emission in Collisionless Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K. I.; Ramirez-Ruiz, E.; Hardee, P.; Mizuno, Y.; Fishman. G. J.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  9. Particle Acceleration, Magnetic Field Generation, and Associated Emission in Collisionless Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron)jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  10. Particle Acceleration, Magnetic Field Generation and Associated Emission in Collisionless Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K. I.; Ramirez-Ruiz, E.; Hardee, P.; Mizuno, Y.; Fishman. G. J.

    2007-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electro-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  11. GRMHD/RMHD Simulations and Stability of Magnetized Spine-Sheath Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Hardee, Philip; Mizuno, Yosuke; Nishikawa, Ken-Ichi

    2007-01-01

    A new general relativistic magnetohydrodynamics (GRMHD ) code "RAISHIN" used to simulate jet generation by rotating and non-rotating black holes with a geometrically thin Keplarian accretion disk finds that the jet develops a spine-sheath structure in the rotating black hole case. Spine-sheath structure and strong magnetic fields significantly modify the Kelvin-Helmholtz (KH) velocity shear driven instability. The RAISHIN code has been used in its relativistic magnetohydrodynamic (RMHD) configuration to study the effects of strong magnetic fields and weakly relativistic sheath motion, cl2, on the KH instability associated with a relativistic, Y = 2.5, jet spine-sheath interaction. In the simulations sound speeds up to ? c/3 and Alfven wave speeds up to ? 0.56 c are considered. Numerical simulation results are compared to theoretical predictions from a new normal mode analysis of the RMHD equations. Increased stability of a weakly magnetized system resulting from c/2 sheath speeds and stabilization of a strongly magnetized system resulting from d 2 sheath speeds is found.

  12. Ambient magnetic field amplification in shock fronts of relativistic jets: an application to GRB afterglows

    NASA Astrophysics Data System (ADS)

    Rocha da Silva, G.; Falceta-Gonçalves, D.; Kowal, G.; de Gouveia Dal Pino, E. M.

    2015-01-01

    Strong downstream magnetic fields of the order of ˜1 G, with large correlation lengths, are believed to cause the large synchrotron emission at the afterglow phase of gamma-ray bursts (GRBs). Despite the recent theoretical efforts, models have failed to fully explain the amplification of the magnetic field, particularly in a matter-dominated scenario. We revisit the problem by considering the synchrotron emission to occur at the expanding shock front of a weakly magnetized relativistic jet over a magnetized surrounding medium. Analytical estimates and a number of high-resolution 2D relativistic magnetohydrodynamical (RMHD) simulations are provided. Jet opening angles of θ = 0°-20°, and ambient to jet density ratios of 10-4-102 were considered. We found that most of the amplification is due to compression of the ambient magnetic field at the contact discontinuity between the reverse and forward shocks at the jet head, with substantial pile-up of the magnetic field lines as the jet propagates sweeping the ambient field lines. The pile-up is maximum for θ → 0, decreasing with θ, but larger than in the spherical blast problem. Values obtained for certain models are able to explain the observed intensities. The maximum correlation lengths found for such strong fields is of lcorr ≤ 1014 cm, 2-6 orders of magnitude larger than the found in previous works.

  13. Shock Structure and Magnetic Fields Generation Associated with Relativistic Jets Unmagnetized Pair Plasma

    NASA Technical Reports Server (NTRS)

    Niemiec, J.; Nishikawa, K.-I.; Hardee, P.; Pohl, M.; Medvedev, M.; Mizuno, Y.; Zhang, B.; Oka, M.; Sol, H.; Hartmann, D.

    2009-01-01

    Using 3D and 2D particle-in-cell simulations we investigate a shock structure, magnetic field generation, and particle acceleration associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized pair plasma. The simulations use long computational grids which allow to study the formation and dynamics of the system in a spatial and temporal way. We find for the first time a relativistic shock system comparable to a predicted magnetohydrodynamic shock structure consisting of leading and trailing shocks separated by a contact discontinuity. Strong electromagnetic fields resulting from the Weibel two-stream instability are generated in the trailing shock where jet matter is thermalized and decelerated. We analyze the formation and nonlinear development through saturation and dissipation of those fields and associated particle acceleration. In the AGN context the trailing shock corresponds to the jet shock at the head of a relativistic astrophysical jet. In the GRB context this trailing shock can be identified with the bow shock driven by relativistic ejecta. The strong electromagnetic field region in the trailing shock provides the emission site for the hot spot at the leading edge of AGN jets and for afterglow emission from GRBs.

  14. Relativistic Jets and Collapsars

    NASA Astrophysics Data System (ADS)

    Zhang, W.; Woosley, S. E.

    2001-05-01

    In order to study the relativistic jets from collapsars, we have developed a special relativistic multiple-dimensional hydrodynamics code similar to the GENESIS code (Aloy et al., ApJS, 122, 151). The code is based on the PPM interpolation algorithm and Marquina's Riemann solver. Using this code, we have simulated the propagation of axisymmetric jets along the rotational axis of collapsed rotating stars (collapsars). Using the progenitors of MacFadyen, Woosley, and Heger, a relativistic jet is injected at a given inner boundary radius. This radius, the opening angle of the jet, its Lorentz factor, and its total energy are parameters of the problem. A highly collimated, relativistic outflow is observed at the surface of the star several seconds later. We will discuss the hydrodynamical focusing of the jet, it's break out properties, time evolution, and sensitivity to the adopted parameters.

  15. Microscopic Processes in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Nordlund, A.; Fredricksen, J.; Sol, H.; Niemiec, J.; Lyubarsky, Y.; Hartmann, D. H.; Fishman, G. J.

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  16. Microscopic Processes in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Nordlund, A.; Fredricksen, J.; Sol, H.; Niemiec, J.; Lyubarsky, Y.; hide

    2008-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  17. Kinematics of and Emission from Helically Orbiting Blobs in a Relativistic Magnetized Jet

    NASA Astrophysics Data System (ADS)

    Mohan, P.; Mangalam, A.

    2015-06-01

    We present a general relativistic (GR) model of jet variability in active galactic nuclei due to orbiting blobs in helical motion along a funnel or cone-shaped magnetic surface anchored to the accretion disk near the black hole. Considering a radiation pressure driven flow in the inner region, we find that it stabilizes the flow, yielding Lorentz factors ranging between 1.1 and 7 at small radii for reasonable initial conditions. Assuming these as inputs, simulated light curves (LCs) for the funnel model include Doppler and gravitational shifts, aberration, light bending, and time delay. These LCs are studied for quasi-periodic oscillations (QPOs) and the power spectral density (PSD) shape, and yield an increased amplitude (˜12%), a beamed portion and a systematic phase shift with respect to that from a previous special relativistic model. The results strongly justify implementing a realistic magnetic surface geometry in Schwarzschild geometry to describe effects on emission from orbital features in the jet close to the horizon radius. A power-law-shaped PSD with a typical slope of -2 and QPOs with timescales in the range of (1.37-130.7) days consistent with optical variability in blazars, emerges from the simulations for black hole masses {{M}\\bullet }=(0.5-5)× {{10}8} {{M}⊙ } and initial Lorentz factors {{γ }jet,i}=2-10. The models presented here can be applied to explain radio, optical, and X-ray variability from a range of jetted sources including active galactic nuclei, X-ray binaries, and neutron stars.

  18. Relativistic electrons and magnetic fields of the M87 jet on the ∼10 Schwarzschild radii scale

    SciTech Connect

    Kino, M.; Takahara, F.; Hada, K.; Doi, A.

    2014-05-01

    We explore energy densities of the magnetic fields and relativistic electrons in the M87 jet. Since the radio core at the jet base is identical to the optically thick surface against synchrotron self-absorption (SSA), the observing frequency is identical to the SSA turnover frequency. As a first step, we assume the radio core has a simple uniform sphere geometry. Using the observed angular size of the radio core measured by the Very Long Baseline Array at 43 GHz, we estimate the energy densities of magnetic fields (U{sub B} ) and relativistic electrons (U{sub e} ) on the basis of the standard SSA formula. Imposing the condition that the Poynting power and kinetic power of relativistic electrons should be smaller than the total power of the jet, we find that (1) the allowed range of the magnetic field strength (B {sub tot}) is 1 G ≤ B {sub tot} ≤ 15 G and that (2) 1 × 10{sup –5} ≤ U{sub e} /U{sub B} ≤ 6 × 10{sup 2} holds. The uncertainty of U{sub e} /U{sub B} comes from the strong dependence on the angular size of the radio core and the minimum Lorentz factor of non-thermal electrons (γ {sub e,min}) in the core. It is still unsettled whether resultant energetics are consistent with either the magnetohydrodynamic jet or the kinetic power dominated jet even on the ∼10 Schwarzschild radii scale.

  19. Relativistic Jets from Collapsars

    NASA Astrophysics Data System (ADS)

    Aloy, M. A.; Müller, E.; Ibáñez, J. M.; Martí, J. M.; MacFadyen, A.

    2000-03-01

    Using a collapsar progenitor model of MacFadyen & Woosley, we have simulated the propagation of an axisymmetric jet through a collapsing rotating massive star with the GENESIS multidimensional relativistic hydrodynamic code. The jet forms as a consequence of an assumed (constant or variable) energy deposition in the range of 1050-1051 ergs s-1 within a 30 deg cone around the rotation axis. The jet flow is strongly beamed (approximately less than a few degrees), spatially inhomogeneous, and time dependent. The jet reaches the surface of the stellar progenitor (R*=2.98x1010 cm) intact. At breakout, the maximum Lorentz factor of the jet flow is 33. After breakout, the jet accelerates into the circumstellar medium, whose density is assumed to decrease exponentially and then become constant, ρext=10-5 g cm-3. Outside the star, the flow begins to expand laterally also (v~c), but the beam remains very well collimated. At a distance of 2.54 R*, where the simulation ends, the Lorentz factor has increased to 44.

  20. Magnetohydrodynamic production of relativistic jets.

    PubMed

    Meier, D L; Koide, S; Uchida, Y

    2001-01-05

    A number of astronomical systems have been discovered that generate collimated flows of plasma with velocities close to the speed of light. In all cases, the central object is probably a neutron star or black hole and is either accreting material from other stars or is in the initial violent stages of formation. Supercomputer simulations of the production of relativistic jets have been based on a magnetohydrodynamic model, in which differential rotation in the system creates a magnetic coil that simultaneously expels and pinches some of the infalling material. The model may explain the basic features of observed jets, including their speed and amount of collimation, and some of the details in the behavior and statistics of different jet-producing sources.

  1. Relativistic MHD Simulations of Collision-induced Magnetic Dissipation in Poynting-flux-dominated Jets/outflows

    NASA Astrophysics Data System (ADS)

    Deng, Wei; Li, Hui; Zhang, Bing; Li, Shengtai

    2015-06-01

    We perform 3D relativistic ideal magnetohydrodynamics (MHD) simulations to study the collisions between high-σ (Poynting-flux-dominated (PFD)) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable PFD jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvénic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in the relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in PFD jets, such as the internal collision-induced magnetic reconnection and turbulence model for gamma-ray bursts, and reconnection triggered mini jets model for active galactic nuclei. The simulation movies are shown in http://www.physics.unlv.edu/∼deng/simulation1.html.

  2. Relativistic MHD simulations of collision-induced magnetic dissipation in poynting-flux-dominated jets/outflows

    SciTech Connect

    Deng, Wei; Li, Hui; Zhang, Bing; Li, Shengtai

    2015-05-29

    We perform 3D relativistic ideal MHD simulations to study the collisions between high-σ (Poynting- ux-dominated) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable Poynting- ux-dominated jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvenic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in the relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini-jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. In conclusion, our results give support to the proposed astrophysical models that invoke signi cant magnetic energy dissipation in Poynting- ux-dominated jets, such as the internal collision-induced magnetic reconnection and turbulence (ICMART) model for GRBs, and reconnection triggered mini-jets model for AGNs.

  3. Relativistic MHD simulations of collision-induced magnetic dissipation in poynting-flux-dominated jets/outflows

    DOE PAGES

    Deng, Wei; Li, Hui; Zhang, Bing; ...

    2015-05-29

    We perform 3D relativistic ideal MHD simulations to study the collisions between high-σ (Poynting- ux-dominated) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable Poynting- ux-dominated jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvenic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in themore » relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini-jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. In conclusion, our results give support to the proposed astrophysical models that invoke signi cant magnetic energy dissipation in Poynting- ux-dominated jets, such as the internal collision-induced magnetic reconnection and turbulence (ICMART) model for GRBs, and reconnection triggered mini-jets model for AGNs.« less

  4. RELATIVISTIC MHD SIMULATIONS OF COLLISION-INDUCED MAGNETIC DISSIPATION IN POYNTING-FLUX-DOMINATED JETS/OUTFLOWS

    SciTech Connect

    Deng, Wei; Zhang, Bing; Li, Hui; Li, Shengtai E-mail: zhang@physics.unlv.edu E-mail: sli@lanl.gov

    2015-06-01

    We perform 3D relativistic ideal magnetohydrodynamics (MHD) simulations to study the collisions between high-σ (Poynting-flux-dominated (PFD)) blobs which contain both poloidal and toroidal magnetic field components. This is meant to mimic the interactions inside a highly variable PFD jet. We discover a significant electromagnetic field (EMF) energy dissipation with an Alfvénic rate with the efficiency around 35%. Detailed analyses show that this dissipation is mostly facilitated by the collision-induced magnetic reconnection. Additional resolution and parameter studies show a robust result that the relative EMF energy dissipation efficiency is nearly independent of the numerical resolution or most physical parameters in the relevant parameter range. The reconnection outflows in our simulation can potentially form the multi-orientation relativistic mini jets as needed for several analytical models. We also find a linear relationship between the σ values before and after the major EMF energy dissipation process. Our results give support to the proposed astrophysical models that invoke significant magnetic energy dissipation in PFD jets, such as the internal collision-induced magnetic reconnection and turbulence model for gamma-ray bursts, and reconnection triggered mini jets model for active galactic nuclei. The simulation movies are shown in http://www.physics.unlv.edu/∼deng/simulation1.html.

  5. Diagnosing particle acceleration in relativistic jets

    NASA Astrophysics Data System (ADS)

    Böttcher, Markus; Baring, Matthew G.; Liang, Edison P.; Summerlin, Errol J.; Fu, Wen; Smith, Ian A.; Roustazadeh, Parisa

    2015-03-01

    The high-energy emission from blazars and other relativistic jet sources indicates that electrons are accelerated to ultra-relativistic (GeV - TeV) energies in these systems. This paper summarizes recent results from numerical studies of two fundamentally different particle acceleration mechanisms potentially at work in relativistic jets: Magnetic-field generation and relativistic particle acceleration in relativistic shear layers, which are likely to be present in relativistic jets, is studied via Particle-in-Cell (PIC) simulations. Diffusive shock acceleration at relativistic shocks is investigated using Monte-Carlo simulations. The resulting magnetic-field configurations and thermal + non-thermal particle distributions are then used to predict multi-wavelength radiative (synchrotron + Compton) signatures of both acceleration scenarios. In particular, we address how anisotropic shear-layer acceleration may be able to circumvent the well-known Lorentz-factor crisis, and how the self-consistent evaluation of thermal + non-thermal particle populations in diffusive shock acceleration simulations provides tests of the bulk Comptonization model for the Big Blue Bump observed in the SEDs of several blazars.

  6. Particle Acceleration and Emission in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

    2003-01-01

    Shock wave acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron's transverse deflection behind the jet head. The 'jitter' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  7. Relativistic Particle-In-Cell Simulations of Particle Accleration in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Hartmann, D. H.; Fishman, J. F.

    2008-01-01

    Highly accelerated particles are observed in astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), microquasars, and Gamma-Ray Bursts (GRBs). Particle-In-Cell (PIC) simulations of relativistic electron-ion and electron-positron jets injected into a stationary medium show that efficient acceleration occurs downstream in the jet. In collisionless relativistic shocks particle acceleration is due to plasma waves and their associated instabilities, e.g., the Buneman instability, other two-stream instabilities, and the Weibel (filamentation) instability. Simulations show that the Weibel instability is responsible for generating and amplifying highly non-uniform, small-scale magnetic fields. The instability depends on strength and direction of the magnetic field. Particles in relativistic jets may be accelerated in a complicated dynamics of relativistic jets with magnetic field. We present results of our recent PIC simulations.

  8. Relativistic Particle-In-Cell Simulations of Particle Accleration in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Mizuno, Y.; Medvedev, M.; Hartmann, D. H.; Fishman, J. F.

    2008-01-01

    Highly accelerated particles are observed in astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), microquasars, and Gamma-Ray Bursts (GRBs). Particle-In-Cell (PIC) simulations of relativistic electron-ion and electron-positron jets injected into a stationary medium show that efficient acceleration occurs downstream in the jet. In collisionless relativistic shocks particle acceleration is due to plasma waves and their associated instabilities, e.g., the Buneman instability, other two-stream instabilities, and the Weibel (filamentation) instability. Simulations show that the Weibel instability is responsible for generating and amplifying highly non-uniform, small-scale magnetic fields. The instability depends on strength and direction of the magnetic field. Particles in relativistic jets may be accelerated in a complicated dynamics of relativistic jets with magnetic field. We present results of our recent PIC simulations.

  9. Relativistic MHD simulations of collision-induced magnetic dissipation in Poynting-flux-dominated jets/outflows

    SciTech Connect

    Deng, Wei

    2015-07-21

    The question of the energy composition of the jets/outflows in high-energy astrophysical systems, e.g. GRBs, AGNs, is taken up first: Matter-flux-dominated (MFD), σ < 1, and/or Poynting-flux-dominated (PFD), σ >1? The standard fireball IS model and dissipative photosphere model are MFD, while the ICMART (Internal-Collision-induced MAgnetic Reconnection and Turbulence) model is PFD. Motivated by ICMART model and other relevant problems, such as “jets in a jet” model of AGNs, the author investigates the models from the EMF energy dissipation efficiency, relativistic outflow generation, and σ evolution points of view, and simulates collisions between high-σ blobs to mimic the situation of the interactions inside the PFD jets/outflows by using a 3D SRMHD code which solves the conservative form of the ideal MHD equations. σb,f is calculated from the simulation results (threshold = 1). The efficiency obtained from this hybrid method is similar to the efficiency got from the energy evolution of the simulations (35.2%). Efficiency is nearly σ independent, which is also confirmed by the hybrid method. σb,i - σb,f provides an interesting linear relationship. Results of several parameter studies of EMF energy dissipation efficiency are shown.

  10. Relativistic MHD simulations of extragalactic jets

    NASA Astrophysics Data System (ADS)

    Leismann, T.; Antón, L.; Aloy, M. A.; Müller, E.; Martí, J. M.; Miralles, J. A.; Ibáñez, J. M.

    2005-06-01

    We have performed a comprehensive parameter study of the morphology and dynamics of axisymmetric, magnetized, relativistic jets by means of numerical simulations. The simulations have been performed with an upgraded version of the GENESIS code which is based on a second-order accurate finite volume method involving an approximate Riemann solver suitable for relativistic ideal magnetohydrodynamic flows, and a method of lines. Starting from pure hydrodynamic models we consider the effect of a magnetic field of increasing strength (up to β ≡ |b|2/2p ≈ 3.3 times the equipartition value) and different topology (purely toroidal or poloidal). We computed several series of models investigating the dependence of the dynamics on the magnetic field in jets of different beam Lorentz factor and adiabatic index. We find that the inclusion of the magnetic field leads to diverse effects which contrary to Newtonian magnetohydrodynamics models do not always scale linearly with the (relative) strength of the magnetic field. The relativistic models show, however, some clear trends. Axisymmetric jets with toroidal magnetic fields produce a cavity which consists of two parts: an inner one surrounding the beam which is compressed by magnetic forces, and an adjacent outer part which is inflated due to the action of the magnetic field. The outer border of the outer part of the cavity is given by the bow-shock where its interaction with the external medium takes place. Toroidal magnetic fields well below equipartition (β = 0.05) combined with a value of the adiabatic index of 4/3 yield extremely smooth jet cavities and stable beams. Prominent nose cones form when jets are confined by toroidal fields and carry a high Poynting flux (σ≡ |b|2/ρ>0.01 and β≥ 1). In contrast, none of our models possessing a poloidal field develops such a nose cone. The size of the nose cone is correlated with the propagation speed of the Mach disc (the smaller the speed the larger is the size). If two

  11. COUNTER-ROTATION IN RELATIVISTIC MAGNETOHYDRODYNAMIC JETS

    SciTech Connect

    Cayatte, V.; Sauty, C.; Vlahakis, N.; Tsinganos, K.; Matsakos, T.; Lima, J. J. G.

    2014-06-10

    Young stellar object observations suggest that some jets rotate in the opposite direction with respect to their disk. In a recent study, Sauty et al. showed that this does not contradict the magnetocentrifugal mechanism that is believed to launch such outflows. Motion signatures that are transverse to the jet axis, in two opposite directions, have recently been measured in M87. One possible interpretation of this motion is that of counter-rotating knots. Here, we extend our previous analytical derivation of counter-rotation to relativistic jets, demonstrating that counter-rotation can indeed take place under rather general conditions. We show that both the magnetic field and a non-negligible enthalpy are necessary at the origin of counter-rotating outflows, and that the effect is associated with a transfer of energy flux from the matter to the electromagnetic field. This can be realized in three cases: if a decreasing enthalpy causes an increase of the Poynting flux, if the flow decelerates, or if strong gradients of the magnetic field are present. An illustration of the involved mechanism is given by an example of a relativistic magnetohydrodynamic jet simulation.

  12. Are relativistic jets monoparametric engines?

    NASA Astrophysics Data System (ADS)

    Georganopoulos, M.; Meyer, E. T.; Fossati, G.; Lister, M. L.

    We adopt as a working hypothesis that relativistic jets are essentially mono-parametric entities, and that their physical properties are a function of a single physical parameter, the same way the physical properties of main sequence stars are mainly a function of the star mass. We propose that the physical parameter is the jet kinetic power, and we use as a proxy for this quantity the low frequency extended radio luminosity (LFERL), an orientation insensitive quantity. We discuss the consequences of this hypothesis for the collective properties of relativistic jets and we show that a blazar sequence should spontaneously emerge on the peak frequency vs luminosity plot as the locus of those sources that are well aligned to the observer's line of sight. We also show that the sources of the same LFERL should form tracks that start from a location on the blazar sequence and move to lower luminosities and peak frequencies in a way that encodes information about the emitting plasma energetics and kinematics and velocity gradients, as well as about the inverse Compton (IC) emission seed photons. We are currently working on collecting the observations that will allow us to put this idea to the test.

  13. Polarization and Structure of Relativistic Parsec-Scale AGN Jets

    SciTech Connect

    Lyutikov, M

    2004-06-10

    We consider the polarization properties of optically thin synchrotron radiation emitted by relativistically moving electron-positron jets carrying large-scale helical magnetic fields. In our model, the jet is cylindrical, and the emitting plasma moves parallel to the jet axis with a characteristic Lorentz factor {Lambda}. We draw attention to the strong influence that the bulk relativistic motion of the emitting relativistic particles has on the observed polarization. Our computations predict and explain the following behavior. (1) For jets unresolved in the direction perpendicular to their direction of propagation, the position angle of the electric vector of the linear polarization has a bimodal distribution, being oriented either parallel or perpendicular to the jet. (2) If an ultra-relativistic jet with {Lambda} >> 1 whose axis makes a small angle to the line of sight, {theta} {approx} 1/{Lambda}, experiences a relatively small change in the direction of propagation, velocity or pitch angle of the magnetic fields, the polarization is likely to remain parallel or perpendicular; on the other hand, in some cases, the degree of polarization can exhibit large variations and the polarization position angle can experience abrupt 90{sup o} changes. This change is more likely to occur in jets with flatter spectra. (3) In order for the jet polarization to be oriented along the jet axis, the intrinsic toroidal magnetic field (in the frame of the jet) should be of the order of or stronger than the intrinsic poloidal field; in this case, the highly relativistic motion of the jet implies that, in the observer's frame, the jet is strongly dominated by the toroidal magnetic field B{sub {phi}}/B{sub z} {ge} {Lambda}. (4) The emission-weighted average pitch angle of the intrinsic helical field in the jet must not be too small to produce polarization along the jet axis. In force-free jets with a smooth distribution of emissivities, the emission should be generated in a limited

  14. The Invariant Twist of Magnetic Fields in the Relativistic Jets of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Contopoulos, Ioannis; Christodoulou, Dimitris M.; Kazanas, Demosthenes; Gabuzda, Denise C.

    2009-01-01

    The origin of cosmic magnetic (B) fields remains an open question. It is generally believed that very weak primordial B fields are amplified by dynamo processes, but it appears unlikely that the amplification proceeds fast enough to account for the fields presently observed in galaxies and galaxy clusters. In an alternative scenario, cosmic B fields are generated near the inner edges of accretion disks in Active Galactic Nuclei (AGNs) by azimuthal electric currents due to the difference between the plasma electron and ion velocities that arises when the electrons are retarded by interactions with photons. While dynamo processes show no preference for the polarity of the (presumably random) seed field that they amplify, this alternative mechanism uniquely relates the polarity of the poloidal B field to the angular velocity of the accretion disk, resulting in a unique direction for the toroidal B field induced by disk rotation. Observations of the toroidal fields of 29 AGN jets revealed by parsec-scale Faraday rotation measurements show a clear asymmetry that is consistent with this model, with the probability that this asymmetry came about by chance being less than 1 %. This lends support to the hypothesis that the Universe is seeded by B fields that are generated in AGN via this mechanism

  15. The Invariant Twist of Magnetic Fields in the Relativistic Jets of Active Galactic Nuclei

    NASA Technical Reports Server (NTRS)

    Contopoulos, Ioannis; Christodoulou, Dimitris M.; Kazanas, Demosthenes; Gabuzda, Denise C.

    2009-01-01

    The origin of cosmic magnetic (B) fields remains an open question. It is generally believed that very weak primordial B fields are amplified by dynamo processes, but it appears unlikely that the amplification proceeds fast enough to account for the fields presently observed in galaxies and galaxy clusters. In an alternative scenario, cosmic B fields are generated near the inner edges of accretion disks in Active Galactic Nuclei (AGNs) by azimuthal electric currents due to the difference between the plasma electron and ion velocities that arises when the electrons are retarded by interactions with photons. While dynamo processes show no preference for the polarity of the (presumably random) seed field that they amplify, this alternative mechanism uniquely relates the polarity of the poloidal B field to the angular velocity of the accretion disk, resulting in a unique direction for the toroidal B field induced by disk rotation. Observations of the toroidal fields of 29 AGN jets revealed by parsec-scale Faraday rotation measurements show a clear asymmetry that is consistent with this model, with the probability that this asymmetry came about by chance being less than 1 %. This lends support to the hypothesis that the Universe is seeded by B fields that are generated in AGN via this mechanism

  16. Relativistic MHD simulations of poynting flux-driven jets

    SciTech Connect

    Guan, Xiaoyue; Li, Hui; Li, Shengtai

    2014-01-20

    Relativistic, magnetized jets are observed to propagate to very large distances in many active galactic nuclei (AGNs). We use three-dimensional relativistic MHD simulations to study the propagation of Poynting flux-driven jets in AGNs. These jets are already assumed to be being launched from the vicinity (∼10{sup 3} gravitational radii) of supermassive black holes. Jet injections are characterized by a model described in Li et al., and we follow the propagation of these jets to ∼parsec scales. We find that these current-carrying jets are always collimated and mildly relativistic. When α, the ratio of toroidal-to-poloidal magnetic flux injection, is large the jet is subject to nonaxisymmetric current-driven instabilities (CDI) which lead to substantial dissipation and reduced jet speed. However, even with the presence of instabilities, the jet is not disrupted and will continue to propagate to large distances. We suggest that the relatively weak impact by the instability is due to the nature of the instability being convective and the fact that the jet magnetic fields are rapidly evolving on Alfvénic time scales. We present the detailed jet properties and show that far from the jet launching region, a substantial amount of magnetic energy has been transformed into kinetic energy and thermal energy, producing a jet magnetization number σ < 1. In addition, we have also studied the effects of a gas pressure supported 'disk' surrounding the injection region, and qualitatively similar global jet behaviors were observed. We stress that jet collimation, CDIs, and the subsequent energy transitions are intrinsic features of current-carrying jets.

  17. Relativistic wind termination - Jets and synchronotron nebulae

    NASA Technical Reports Server (NTRS)

    Michel, F. C.

    1985-01-01

    An idealized model describing the termination of a relativistic wind owing to its interaction with surrounding nonrelativistic matter, such as the interaction of a pulsar wind with the supernova remnant shell is examined. It is assumed that the large-scale electric and magnetic fields out to the termination distance are controlled by the wind source, in contrast to previous work treating the wind as an isotropic MHD flow. Two effects are found: forced synchrotron radiation from the bulk of the injected particles, and formation of oppositely directed jets of ultrarelativistic particles.

  18. String Mechanism for Relativistic Jet Formation

    NASA Astrophysics Data System (ADS)

    Dyadechkin, S. A.; Semenov, V. S.; Punsly, B.; Biernat, H. K.

    Here we present our latest studies of relativistic jet formation in the vicinity of a rotating black hole where the reconnection process has been taken into account. In order to simplify the problem, we use Lagrangian formalism and develop a method which enables us to consider a magnetized plasma as a set of magnetic flux tubes [5,6]. Within the limits of the Lagrangian approach, we perform numerical simulations of the flux tube (nonlinear string) behavior which clearly demonstrates the process of relativistic jet formation in the form of outgoing torsional nonlinear aves. It turns out that the jet is produced deep inside the ergosphere where the flux tube takes away spinning energy from the black hole due to the nonlocal Penrose process [2]. This is similar to the Blandford-Znajek (BZ) mechanism to some extent [8], however, the string mechanism is essentially time dependent. It is shown that the leading part of the accreting tube gains negative energy and therefore has to stay in the ergosphere forever. Simultaneously, another part of the tube propagates along the spinning axis away from the hole with nearly the speed of light. As a result, the tube is continuously stretching and our mechanism is essentially time dependent. Obviously, such process cannot last infinitely long and we have to take into account the reconnection process. Due to reconnection, the topology of the flux tube is changed and it gives rise to a plasmoid creation which propagates along spin axis of the hole with relativistic speed carrying off the energy and angular momentum away from the black hole.

  19. SYNCHROTRON RADIATION OF SELF-COLLIMATING RELATIVISTIC MAGNETOHYDRODYNAMIC JETS

    SciTech Connect

    Porth, Oliver; Fendt, Christian; Vaidya, Bhargav; Meliani, Zakaria E-mail: fendt@mpia.de

    2011-08-10

    The goal of this paper is to derive signatures of synchrotron radiation from state-of-the-art simulation models of collimating relativistic magnetohydrodynamic (MHD) jets featuring a large-scale helical magnetic field. We perform axisymmetric special relativistic MHD simulations of the jet acceleration region using the PLUTO code. The computational domain extends from the slow-magnetosonic launching surface of the disk up to 6000{sup 2} Schwarzschild radii allowing jets to reach highly relativistic Lorentz factors. The Poynting-dominated disk wind develops into a jet with Lorentz factors of {Gamma} {approx_equal} 8 and is collimated to 1{sup 0}. In addition to the disk jet, we evolve a thermally driven spine jet emanating from a hypothetical black hole corona. Solving the linearly polarized synchrotron radiation transport within the jet, we derive very long baseline interferometry radio and (sub-) millimeter diagnostics such as core shift, polarization structure, intensity maps, spectra, and Faraday rotation measure (RM) directly from the Stokes parameters. We also investigate depolarization and the detectability of a {lambda}{sup 2}-law RM depending on beam resolution and observing frequency. We find non-monotonic intrinsic RM profiles that could be detected at a resolution of 100 Schwarzschild radii. In our collimating jet geometry, the strict bimodality in the polarization direction (as predicted by Pariev et al.) can be circumvented. Due to relativistic aberration, asymmetries in the polarization vectors across the jet can hint at the spin direction of the central engine.

  20. Relativistic HD and MHD modelling for AGN jets

    NASA Astrophysics Data System (ADS)

    Keppens, R.; Porth, O.; Monceau-Baroux, R.; Walg, S.

    2013-12-01

    Relativistic hydro and magnetohydrodynamics (MHD) provide a continuum fluid description for plasma dynamics characterized by shock-dominated flows approaching the speed of light. Significant progress in its numerical modelling emerged in the last two decades; we highlight selected examples of modern grid-adaptive, massively parallel simulations realized by our open-source software MPI-AMRVAC (Keppens et al 2012 J. Comput. Phys. 231 718). Hydrodynamical models quantify how energy transfer from active galactic nuclei (AGN) jets to their surrounding interstellar/intergalactic medium (ISM/IGM) gets mediated through shocks and various fluid instability mechanisms (Monceau-Baroux et al 2012 Astron. Astrophys. 545 A62). With jet parameters representative for Fanaroff-Riley type-II jets with finite opening angles, we can quantify the ISM volumes affected by jet injection and distinguish the roles of mixing versus shock-heating in cocoon regions. This provides insight in energy feedback by AGN jets, usually incorporated parametrically in cosmological evolution scenarios. We discuss recent axisymmetric studies up to full 3D simulations for precessing relativistic jets, where synthetic radio maps can confront observations. While relativistic hydrodynamic models allow one to better constrain dynamical parameters like the Lorentz factor and density contrast between jets and their surroundings, the role of magnetic fields in AGN jet dynamics and propagation characteristics needs full relativistic MHD treatments. Then, we can demonstrate the collimating properties of an overal helical magnetic field backbone and study differences between poloidal versus toroidal field dominated scenarios (Keppens et al 2008 Astron. Astrophys. 486 663). Full 3D simulations allow one to consider the fate of non-axisymmetric perturbations on relativistic jet propagation from rotating magnetospheres (Porth 2013 Mon. Not. R. Astron. Soc. 429 2482). Self-stabilization mechanisms related to the detailed

  1. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.

    1999-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.

  2. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.

    2001-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.

  3. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Frank, J.; Sol, H.

    1999-05-01

    Koide et al have investigated the dynamics of an accretion disk initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state or in hydrostatic equilibrium) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code on a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics. 3-D RMHD simulations wil be also performed to investigate the dynamics of a jet with a helical mangetic field in it.

  4. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.

    2000-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system. We will investigate how the third dimension affects the global disk dynamics and jet generation.

  5. Jet Formation with 3-D General Relativistic MHD Simulations

    NASA Astrophysics Data System (ADS)

    Richardson, G. A.; Nishikawa, K.-I.; Preece, R.; Hardee, P.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Hughes, J. P.; Fishman, J.

    2002-12-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (in a steady-state infalling state) around a non-rotating black hole using 3-D GRMHD with the ``axisymmetry'' along the z-direction. The magnetic field is tightly twisted by the rotation of the accretion disk, and plasmas in the shocked region of the disk are accelerated by the J x B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and the magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.

  6. 3-D General Relativistic MHD Simulations of Generating Jets

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ken-Ichi; Koide, Shinji; Shibata, Kazunari; Kudoh, Takashiro; Sol, Helene; Hughes, John

    2002-04-01

    We have investigated the dynamics of an accretion disk around Schwarzschild black holes initially threaded by a uniform poloidal magnetic field in a non-rotating corona (either in a steady-state infalling state) around a non-rotating black hole using a 3-D GRMHD with the ``axisymmetry'' along the z-direction. Magnetic field is tightly twisted by the rotation of the disk, and plasmas in the shocked region of the disk are accelerated by J × B force to form bipolar relativistic jets. In order to investigate variabilities of generated relativistic jets and magnetic field structure inside jets, we have performed calculations using the 3-D GRMHD code with a full 3-dimensional system without the axisymmetry. We have investigated how the third dimension affects the global disk dynamics and jet generation. We will perform simulations with various incoming flows from an accompanying star.

  7. Jets in relativistic heavy ion collisions

    SciTech Connect

    Wang, Xin-Nian; Gyulassy, M.

    1990-09-01

    Several aspects of hard and semihard QCD jets in relativistic heavy ion collisions are discussed, including multiproduction of minijets and the interaction of a jet with dense nuclear matter. The reduction of jet quenching effect in deconfined phase of nuclear matter is speculated to provide a signature of the formation of quark gluon plasma. HIJING Monte Carlo program which can simulate events of jets production and quenching in heavy ion collisions is briefly described. 35 refs., 13 figs.

  8. Transmission line analogy for relativistic Poynting-flux jets

    NASA Astrophysics Data System (ADS)

    Lovelace, R. V. E.; Kronberg, P. P.

    2013-04-01

    Radio emission, polarization and Faraday rotation maps of the radio jet of the galaxy 3C 303 have shown that one knot of this jet carries a galactic-scale electric current and that it is magnetically dominated. We develop the theory of magnetically dominated or Poynting-flux jets by making an analogy of a Poynting jet with a transmission line or waveguide carrying a net current and having a potential drop across it (from the jet's axis to its radius) and a definite impedance which we derive. The electromagnetic energy flow in the jet is the jet impedance times the square of the jet current. The observed current in 3C 303 can be used to calculate the electromagnetic energy flow in this magnetically dominated jet. Time dependent but not necessarily small perturbations of a Poynting-flux jet are described by the `telegrapher's equations'. These predict the propagation speed of disturbances and the effective wave impedance for forward and backward propagating wave components. A localized disturbance of a Poynting jet gives rise to localized dissipation in the jet which may explain the enhanced synchrotron radiation in the knots of the 3C 303 jet, and also in the apparently stationary knot HST-1 in the jet near the nucleus of the nearby galaxy M87. For a relativistic Poynting jet on parsec scales, the reflected voltage wave from an inductive termination or load can lead to a backward propagating wave which breaks down the magnetic insulation of the jet giving |{boldsymbol E}| /|{boldsymbol B}|ge 1. At the threshold for breakdown, |{boldsymbol E}|/|{boldsymbol B}|=1, positive and negative particles are directly accelerated in the {boldsymbol E} × {boldsymbol B} direction which is approximately along the jet axis. Acceleration can occur up to Lorentz factors ˜107. This particle acceleration mechanism is distinct from that in shock waves and that in magnetic field reconnection.

  9. Particle Acceleration in Relativistic Jets Due to Weibel Instability

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

    2004-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  10. Microscopic Processes On Radiation from Accelerated Particles in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P. E.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Sol, H.; Niemiec, J.; Pohl, M.; Nordlund, A.; Fredriksen, J.; Lyubarsky, Y.; Hartmann, D. H.; Fishman, G. J.

    2009-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The jitter'' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  11. Microscopic Processes On Radiation from Accelerated Particles in Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P. E.; Mizuno, Y.; Medvedev, M.; Zhang, B.; Sol, H.; Niemiec, J.; Pohl, M.; Nordlund, A.; Fredriksen, J.; hide

    2009-01-01

    Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electro-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the collisionless relativistic shock particle acceleration is due to plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The jitter'' radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  12. Substructures in Simulations of Relativistic Jet Formation

    NASA Astrophysics Data System (ADS)

    Garcia, Raphael de Oliveira; Oliveira, Samuel Rocha de

    2017-02-01

    We present a set of simulations of relativistic jets from accretion disk initial setup with numerical solutions of a system of general-relativistic magnetohydrodynamics (GRMHD) partial differential equations in a fixed black hole (BH) spacetime which is able to show substructures formations inside the jet as well as lobe formation on the jet head. For this, we used a central scheme of finite volume method without dimensional split and with no Riemann solvers namely the Nessyahu-Tadmor method. Thus, we were able to obtain stable numerical solutions with spurious oscillations under control and with no excessive numerical dissipation. Therefore, we developed some setups for initial conditions capable of simulating the formation of relativistic jets from the accretion disk falling onto central black hole until its ejection, both immersed in a magnetosphere. In our simulations, we were able to observe some substructure of a jet created from an accretion initial disk, namely, jet head, knots, cocoon, and lobe. Also, we present an explanation for cocoon formation and lobe formation. Each initial scenario was determined by ratio between disk density and magnetosphere density, showing that this relation is very important for the shape of the jet and its substructures.

  13. Substructures in Simulations of Relativistic Jet Formation

    NASA Astrophysics Data System (ADS)

    Garcia, Raphael de Oliveira; Oliveira, Samuel Rocha de

    2017-04-01

    We present a set of simulations of relativistic jets from accretion disk initial setup with numerical solutions of a system of general-relativistic magnetohydrodynamics (GRMHD) partial differential equations in a fixed black hole (BH) spacetime which is able to show substructures formations inside the jet as well as lobe formation on the jet head. For this, we used a central scheme of finite volume method without dimensional split and with no Riemann solvers namely the Nessyahu-Tadmor method. Thus, we were able to obtain stable numerical solutions with spurious oscillations under control and with no excessive numerical dissipation. Therefore, we developed some setups for initial conditions capable of simulating the formation of relativistic jets from the accretion disk falling onto central black hole until its ejection, both immersed in a magnetosphere. In our simulations, we were able to observe some substructure of a jet created from an accretion initial disk, namely, jet head, knots, cocoon, and lobe. Also, we present an explanation for cocoon formation and lobe formation. Each initial scenario was determined by ratio between disk density and magnetosphere density, showing that this relation is very important for the shape of the jet and its substructures.

  14. Particle Acceleration in Relativistic Jets due to Weibel Instability

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

    2003-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The jitter radiation (Medvedev 2000) from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  15. General Relativistic MHD Simulations of Jet Formation

    NASA Technical Reports Server (NTRS)

    Mizuno, Y.; Nishikawa, K.-I.; Hardee, P.; Koide, S.; Fishman, G. J.

    2005-01-01

    We have performed 3-dimensional general relativistic magnetohydrodynamic (GRMHD) simulations of jet formation from an accretion disk with/without initial perturbation around a rotating black hole. We input a sinusoidal perturbation (m = 5 mode) in the rotation velocity of the accretion disk. The simulation results show the formation of a relativistic jet from the accretion disk. Although the initial perturbation becomes weakened by the coupling among different modes, it survives and triggers lower modes. As a result, complex non-axisymmetric density structure develops in the disk and the jet. Newtonian MHD simulations of jet formation with a non-axisymmetric mode show the growth of the m = 2 mode but GRMHD simulations cannot see the clear growth of the m = 2 mode.

  16. Inductive and Electrostatic Acceleration in Relativistic Jet-Plasma Interactions

    SciTech Connect

    Ng, Johnny S.T.; Noble, Robert J.; /SLAC

    2005-07-13

    We report on the observation of rapid particle acceleration in numerical simulations of relativistic jet-plasma interactions and discuss the underlying mechanisms. The dynamics of a charge-neutral, narrow, electron-positron jet propagating through an unmagnetized electron-ion plasma was investigated using a three-dimensional, electromagnetic, particle-in-cell computer code. The interaction excited magnetic filamentation as well as electrostatic (longitudinal) plasma instabilities. In some cases, the longitudinal electric fields generated inductively and electrostatically reached the cold plasma wave-breaking limit, and the longitudinal momentum of about half the positrons increased by 50% with a maximum gain exceeding a factor of two. The results are relevant to understanding the micro-physics at the interface region of an astrophysical jet with the interstellar plasma, for example, the edge of a wide jet or the jet-termination point.

  17. Relativistic Jets in Active Galactic Nuclei and Microquasars

    NASA Astrophysics Data System (ADS)

    Romero, Gustavo E.; Boettcher, M.; Markoff, S.; Tavecchio, F.

    2017-07-01

    Collimated outflows (jets) appear to be a ubiquitous phenomenon associated with the accretion of material onto a compact object. Despite this ubiquity, many fundamental physics aspects of jets are still poorly understood and constrained. These include the mechanism of launching and accelerating jets, the connection between these processes and the nature of the accretion flow, and the role of magnetic fields; the physics responsible for the collimation of jets over tens of thousands to even millions of gravitational radii of the central accreting object; the matter content of jets; the location of the region(s) accelerating particles to TeV (possibly even PeV and EeV) energies (as evidenced by γ-ray emission observed from many jet sources) and the physical processes responsible for this particle acceleration; the radiative processes giving rise to the observed multi-wavelength emission; and the topology of magnetic fields and their role in the jet collimation and particle acceleration processes. This chapter reviews the main knowns and unknowns in our current understanding of relativistic jets, in the context of the main model ingredients for Galactic and extragalactic jet sources. It discusses aspects specific to active Galactic nuclei (especially blazars) and microquasars, and then presents a comparative discussion of similarities and differences between them.

  18. Relativistic Jets in Active Galactic Nuclei and Microquasars

    NASA Astrophysics Data System (ADS)

    Romero, Gustavo E.; Boettcher, M.; Markoff, S.; Tavecchio, F.

    2017-01-01

    Collimated outflows (jets) appear to be a ubiquitous phenomenon associated with the accretion of material onto a compact object. Despite this ubiquity, many fundamental physics aspects of jets are still poorly understood and constrained. These include the mechanism of launching and accelerating jets, the connection between these processes and the nature of the accretion flow, and the role of magnetic fields; the physics responsible for the collimation of jets over tens of thousands to even millions of gravitational radii of the central accreting object; the matter content of jets; the location of the region(s) accelerating particles to TeV (possibly even PeV and EeV) energies (as evidenced by γ-ray emission observed from many jet sources) and the physical processes responsible for this particle acceleration; the radiative processes giving rise to the observed multi-wavelength emission; and the topology of magnetic fields and their role in the jet collimation and particle acceleration processes. This chapter reviews the main knowns and unknowns in our current understanding of relativistic jets, in the context of the main model ingredients for Galactic and extragalactic jet sources. It discusses aspects specific to active Galactic nuclei (especially blazars) and microquasars, and then presents a comparative discussion of similarities and differences between them.

  19. Determining the Macroscopic Properties of Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Hardee, P. E.

    2004-08-01

    The resolved relativistic jets contain structures whose observed proper motions are typically assumed to indicate the jet flow speed. In addition to structures moving with the flow, various normal mode structures such as pinching or helical and elliptical twisting can be produced by ejection events or twisting perturbations to the jet flow. The normal mode structures associated with relativistic jets, as revealed by numerical simulation, theoretical calculation, and suggested by observation, move more slowly than the jet speed. The pattern speed is related to the jet speed by the sound speed in the jet and in the surrounding medium. In the event that normal mode structures are observed, and where proper motions of pattern and flow speed are available or can be estimated, it is possible to determine the sound speed in the jet and surrounding medium. Where spatial development of normal mode structures is observed, it is possible to make inferences as to the heating rate/macroscopic viscosity of the jet fluid. Ultimately it may prove possible to separate the microscopic energization of the synchrotron radiating particles from the macroscopic heating of the jet fluid. Here I present the relevant properties of useful normal mode structures and illustrate the use of this technique. Various aspects of the work presented here have involved collaboration with I. Agudo (Max-Planck, Bonn), M.A. Aloy (Max-Planck, Garching), J. Eilek (NM Tech), J.L. Gómez (U. Valencia), P. Hughes (U. Michigan), A. Lobanov (Max-Planck, Bonn), J.M. Martí (U. Valencia), & C. Walker (NRAO).

  20. Relativistic hydrodynamic jets in the intracluster medium

    NASA Astrophysics Data System (ADS)

    Choi, Eunwoo

    2017-08-01

    We have performed the first three-dimensional relativistic hydrodynamic simulations of extragalactic jets of pure leptonic and baryonic plasma compositions propagating into a hydrostatic intracluster medium (ICM) environment. The numerical simulations use a general equation of state for a multicomponent relativistic gas, which closely reproduces the Synge equation of state for a relativistic perfect gas. We find that morphological and dynamical differences between leptonic and baryonic jets are much less evident than those between hot and cold jets. In all these models, the jets first propagate with essentially constant velocities within the core radius of the ICM and then accelerate progressively so as to increase the jet advance velocity by a factor of between 1.2 and 1.6 at the end of simulations, depending upon the models. The temporal evolution of the average cavity pressure is not consistent with that expected by the extended theoretical model even if the average cavity pressure decreases as a function of time with a power law. Our simulations produce synthetic radio images that are dominated by bright hot spots and appear similar to observations of the extended radio galaxies with collimated radio jets. These bright radio lobes would be visible as dark regions in X-ray images and are morphologically similar to observed X-ray cavities in the ICM. This supports the expectation that the bow shock surrounding the head of the jet is important mechanism for producing X-ray cavities in the ICM. Although there are quantitative differences among the models, the total radio and X-ray intensity curves show qualitatively similar trends in all of them.

  1. Efficient acceleration of relativistic magnetohydrodynamic jets

    NASA Astrophysics Data System (ADS)

    Toma, Kenji; Takahara, Fumio

    2013-08-01

    Relativistic jets in active galactic nuclei, galactic microquasars, and gamma-ray bursts are widely considered to be magnetohydrodynamically driven by black hole accretion systems, although the conversion mechanism from the Poynting into the particle kinetic energy flux is still open. Recent detailed numerical and analytical studies of global structures of steady, axisymmetric magnetohydrodynamic (MHD) flows with specific boundary conditions have not reproduced as rapid an energy conversion as required by observations. In order to find more suitable boundary conditions, we focus on the flow along a poloidal magnetic field line just inside the external boundary, without treating the transfield force balance in detail. We find some examples of the poloidal field structure and corresponding external pressure profile for an efficient and rapid energy conversion as required by observations, and that the rapid acceleration requires a rapid decrease of the external pressure above the accretion disk. We also clarify the differences between the fast magnetosonic point of the MHD flow and the sonic point of the de Laval nozzle.

  2. Laser Created Relativistic Positron Jets

    SciTech Connect

    Chen, H; Wilks, S C; Meyerhofer, D D; Bonlie, J; Chen, C D; Chen, S N; Courtois, C; Elberson, L; Gregori, G; Kruer, W; Landoas, O; Mithen, J; Murphy, C; Nilson, P; Price, D; Scheider, M; Shepherd, R; Stoeckl, C; Tabak, M; Tommasini, R; Beiersdorder, P

    2009-10-08

    Electron-positron jets with MeV temperature are thought to be present in a wide variety of astrophysical phenomena such as active galaxies, quasars, gamma ray bursts and black holes. They have now been created in the laboratory in a controlled fashion by irradiating a gold target with an intense picosecond duration laser pulse. About 10{sup 11} MeV positrons are emitted from the rear surface of the target in a 15 to 22-degree cone for a duration comparable to the laser pulse. These positron jets are quasi-monoenergetic (E/{delta}E {approx} 5) with peak energies controllable from 3-19 MeV. They have temperatures from 1-4 MeV in the beam frame in both the longitudinal and transverse directions. Positron production has been studied extensively in recent decades at low energies (sub-MeV) in areas related to surface science, positron emission tomography, basic antimatter science such as antihydrogen experiments, Bose-Einstein condensed positronium, and basic plasma physics. However, the experimental tools to produce very high temperature positrons and high-flux positron jets needed to simulate astrophysical positron conditions have so far been absent. The MeV temperature jets of positrons and electrons produced in our experiments offer a first step to evaluate the physics models used to explain some of the most energetic phenomena in the universe.

  3. RESISTIVE MAGNETOHYDRODYNAMIC SIMULATIONS OF RELATIVISTIC MAGNETIC RECONNECTION

    SciTech Connect

    Zenitani, Seiji; Hesse, Michael; Klimas, Alex

    2010-06-20

    Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten-Lan-van Leer method is employed. Under a localized resistivity, the system exhibits a fast reconnection jet with an Alfvenic Lorentz factor inside a narrow Petschek-type exhaust. Various shock structures are resolved in and around the plasmoid such as the post-plasmoid vertical shocks and the 'diamond-chain' structure due to multiple shock reflections. Under a uniform resistivity, Sweet-Parker-type reconnection slowly evolves. Under a current-dependent resistivity, plasmoids are repeatedly formed in an elongated current sheet. It is concluded that the resistivity model is of critical importance for RRMHD modeling of relativistic magnetic reconnection.

  4. Resistive Magnetohydrodynamic Simulations of Relativistic Magnetic Reconnection

    NASA Technical Reports Server (NTRS)

    Zenitani, Seiji; Hesse, Michael; Klimas, Alex

    2010-01-01

    Resistive relativistic magnetohydrodynamic (RRMHD) simulations are applied to investigate the system evolution of relativistic magnetic reconnection. A time-split Harten-Lan-van Leer method is employed. Under a localized resistivity, the system exhibits a fast reconnection jet with an Alfv enic Lorentz factor inside a narrow Petschek-type exhaust. Various shock structures are resolved in and around the plasmoid such as the post-plasmoid vertical shocks and the "diamond-chain" structure due to multiple shock reflections. Under a uniform resistivity, Sweet-Parker-type reconnection slowly evolves. Under a current-dependent resistivity, plasmoids are repeatedly formed in an elongated current sheet. It is concluded that the resistivity model is of critical importance for RRMHD modeling of relativistic magnetic reconnection.

  5. Reconfinement shocks in relativistic AGN jets

    SciTech Connect

    Nalewajko, Krzysztof; Sikora, Marek

    2008-12-24

    Stationary knots observed in many AGN jets can be explained in terms of a reconfinement shock that forms when relativistic flow of the jet matter collides with the external medium. The position of these knots can be used, together with information on external pressure profile, to constrain dynamical parameters of the jet. We present a semi-analytical model for the dynamical structure of reconfinement shocks, taking into account exact conservation laws both across the shock surface and in the zone of the shocked jet matter. We show that, due to the transverse pressure gradient in the shock zone, the position of the reconfinement is larger than predicted by simple models. A portion of kinetic energy is converted at the shock surface to internal energy, with efficiency increasing strongly with both bulk Lorentz factor of the jet matter and the jet half-opening angle. Our model may be useful as a framework for modeling non-thermal radiation produced within the stationary features.

  6. On the deceleration of relativistic jets in active galactic nuclei- I. Radiation drag

    NASA Astrophysics Data System (ADS)

    Beskin, V. S.; Chernoglazov, A. V.

    2016-12-01

    Deceleration of relativistic jets from active galactic nuclei (AGNs) detected recently by the Monitoring Of Jets in Active galactic nuclei with Very Long Baseline Array Experiments (MOJAVE) team is discussed in connection with the interaction of the jet material with an external photon field. The appropriate energy density of the isotropic photon field necessary to decelerate jets is determined. It is shown that disturbances of the electric potential and magnetic surfaces play an important role in the general dynamics of particle deceleration.

  7. The Formation of Relativistic Jets from Kerr Black Holes

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Richardson, G.; Preece, R.; Hardee, P.; Koide, S.; Shibata, K.; Kudoh, T.; Sol, H.; Fishman, G. J.

    2003-01-01

    We have performed the first fully three-dimensional general relativistic magnetohydrodynamics (GRMHD) simulation for Schwarzschild and Kerr black holes with a free falling corona and thin accretion disk. The initial simulation results with a Schwarzschild metric show that a jet is created as in the previous axisymmetric simulations with mirror symmetry at the equator. However, the time to form the jet is slightly longer than in the 2-D axisymmetric simulation. We expect that the dynamics of jet formation are modified due to the additional freedom in the azimuth dimension without axisymmetry with respect to the Z axis and reflection symmetry respect to the equatorial plane. The jet which is initially formed due to the twisted magnetic fields and shocks becomes a wind at the later time. The wind flows out with a much wider angle than the initial jet. The twisted magnetic fields at the earlier time were untwisted and less pinched. The accretion disk became thicker than the initial condition. Further simulations with initial perturbations will provide insights for accretion dynamics with instabilities such as magneto-rotational instability (MRI) and accretion-eject instability (AEI). These instabilities may contribute to variabilities observed in microquasars and AGN jets.

  8. Retardation magnification and the appearance of relativistic jets

    NASA Astrophysics Data System (ADS)

    Jester, Sebastian

    2008-10-01

    Thanks to the availability of high-resolution high-sensitivity telescopes such as the Very Large Array, the Hubble Space Telescope and the Chandra X-Ray Observatory, there is now a wealth of observational data on relativistic jets from active galactic nuclei (AGN) as well as galactic sources such as black hole X-ray binaries. Since the jet speeds cannot be constrained well from observations, but are generally believed to be relativistic, physical quantities inferred from observables are commonly expressed in terms of the unknown beaming parameters: the bulk Lorentz factor and the line-of-sight angle, usually in their combination as relativistic Doppler factor. This paper aims to resolve the discrepancies existing in the literature about such `debeaming' of derived quantities, in particular regarding the minimum-energy magnetic field estimate. The discrepancies arise because the distinction is not normally made between the case of a fixed source observed with different beaming parameters and the case where the source projection on the sky is held fixed. The former is usually considered, but it is the latter that corresponds to interpreting actual jet observations. Furthermore, attention is drawn to the fact that apparent superluminal motion has a spatial corollary, here called `retardation magnification', which implies that most parts of a relativistic jet that are actually present in the observer's frame (a `world map' in relativity terminology) are in fact hidden on the observer's image (the `world picture' in general, or `supersnapshot' in the special case of astronomy). Portions of this work were carried at the Particle Astrophysics Center, Fermilab MS 127, PO Box 500, Batavia, IL 60510, USA; and while the author was an Otto Hahn fellow of the Max-Planck-Gesellschaft at the Department of Physics and Astronomy, University of Southampton, Southampton SO17 1BJ. E-mail: jester@mpia.de

  9. THREE-DIMENSIONAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATIONS OF CURRENT-DRIVEN INSTABILITY. III. ROTATING RELATIVISTIC JETS

    SciTech Connect

    Mizuno, Yosuke; Lyubarsky, Yuri; Nishikawa, Ken-Ichi; Hardee, Philip E.

    2012-09-20

    We have investigated the influence of jet rotation and differential motion on the linear and nonlinear development of the current-driven (CD) kink instability of force-free helical magnetic equilibria via three-dimensional relativistic magnetohydrodynamic simulations. In this study, we follow the temporal development within a periodic computational box. Displacement of the initial helical magnetic field leads to the growth of the CD kink instability. We find that, in accordance with the linear stability theory, the development of the instability depends on the lateral distribution of the poloidal magnetic field. If the poloidal field significantly decreases outward from the axis, then the initial small perturbations grow strongly, and if multiple wavelengths are excited, then nonlinear interaction eventually disrupts the initial cylindrical configuration. When the profile of the poloidal field is shallow, the instability develops slowly and eventually saturates. We briefly discuss implications of our findings for Poynting-dominated jets.

  10. SCALING OF THE ANOMALOUS BOOST IN RELATIVISTIC JET BOUNDARY LAYER

    SciTech Connect

    Zenitani, Seiji; Hesse, Michael; Klimas, Alex

    2010-04-01

    We investigate the one-dimensional interaction of a relativistic jet and an external medium. Relativistic magnetohydrodynamic simulations show an anomalous boost of the jet fluid in the boundary layer, as previously reported. We describe the boost mechanism using an ideal relativistic fluid and magnetohydrodynamic theory. The kinetic model is also examined for further understanding. Simple scaling laws for the maximum Lorentz factor are derived, and verified by the simulations.

  11. Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-IchiI.; Hededal, C.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G.

    2004-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (m) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient parallel magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. New simulations with an ambient perpendicular magnetic field show the strong interaction between the relativistic jet and the magnetic fields. The magnetic fields are piled up by the jet and the jet electrons are bent, which creates currents and displacement currents. At the nonlinear stage, the magnetic fields are reversed by the current and the reconnection may take place. Due to these dynamics the jet and ambient electron are strongly accelerated in both parallel and perpendicular directions.

  12. Particle Acceleration, Magnetic Field Generation in Relativistic Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, Ken-Ichi; Hardee, P.; Hededal, C. B.; Richardson, G.; Sol, H.; Preece, R.; Fishman, G. J.

    2005-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient parallel magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. New simulations with an ambient perpendicular magnetic field show the strong interaction between the relativistic jet and the magnetic fields. The magnetic fields are piled up by the jet and the jet electrons are bent, which creates currents and displacement currents. At the nonlinear stage, the magnetic fields are reversed by the current and the reconnection may take place. Due to these dynamics the jet and ambient electron are strongly accelerated in both parallel and perpendicular directions.

  13. Radiation from Relativistic Shocks with Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishkawa, K.; Medvedev, M.; Zhang, B.; Hardee, P.; Niemiec, J.; Mizuno, A.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Oka, M.; Fishman, J.

    2009-01-01

    Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs at shocked region. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the shock. The "jitter" radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants. New recent calculation of spectra with various different Lorentz factors of jets (two electrons) and initial magnetic fields. New spectra based on small simulations will be presented.

  14. A General Relativistic Magnetohydrodynamic Simulation of Jet Formation

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Richardson, G.; Koide, S.; Shibata, K.; Kudoh, T.; Hardee, P.; Fishman, G. J.

    2005-01-01

    We have performed a fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation ofjet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results show that a bipolar jet (velocity approx.0.3c) is created, as shown by previous two-dimensional axi- symmetric simulations with mirror symmetry at the equator. The three-dimensional simulation ran over 100 light crossing time units (T(sub s) = r(sub s)/c, where r(sub s = 2GM/c(sup 2), which is considerably longer than the previous simulations. We show that the jet is initially formed as predicted owing in part to magnetic pressure from the twisting of the initially uniform magnetic field and from gas pressure associated with shock formation in the region around r = 3r(sub s). At later times, the accretion disk becomes thick and the jet fades resulting in a wind that is ejected from the surface ofthe thickened (torus-like) disk. It should be noted that no streaming matter from a donor is included at the outer boundary in the simulation (an isolated black hole not binary black hole). The wind flows outward with a wider angle than the initial jet. The widening of the jet is consistent with the outward-moving torsional Alfven waves. This evolution of disk-jet coupling suggests that the jet fades with a thickened accretion disk because of the iack of streaming materiai from an accompanying star.

  15. Evolution of Global Relativistic Jets: Collimations and Expansion with kKHI and the Weibel Instability

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ken-Ichi; Trier Trier Frederiksen, Jacob; Nordlund, Aake; Mizuno, Yosuke; Hardee, Philip E.; Niemiec, Jacek; Gomez, Jose; Pe'er, Asaf; Dutan, Ioana; Meli, Athina; Sol, Helene; Pohl, Martin; Hartmann, Dieter

    2016-04-01

    In the study of relativistic jets one of the key open questions is their interaction with the environment. Here, we study the initial evolution of both electron-proton (e-- p+) and electron-positron (e±) relativistic jets, focusing on their lateral interaction with ambient plasma. We follow the evolution of toroidal magnetic fields generated by both the kinetic Kelvin-Helmholtz (kKH) and Mushroom instabilities (MI). For an e-- p+ jet, the induced magnetic field collimates the jet and electrons are perpendicularly accelerated. As the instabilities saturate and subsequently weaken, the magnetic polarity switches from clockwise to counter-clockwise in the middle of the jet. For an e± jet, we find strong mixing of electrons and positrons with the ambient plasma, resulting in the creation of a bow shock. The merging of current filaments generates density inhomogeneities which initiate a forward shock. Strong jet-ambient plasma mixing prevents a full development of the jet (on the scale studied), revealing evidence for both jet collimation and particle acceleration in the forming bow shock. Differences in the magnetic field structure generated by e-- p+ and e± jets may contribute to the polarization properties of the observed emission in AGN jets and gamma ray bursts.

  16. Evolution of Global Relativistic Jets: Collimations and Expansion with kKHI and the Weibel Instability

    NASA Astrophysics Data System (ADS)

    Nishikawa, Ken-ichi; Hardee, Phil; Hartmann, Dieter; Niemiec, Jacek; Pohl, Martin; Nordlund, Aake; Sol, Helene; Gomez, Jose L.; Dutan, Ioana; Mizuno, Yosuke; Meli, Athina; Peer, Asaf; Frederiksen, Jacob

    2016-07-01

    In the study of relativistic jets one of the key open questions is their interaction with the environment. Here, we study the initial evolution of both electron-proton (e ^{-}- p ^{+}) and electron-positron (e±) relativistic jets, focusing on their lateral interaction with ambient plasma. We follow the evolution of toroidal magnetic fields generated by both the kinetic Kelvin-Helmholtz (kKH) and Mushroom instabilities (MI). For an e ^{-}- p ^{+} jet, the induced magnetic field collimates the jet and electrons are perpendicularly accelerated. As the instabilities saturate and subsequently weaken, the magnetic polarity switches from clockwise to counter-clockwise in the middle of jet. For an e± jet, we find strong mixing of electrons and positrons with the ambient plasma, resulting in the creation of a bow shock. The merging of current filaments generates density inhomogeneities which initiate a forward shock. Strong jet ambient plasma mixing prevents a full development of the jet (on the scale studied), revealing evidence for both jet collimation and particle acceleration in the forming bow shock. Differences in the magnetic field structure generated by e ^{-}- p ^{+} and e± jets may contribute to the polarization properties of the observed emission in AGN jets and gamma ray bursts.

  17. Evolution of Global Relativistic Jets: Collimations and Expansion with kKHI and the Weibel Instability

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Frederiksen, J. T.; Nordlund, Å.; Mizuno, Y.; Hardee, P. E.; Niemiec, J.; Gómez, J. L.; Pe'er, A.; Duţan, I.; Meli, A.; Sol, H.; Pohl, M.; Hartmann, D. H.

    2016-04-01

    In the study of relativistic jets one of the key open questions is their interaction with the environment. Here we study the initial evolution of both electron-proton ({e}{--}-{p}+) and electron-positron (e±) relativistic jets, focusing on their lateral interaction with ambient plasma. We follow the evolution of toroidal magnetic fields generated by both the kinetic Kelvin-Helmholtz and Mushroom instabilities. For an {e}{--}-{p}+ jet, the induced magnetic field collimates the jet and electrons are perpendicularly accelerated. As the instabilities saturate and subsequently weaken, the magnetic polarity switches from clockwise to counterclockwise in the middle of the jet. For an e± jet, we find strong mixing of electrons and positrons with the ambient plasma, resulting in the creation of a bow shock. The merging of current filaments generates density inhomogeneities that initiate a forward shock. Strong jet-ambient plasma mixing prevents a full development of the jet (on the scale studied), revealing evidence for both jet collimation and particle acceleration in the forming bow shock. Differences in the magnetic field structure generated by {e}{--}-{p}+ and e± jets may contribute to the polarization properties of the observed emission in AGN jets and gamma-ray bursts.

  18. Entropy production in relativistic jet boundary layers

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna; Begelman, Mitchell C.

    2015-01-01

    Hot relativistic jets, passing through a background medium with a pressure gradient p ∝ r-η where 2 < η ≤ 8/3, develop a shocked boundary layer containing a significant fraction of the jet power. In previous work, we developed a self-similar description of the boundary layer assuming isentropic flow, but we found that such models respect global energy conservation only for the special case η = 8/3. Here, we demonstrate that models with η < 8/3 can be made self-consistent if we relax the assumption of constant specific entropy. Instead, the entropy must increase with increasing r along the boundary layer, presumably due to multiple shocks driven into the flow as it gradually collimates. The increase in specific entropy slows the acceleration rate of the flow and provides a source of internal energy that could be channelled into radiation. We suggest that this process may be important for determining the radiative characteristics of tidal disruption events and gamma-ray bursts from collapsars.

  19. General relativistic magnetohydrodynamical simulations of the jet in M 87

    NASA Astrophysics Data System (ADS)

    Mościbrodzka, Monika; Falcke, Heino; Shiokawa, Hotaka

    2016-02-01

    Context. The connection between black hole, accretion disk, and radio jet can be constrained best by fitting models to observations of nearby low-luminosity galactic nuclei, in particular the well-studied sources Sgr A* and M 87. There has been considerable progress in modeling the central engine of active galactic nuclei by an accreting supermassive black hole coupled to a relativistic plasma jet. However, can a single model be applied to a range of black hole masses and accretion rates? Aims: Here we want to compare the latest three-dimensional numerical model, originally developed for Sgr A* in the center of the Milky Way, to radio observations of the much more powerful and more massive black hole in M 87. Methods: We postprocess three-dimensional GRMHD models of a jet-producing radiatively inefficient accretion flow around a spinning black hole using relativistic radiative transfer and ray-tracing to produce model spectra and images. As a key new ingredient in these models, we allow the proton-electron coupling in these simulations depend on the magnetic properties of the plasma. Results: We find that the radio emission in M 87 is described well by a combination of a two-temperature accretion flow and a hot single-temperature jet. Most of the radio emission in our simulations comes from the jet sheath. The model fits the basic observed characteristics of the M 87 radio core: it is "edge-brightened", starts subluminally, has a flat spectrum, and increases in size with wavelength. The best fit model has a mass-accretion rate of Ṁ ~ 9 × 10-3M⊙ yr-1 and a total jet power of Pj ~ 1043 erg s-1. Emission at λ = 1.3 mm is produced by the counter-jet close to the event horizon. Its characteristic crescent shape surrounding the black hole shadow could be resolved by future millimeter-wave VLBI experiments. Conclusions: The model was successfully derived from one for the supermassive black hole in the center of the Milky Way by appropriately scaling mass and

  20. Relativistic jet feedback in high-redshift galaxies - I. Dynamics

    NASA Astrophysics Data System (ADS)

    Mukherjee, Dipanjan; Bicknell, Geoffrey V.; Sutherland, Ralph; Wagner, Alex

    2016-09-01

    We present the results of 3D relativistic hydrodynamic simulations of interaction of active galactic nucleus jets with a dense turbulent two-phase interstellar medium, which would be typical of high-redshift galaxies. We describe the effect of the jet on the evolution of the density of the turbulent interstellar medium (ISM). The jet-driven energy bubble affects the gas to distances up to several kiloparsecs from the injection region. The shocks resulting from such interactions create a multiphase ISM and radial outflows. One of the striking result of this work is that low-power jets (Pjet ≲ 1043 ergs-1), although less efficient in accelerating clouds, are trapped in the ISM for a longer time and hence affect the ISM over a larger volume. Jets of higher power drill through with relative ease. Although the relativistic jets launch strong outflows, there is little net mass ejection to very large distances, supporting a galactic fountain scenario for local feedback.

  1. On Lorentz invariants in relativistic magnetic reconnection

    SciTech Connect

    Yang, Shu-Di; Wang, Xiao-Gang

    2016-08-15

    Lorentz invariants whose nonrelativistic correspondences play important roles in magnetic reconnection are discussed in this paper. Particularly, the relativistic invariant of the magnetic reconnection rate is defined and investigated in a covariant two-fluid model. Certain Lorentz covariant representations for energy conversion and magnetic structures in reconnection processes are also investigated. Furthermore, relativistic measures for topological features of reconnection sites, particularly magnetic nulls and separatrices, are analyzed.

  2. QUASI-STATIC MODEL OF MAGNETICALLY COLLIMATED JETS AND RADIO LOBES. II. JET STRUCTURE AND STABILITY

    SciTech Connect

    Colgate, Stirling A.; Li, Hui; Fowler, T. Kenneth; Hooper, E. Bickford; McClenaghan, Joseph; Lin, Zhihong

    2015-11-10

    This is the second in a series of companion papers showing that when an efficient dynamo can be maintained by accretion disks around supermassive black holes in active galactic nuclei, it can lead to the formation of a powerful, magnetically driven, and mediated helix that could explain both the observed radio jet/lobe structures and ultimately the enormous power inferred from the observed ultrahigh-energy cosmic rays. In the first paper, we showed self-consistently that minimizing viscous dissipation in the disk naturally leads to jets of maximum power with boundary conditions known to yield jets as a low-density, magnetically collimated tower, consistent with observational constraints of wire-like currents at distances far from the black hole. In this paper we show that these magnetic towers remain collimated as they grow in length at nonrelativistic velocities. Differences with relativistic jet models are explained by three-dimensional magnetic structures derived from a detailed examination of stability properties of the tower model, including a broad diffuse pinch with current profiles predicted by a detailed jet solution outside the collimated central column treated as an electric circuit. We justify our model in part by the derived jet dimensions in reasonable agreement with observations. Using these jet properties, we also discuss the implications for relativistic particle acceleration in nonrelativistically moving jets. The appendices justify the low jet densities yielding our results and speculate how to reconcile our nonrelativistic treatment with general relativistic MHD simulations.

  3. A magnetohydrodynamic model of the M87 jet. II. Self-consistent quad-shock jet model for optical relativistic motions and particle acceleration

    SciTech Connect

    Nakamura, Masanori

    2014-04-20

    We describe a new paradigm for understanding both relativistic motions and particle acceleration in the M87 jet: a magnetically dominated relativistic flow that naturally produces four relativistic magnetohydrodynamic (MHD) shocks (forward/reverse fast and slow modes). We apply this model to a set of optical super- and subluminal motions discovered by Biretta and coworkers with the Hubble Space Telescope during 1994-1998. The model concept consists of ejection of a single relativistic Poynting jet, which possesses a coherent helical (poloidal + toroidal) magnetic component, at the remarkably flaring point HST-1. We are able to reproduce quantitatively proper motions of components seen in the optical observations of HST-1 with the same model we used previously to describe similar features in radio very long baseline interferometry observations in 2005-2006. This indicates that the quad relativistic MHD shock model can be applied generally to recurring pairs of super/subluminal knots ejected from the upstream edge of the HST-1 complex as observed from radio to optical wavelengths, with forward/reverse fast-mode MHD shocks then responsible for observed moving features. Moreover, we identify such intrinsic properties as the shock compression ratio, degree of magnetization, and magnetic obliquity and show that they are suitable to mediate diffusive shock acceleration of relativistic particles via the first-order Fermi process. We suggest that relativistic MHD shocks in Poynting-flux-dominated helical jets may play a role in explaining observed emission and proper motions in many active galactic nuclei.

  4. Magnetically driven jets and winds: Exact solutions

    NASA Technical Reports Server (NTRS)

    Contopoulos, J.; Lovelace, R. V. E.

    1994-01-01

    We present a general class of self-similar solutions of the full set of MHD equations that include matter flow, electromagnetic fields, pressure, and gravity. The solutions represent axisymmetric, time-independent, nonrelativistic, ideal, magnetohydrodynamic, collimated outflows (jet and winds) from magnetized accretion disks around compact objects. The magnetic field extracts angular momentum from the disk, accelerates the outflows perpedicular to the disk, and provides collimation at large distances. The terminal outflow velocities are of the order of or greater than the rotational velocity of the disk at the base of the flow. When a nonzero electric current flows along the jet, the outflow radius oscillates with axial distance, whereas when the total electric current is zero (with the return current flowing across the jet's cross section), the outflow radius increase to a maximum and then decreases. The method can also be applied to relativistic outflows.

  5. Relativistic Jet Properties of GeV-TeV Blazars and Possible Implications for the Jet Formation, Composition, and Cavity

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Zhang, Shuang-Nan; Liang, En-Wei; Sun, Xiao Na

    We present spectral energy distributions (SEDs) fits to a sample of GeV-TeV flat spectrum radio quasars (FSRQs) and compare the jet properties between FSRQs and BL Lacs. We show that the SEDs can be fit with the single-zone leptonic model, and both the minimum and broken Lorentz factors of relativistic electrons can be constrained, with medians of gamma_{min}˜ 48 and gamma_b˜ 240. No statistical difference on the Doppler factors between the FSRQs and BL Lacs is found. Assuming that the jet power is carried by electron-proton pairs, the magnetic field, and the radiation field, we calculate the powers of these components and the total jet power (P_jet) based on our fitting results, hence derive the radiation efficiency and magnetization parameter of the jets. It is found that the FSRQ jets are dominated by the Poynting flux and have a high radiation efficiency, whereas the BL Lac jets are dominated by particles and have a lower radiation efficiency than FSRQs. Interestingly, different from BL Lacs, P_jet of FSRQs are proportional to their central black hole (BH) masses. Measuring the jet production and radiation rates per central BH mass with P_jet/L_Edd and P_r/L_Edd, we find P_r/L_Edd~ (P_jet/L_Edd)({1.24±) 0.16} for FSRQs and P_r/L_Edd~ (P_jet/L_Edd)({0.85±) 0.09} for BL Lacs. The distribution of P_jet/L_Edd of FSRQs is in a narrow range, whereas it varies over several orders of magnitude for BL Lacs. These results likely suggest that the essential difference of FSRQs and BL Lacs may be due to the different jet production mechanisms. The dominating formation mechanism of FSRQ jets may be the BZ process. BL Lac jets may be produced via the BP and/or BZ processes, depending on structures and accretion rates of accretion disks. P_jet is correlated with the cavity kinetic power L_kin for our blazar sample. The magnetic field energy in the jets may provide the cavity kinetic energy for FSRQs and the kinetic energy of cold protons in the jets may be crucial for

  6. The role of the Weibel instability at the reconnection jet front in relativistic pair plasma reconnection

    SciTech Connect

    Zenitani, S.; Hesse, M.

    2008-02-15

    The role of the Weibel instability is investigated for the first time in the context of the large-scale magnetic reconnection problem. A late-time evolution of magnetic reconnection in relativistic pair plasmas is demonstrated by particle-in-cell simulations. In the outflow regions, powerful reconnection jets pile up the magnetic fields and then a contact discontinuity appears there. Further downstream, it is found that the two-dimensional extension of the relativistic Weibel instability generates electromagnetic fields, which are comparable to the antiparallel or piled-up fields. In a microscopic viewpoint, the instability allows the plasma's multiple interactions with the discontinuity. In a macroscopic viewpoint, the instability leads to rapid expansion of the current sheet and then the reconnection jet front further propagates into the downstream. Possible application to the three-dimensional case is briefly discussed.

  7. Intrinsic physical conditions and structure of relativistic jets in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Nokhrina, E. E.; Beskin, V. S.; Kovalev, Y. Y.; Zheltoukhov, A. A.

    2015-03-01

    The analysis of the frequency dependence of the observed shift of the cores of relativistic jets in active galactic nuclei (AGNs) allows us to evaluate the number density of the outflowing plasma ne and, hence, the multiplicity parameter λ = ne/nGJ, where nGJ is the Goldreich-Julian number density. We have obtained the median value for λmed = 3 × 1013 and the median value for the Michel magnetization parameter σM, med = 8 from an analysis of 97 sources. Since the magnetization parameter can be interpreted as the maximum possible Lorentz factor Γ of the bulk motion which can be obtained for relativistic magnetohydrodynamic (MHD) flow, this estimate is in agreement with the observed superluminal motion of bright features in AGN jets. Moreover, knowing these key parameters, one can determine the transverse structure of the flow. We show that the poloidal magnetic field and particle number density are much larger in the centre of the jet than near the jet boundary. The MHD model can also explain the typical observed level of jet acceleration. Finally, casual connectivity of strongly collimated jets is discussed.

  8. Magnetic Field Topology in Jets

    NASA Technical Reports Server (NTRS)

    Gardiner, T. A.; Frank, A.

    2000-01-01

    We present results on the magnetic field topology in a pulsed radiative. jet. For initially helical magnetic fields and periodic velocity variations, we find that the magnetic field alternates along the, length of the jet from toroidally dominated in the knots to possibly poloidally dominated in the intervening regions.

  9. Magnetic Field Topology in Jets

    NASA Technical Reports Server (NTRS)

    Gardiner, T. A.; Frank, A.

    2000-01-01

    We present results on the magnetic field topology in a pulsed radiative. jet. For initially helical magnetic fields and periodic velocity variations, we find that the magnetic field alternates along the, length of the jet from toroidally dominated in the knots to possibly poloidally dominated in the intervening regions.

  10. Discovery of a Pseudobulge Galaxy Launching Powerful Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Kotilainen, Jari K.; León-Tavares, Jonathan; Olguín-Iglesias, Alejandro; Baes, Maarten; Anórve, Christopher; Chavushyan, Vahram; Carrasco, Luis

    2016-12-01

    Supermassive black holes launching plasma jets at close to the speed of light, producing gamma-rays, have ubiquitously been found to be hosted by massive elliptical galaxies. Since elliptical galaxies are generally believed to be built through galaxy mergers, active galactic nuclei (AGN) launching relativistic jets are associated with the latest stages of galaxy evolution. We have discovered a pseudobulge morphology in the host galaxy of the gamma-ray AGN PKS 2004-447. This is the first gamma-ray emitter radio-loud AGN found to have been launched from a system where both the black hole and host galaxy have been actively growing via secular processes. This is evidence of an alternative black hole-galaxy co-evolutionary path to develop powerful relativistic jets, which is not merger driven.

  11. Relativistic plasmas in AGN jets. From synchrotron radiation to γ-ray emission

    NASA Astrophysics Data System (ADS)

    La Mura, Giovanni; Busetto, Giovanni; Ciroi, Stefano; Rafanelli, Piero; Berton, Marco; Congiu, Enrico; Cracco, Valentina; Frezzato, Michele

    2017-02-01

    Relativistic jets of plasma are a key ingredient of many types of Active Galactic Nuclei (AGN). Today we know that AGNs are powered by the accretion of interstellar material into the gravitational field of a Super Massive Black Hole, and that this process can release as much power as an entire galaxy the size of the Milky Way, from a region that is comparable to the Solar System in size. Depending on the properties of the central energy source, a large fraction of this power can be involved in the acceleration of magnetized plasmas at relativistic speeds, to form large-scale jets. The presence of jets affects the spectrum of AGNs through the emission of synchrotron radiation and Inverse Compton scattering of low energy photons, thus leading to a prominent non-thermal spectrum, sometimes extending from radio frequencies all the way up to γ-ray energies. Here we review some characteristic processes of radiation emission in AGN jets, which lead to the emission of photons in the radio, optical, X-ray and γ-ray bands, and we present the results of a spectroscopic campaign of optical counterparts. We discuss our observations and their connection with γ-ray properties in a scenario that traces the role of relativistic jets in different classes of AGNs, detected in both the local and the remote Universe. Contribution to the Topical Issue "Physics of Ionized Gases (SPIG 2016)", edited by Goran Poparic, Bratislav Obradovic, Dragana Maric and Aleksandar Milosavljevic

  12. The physics of gamma-ray bursts & relativistic jets

    NASA Astrophysics Data System (ADS)

    Kumar, Pawan; Zhang, Bing

    2015-02-01

    We provide a comprehensive review of major developments in our understanding of gamma-ray bursts, with particular focus on the discoveries made within the last fifteen years when their true nature was uncovered. We describe the observational properties of photons from the radio to 100s GeV bands, both in the prompt emission and the afterglow phases. Mechanisms for the generation of these photons in GRBs are discussed and confronted with observations to shed light on the physical properties of these explosions, their progenitor stars and the surrounding medium. After presenting observational evidence that a powerful, collimated, jet moving at close to the speed of light is produced in these explosions, we describe our current understanding regarding the generation, acceleration, and dissipation of the jet. We discuss mounting observational evidence that long duration GRBs are produced when massive stars die, and that at least some short duration bursts are associated with old, roughly solar mass, compact stars. The question of whether a black-hole or a strongly magnetized, rapidly rotating neutron star is produced in these explosions is also discussed. We provide a brief summary of what we have learned about relativistic collisionless shocks and particle acceleration from GRB afterglow studies, and discuss the current understanding of radiation mechanism during the prompt emission phase. We discuss theoretical predictions of possible high-energy neutrino emission from GRBs and the current observational constraints. Finally, we discuss how these explosions may be used to study cosmology, e.g. star formation, metal enrichment, reionization history, as well as the formation of first stars and galaxies in the universe.

  13. Anomalous magnetic viscosity in relativistic accretion disks

    NASA Astrophysics Data System (ADS)

    Lin, Fujun; Liu, Sanqiu; Li, Xiaoqing

    2013-07-01

    It has been proved that the self-generated magnetic fields by transverse plasmons in the relativistic regime are modulationally unstable, leading to a self-similar collapse of the magnetic flux tubes and resulting in local magnetic structures; highly spatially intermittent flux is responsible for generating the anomalous viscosity. We derive the anomalous magnetic viscosity coefficient, in accretion disks around compact objects, such as black holes, pulsars and quasars, where the plasmas are relativistic, in order to help clarify the nature of viscosity in the theory of accretion disks. The results indicate that, the magnetic viscosity is modified by the relativistic effects of plasmas, and its' strength would be 1015 stronger than the molecular viscosity, which may be helpful in explaining the observations.

  14. Nuclear composition of magnetized gamma-ray burst jets

    NASA Astrophysics Data System (ADS)

    Shibata, Sanshiro; Tominaga, Nozomu

    2015-06-01

    We investigate the fraction of metal nuclei in the relativistic jets of gamma-ray bursts associated with core-collapse supernovae. We simulate the fallback in jet-induced explosions with two-dimensional relativistic hydrodynamics calculations and the jet acceleration with steady, radial, relativistic magnetohydrodynamics calculations, and derive the detailed nuclear composition of the jet by post-processing calculation. We found that if the temperature at the jet launch site is above 4.7 × 109 K, quasi-statistical equilibrium is established and heavy nuclei are dissociated into light particles such as 4He during the acceleration of the jets. The criterion for the survival of metal nuclei is written in terms of the isotropic jet luminosity as L_j^iso ≲ 3.9 × 10^{50} ( R_i/107 cm)^2(1 + σi) erg s-1, where Ri and σi are the initial radius of the jets and the initial magnetization parameter, respectively. If the jet is initially dominated by radiation field (i.e., σi ≪ 1) and the isotropic luminosity is relatively high (L_j^iso ≳ 4 × 10^{52} erg s-1), the metal nuclei cannot survive in the jet. On the other hand, if the jet is mainly accelerated by magnetic field (i.e., σi ≫ 1), metal nuclei initially contained in the jet can survive without serious dissociation even in the case of a high-luminosity jet. If the jet contains metal nuclei, the dominant nuclei are 28Si, 16O, and 32S and the mean mass number can be ˜ 25.

  15. General relativistic study of astrophysical jets with internal shocks

    NASA Astrophysics Data System (ADS)

    Vyas, Mukesh K.; Chattopadhyay, Indranil

    2017-08-01

    We explore the possibility of the formation of steady internal shocks in jets around black holes. We consider a fluid described by a relativistic equation of state, flowing about the axis of symmetry (θ = 0) in a Schwarzschild metric. We use two models for the jet geometry: (i) a conical geometry and (ii) a geometry with non-conical cross-section. A jet with conical geometry has a smooth flow, while the jet with non-conical cross-section undergoes multiple sonic points and even standing shock. The jet shock becomes stronger, as the shock location is situated farther from the central black hole. Jets with very high energy and very low energy do not harbour shocks, but jets with intermediate energies do harbour shocks. One advantage of these shocks, as opposed to shocks mediated by external medium, is that these shocks have no effect on the jet terminal speed, but may act as possible sites for particle acceleration. Typically, a jet with specific energy 1.8c2 will achieve a terminal speed of v∞ = 0.813c for jet with any geometry, where, c is the speed of light in vacuum. But for a jet of non-conical cross-section for which the length scale of the inner torus of the accretion disc is 40rg, then, in addition, a steady shock will form at rsh ∼ 7.5rg and compression ratio of R ∼ 2.7. Moreover, electron-proton jet seems to harbour the strongest shock. We will discuss possible consequences of such a scenario.

  16. A General Relativistic Magnetohydrodynamics Simulation of Jet Formation with a State Transition

    NASA Technical Reports Server (NTRS)

    Nishikawa, K. I.; Richardson, G.; Koide, S.; Shibata, K.; Kudoh, T.; Hardee, P.; Fushman, G. J.

    2004-01-01

    We have performed the first fully three-dimensional general relativistic magnetohydrodynamic (GRMHD) simulation of jet formation from a thin accretion disk around a Schwarzschild black hole with a free-falling corona. The initial simulation results show that a bipolar jet (velocity sim 0.3c) is created as shown by previous two-dimensional axisymmetric simulations with mirror symmetry at the equator. The 3-D simulation ran over one hundred light-crossing time units which is considerably longer than the previous simulations. We show that the jet is initially formed as predicted due in part to magnetic pressure from the twisting the initially uniform magnetic field and from gas pressure associated with shock formation. At later times, the accretion disk becomes thick and the jet fades resulting in a wind that is ejected from the surface of the thickened (torus-like) disk. It should be noted that no streaming matter from a donor is included at the outer boundary in the simulation (an isolated black hole not binary black hole). The wind flows outwards with a wider angle than the initial jet. The widening of the jet is consistent with the outward moving shock wave. This evolution of jet-disk coupling suggests that the low/hard state of the jet system may switch to the high/soft state with a wind, as the accretion rate diminishes.

  17. Megaparsec relativistic jets launched from an accreting supermassive black hole in an extreme spiral galaxy

    SciTech Connect

    Bagchi, Joydeep; Vivek, M.; Srianand, Raghunathan; Gopal-Krishna; Vikram, Vinu; Hota, Ananda; Biju, K. G.; Sirothia, S. K.; Jacob, Joe

    2014-06-20

    The radio galaxy phenomenon is directly connected to mass-accreting, spinning supermassive black holes found in the active galactic nuclei. It is still unclear how the collimated jets of relativistic plasma on hundreds to thousands of kiloparsec scales form and why they are nearly always launched from the nuclei of bulge-dominated elliptical galaxies and not flat spirals. Here we present the discovery of the giant radio source J2345–0449 (z = 0.0755), a clear and extremely rare counterexample where relativistic jets are ejected from a luminous and massive spiral galaxy on a scale of ∼1.6 Mpc, the largest known so far. Extreme physical properties observed for this bulgeless spiral host, such as its high optical and infrared luminosity, large dynamical mass, rapid disk rotation, and episodic jet activity, are possibly the results of its unusual formation history, which has also assembled, via gas accretion from a disk, its central black hole of mass >2 × 10{sup 8} M {sub ☉}. The very high mid-IR luminosity of the galaxy suggests that it is actively forming stars and still building a massive disk. We argue that the launch of these powerful jets is facilitated by an advection-dominated, magnetized accretion flow at a low Eddington rate onto this unusually massive (for a bulgeless disk galaxy) and possibly fast spinning central black hole. Therefore, J2345–0449 is an extremely rare, unusual galactic system whose properties challenge the standard paradigms for black hole growth and the formation of relativistic jets in disk galaxies. Thus, it provides fundamental insight into accretion disk-relativistic jet coupling processes.

  18. Relativistic tidal acceleration of astrophysical jets

    NASA Astrophysics Data System (ADS)

    Bini, Donato; Chicone, Carmen; Mashhoon, Bahram

    2017-05-01

    Within the framework of general relativity, we investigate the tidal acceleration of astrophysical jets relative to the central collapsed configuration ("Kerr source"). To simplify matters, we neglect electromagnetic forces throughout; however, these must be included in a complete analysis. The rest frame of the Kerr source is locally defined via the set of hypothetical static observers in the spacetime exterior to the source. Relative to such a fiducial observer fixed on the rotation axis of the Kerr source, jet particles are tidally accelerated to almost the speed of light if their outflow speed is above a certain threshold, given roughly by one-half of the Newtonian escape velocity at the location of the reference observer; otherwise, the particles reach a certain height, reverse direction and fall back toward the gravitational source.

  19. Causality and Communication: Relativistic astrophysical jets and the implementation of science communication training in astronomy classes

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    Part I: Relativistic jets emitted from the centers of some galaxies (called active galaxies) exhibit many interesting behaviors that are not yet fully understood: acceleration and collimation over vast distances, for instance, and occasional flaring activity. In the first part of my thesis, I examine the possibility of collimation and acceleration of relativistic jets by the pressure of the ambient medium surrounding the jet base. I discuss the differences in predicted jet behavior due to including the effects of a magnetic field threading the jet interior, and I describe the conditions that create some observed jet shapes, such as the "hollow cone" structure seen in M87 and similar jets. I also discuss what happens when the pressure outside of the jet drops so slowly that the jet shocks repeatedly, generating entropy at its boundary. Finally, I examine the spectra of the 40 brightest gamma-ray flares from blazars (active galaxies with jets pointed toward us) recorded by the Fermi Gamma-ray Space Telescope in its first four years of operation. I develop models to describe the observed behavior of these flares and discuss the physical implications of these models. Part II: The ability to clearly communicate scientific concepts to both peers and the lay public is an important component of being a scientist. Few training programs exist, however, for scientists to obtain these skills. In the second part of my thesis, I examine the impact of two different training efforts for very early-career scientists: first, a short science communication workshop for science, technology, engineering and math (STEM) graduate students, and second, science communication training integrated into existing astronomy classes for undergraduate STEM majors and early STEM graduate students. I evaluate whether the students' written communication skills demonstrate measurable improvement after training, and track students' attitudes toward science communication.

  20. The power of relativistic jets is larger than the luminosity of their accretion disks.

    PubMed

    Ghisellini, G; Tavecchio, F; Maraschi, L; Celotti, A; Sbarrato, T

    2014-11-20

    Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central supermassive black hole, as well as from the magnetic field near the event horizon. The physical mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation, but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous samples used prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power, as measured through the γ-ray luminosity, and accretion luminosity, as measured by the broad emission lines, with the jet power dominating the disk luminosity, in agreement with numerical simulations. This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter.

  1. The power of relativistic jets is larger than the luminosity of their accretion disks

    NASA Astrophysics Data System (ADS)

    Ghisellini, G.; Tavecchio, F.; Maraschi, L.; Celotti, A.; Sbarrato, T.

    2014-11-01

    Theoretical models for the production of relativistic jets from active galactic nuclei predict that jet power arises from the spin and mass of the central supermassive black hole, as well as from the magnetic field near the event horizon. The physical mechanism underlying the contribution from the magnetic field is the torque exerted on the rotating black hole by the field amplified by the accreting material. If the squared magnetic field is proportional to the accretion rate, then there will be a correlation between jet power and accretion luminosity. There is evidence for such a correlation, but inadequate knowledge of the accretion luminosity of the limited and inhomogeneous samples used prevented a firm conclusion. Here we report an analysis of archival observations of a sample of blazars (quasars whose jets point towards Earth) that overcomes previous limitations. We find a clear correlation between jet power, as measured through the γ-ray luminosity, and accretion luminosity, as measured by the broad emission lines, with the jet power dominating the disk luminosity, in agreement with numerical simulations. This implies that the magnetic field threading the black hole horizon reaches the maximum value sustainable by the accreting matter.

  2. A "Boosted Fireball" Model for Structured Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Duffell, Paul C.; MacFadyen, Andrew I.

    2013-10-01

    We present a model for relativistic jets which generates a particular angular distribution of Lorentz factor and energy per solid angle. We consider a fireball with specific internal energy E/M launched with bulk Lorentz factor γ B . In its center-of-momentum frame the fireball expands isotropically, converting its internal energy into radially expanding flow with asymptotic Lorentz factor η0 ~ E/M. In the lab frame the flow is beamed, expanding with Lorentz factor Γ = 2η0γ B in the direction of its initial bulk motion and with characteristic opening angle θ0 ~ 1/γ B . The flow is jet-like with Γθ0 ~ 2η0 such that jets with Γ > 1/θ0 are naturally produced. The choice η0 ~ γ B ~ 10 yields a jet with Γ ~ 200 on-axis and angular structure characterized by opening angle θ0 ~ 0.1 of relevance for cosmological gamma-ray bursts (GRBs), while γ B >~ 1 may be relevant for low-luminosity GRBs. The model produces a family of outflows, of relevance for different relativistic phenomena with structures completely determined by η0 and γ B . We calculate the energy per unit solid angle for the model and use it to compute light curves for comparison with the widely used top-hat model. The jet break in the boosted fireball light curve is greatly subdued when compared to the top-hat model because the edge of the jet is smoother than for a top-hat. This may explain missing jet breaks in afterglow light curves.

  3. Radiative interaction between the relativistic jet and optically thick envelope in tidal disruption events

    NASA Astrophysics Data System (ADS)

    Lu, Wenbin; Krolik, Julian; Crumley, Patrick; Kumar, Pawan

    2017-10-01

    Reverberation observations yielding a lag spectrum have uncovered an Fe K α fluorescence line in the tidal disruption event (TDE) Swift J1644+57. The discovery paper used the lag spectrum to argue that the source of the X-ray continuum was located very close to the black hole (∼30 gravitational radii) and moved subrelativistically. We reanalyse the lag spectrum, pointing out that dilution effects cause it to indicate a geometric scale an order of magnitude larger than inferred by Kara et al. If the X-ray continuum is produced by a relativistic jet, as suggested by the rapid variability, high luminosity and hard spectrum, this larger scale predicts an Fe ionization state consistent with efficient K α photon production. Moreover, the momentum of the jet X-rays impinging on the surrounding accretion flow on this large scale accelerates a layer of gas to speeds ∼0.1-0.2c, consistent with the blueshifted line profile. Implications of our results on the global picture of jetted TDEs are discussed. A power-law γ/X-ray spectrum may be produced by external ultraviolet (UV)-optical photons being repetitively inverse-Compton scattered by cold electrons in the jet, although our model for the K α reverberation does not depend on the jet radiation mechanism (magnetic reconnection in a Poynting jet is still a viable mechanism). The non-relativistic wind driven by jet radiation may explain the late-time radio rebrightening in Swift J1644+57. This energy injection may also cause the thermal UV-optical emission from jetted TDEs to be systematically brighter than in non-jetted ones.

  4. Relativistic Magnetic Reconnection in the Laboratory

    NASA Astrophysics Data System (ADS)

    Krushelnick, Karl; Raymond, Anthony; Dong, Cf; McKelvey, A.; Zulick, C.; Alexander, N.; Bhattacharjee, A.; Campbell, Pt; Chen, H.; Chvykov, V.; Del Rio, E.; Fitzsimmons, P.; Fox, W.; Hou, Bx; Maksimchuk, A.; Mileham, C.; Nees, J.; Nilson, Pm; Stoekl, C.; Thomas, Agr; Wei, Ms; Yanovsky, V.; Willingale, L.

    2016-10-01

    Magnetic reconnection is a fundamental plasma process involving an exchange of magnetic energy to plasma kinetic energy through changes in the magnetic field topology. Here we present experimental measurements using the OMEGA EP laser at LLE and the HERCULES laser at the University of Michigan as well as numerical modeling which indicate that relativistic magnetic reconnection can be driven by short-pulse, high-intensity lasers that produce a relativistic plasma along with very strong magnetic fields. Evidence of magnetic reconnection was identified by the plasma's X-ray emission patterns, changes to the electron energy spectrum, and by measuring the time over which reconnection occurs. Funded by DOE Award No. DE-NA0002727.

  5. Relativistic Magnetic Reconnection around rotating black holes

    NASA Astrophysics Data System (ADS)

    Asenjo, Felipe; Comisso, Luca

    2016-10-01

    In recent years, the classical Sweet-Parker and Petschek models have been extended in the special relativistic regime, both for MHD plasmas and two-fluid electron-positron plasmas. Nevertheless, there could be situations, like in the vicinity of black holes, where also general relativistic effects can become important. Here, we calculate analytically the reconnection rate and other relevant quantities in a magnetic reconnection process around a rotating black hole. A striking result is that the black hole rotation is capable to produce an enhancement of the rate at which magnetic reconnection proceeds. This work is supported by Fondecyt-Chile, Grant No. 11140025.

  6. What powers the most relativistic jets? - I. BL Lacs

    NASA Astrophysics Data System (ADS)

    Gardner, Emma; Done, Chris

    2014-02-01

    The dramatic relativistic jets pointing directly at us in BL Lacertae (BL Lac) objects can be well modelled by bulk motion beaming of synchrotron self-Compton emission powered by a low Eddington fraction accretion flow. Nearly 500 of these active galactic nuclei (AGN) are seen in the second Fermi Large Area Telescope catalogue of AGN. We combine the jet models which describe individual spectra with the expected jet parameter scalings with mass and mass accretion rate to predict the expected number of Fermi detected sources given the number densities of AGN from cosmological simulations. We select only sources with Eddington scaled mass accretion rate <0.01 (i.e. radiatively inefficient flows), and include cooling, orientation effects and the effects of absorption from pair production on the extragalactic infrared background. These models overpredict the number of Fermi detected BL Lacs by a factor of 1000! This clearly shows that one of the underlying assumptions is incorrect, almost certainly that jets do not scale simply with mass and accretion rate. The most plausible additional parameter which can affect the region producing the Fermi emission is black hole spin. We can reproduce the observed numbers of BL Lacs if such relativistic jets are only produced by the highest spin (a* > 0.8) black holes, in agreement with the longstanding spin-jet paradigm. This also requires that high spins are intrinsically rare, as predicted by the cosmological simulations for growing black hole mass via chaotic (randomly aligned) accretion episodes, where only the most massive black holes have high spin due to black hole-black hole mergers.

  7. Simulations of AGN jets: magnetic kink instability versus conical shocks

    NASA Astrophysics Data System (ADS)

    Barniol Duran, Rodolfo; Tchekhovskoy, Alexander; Giannios, Dimitrios

    2017-08-01

    Relativistic jets in active galactic nuclei (AGN) convert as much as half of their energy into radiation. To explore the poorly understood processes that are responsible for this conversion, we carry out fully 3D magnetohydrodynamic (MHD) simulations of relativistic magnetized jets. Unlike the standard approach of injecting the jets at large radii, our simulated jets self-consistently form at the source and propagate and accelerate outwards for several orders of magnitude in distance before they interact with the ambient medium. We find that this interaction can trigger strong energy dissipation of two kinds inside the jets, depending on the properties of the ambient medium. Those jets that form in a new outburst and drill a fresh hole through the ambient medium fall victim to a 3D magnetic kink instability and dissipate their energy primarily through magnetic reconnection in the current sheets formed by the instability. On the other hand, those jets that form during repeated cycles of AGN activity and escape through a pre-existing hole in the ambient medium maintain their stability and dissipate their energy primarily at MHD recollimation shocks. In both cases, the dissipation region can be associated with a change in the density profile of the ambient gas. The Bondi radius in AGN jets serves as such a location.

  8. Magnetically driven jets and winds

    NASA Technical Reports Server (NTRS)

    Lovelace, R. V. E.; Berk, H. L.; Contopoulos, J.

    1991-01-01

    Four equations for the origin and propagation of nonrelativistic jets and winds are derived from the basic conservation laws of ideal MHD. The axial current density is negative in the vicinity of the axis and positive at larger radii; there is no net current because this is energetically favored. The magnetic field is essential for the jet solutions in that the zz-component of the magnetic stress acts, in opposition to gravity, to drive matter through the slow magnetosonic critical point. For a representative self-consistent disk/jet solution relevant to a protostellar system, the reaction of the accreted mass expelled in the jets is 0.1, the ratio of the power carried by the jets to the disk luminosity is 0.66, and the ratio of the boundary layer to disk luminosities is less than about 0.13. The star's rotation rate decreases with time even for rotation rates much less than the breakup rate.

  9. VARIABILITY IN ACTIVE GALACTIC NUCLEI FROM PROPAGATING TURBULENT RELATIVISTIC JETS

    SciTech Connect

    Pollack, Maxwell; Pauls, David; Wiita, Paul J.

    2016-03-20

    We use the Athena hydrodynamics code to model propagating two-dimensional relativistic jets as approximations to the growth of radio-loud active galactic nuclei for various input jet velocities and jet-to-ambient matter density ratios. Using results from these simulations we estimate the changing synchrotron emission by summing the fluxes from a vertical strip of zones behind the reconfinement shock, which is nearly stationary, and from which a substantial portion of the flux variability should arise. We explore a wide range of timescales by considering two light curves from each simulation; one uses a relativistic turbulence code with bulk velocities taken from our simulations as input, while the other uses the bulk velocity data to compute fluctuations caused by variations in the Doppler boosting due to changes in the direction and the speed of the flow through all zones in the strip. We then calculate power spectral densities (PSDs) from the light curves for both turbulent and bulk velocity origins for variability. The range of the power-law slopes of the PSDs for the turbulence induced variations is −1.8 to −2.3, while for the bulk velocity produced variations this range is −2.1 to −2.9; these are in agreement with most observations. When superimposed, these power spectra span a very large range in frequency (about five decades), with the turbulent fluctuations yielding most of the shorter timescale variations and the bulk flow changes dominating the longer periods.

  10. Photospheric Emission from Collapsar Jets in 3D Relativistic Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Ito, Hirotaka; Matsumoto, Jin; Nagataki, Shigehiro; Warren, Donald C.; Barkov, Maxim V.

    2015-12-01

    We explore the photospheric emission from a relativistic jet breaking out from a massive stellar envelope based on relativistic hydrodynamical simulations and post-process radiation transfer calculations in three dimensions. To investigate the impact of three-dimensional (3D) dynamics on the emission, two models of injection conditions are considered for the jet at the center of the progenitor star: one with periodic precession and another without precession. We show that structures developed within the jet due to the interaction with the stellar envelope, as well as due to the precession, have a significant imprint on the resulting emission. Particularly, we find that the signature of precession activity by the central engine is not smeared out and can be directly observed in the light curve as a periodic signal. We also show that non-thermal features, which can account for observations of gamma-ray bursts, are produced in the resulting spectra even though only thermal photons are injected initially and the effect of non-thermal particles is not considered.

  11. PHOTOSPHERIC EMISSION FROM COLLAPSAR JETS IN 3D RELATIVISTIC HYDRODYNAMICS

    SciTech Connect

    Ito, Hirotaka; Matsumoto, Jin; Nagataki, Shigehiro; Warren, Donald C.; Barkov, Maxim V.

    2015-12-01

    We explore the photospheric emission from a relativistic jet breaking out from a massive stellar envelope based on relativistic hydrodynamical simulations and post-process radiation transfer calculations in three dimensions. To investigate the impact of three-dimensional (3D) dynamics on the emission, two models of injection conditions are considered for the jet at the center of the progenitor star: one with periodic precession and another without precession. We show that structures developed within the jet due to the interaction with the stellar envelope, as well as due to the precession, have a significant imprint on the resulting emission. Particularly, we find that the signature of precession activity by the central engine is not smeared out and can be directly observed in the light curve as a periodic signal. We also show that non-thermal features, which can account for observations of gamma-ray bursts, are produced in the resulting spectra even though only thermal photons are injected initially and the effect of non-thermal particles is not considered.

  12. On the stability and energy dissipation in magnetized radio galaxy jets.

    NASA Astrophysics Data System (ADS)

    Bromberg, Omer; Tchekhovskoy, Alexander

    2016-07-01

    It is commonly accepted that the relativistic jets observed in radio galaxies are launched magnetically and are powered by the rotational energy of the central supermassive black hole. Such jets carry most of their energy in the form of electromagnetic Poynting flux. However by the time the ejecta reach the emission zone most of that energy is transferred to relativistic motions of the jet material with a large fraction given to non-thermal particles, which calls for an efficient dissipation mechanism to work within the jet without compromising its integrity. Understanding the energy dissipation mechanisms and stability of Poynting flux dominated jets is therefore crucial for modeling these astrophysical objects. In this talk I will present the first self consistent 3D simulations of the formation and propagation of highly magnetized (σ ˜25), relativistic jets in a medium. We find that the jets develop two types of instability: i) a local, "internal" kink mode which efficiently dissipates half of the magnetic energy into heat, and ii) a global "external" mode that grows on longer time scales and causes the jets to bend sideways and wobble. Low power jets propagating in media with flat density profiles, such as galaxy cluster cores, are susceptible to the global mode, and develop FRI like morphology. High power jets remain stable as they cross the cores, break out and accelerate to large distances, appearing as FRII jets. Thus magnetic kink instability can account for both the magnetic energy dissipation and the population dichotomy in radio galaxy jets.

  13. The Innermost Regions of Relativistic Jets: Wrapping Up the Enigma

    NASA Astrophysics Data System (ADS)

    Marscher, Alan P.

    2013-12-01

    What are relativistic jets like within a million Schwarzschild radii of the accreting black hole that powers them? A meeting in Granada, Spain in June 2013, organized by José L. Gómez and his conspirators brought together observers and theorists to survey the current state of observational data and efforts to interpret them. This conference summary reviews the results, insights, arguments, conflicts, and agreements that occurred during five sunny days spent in a windowless room in a hotel at the bottom of the hill that holds the heart of the beautiful city.

  14. Relativistic Quasimonoenergetic Positron Jets from Intense Laser-Solid Interactions

    NASA Astrophysics Data System (ADS)

    Chen, Hui; Wilks, S. C.; Meyerhofer, D. D.; Bonlie, J.; Chen, C. D.; Chen, S. N.; Courtois, C.; Elberson, L.; Gregori, G.; Kruer, W.; Landoas, O.; Mithen, J.; Myatt, J.; Murphy, C. D.; Nilson, P.; Price, D.; Schneider, M.; Shepherd, R.; Stoeckl, C.; Tabak, M.; Tommasini, R.; Beiersdorfer, P.

    2010-07-01

    Detailed angle and energy resolved measurements of positrons ejected from the back of a gold target that was irradiated with an intense picosecond duration laser pulse reveal that the positrons are ejected in a collimated relativistic jet. The laser-positron energy conversion efficiency is ˜2×10-4. The jets have ˜20 degree angular divergence and the energy distributions are quasimonoenergetic with energy of 4 to 20 MeV and a beam temperature of ˜1MeV. The sheath electric field on the surface of the target is shown to determine the positron energy. The positron angular and energy distribution is controlled by varying the sheath field, through the laser conditions and target geometry.

  15. Probing acceleration and turbulence at relativistic shocks in blazar jets

    NASA Astrophysics Data System (ADS)

    Baring, Matthew G.; Böttcher, Markus; Summerlin, Errol J.

    2017-02-01

    Diffusive shock acceleration (DSA) at relativistic shocks is widely thought to be an important acceleration mechanism in various astrophysical jet sources, including radio-loud active galactic nuclei such as blazars. Such acceleration can produce the non-thermal particles that emit the broad-band continuum radiation that is detected from extragalactic jets. An important recent development for blazar science is the ability of Fermi-Large Area Telescope spectroscopy to pin down the shape of the distribution of the underlying non-thermal particle population. This paper highlights how multiwavelength spectra spanning optical to X-ray to gamma-ray bands can be used to probe diffusive acceleration in relativistic, oblique, magnetohydrodynamic (MHD) shocks in blazar jets. Diagnostics on the MHD turbulence near such shocks are obtained using thermal and non-thermal particle distributions resulting from detailed Monte Carlo simulations of DSA. These probes are afforded by the characteristic property that the synchrotron νFν peak energy does not appear in the gamma-ray band above 100 MeV. We investigate self-consistently the radiative synchrotron and inverse Compton signatures of the simulated particle distributions. Important constraints on the diffusive mean free paths of electrons, and the level of electromagnetic field turbulence are identified for three different case study blazars, Mrk 501, BL Lacertae and AO 0235+164. The X-ray excess of AO 0235+164 in a flare state can be modelled as the signature of bulk Compton scattering of external radiation fields, thereby tightly constraining the energy-dependence of the diffusion coefficient for electrons. The concomitant interpretations that turbulence levels decline with remoteness from jet shocks, and the probable significant role for non-gyroresonant diffusion, are posited.

  16. Rotation and toroidal magnetic field effects on the stability of two-component jets

    NASA Astrophysics Data System (ADS)

    Millas, Dimitrios; Keppens, Rony; Meliani, Zakaria

    2017-09-01

    Several observations of astrophysical jets show evidence of a structure in the direction perpendicular to the jet axis, leading to the development of 'spine and sheath' models of jets. Most studies focus on a two-component jet consisting of a highly relativistic inner jet and a slower - but still relativistic - outer jet surrounded by an unmagnetized environment. These jets are believed to be susceptible to a relativistic Rayleigh-Taylor-type instability, depending on the effective inertia ratio of the two components. We extend previous studies by taking into account the presence of a non-zero toroidal magnetic field. Different values of magnetization are examined to detect possible differences in the evolution and stability of the jet. We find that the toroidal field, above a certain level of magnetization σ, roughly equal to 0.01, can stabilize the jet against the previously mentioned instabilities and that there is a clear trend in the behaviour of the average Lorentz factor and the effective radius of the jet when we continuously increase the magnetization. The simulations are performed using the relativistic MHD module from the open source, parallel, grid adaptive, mpi-amrvac code.

  17. Particle Acceleration and Radiation associated with Magnetic Field Generation from Relativistic Collisionless Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Hardee, P. E.; Richardson, G. A.; Preece, R. D.; Sol, H.; Fishman, G. J.

    2003-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating through an ambient plasma with and without initial magnetic fields. We find only small differences in the results between no ambient and weak ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates particles perpendicular and parallel to the jet propagation direction. While some Fermi acceleration may occur at the jet front, the majority of electron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that this instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields, which contribute to the electron s transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.

  18. Relativistic electron in curved magnetic fields

    NASA Technical Reports Server (NTRS)

    An, S.

    1985-01-01

    Making use of the perturbation method based on the nonlinear differential equation theory, the author investigates the classical motion of a relativistic electron in a class of curved magnetic fields which may be written as B=B(O,B sub phi, O) in cylindrical coordinates (R. phi, Z). Under general astrophysical conditions the author derives the analytical expressions of the motion orbit, pitch angle, etc., of the electron in their dependence upon parameters characterizing the magnetic field and electron. The effects of non-zero curvature of magnetic field lines on the motion of electrons and applicabilities of these results to astrophysics are also discussed.

  19. Relativistic Beaming and the Intrinsic Properties of Extragalactic Radio Jets

    NASA Astrophysics Data System (ADS)

    Cohen, M. H.; Lister, M. L.; Homan, D. C.; Kadler, M.; Kellermann, K. I.; Kovalev, Y. Y.; Vermeulen, R. C.

    2007-03-01

    Relations between the observed quantities for a beamed radio jet, which are the apparent transverse speed and the apparent luminosity (βapp, L), and the intrinsic quantities, which are the Lorentz factor and the intrinsic luminosity (γ, L0), are investigated. The inversion from measured to intrinsic values is not unique, but approximate limits to γ and L0 can be found using probability arguments. Roughly half the sources in a flux density-limited, beamed sample have a value of γ close to the measured value of βapp. The methods are applied to observations of 119 AGN jets made with the VLBA at 15 GHz during 1994-2002. The results strongly support the common relativistic beam model for an extragalactic radio jet. The (βapp, L) data are closely bounded by a theoretical envelope, an ``aspect'' curve for γ=32 and L0=1025 W Hz-1. This gives limits to the maximum values of γ and L0 in the sample: γmax~32, and L0,max~1026 W Hz-1. No sources with both high values of βapp and low values of L are observed. This is not the result of selection effects due to the observing limits, which are a flux density of S>0.5 Jy and an angular velocity of μ<4 mas yr-1. Many of the fastest quasars have a pattern Lorentz factor, γp, that is close to that of the beam, γb, but some of the slow quasars must have γp<<γb. Three of the 10 galaxies in the sample have a superluminal feature, with speeds up to βapp~6. The others are at most mildly relativistic. The galaxies are not off-axis versions of the powerful quasars, but Cygnus A might be an exception.

  20. The host galaxies of AGN with powerful relativistic jets

    NASA Astrophysics Data System (ADS)

    Olguín-Iglesias, A.; León-Tavares, J.; Kotilainen, J. K.; Chavushyan, V.; Tornikoski, M.; Valtaoja, E.; Añorve, C.; Valdés, J.; Carrasco, L.

    2016-08-01

    We present deep Near-infrared (NIR) images of a sample of 19 intermediate-redshift (0.3relativistic jets (L1.4GHz >10^27 WHz^-1), previously classified as flat-spectrum radio quasars. We also compile host galaxy and nuclear magnitudes for blazars from literature. The combined sample (this work and compilation) contains 100 radio-loud AGN with host galaxy detections and a broad range of radio luminosities L1.4GHz = 10^23.7 - 10^28.3WHz^-1, allowing us to divide our sample into high-excitation (quasar-mode; HERGs) and low-excitation (radio-mode; LERGs) radio galaxies. The host galaxies of our sample are bright and seem to follow the Kormendy relation. Nuclear emission (dominated by non-thermal mechanisms) and host-galaxy magnitudes show a slightly negative weak trend for LERGs. On the other hand, the m_bulge -m_nuc relation is statistically significant for HERGs. Although it may be affected by selection effects, this correlation suggests a close coupling between the relativistic jets and their host galaxy. Our findings are consistent with the excitation state (LERG/HERG) scenario. In this view, LERGs emit the bulk of their energy in the form of radio jets, producing a strong feedback mechanism, and HERGs are affected by galaxy mergers and interactions, which provide a common supply of cold gas to feed both nuclear activity and star formation episodes.

  1. Dudley's dilemma: Magnetic moments in relativistic theories

    NASA Astrophysics Data System (ADS)

    McNeil, J. A.

    1986-10-01

    In 1975 L. Dudley Miller showed how the basic phenomenology of the major shell and spin-orbit splittings constrained the relativistic scalar/vector structure model to values of the potentials incompatible with the observed magnetic moments of nuclei one nucleon away from closed shell [1]. In this talk the resolution of this problem is presented from three different perspectives. First a self-consistent Landau-Migdal approach is used to define the single particle isoscalar current in infinite nuclear matter. The constraint of self-consistency provides a vector suppression factor to the single particle current which returns the current to its nonrelativistic form and resolves the problem. The same suppression factor is shown to follow as well from either a consideration of gauge invariance or (equivalently) the relativistic random phase approximation. Local density approximation calculations of isoscalar magnetic moments of nuclei one nucleon away from closed shell recover the Schmidt values, thus resolving this longstanding problem.

  2. EVIDENCE OF THE DYNAMICS OF RELATIVISTIC JET LAUNCHING IN QUASARS

    SciTech Connect

    Punsly, Brian

    2015-06-10

    Hubble Space Telescope (HST) spectra of the EUV, the optically thick emission from the innermost accretion flow onto the central supermassive black hole, indicate that radio loud quasars (RLQs) tend to be EUV weak compared to the radio-quiet quasars; yet the remainder of the optically thick thermal continuum is indistinguishable. The deficit of EUV emission in RLQs has a straightforward interpretation as a missing or a suppressed innermost region of local energy dissipation in the accretion flow. This article is an examination of the evidence for a distribution of magnetic flux tubes in the innermost accretion flow that results in magnetically arrested accretion (MAA) and creates the EUV deficit. These same flux tubes and possibly the interior magnetic flux that they encircle are the sources of the jet power as well. In the MAA scenario, islands of large-scale vertical magnetic flux perforate the innermost accretion flow of RLQs. The first prediction of the theory that is supported by the HST data is that the strength of the (large-scale poloidal magnetic fields) jets in the MAA region is regulated by the ram pressure of the accretion flow in the quasar environment. The second prediction that is supported by the HST data is that the rotating magnetic islands remove energy from the accretion flow as a Poynting flux dominated jet in proportion to the square of the fraction of the EUV emitting gas that is displaced by these islands.

  3. Electromagnetic wave in a relativistic magnetized plasma

    SciTech Connect

    Krasovitskiy, V. B.

    2009-12-15

    Results are presented from a theoretical investigation of the dispersion properties of a relativistic plasma in which an electromagnetic wave propagates along an external magnetic field. The dielectric tensor in integral form is simplified by separating its imaginary and real parts. A dispersion relation for an electromagnetic wave is obtained that makes it possible to analyze the dispersion and collisionless damping of electromagnetic perturbations over a broad parameter range for both nonrelativistic and ultrarelativistic plasmas.

  4. Jet shapes and jet cross sections in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Zhang, Ben-Wei

    2009-10-01

    Energetic partons traversing a hot/dense nuclear medium are expected to lose a large fraction of their energy. In fact, the stopping power of strongly-interacting matter for color-charged particles has, by far, the largest experimentally established effect: the attenuation of the cross section for final-state observables of large mass/momentum/energy. This jet quenching mechanism has been used to successfully explain the strong suppression of the hadron spectra at large transverse momentum observed in nucleus-nucleus collisions at the Relativistic Heavy Ion Collider (RHIC). However, at present, most measurements of hard processes are limited to single particles and particle correlations, which are only the leading fragments of a jet. Experimental advances at RHIC and new opportunities provided by LHC will allow for innovative and much more definitive tests of the mechanisms of parton attenuation in matter. In this study we demonstrate that jet shape and jet cross section measurements are precisely the tools to probe the underlying QCD theory. We present a first step in understanding these shapes and cross sections in heavy ion reactions. Our approach allows for detailed simulations of the experimental acceptance/cuts that help isolate jets in such high-multiplicity environment. It is demonstrated for the first time that the pattern of stimulated gluon emission can be correlated with a variable quenching of the jet rates and provide an approximately model-independent approach to determining the characteristics of the medium-induced bremsstrahlung spectrum. Surprisingly, in realistic simulations of parton propagation through the QGP we find a minimal increase in the mean jet radius even for large jet attenuation. Jet broadening is manifest in the tails of the energy distribution away from the jet axis and its qualification may need high statistics measurements.

  5. Evolution of magnetization in relativistic collisionless shocks

    NASA Astrophysics Data System (ADS)

    Keshet, Uri; Katz, Boaz; Spitkovsky, Anatoly; Waxman, Eli

    Magnetic field generation and particle acceleration in relativistic collisionless shocks are believed to be essential to the emission of radiation in various astronomical sources. These processes are tightly connected but no self-consistent model simultaneously accounts for both. We have used unprecedentedly large ab-initio particle-in-cell simulations to evolve shocks to late times where particle acceleration has a strong effect on the shock structure. The energetic particles accelerated by the shock are found to drive magnetic field evolution on a time scale 104 plasma times. Progressively stronger magnetic fields are generated on larger scales in a growing region around the shock, in which magnetic fields and accelerated particles carry 1% and 10% of the downstream energy flux, respectively. These results suggest limits on acceleration and magnetization in astronomical flows. A possible self-similar steady-state configuration which naturally reproduces the flat particle spectra observed will be discussed.

  6. Interplanetary Magnetic Field Guiding Relativistic Particles

    NASA Technical Reports Server (NTRS)

    Masson, S.; Demoulin, P.; Dasso, S.; Klein, K. L.

    2011-01-01

    The origin and the propagation of relativistic solar particles (0.5 to few Ge V) in the interplanetary medium remains a debated topic. These relativistic particles, detected at the Earth by neutron monitors have been previously accelerated close to the Sun and are guided by the interplanetary magnetic field (IMF) lines, connecting the acceleration site and the Earth. Usually, the nominal Parker spiral is considered for ensuring the magnetic connection to the Earth. However, in most GLEs the IMF is highly disturbed, and the active regions associated to the GLEs are not always located close to the solar footprint of the nominal Parker spiral. A possible explanation is that relativistic particles are propagating in transient magnetic structures, such as Interplanetary Coronal Mass Ejections (ICMEs). In order to check this interpretation, we studied in detail the interplanetary medium where the particles propagate for 10 GLEs of the last solar cycle. Using the magnetic field and the plasma parameter measurements (ACE/MAG and ACE/SWEPAM), we found widely different IMF configurations. In an independent approach we develop and apply an improved method of the velocity dispersion analysis to energetic protons measured by SoHO/ERNE. We determined the effective path length and the solar release time of protons from these data and also combined them with the neutron monitor data. We found that in most of the GLEs, protons propagate in transient magnetic structures. Moreover, the comparison between the interplanetary magnetic structure and the interplanetary length suggest that the timing of particle arrival at Earth is dominantly determined by the type of IMF in which high energetic particles are propagating. Finally we find that these energetic protons are not significantly scattered during their transport to Earth.

  7. On the acceleration and deceleration of relativistic jets in active galactic nuclei - II. Mass loading

    NASA Astrophysics Data System (ADS)

    Nokhrina, E. E.; Beskin, V. S.

    2017-08-01

    The effect of mass loading of the magnetohydrodynamic (MHD) flow in relativistic jets from active galactic nuclei (AGNs) due to γγ → e+e- conversion is considered analytically. We argue that the effects of charge average separation due to specific initial pairs' motion lead to partial magnetic and electric field screening or enhancement. The effect of the field screening has not been considered earlier. The pairs with the centre of mass moving faster or slower than the bulk plasma flow create a surface charge and a current that either screen or enhance both electric and magnetic fields in a pair creation domain. This impacts the bulk flow motion, which either accelerates or decelerates. The pairs with the centre of mass moving with exactly the drift velocity do not induce the field disturbance. In this case, the flow decelerates due to pure mass loading. For these different cases, the Lorentz factor of the loaded outflow is calculated as a function of loading pair number density. The effect may be important on sub-parsec to parsec scales due to the conversion of TeV jet radiation on the soft infrared to the ultraviolet external isotropic photon field. This leads to a jet outer shell acceleration. The conversion of MeV jet radiation on larger scales may account for the flow deceleration due to pure mass loading. The proposed mechanism may be a source of internal shocks and instabilities in the pair creation region.

  8. Gamma-ray polarization of the synchrotron self-compton process from a highly relativistic jet

    SciTech Connect

    Chang, Zhe; Lin, Hai-Nan

    2014-11-01

    The high polarization observed in the prompt phase of some gamma-ray bursts invites extensive study of the emission mechanism. In this paper, we investigate the polarization properties of the synchrotron self-Compton (SSC) process from a highly relativistic jet. A magnetic-dominated, baryon-loaded jet ejected from the central engine travels with a large Lorentz factor. Shells with slightly different velocities collide with each other and produce shocks. The shocks accelerate electrons to a power-law distribution and, at the same time, magnify the magnetic field. Electrons move in the magnetic field and produce synchrotron photons. Synchrotron photons suffer from the Compton scattering (CS) process and then are detected by an observer located slightly off-axis. We analytically derive the formulae of photon polarization in the SSC process in two magnetic configurations: a magnetic field in the shock plane and perpendicular to the shock plane. We show that photons induced by the SSC process can be highly polarized, with the maximum polarization Π ∼ 24% in the energy band [0.5, 5] MeV. The polarization depends on the viewing angles, peaking in the plane perpendicular to the magnetic field. In the energy band [0.05, 0.5] MeV, in which most γ-ray polarimeters are active, the polarization is about twice that in the Thomson limit, reaching Π ∼ 20%. This implies that the Klein-Nishina effect, which is often neglected in the literature, should be carefully considered.

  9. Gamma-Ray Polarization of the Synchrotron Self-compton Process from a Highly Relativistic Jet

    NASA Astrophysics Data System (ADS)

    Chang, Zhe; Lin, Hai-Nan

    2014-11-01

    The high polarization observed in the prompt phase of some gamma-ray bursts invites extensive study of the emission mechanism. In this paper, we investigate the polarization properties of the synchrotron self-Compton (SSC) process from a highly relativistic jet. A magnetic-dominated, baryon-loaded jet ejected from the central engine travels with a large Lorentz factor. Shells with slightly different velocities collide with each other and produce shocks. The shocks accelerate electrons to a power-law distribution and, at the same time, magnify the magnetic field. Electrons move in the magnetic field and produce synchrotron photons. Synchrotron photons suffer from the Compton scattering (CS) process and then are detected by an observer located slightly off-axis. We analytically derive the formulae of photon polarization in the SSC process in two magnetic configurations: a magnetic field in the shock plane and perpendicular to the shock plane. We show that photons induced by the SSC process can be highly polarized, with the maximum polarization Π ~ 24% in the energy band [0.5, 5] MeV. The polarization depends on the viewing angles, peaking in the plane perpendicular to the magnetic field. In the energy band [0.05, 0.5] MeV, in which most γ-ray polarimeters are active, the polarization is about twice that in the Thomson limit, reaching Π ~ 20%. This implies that the Klein-Nishina effect, which is often neglected in the literature, should be carefully considered.

  10. Relativistic jets in Narrow-Line Seyfert 1

    NASA Astrophysics Data System (ADS)

    Foschini, L.; Angelakis, E.; Bonnoli, G.; Calderone, G.; Colpi, M.; D'Ammando, F.; Donato, D.; Falcone, A.; Fuhrmann, L.; Ghisellini, G.; Ghirlanda, G.; Hauser, M.; Kovalev, Y. Y.; Maraschi, L.; Nieppola, E.; Richards, J.; Stamerra, A.; Tagliaferri, G.; Tavecchio, F.; Thompson, D. J.; Tibolla, O.; Tramacere, A.; Wagner, S.

    2011-02-01

    Narrow-Line Seyfert 1 (NLS1) class of active galactic nuclei (AGNs) is generally radio-quiet, but a small percent of them are radio-loud. The recent discovery by Fermi/LAT of high-energy γ-ray emission from 4 NLS1s proved the existence of relativistic jets in these systems. It is therefore important to study this new class of γ-ray emitting AGNs. Here we report preliminary results about the observations of the July 2010 γ-ray outburst of PMN J0948+0022, when the source flux exceeded for the first time 10-6 ph cm-2 s-1 (E > 100 MeV).

  11. Signatures of Dissipation Processes in Magnetically Dominated Regions in Astrophysical Jets

    NASA Astrophysics Data System (ADS)

    Li, Hui

    Modern observations have shown that disk-jet-lobe systems driven by supermassive black holes play an important feedback role in cosmic structure evolution, as well as in explaining cosmic magnetic fields and energetic cosmic rays. Highly collimated bi-polar jets can traverse tremendous distances, and energy carried by jets is further converted to accelerate particles to extraordinary energies, likely via both magnetic reconnection and shocks. These particles then radiate from radio to tens of TeV, including polarized signatures that are yielding intriguing constraints on jet properties. This proposal presents a systematic and integrated study of relativistic jets, utilizing our state-of-the-art three-dimensional relativistic magnetohydrodynamics (LA-COMPASS), particle-in-cell (VPIC), polarized radiation transport (3DPol) codes, as well as analytic tools. The proposed studies focus on the energy dissipation processes along three fronts: (1) the stability of relativistic jets, emphasizing the role of current-driven instabilities and their nonlinear saturation; (2) the particle acceleration processes through magnetic field dissipation with varying degrees of magnetic dominance, especially the role of relativistic turbulence and current sheet reconnection in jets; (3) the transport of temporal and spatial dependent polarized radiation as cooling of the relativistic plasmas. More importantly, we plan to integrate the studies of magnetic fields, particles and radiation evolution so that we derive physical constraints on the jets and their emission regions. We will provide useful predictions for the multi-wavelength spectral energy distributions and light curves of AGN jets, especially the polarized emission evolution. These results will be guided by and compared with available observations of AGN jets. The outcome from the proposed studies will be of direct relevance to a wide range of NASA missions, such as Fermi, Chandra and HST, in terms of interpreting the data from

  12. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Mizuno, Y.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2010-01-01

    Recent PIC simulations of relativistic electron-positron (electron-ion) jets injected into a stationary medium show that particle acceleration occurs at shocked regions. Simulations show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields and particle acceleration. These magnetic fields contribute to the electron's transverse deflection behind the shock. The jitter'' radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation, which is calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants. We will present detailed spectra for conditions relevant of various astrophysical sites of shock formation via the Weibel instability. In particular we will discuss the application to GRBs and SNRs

  13. The Relationship Between X-Rays and Relativistic Jets

    NASA Technical Reports Server (NTRS)

    Marscher, A. P.; Jorstad, S. G.; McHardy, I. M.; Aller, M. F.; Balonek, T. J.; Villata, M.; Raiteri, C. M.; Ostorero, L.; Tosti, G.; Terasranta, H.

    2002-01-01

    We present recent multiwaveband observations centered on X-ray monitoring of blazars and the radio galaxy 3C 120 with the RXTE satellite, In 3C 120, we observed four X-ray dips, each followed by ejections of superluminal radio knots down the jet. This behavior, similar to that of the microquasar GRS 1915+105, is interpreted as infall of a piece of the inner accretion disk causing ejection of energy into the relativistic jet. The X-ray emission from the quasars PKS 1510-089, 3C 279, and 3C 273 is highly variable on timescales as short as approximately 1 day. Over 2 years, X-ray flares in PKS 1510-089 occurred about 2 weeks after radio outbursts, which can be explained by light-travel delays. In 3C 279 the X-ray and optical variations are usually well correlated, with very little, if any, time delay. We conclude that the X-ray and optical emission from blazars occurs near the radio core rather than close to the black hole.

  14. Chiral magnetic plasmons in anomalous relativistic matter

    NASA Astrophysics Data System (ADS)

    Gorbar, E. V.; Miransky, V. A.; Shovkovy, I. A.; Sukhachov, P. O.

    2017-03-01

    The chiral plasmon modes of relativistic matter in background magnetic and strain-induced pseudomagnetic fields are studied in detail using the consistent chiral kinetic theory. The results reveal a number of anomalous features of these chiral magnetic and pseudomagnetic plasmons that could be used to identify them in experiment. In a system with nonzero electric (chiral) chemical potential, the background magnetic (pseudomagnetic) fields not only modify the values of the plasmon frequencies in the long-wavelength limit, but also affect the qualitative dependence on the wave vector. Similar modifications can be also induced by the chiral shift parameter in Weyl materials. Interestingly, even in the absence of the chiral shift and external fields, the chiral chemical potential alone leads to a splitting of plasmon energies at linear order in the wave vector.

  15. Relativistic laser pulse compression in magnetized plasmas

    SciTech Connect

    Liang, Yun; Sang, Hai-Bo Wan, Feng; Lv, Chong; Xie, Bai-Song

    2015-07-15

    The self-compression of a weak relativistic Gaussian laser pulse propagating in a magnetized plasma is investigated. The nonlinear Schrödinger equation, which describes the laser pulse amplitude evolution, is deduced and solved numerically. The pulse compression is observed in the cases of both left- and right-hand circular polarized lasers. It is found that the compressed velocity is increased for the left-hand circular polarized laser fields, while decreased for the right-hand ones, which is reinforced as the enhancement of the external magnetic field. We find a 100 fs left-hand circular polarized laser pulse is compressed in a magnetized (1757 T) plasma medium by more than ten times. The results in this paper indicate the possibility of generating particularly intense and short pulses.

  16. Relativistic thermal plasmas - Effects of magnetic fields

    NASA Technical Reports Server (NTRS)

    Araki, S.; Lightman, A. P.

    1983-01-01

    Processes and equilibria in finite, relativistic, thermal plasmas are investigated, taking into account electron-positron creation and annihilation, photon production by internal processes, and photon production by a magnetic field. Inclusion of the latter extends previous work on such plasmas. The basic relations for thermal, Comptonized synchrotron emission are analyzed, including emission and absorption without Comptonization, Comptonized thermal synchrotron emission, and the Comptonized synchrotron and bremsstrahlung luminosities. Pair equilibria are calculated, including approximations and dimensionless parameters, the pair balance equation, maximum temperatures and field strengths, and individual models and cooling curves.

  17. R Aqr: a prototype for non-relativistic astrophysical jets and a key for understanding jet formation

    NASA Astrophysics Data System (ADS)

    Stute, Matthias

    2013-10-01

    R Aqr is a well-known prototype for non-relativistic astrophysical jets. The R Aqr jet has been extensively observed in the ultraviolet, optical, and radio regimes. We propose to re-visit this enigmatic object with HST after twelve years, in order to measure the proper motions of its inner knots with unprecedented accuracy, to derive emission lines ratios for these knots, and to investigate the width of the jet at several distances from the jet source. We will compare the results with numerical models of radiative shocks in propagating jets and of jet formation models and will determine the kinematics of the jet, the history of ejection events and basic parameters of the jet engine as e.g. the launching radius of the jet-ejecting accretion disk.

  18. Relativistic baryonic jets from an ultraluminous supersoft X-ray source

    NASA Astrophysics Data System (ADS)

    Liu, Ji-Feng; Bai, Yu; Wang, Song; Justham, Stephen; Lu, You-Jun; Gu, Wei-Min; Liu, Qing-Zhong; di Stefano, Rosanne; Guo, Jin-Cheng; Cabrera-Lavers, Antonio; Álvarez, Pedro; Cao, Yi; Kulkarni, Shri

    2015-12-01

    The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Hα emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1’s soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.

  19. Relativistic baryonic jets from an ultraluminous supersoft X-ray source.

    PubMed

    Liu, Ji-Feng; Bai, Yu; Wang, Song; Justham, Stephen; Lu, You-Jun; Gu, Wei-Min; Liu, Qing-Zhong; Di Stefano, Rosanne; Guo, Jin-Cheng; Cabrera-Lavers, Antonio; Álvarez, Pedro; Cao, Yi; Kulkarni, Shri

    2015-12-03

    The formation of relativistic jets by an accreting compact object is one of the fundamental mysteries of astrophysics. Although the theory is poorly understood, observations of relativistic jets from systems known as microquasars (compact binary stars) have led to a well established phenomenology. Relativistic jets are not expected to be produced by sources with soft or supersoft X-ray spectra, although two such systems are known to produce relatively low-velocity bipolar outflows. Here we report the optical spectra of an ultraluminous supersoft X-ray source (ULS) in the nearby galaxy M81 (M81 ULS-1; refs 9, 10). Unexpectedly, the spectra show blueshifted, broad Hα emission lines, characteristic of baryonic jets with relativistic speeds. These time-variable emission lines have projected velocities of about 17 per cent of the speed of light, and seem to be similar to those from the prototype microquasar SS 433 (refs 11, 12). Such relativistic jets are not expected to be launched from white dwarfs, and an origin from a black hole or a neutron star is hard to reconcile with the persistence of M81 ULS-1's soft X-rays. Thus the unexpected presence of relativistic jets in a ULS challenges canonical theories of jet formation, but might be explained by a long-speculated, supercritically accreting black hole with optically thick outflows.

  20. General Relativistic Magnetohydrodynamic Simulations of Jet Formation with a Thin Keplerian Disk

    NASA Technical Reports Server (NTRS)

    Mizuno, Yosuke; Nishikawa, Ken-Ichi; Koide, Shinji; Hardee, Philip; Gerald, J. Fishman

    2006-01-01

    We have performed several simulations of black hole systems (non-rotating, black hole spin parameter a = 0.0 and rapidly rotating, a = 0.95) with a geometrically thin Keplerian disk using the newly developed RAISHIN code. The simulation results show the formation of jets driven by the Lorentz force and the gas pressure gradient. The jets have mildly relativistic speed (greater than or equal to 0.4 c). The matter is continuously supplied from the accretion disk and the jet propagates outward until each applicable terminal simulation time (non-rotating: t/tau S = 275 and rotating: t/tau S = 200, tau s equivalent to r(sub s/c). It appears that a rotating black hole creates an additional, faster, and more collimated inner outflow (greater than or equal to 0.5 c) formed and accelerated by the twisted magnetic field resulting from frame-dragging in the black hole ergosphere. This new result indicates that jet kinematic structure depends on black hole rotation.

  1. Using radiative energy losses to constrain the magnetization and magnetic reconnection rate at the base of black hole jets

    NASA Astrophysics Data System (ADS)

    Potter, William J.

    2017-02-01

    We calculate the severe radiative energy losses which occur at the base of black hole jets using a relativistic fluid jet model, including in situ acceleration of non-thermal leptons by magnetic reconnection. Our results demonstrate that including a self-consistent treatment of radiative energy losses is necessary to perform accurate magnetohydrodynamic simulations of powerful jets and that jet spectra calculated via post-processing are liable to vastly overestimate the amount of non-thermal emission. If no more than 95 per cent of the initial total jet power is radiated away by the plasma travels as it travels along the length of the jet, we can place a lower bound on the magnetization of the jet plasma at the base of the jet. For typical powerful jets, we find that the plasma at the jet base is required to be highly magnetized, with at least 10 000 times more energy contained in magnetic fields than in non-thermal leptons. Using a simple power-law model of magnetic reconnection, motivated by simulations of collisionless reconnection, we determine the allowed range of the large-scale average reconnection rate along the jet, by restricting the total radiative energy losses incurred and the distance at which the jet first comes into equipartition. We calculate analytic expressions for the cumulative radiative energy losses due to synchrotron and inverse-Compton emission along jets, and derive analytic formulae for the constraint on the initial magnetization.

  2. Magnetic Fields In Relativistic Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Santana, Rodolfo; Barniol Duran, R.; Kumar, P.

    2013-01-01

    We present a systematic study on magnetic fields in Gamma-Ray Burst (GRB) relativistic shocks by making use of X-ray and optical afterglow observations, mostly coming from the Swift satellite. We use two methods to constrain the afterglow parameter epsilon_B (the fraction of energy in the magnetic field in the shocked plasma): 1. For the X-ray sample, the observed flux at the end of the X-ray steep decline is larger than or equal to the flux from the external-forward shock. 2. The observed optical afterglow flux arises from the external-forward shock emission. From the method for our X-ray sample (60 GRBs), we determine an upper limit on epsilon_B and from the method for our optical sample (35 GRBs), we determine a measurement for epsilon_B. Combining our X-ray and optical results, the median value we found for epsilon_B is ~ 10^-5. The distributions of epsilon_B from our X-ray and optical samples showed a wide distribution, with epsilon_B ranging from ~ 10^-7 - 10^-3. To characterize how much magnetic field amplification is needed, beyond shock compression of the seed magnetic field, we expressed our results for epsilon_B in terms of an amplification factor, AF. For both our X-ray and optical samples, the median value we found is AF ˜ 50-70. The distributions of AF from our X-ray and optical samples also showed a wide distribution, with AF ranging from ~ 1-1000. These results for epsilon_B and AF suggest that a weak amplification, in addition to shock compression, is needed to explain the afterglow observations. Our main conclusion is that shock compression and weak amplification of the magnetic field in GRB relativistic external shocks is sufficient to explain the afterglow data.

  3. Relativistic nonlinear plasma waves in a magnetic field

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Pellat, R.

    1975-01-01

    Five relativistic plane nonlinear waves were investigated: circularly polarized waves and electrostatic plasma oscillations propagating parallel to the magnetic field, relativistic Alfven waves, linearly polarized transverse waves propagating in zero magnetic field, and the relativistic analog of the extraordinary mode propagating at an arbitrary angle to the magnetic field. When the ions are driven relativistic, they behave like electrons, and the assumption of an 'electron-positron' plasma leads to equations which have the form of a one-dimensional potential well. The solutions indicate that a large-amplitude superluminous wave determines the average plasma properties.

  4. RELATIVISTIC TWO-FLUID SIMULATIONS OF GUIDE FIELD MAGNETIC RECONNECTION

    SciTech Connect

    Zenitani, Seiji; Hesse, Michael; Klimas, Alex

    2009-11-01

    The nonlinear evolution of relativistic magnetic reconnection in sheared magnetic configuration (with a guide field) is investigated by using two-dimensional relativistic two-fluid simulations. Relativistic guide field reconnection features the charge separation and the guide field compression in and around the outflow channel. As the guide field increases, the composition of the outgoing energy changes from enthalpy-dominated to Poynting-dominated. The inertial effects of the two-fluid model play an important role to sustain magnetic reconnection. Implications for the single-fluid magnetohydrodynamic approach and the physics models of relativistic reconnection are briefly addressed.

  5. What is the Structure of Relativistic Jets in AGN on Scales of Light Days?

    DTIC Science & Technology

    2009-02-11

    differences between radio-loud and radio-quiet quasars that manifest themselves near the supermassive black hole . We can also use relativistic jets to...identify supermassive binary black holes remaining from galaxy mergers, and use orbital motion to derive the masses of the black holes . The search for...differences between radio-loud and radio-quiet quasars that manifest themselves near the supermassive black hole . We can also use relativistic jets

  6. Relativistic Magnetic Reconnection in Kerr Spacetime.

    PubMed

    Asenjo, Felipe A; Comisso, Luca

    2017-02-03

    The magnetic reconnection process is analyzed for relativistic magnetohydrodynamical plasmas around rotating black holes. A simple generalization of the Sweet-Parker model is used as a first approximation to the problem. The reconnection rate, as well as other important properties of the reconnection layer, has been calculated taking into account the effect of spacetime curvature. Azimuthal and radial current sheet configurations in the equatorial plane of the black hole have been studied, and the case of small black hole rotation rate has been analyzed. For the azimuthal configuration, it is found that the black hole rotation decreases the reconnection rate. On the other hand, in the radial configuration, it is the gravitational force created by the black hole mass that decreases the reconnection rate. These results establish a fundamental interaction between gravity and magnetic reconnection in astrophysical contexts.

  7. Relativistic Magnetic Reconnection in Kerr Spacetime

    NASA Astrophysics Data System (ADS)

    Asenjo, Felipe A.; Comisso, Luca

    2017-02-01

    The magnetic reconnection process is analyzed for relativistic magnetohydrodynamical plasmas around rotating black holes. A simple generalization of the Sweet-Parker model is used as a first approximation to the problem. The reconnection rate, as well as other important properties of the reconnection layer, has been calculated taking into account the effect of spacetime curvature. Azimuthal and radial current sheet configurations in the equatorial plane of the black hole have been studied, and the case of small black hole rotation rate has been analyzed. For the azimuthal configuration, it is found that the black hole rotation decreases the reconnection rate. On the other hand, in the radial configuration, it is the gravitational force created by the black hole mass that decreases the reconnection rate. These results establish a fundamental interaction between gravity and magnetic reconnection in astrophysical contexts.

  8. Polarization of gamma-ray burst afterglows in the synchrotron self-Compton process from a highly relativistic jet

    NASA Astrophysics Data System (ADS)

    Lin, Hai-Nan; Li, Xin; Chang, Zhe

    2017-04-01

    Linear polarization has been observed in both the prompt phase and afterglow of some bright gamma-ray bursts (GRBs). Polarization in the prompt phase spans a wide range, and may be as high as ≳ 50%. In the afterglow phase, however, it is usually below 10%. According to the standard fireball model, GRBs are produced by synchrotron radiation and Compton scattering process in a highly relativistic jet ejected from the central engine. It is widely accepted that prompt emissions occur in the internal shock when shells with different velocities collide with each other, and the magnetic field advected by the jet from the central engine can be ordered on a large scale. On the other hand, afterglows are often assumed to occur in the external shock when the jet collides with interstellar medium, and the magnetic field produced by the shock through, for example, Weibel instability, is possibly random. In this paper, we calculate the polarization properties of the synchrotron self-Compton process from a highly relativistic jet, in which the magnetic field is randomly distributed in the shock plane. We also consider the generalized situation where a uniform magnetic component perpendicular to the shock plane is superposed on the random magnetic component. We show that it is difficult for the polarization to be larger than 10% if the seed electrons are isotropic in the jet frame. This may account for the observed upper limit of polarization in the afterglow phase of GRBs. In addition, if the random and uniform magnetic components decay with time at different speeds, then the polarization angle may change 90° during the temporal evolution. Supported by Fundamental Research Funds for the Central Universities (106112016CDJCR301206), National Natural Science Fund of China (11375203, 11603005), and Open Project Program of State Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, China (Y5KF181CJ1)

  9. TENTATIVE EVIDENCE FOR RELATIVISTIC ELECTRONS GENERATED BY THE JET OF THE YOUNG SUN-LIKE STAR DG Tau

    SciTech Connect

    Ainsworth, Rachael E.; Ray, Tom P.; Taylor, Andrew M.; Scaife, Anna M. M.; Green, David A.; Buckle, Jane V.

    2014-09-01

    Synchrotron emission has recently been detected in the jet of a massive protostar, providing further evidence that certain jet formation characteristics for young stars are similar to those found for highly relativistic jets from active galactic nuclei. We present data at 325 and 610 MHz taken with the Giant Metrewave Radio Telescope of the young, low-mass star DG Tau, an analog of the Sun soon after its birth. This is the first investigation of a low-mass young stellar object at such low frequencies. We detect emission with a synchrotron spectral index in the proximity of the DG Tau jet and interpret this emission as a prominent bow shock associated with this outflow. This result provides tentative evidence for the acceleration of particles to relativistic energies due to the shock impact of this otherwise very low-power jet against the ambient medium. We calculate the equipartition magnetic field strength B {sub min} ≈ 0.11 mG and particle energy E {sub min} ≈ 4 × 10{sup 40} erg, which are the minimum requirements to account for the synchrotron emission of the DG Tau bow shock. These results suggest the possibility of low energy cosmic rays being generated by young Sun-like stars.

  10. Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-L.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

    2004-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. The non-linear fluctuation amplitudes of densities, currents, electric, and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper at the comparable simulation time. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. Additionally, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by the Weibel instability scale proportional to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform: small-scale magnetic fields which contribute to the electron's (positron's) transverse deflection behind the jet head. This small scale magnetic field structure

  11. Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

    2004-01-01

    Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. The non-linear fluctuation amplitudes of densities, currents, electric, and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. Additionally, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by the Weibel instability scale proportional to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform, small-scale magnetic fields which contribute to the electron's (positron's) transverse deflection behind the jet head. This small scale magnetic field structure is appropriate to the generation

  12. Particle Acceleration and Magnetic Field Generation in Electron-Positron Relativistic Shocks

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Hardee, P.; Richardson, G.; Preece, R.; Sol, H.; Fishman, G. J.

    2005-01-01

    Shock acceleration is a ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel, and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a three-dimensional relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic electron-positron jet front propagating into an ambient electron-positron plasma with and without initial magnetic fields. We find small differences in the results for no ambient and modest ambient magnetic fields. New simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. Furthermore, the nonlinear fluctuation amplitudes of densities, currents, and electric and magnetic fields in the electron-positron shock are larger than those found in the electron-ion shock studied in a previous paper at a comparable simulation time. This comes from the fact that both electrons and positrons contribute to generation of the Weibel instability. In addition, we have performed simulations with different electron skin depths. We find that growth times scale inversely with the plasma frequency, and the sizes of structures created by tine Weibel instability scale proportionally to the electron skin depth. This is the expected result and indicates that the simulations have sufficient grid resolution. While some Fermi acceleration may occur at the jet front, the majority of electron and positron acceleration takes place behind the jet front and cannot be characterized as Fermi acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying nonuniform, small-scale magnetic fields, which contribute to the electron s (positron s) transverse deflection behind the jet head. This

  13. Relativistic transport theory for a two-temperature magnetized plasma

    SciTech Connect

    Metens, T.; Balescu, R. )

    1990-09-01

    The relativistic kinetic theory of linear transport is worked out within the framework of a new moment method. A complete analytical study of the transport in a two-temperature inhomogeneous magnetized fusion plasma is given. The transport relations and coefficients are derived from the kinetic equation with the full relativistic Beliaev--Budker collision operator and the impact of relativistic effects on the confinement are investigated.

  14. The radiative efficiency of relativistic jet and wind: a case study of GRB 070110

    NASA Astrophysics Data System (ADS)

    Du, Shuang; Lü, Hou-Jun; Zhong, Shu-Qing; Liang, En-Wei

    2016-11-01

    A rapidly spinning, strongly magnetized neutron star (NS) is invoked as the central engine for some gamma-ray bursts (GRBs), especially, the `internal plateau' feature of X-ray afterglow. However, for these `internal plateau' GRBs, how to produce their prompt emission remains an open question. Two different physical processes have been proposed in the literature, (1) a new-born NS is surrounded by a hyper-accreting and neutrino cooling disc, the GRB jet can be powered by neutrino annihilation aligning the spin axis; (2) a differentially rotating millisecond pulsar was formed due to different angular velocity between the interior core and outer shell parts of the NS, which can power an episodic GRB jet. In this paper, by analysing the data of one peculiar GRB 070110 (with internal plateau), we try to test which model is being favoured. By deriving the physical parameters of magnetar with observational data, the parameter regime for initial period (P0) and surface polar cap magnetic field (Bp) of the central NS are 0.96 ˜ 1.2 ms and (2.4 ˜ 3.7) × 1014 G, respectively. The radiative efficiency of prompt emission is about ηγ ˜ 6 per cent. However, the radiative efficiency of internal plateau (ηX) is larger than 31 per cent assuming the MNS ˜ 1.4 M⊙ and P0˜ 1.2 ms. The clear difference between the radiation efficiencies of prompt emission and internal plateau implies that they maybe originated from different components (e.g. prompt emission from the relativistic jet powered by neutrino annihilation, while the internal plateau from the magnetic outflow wind).

  15. Role of the Kelvin-Helmholtz instability in the evolution of magnetized relativistic sheared plasma flows

    NASA Astrophysics Data System (ADS)

    Hamlin, Nathaniel D.; Newman, William I.

    2013-04-01

    We explore, via analytical and numerical methods, the Kelvin-Helmholtz (KH) instability in relativistic magnetized plasmas, with applications to astrophysical jets. We solve the single-fluid relativistic magnetohydrodynamic (RMHD) equations in conservative form using a scheme which is fourth order in space and time. To recover the primitive RMHD variables, we use a highly accurate, rapidly convergent algorithm which improves upon such schemes as the Newton-Raphson method. Although the exact RMHD equations are marginally stable, numerical discretization renders them unstable. We include numerical viscosity to restore numerical stability. In relativistic flows, diffusion can lead to a mathematical anomaly associated with frame transformations. However, in our KH studies, we remain in the rest frame of the system, and therefore do not encounter this anomaly. We use a two-dimensional slab geometry with periodic boundary conditions in both directions. The initial unperturbed velocity peaks along the central axis and vanishes asymptotically at the transverse boundaries. Remaining unperturbed quantities are uniform, with a flow-aligned unperturbed magnetic field. The early evolution in the nonlinear regime corresponds to the formation of counter-rotating vortices, connected by filaments, which persist in the absence of a magnetic field. A magnetic field inhibits the vortices through a series of stages, namely, field amplification, vortex disruption, turbulent breakdown, and an approach to a flow-aligned equilibrium configuration. Similar stages have been discussed in MHD literature. We examine how and to what extent these stages manifest in RMHD for a set of representative field strengths. To characterize field strength, we define a relativistic extension of the Alfvénic Mach number MA. We observe close complementarity between flow and magnetic field behavior. Weaker fields exhibit more vortex rotation, magnetic reconnection, jet broadening, and intermediate turbulence

  16. Exact general relativistic disks with magnetic fields

    NASA Astrophysics Data System (ADS)

    Letelier, Patricio S.

    1999-11-01

    The well-known ``displace, cut, and reflect'' method used to generate cold disks from given solutions of Einstein equations is extended to solutions of Einstein-Maxwell equations. Four exact solutions of the these last equations are used to construct models of hot disks with surface density, azimuthal pressure, and azimuthal current. The solutions are closely related to Kerr, Taub-NUT, Lynden-Bell-Pinault, and to a one-soliton solution. We find that the presence of the magnetic field can change in a nontrivial way the different properties of the disks. In particular, the pure general relativistic instability studied by Bic̆ák, Lynden-Bell, and Katz [Phys. Rev. D 47, 4334 (1993)] can be enhanced or cured by different distributions of currents inside the disk. These currents, outside the disk, generate a variety of axial symmetric magnetic fields. As far as we know these are the first models of hot disks studied in the context of general relativity.

  17. Relativistic jet models for the BL Lacertae object Mrk 421 during three epochs of observation

    NASA Technical Reports Server (NTRS)

    Mufson, S. L.; Hutter, D. J.; Kondo, Y.; Wisniewski, W. Z.

    1988-01-01

    Coordinated observation of the nearby BL Lacertae object Mrk 421 obtained during May 1980, January 1984, and March 1984 are described. These observations give a time-frozen picture of the continuous spectrum of Mrk 421 at X-ray, ultraviolet, optical, and radio wavelengths. The observed spectra have been fitted to an inhomogeneous relativistic jet model. In general, the models reproduce the data well. Many of the observed differences during the three epochs can be attributed to variations in the opening angle of the jet and in the angle that the jet makes to the line of sight. The jet models obtained here are compared with the homogeneous, spherically symmetric, synchrotron self-Compton models for this source. The models are also compared with the relativistic jet models obtained for other active galactic nuclei.

  18. General Relativistic Magnetohydrodynamic Simulations of Magnetically Choked Accretion Flows around Black Holes

    SciTech Connect

    McKinney, Jonathan C.; Tchekhovskoy, Alexander; Blandford, Roger D.

    2012-04-26

    Black hole (BH) accretion flows and jets are qualitatively affected by the presence of ordered magnetic fields. We study fully three-dimensional global general relativistic magnetohydrodynamic (MHD) simulations of radially extended and thick (height H to cylindrical radius R ratio of |H/R| {approx} 0.2-1) accretion flows around BHs with various dimensionless spins (a/M, with BH mass M) and with initially toroidally-dominated ({phi}-directed) and poloidally-dominated (R-z directed) magnetic fields. Firstly, for toroidal field models and BHs with high enough |a/M|, coherent large-scale (i.e. >> H) dipolar poloidal magnetic flux patches emerge, thread the BH, and generate transient relativistic jets. Secondly, for poloidal field models, poloidal magnetic flux readily accretes through the disk from large radii and builds-up to a natural saturation point near the BH. While models with |H/R| {approx} 1 and |a/M| {le} 0.5 do not launch jets due to quenching by mass infall, for sufficiently high |a/M| or low |H/R| the polar magnetic field compresses the inflow into a geometrically thin highly non-axisymmetric 'magnetically choked accretion flow' (MCAF) within which the standard linear magneto-rotational instability is suppressed. The condition of a highly-magnetized state over most of the horizon is optimal for the Blandford-Znajek mechanism that generates persistent relativistic jets with and 100% efficiency for |a/M| {approx}> 0.9. A magnetic Rayleigh-Taylor and Kelvin-Helmholtz unstable magnetospheric interface forms between the compressed inflow and bulging jet magnetosphere, which drives a new jet-disk oscillation (JDO) type of quasi-periodic oscillation (QPO) mechanism. The high-frequency QPO has spherical harmonic |m| = 1 mode period of {tau} {approx} 70GM/c{sup 3} for a/M {approx} 0.9 with coherence quality factors Q {approx}> 10. Overall, our models are qualitatively distinct from most prior MHD simulations (typically, |H/R| << 1 and poloidal flux is limited by

  19. Magnetic tuning of the relativistic BCS-BEC crossover

    NASA Astrophysics Data System (ADS)

    Wang, Jin-Cheng; de La Incera, Vivian; Ferrer, Efrain J.; Wang, Qun

    2011-09-01

    The effect of an applied magnetic field in the crossover from Bose-Einstein condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) pairing regimes is investigated. We use a model of relativistic fermions and bosons inspired by those previously used in the context of cold fermionic atoms and in the magnetic-color-flavor-locking phase of color superconductivity. It turns out that, as with cold atom systems, an applied magnetic field can also tune the BCS-BEC crossover in the relativistic case. We find that no matter what the initial state is at B=0, for large enough magnetic fields the system always settles into a pure BCS regime. In contrast to the atomic case, the magnetic field tuning of the crossover in the relativistic system is not connected to a Feshbach resonance, but to the relative numbers of Landau levels with either BEC or BCS type of dispersion relations that are occupied at each magnetic field strength.

  20. Studying Absorption Line Feature in the Relativistic Jet Source GRS 1915+105

    NASA Technical Reports Server (NTRS)

    Tavani, Marco

    1998-01-01

    The galactic superluminal source GRS 1915+105 is among the most interesting objects in our Galaxy. It is subject to erratic accretion instabilities with energization of relativistic jets producing X-ray, optical and radio emission. This source was observed by ASCA on Sept. 27, 1994, April 20, 1995, October 23, 1996 and April 25, 1997 as part of a long timescale investigation. We detected strong variability of the source, and in particular the existence of burst/dip structure in October 1996 and April 1997. Clear evidence of transient absorption features at 6.7, 7.0 and 8.0 keV was obtained for the first time in September 1994 and April 1995. Given the phenomenology of plasmoid energization and ejection, these transient spectral features might be produced by material entrained in the radio jets or in other high-velocity outflows. Our contribution to the interpretation is to incorporate these observations into a overall theoretical picture for GRS 1915+105 also taking into account other observations by XTE and BSAX. The emerging picture is complex. The central source is subject to (most likely) super-Eddington instabilities mediated by magnetic field build-up, reconnection and dissipation in the form of blobs that eventually leads to the formation of transient spectral features from the surrounding of the plasmoid emitting region. A comprehensive theoretical investigation is in progress.

  1. Swift J1644+57: an ideal test bed of radiation mechanisms in a relativistic super-Eddington jet

    NASA Astrophysics Data System (ADS)

    Crumley, P.; Lu, W.; Santana, R.; Hernández, R. A.; Kumar, P.; Markoff, S.

    2016-07-01

    Within the first 10 d after Swift discovered the jetted tidal disruption event (TDE) Sw J1644+57, simultaneous observations in the radio, near-infrared, optical, X-ray, and γ-ray bands were carried out. These multiwavelength data provide a unique opportunity to constrain the emission mechanism and make-up of a relativistic super-Eddington jet. We consider an exhaustive variety of radiation mechanisms for the generation of X-rays in this TDE, and rule out many processes such as synchrotron self-Compton, photospheric and proton synchrotron. The infrared-to-γ-ray data for Sw J1644+57 are consistent with synchrotron and external-inverse-Compton (EIC) processes provided that electrons in the jet are continuously accelerated on a time-scale shorter than ˜1 per cent of the dynamical time to maintain a power-law distribution. The requirement of continuous electron acceleration points to magnetic reconnection in a Poynting flux-dominated jet. The EIC process may require fine tuning to explain the observed temporal decay of the X-ray light curve, whereas the synchrotron process in a magnetic jet needs no fine tuning for this TDE.

  2. Pondermotive acceleration of charged particles along the relativistic jets of an accreting blackhole

    NASA Astrophysics Data System (ADS)

    Ebisuzaki, T.; Tajima, T.

    2014-05-01

    Accreting blackholes such as miniquasars and active galactic nuclei can contribute to the highest energy components of intra- (˜1015 eV) galactic and extra-galactic components (˜1020 eV) of cosmic rays. Alfven wave pulses which are excited in the accretion disk around blackholes propagate in relativistic jets. Because of their highly non-linear nature of the waves, charged particles (protons, ions, and electrons) can be accelerated to high energies in relativistic jets in accreting blackhole systems, the central engine of miniquasars and active galactic nuclei.

  3. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Nordlund, A.; Frederiksen, J.; Mizuno, Y.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, G. J.

    2011-01-01

    Using our new 3-D relativistic particle-in-cell (PIC) code, we investigated long-term particle acceleration associated with a relativistic electron-positron jet propagating in an unmagnetized ambient electron-positron plasma. The simulations were performed using a much longer simulation system than our previous simulations in order to investigate the full nonlinear stage of the Weibel instability and its particle acceleration mechanism. Cold jet electrons are thermalized and ambient electrons are accelerated in the resulting shocks. Acceleration of ambient electrons leads to a maximum ambient electron density three times larger than the original value as predicted by hydrodynamic compression. Behind the bow shock, in the jet shock, strong electromagnetic fields are generated. These fields may lead to time dependent afterglow emission. In order to go beyond the standard synchrotron model used in astrophysical objects we have used PIC simulations and calculated radiation based on first principles. We calculated radiation from electrons propagating in a uniform parallel magnetic field to verify the technique. We also used the technique to calculate emission from electrons based on simulations with a small system. We obtain spectra which are consistent with those generated from electrons propagating in turbulent magnetic fields. This turbulent magnetic field is similar to the magnetic field generated at an early nonlinear stage of the Weibel instability. A fully developed shock within a larger system may generate a jitter/synchrotron spectrum.

  4. Magnetic Fields in Relativistic Collisionless Shocks

    NASA Astrophysics Data System (ADS)

    Santana, Rodolfo; Barniol Duran, Rodolfo; Kumar, Pawan

    2014-04-01

    We present a systematic study on magnetic fields in gamma-ray burst (GRB) external forward shocks (FSs). There are 60 (35) GRBs in our X-ray (optical) sample, mostly from Swift. We use two methods to study epsilon B (fraction of energy in magnetic field in the FS): (1) for the X-ray sample, we use the constraint that the observed flux at the end of the steep decline is >= X-ray FS flux; (2) for the optical sample, we use the condition that the observed flux arises from the FS (optical sample light curves decline as ~t -1, as expected for the FS). Making a reasonable assumption on E (jet isotropic equivalent kinetic energy), we converted these conditions into an upper limit (measurement) on epsilon B n 2/(p + 1) for our X-ray (optical) sample, where n is the circumburst density and p is the electron index. Taking n = 1 cm-3, the distribution of epsilon B measurements (upper limits) for our optical (X-ray) sample has a range of ~10-8-10-3 (~10-6-10-3) and median of ~few × 10-5 (~few × 10-5). To characterize how much amplification is needed, beyond shock compression of a seed magnetic field ~10 μG, we expressed our results in terms of an amplification factor, AF, which is very weakly dependent on n (AFvpropn 0.21). The range of AF measurements (upper limits) for our optical (X-ray) sample is ~1-1000 (~10-300) with a median of ~50 (~50). These results suggest that some amplification, in addition to shock compression, is needed to explain the afterglow observations.

  5. Magnetic fields in relativistic collisionless shocks

    SciTech Connect

    Santana, Rodolfo; Kumar, Pawan; Barniol Duran, Rodolfo E-mail: pk@astro.as.utexas.edu

    2014-04-10

    We present a systematic study on magnetic fields in gamma-ray burst (GRB) external forward shocks (FSs). There are 60 (35) GRBs in our X-ray (optical) sample, mostly from Swift. We use two methods to study ε {sub B} (fraction of energy in magnetic field in the FS): (1) for the X-ray sample, we use the constraint that the observed flux at the end of the steep decline is ≥ X-ray FS flux; (2) for the optical sample, we use the condition that the observed flux arises from the FS (optical sample light curves decline as ∼t {sup –1}, as expected for the FS). Making a reasonable assumption on E (jet isotropic equivalent kinetic energy), we converted these conditions into an upper limit (measurement) on ε {sub B} n {sup 2/(p+1)} for our X-ray (optical) sample, where n is the circumburst density and p is the electron index. Taking n = 1 cm{sup –3}, the distribution of ε {sub B} measurements (upper limits) for our optical (X-ray) sample has a range of ∼10{sup –8}-10{sup –3} (∼10{sup –6}-10{sup –3}) and median of ∼few × 10{sup –5} (∼few × 10{sup –5}). To characterize how much amplification is needed, beyond shock compression of a seed magnetic field ∼10 μG, we expressed our results in terms of an amplification factor, AF, which is very weakly dependent on n (AF∝n {sup 0.21}). The range of AF measurements (upper limits) for our optical (X-ray) sample is ∼1-1000 (∼10-300) with a median of ∼50 (∼50). These results suggest that some amplification, in addition to shock compression, is needed to explain the afterglow observations.

  6. Relativistic Jets on all Scales in Accreting Black Holes: Contributions from Simbol-X

    NASA Astrophysics Data System (ADS)

    Corbel, Stéphane

    2009-05-01

    In the last several years, multiwavelength observations of accreting black holes have allowed a general characterisation of black holes properties as they evolve along the course of their outburst cycles. Relativistic jets, in their multiple forms, have profoundly impacted our perception and understanding of emission processes in these systems. In these Proceedings, I will highlight some possible contributions from Simbol-X related to jets in accreting sources.

  7. Relativistic Jets on all Scales in Accreting Black Holes: Contributions from Simbol-X

    SciTech Connect

    Corbel, Stephane

    2009-05-11

    In the last several years, multiwavelength observations of accreting black holes have allowed a general characterisation of black holes properties as they evolve along the course of their outburst cycles. Relativistic jets, in their multiple forms, have profoundly impacted our perception and understanding of emission processes in these systems. In these Proceedings, I will highlight some possible contributions from Simbol-X related to jets in accreting sources.

  8. Particle acceleration in relativistic magnetized collisionless pair shocks: a survey of magnetic inclination angles

    NASA Astrophysics Data System (ADS)

    Sironi, Lorenzo

    on the models of AGN jets, pulsar wind nebulae and GRBs that require particle acceleration in magnetized relativistic shocks.

  9. Instability of Toroidal Magnetic Field in Jets and Plerions

    NASA Astrophysics Data System (ADS)

    Begelman, Mitchell C.

    1998-01-01

    Astrophysical jets and pulsar-fed supernova remnants (plerions) are expected to develop highly organized magnetic structures dominated by concentric loops of toroidal field, Bφ. It has been argued that such structures could explain the polarization properties of some jets and contribute to their lateral confinement through magnetic tension forces. A concentric toroidal field geometry is also central to the Rees-Gunn model for the Crab Nebula, the archetypal plerion, and leads to the deduction that the Crab pulsar's wind must have a weak magnetic field. Yet this kind of equilibrium between magnetic and gas pressure forces, the ``equilibrium Z-pinch'' of the controlled fusion literature, is well known to be susceptible to disruptive localized instabilities, even when the magnetic field is weak and/or boundary conditions (e.g., a dense external medium) slow or suppress global modes. Thus, the magnetic field structures imputed to the interiors of jets and plerions are unlikely to persist for very long. To determine the growth rates of Z-pinch instabilities under astrophysical conditions, I derive a dispersion relation that is valid for the relativistic fluids of which jets and plerions may be composed, in the ideal magnetohydrodynamics (MHD) limit. The dominant instabilities are kink (m = 1) and pinch (m = 0) modes. The former generally dominate, destroying the concentric field structure and probably driving the system toward a more chaotic state in which the mean field strength is independent of radius (and in which resistive dissipation of the field may be enhanced). I estimate the timescales over which the field structure is likely to be rearranged and relate these to distances along relativistic jets and radii from the central pulsar in a plerion. I conclude that the central tenet of the Rees-Gunn model for the Crab Nebula, the existence of a concentric toroidal field well outside the pulsar wind's termination shock, is physically unrealistic. With this assumption

  10. Estakhr's Proper-Time Averaged of Material-Geodesic Equations (an umberella term equation for Relativistic Astrophysics, Relativistic Jets, Gamma-Ray Burst, Big Bang Hydrodynamics, Supernova Hydrodynamics)

    NASA Astrophysics Data System (ADS)

    Estakhr, Ahmad Reza

    2016-10-01

    DJ̲μ/Dτ =J̲ν ∂νU̲μ + ∂νT̲μν +Γαβμ J̲αU̲β ︷ Steady Component + ∂νRμν +Γαβμ Rαβ ︷ Perturbations EAMG equations are proper time-averaged equations of relativistic motion for fluid flow and used to describe Relativistic Turbulent Flows. The EAMG equations are used to describe Relativistic Jet.

  11. Simulations and synchrotron radiation from the relativistic jet base

    NASA Astrophysics Data System (ADS)

    Porth, O.

    The central acceleration region of active galactic nuclei (AGN) is simulated for a two-component spine and sheath jet. For the steady jet component we perform the spatially resolved polarized synchrotron transfer producing observables as radio maps, spectra and derived rotation measures. The wealth of detail obtained this way helps to assess the physical processes (such as internal Faraday rotation) and model assumptions.

  12. Scaling of Magnetic Reconnection in Relativistic Collisionless Pair Plasmas

    NASA Technical Reports Server (NTRS)

    Liu, Yi-Hsin; Guo, Fan; Daughton, William; Li, Hui; Hesse, Michael

    2015-01-01

    Using fully kinetic simulations, we study the scaling of the inflow speed of collisionless magnetic reconnection in electron-positron plasmas from the non-relativistic to ultra-relativistic limit. In the anti-parallel configuration, the inflow speed increases with the upstream magnetization parameter sigma and approaches the speed of light when sigma is greater than O(100), leading to an enhanced reconnection rate. In all regimes, the divergence of the pressure tensor is the dominant term responsible for breaking the frozen-in condition at the x-line. The observed scaling agrees well with a simple model that accounts for the Lorentz contraction of the plasma passing through the diffusion region. The results demonstrate that the aspect ratio of the diffusion region, modified by the compression factor of proper density, remains approximately 0.1 in both the non-relativistic and relativistic limits.

  13. WHAT IS ON TAP? THE ROLE OF SPIN IN COMPACT OBJECTS AND RELATIVISTIC JETS

    SciTech Connect

    King, Ashley L.; Miller, Jon M.; Gueltekin, Kayhan; Walton, Dominic J.; Fabian, Andrew C.; Reynolds, Christopher S.; Nandra, Kirpaul

    2013-07-10

    We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes 3 different Seyfert samples with a total of 37 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with more relativistically blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3{sigma} confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3{sigma} confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4{sigma} and 4.1{sigma} confidence level, respectively) between radio luminosity per bolometric luminosity and spin, as well as radio luminosity corrected for the fundamental plane (i.e., log ({nu}L{sub R}/L{sub Bol}{sup 0.67}/M{sub BH}{sup 0.78})) and spin, using our entire sample of black holes and neutrons stars. Again, although tentative, these relations point to the possibility that the mass accretion rate, i.e., bolometric luminosity, is also important in determining the jet luminosity, in addition to spin. Our analysis suggests that mass accretion rate and disk or coronal magnetic field strength may be the

  14. Searches for relativistic magnetic monopoles in IceCube

    DOE PAGES

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; ...

    2016-03-10

    Various extensions of the Standard Model motivate the existence of stable magnetic monopoles that could have been created during an early high-energy epoch of the Universe. These primordial magnetic monopoles would be gradually accelerated by cosmic magnetic fields and could reach high velocities that make them visible in Cherenkov detectors such as IceCube. Equivalently to electrically charged particles, magnetic monopoles produce direct and indirect Cherenkov light while traversing through matter at relativistic velocities. This paper describes searches for relativistic ((Formula presented.)) and mildly relativistic ((Formula presented.)) monopoles, each using one year of data taken in 2008/2009 and 2011/2012, respectively. Nomore » monopole candidate was detected. For a velocity above (Formula presented.) the monopole flux is constrained down to a level of (Formula presented.). This is an improvement of almost two orders of magnitude over previous limits.« less

  15. Searches for relativistic magnetic monopoles in IceCube

    SciTech Connect

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Ansseau, I.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Tjus, J. Becker; Becker, K. -H.; Beiser, E.; Benabderrahmane, M. L.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H. -P.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Fösig, C. -C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gier, D.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kiryluk, J.; Kläs, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, G.; Kroll, M.; Krückl, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mandelartz, M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O’Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Pütz, J.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Richter, S.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Sabbatini, L.; Sander, H. -G.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Schatto, K.; Scheriau, F.; Schimp, M.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schulte, L.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.

    2016-03-10

    Various extensions of the Standard Model motivate the existence of stable magnetic monopoles that could have been created during an early high-energy epoch of the Universe. These primordial magnetic monopoles would be gradually accelerated by cosmic magnetic fields and could reach high velocities that make them visible in Cherenkov detectors such as IceCube. Equivalently to electrically charged particles, magnetic monopoles produce direct and indirect Cherenkov light while traversing through matter at relativistic velocities. This paper describes searches for relativistic ((Formula presented.)) and mildly relativistic ((Formula presented.)) monopoles, each using one year of data taken in 2008/2009 and 2011/2012, respectively. No monopole candidate was detected. For a velocity above (Formula presented.) the monopole flux is constrained down to a level of (Formula presented.). This is an improvement of almost two orders of magnitude over previous limits.

  16. SCALING LAW OF RELATIVISTIC SWEET-PARKER-TYPE MAGNETIC RECONNECTION

    SciTech Connect

    Takahashi, Hiroyuki R.; Kudoh, Takahiro; Masada, Youhei; Matsumoto, Jin

    2011-10-01

    Relativistic Sweet-Parker-type magnetic reconnection is investigated by relativistic resistive magnetohydrodynamic (RRMHD) simulations. As an initial setting, we assume anti-parallel magnetic fields and a spatially uniform resistivity. A perturbation imposed on the magnetic fields triggers magnetic reconnection around a current sheet, and the plasma inflows into the reconnection region. The inflows are then heated due to ohmic dissipation in the diffusion region and finally become relativistically hot outflows. The outflows are not accelerated to ultrarelativistic speeds (i.e., Lorentz factor {approx_equal} 1), even when the magnetic energy dominates the thermal and rest mass energies in the inflow region. Most of the magnetic energy in the inflow region is converted into the thermal energy of the outflow during the reconnection process. The energy conversion from magnetic to thermal energy in the diffusion region results in an increase in the plasma inertia. This prevents the outflows from being accelerated to ultrarelativistic speeds. We find that the reconnection rate R obeys the scaling relation R{approx_equal}S{sup -0.5}, where S is the Lundquist number. This feature is the same as that of non-relativistic reconnection. Our results are consistent with the theoretical predictions of Lyubarsky for Sweet-Parker-type magnetic reconnection.

  17. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.-I.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Hartmann, D. H.; Fishman, J. F.

    2009-01-01

    Plasma instabilities excited in collisionless shocks are responsible for particle acceleration. We have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic-like shock structure. In the leading shock, electron density increases by a factor of about 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. These magnetic fields contribute to the electron's transverse deflection behind the shock. The jitter'' radiation from deflected electrons in turbulent magnetic fields has different properties than synchrotron radiation, which is calculated in a uniform magnetic field. This jitter radiation may be important for understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets in general, and supernova remnants. New spectra based on simulations will be presented.

  18. Magnetic Field Generation in Core-sheath Jets via the Kinetic Kelvin-Helmholtz Instability

    NASA Astrophysics Data System (ADS)

    Nishikawa, K.-I.; Hardee, P. E.; Duţan, I.; Niemiec, J.; Medvedev, M.; Mizuno, Y.; Meli, A.; Sol, H.; Zhang, B.; Pohl, M.; Hartmann, D. H.

    2014-09-01

    We have investigated magnetic field generation in velocity shears via the kinetic Kelvin-Helmholtz instability (kKHI) using a relativistic plasma jet core and stationary plasma sheath. Our three-dimensional particle-in-cell simulations consider plasma jet cores with Lorentz factors of 1.5, 5, and 15 for both electron-proton and electron-positron plasmas. For electron-proton plasmas, we find generation of strong large-scale DC currents and magnetic fields that extend over the entire shear surface and reach thicknesses of a few tens of electron skin depths. For electron-positron plasmas, we find generation of alternating currents and magnetic fields. Jet and sheath plasmas are accelerated across the shear surface in the strong magnetic fields generated by the kKHI. The mixing of jet and sheath plasmas generates a transverse structure similar to that produced by the Weibel instability.

  19. Radio evidence for AGN activity: relativistic jets as tracers of SMBHs

    NASA Astrophysics Data System (ADS)

    Kellermann, Kenneth I.

    2016-02-01

    Although the radio emission from most quasars appears to be associated with star forming activity in the host galaxy, about ten percent of optically selected quasars have very luminous relativistic jets apparently powered by a SMBH which is located at the base of the jet. When these jets are pointed close to the line of sight their apparent luminosity is enhanced by Doppler boosting and appears highly variable. High resolution radio interferometry shows directly the outflow of relativistic plasma jets from the SMBH. Apparent transverse velocities in these so-called ``blazars'' are typically about 7c but reach as much as 50c indicating true velocities within one percent of the speed of light. The jets appear to be collimated and accelerated in regions as much as a hundred parsecs downstream from the SMBH. Measurements made with Earth to space interferometers indicate apparent brightness temperatures of ~ 1014 K or more. This is well in excess of the limits imposed by inverse Compton cooling. The modest Doppler factors deduced from the observed ejection speeds appear to be inadequate to explain the high observed brightness temperatures in terms of relativistic boosting.

  20. Self-magnetized effects in relativistic cold plasmas due to ponderomotive forces: application to relativistic magnetic guiding of light.

    PubMed

    Lehner, T; di Menza, L

    2002-01-01

    Nonlinear equations are derived relevant to describe the propagation of powerful electromagnetic fields launched within a plasma. The nonlinear generation of self-induced collective electromagnetic perturbations are obtained with matter lying in the relativistic regime. Our main result is the self-consistent treatment of the coupled equations between the pump and its self-induced fields. In particular, a mechanism is pointed out for self-generation of quasistatic magnetic field that is due to the relativistic ponderomotive force. This process is found to be more efficient to produce quasistatic magnetic fields, as confirmed by recent experiments, as compared to known effects such as the inverse Faraday effect. As an application, we investigate conditions for relativistic magnetic guiding of light to occur under the combined action of the self-induced density and magnetic field.

  1. A Universal Scaling for the Energetics of Relativistic Jets From Black Hole Systems

    NASA Technical Reports Server (NTRS)

    Nemmen, R. S.; Georganopoulos, M.; Guiriec, S.; Meyer, E. T.; Gehrels, N.; Sambruna, R. M.

    2013-01-01

    Black holes generate collimated, relativistic jets which have been observed in gamma-ray bursts (GRBs), microquasars, and at the center of some galaxies (active galactic nuclei; AGN). How jet physics scales from stellar black holes in GRBs to the supermassive ones in AGNs is still unknown. Here we show that jets produced by AGNs and GRBs exhibit the same correlation between the kinetic power carried by accelerated particles and the gamma-ray luminosity, with AGNs and GRBs lying at the low and high-luminosity ends, respectively, of the correlation. This result implies that the efficiency of energy dissipation in jets produced in black hole systems is similar over 10 orders of magnitude in jet power, establishing a physical analogy between AGN and GRBs.

  2. A universal scaling for the energetics of relativistic jets from black hole systems.

    PubMed

    Nemmen, R S; Georganopoulos, M; Guiriec, S; Meyer, E T; Gehrels, N; Sambruna, R M

    2012-12-14

    Black holes generate collimated, relativistic jets, which have been observed in gamma-ray bursts (GRBs), microquasars, and at the center of some galaxies [active galactic nuclei (AGN)]. How jet physics scales from stellar black holes in GRBs to the supermassive ones in AGN is still unknown. Here, we show that jets produced by AGN and GRBs exhibit the same correlation between the kinetic power carried by accelerated particles and the gamma-ray luminosity, with AGN and GRBs lying at the low- and high-luminosity ends, respectively, of the correlation. This result implies that the efficiency of energy dissipation in jets produced in black hole systems is similar over 10 orders of magnitude in jet power, establishing a physical analogy between AGN and GRBs.

  3. INVERSE CASCADE OF NONHELICAL MAGNETIC TURBULENCE IN A RELATIVISTIC FLUID

    SciTech Connect

    Zrake, Jonathan

    2014-10-20

    The free decay of nonhelical relativistic magnetohydrodynamic turbulence is studied numerically, and found to exhibit cascading of magnetic energy toward large scales. Evolution of the magnetic energy spectrum P{sub M} (k, t) is self-similar in time and well modeled by a broken power law with subinertial and inertial range indices very close to 7/2 and –2, respectively. The magnetic coherence scale is found to grow in time as t {sup 2/5}, much too slow to account for optical polarization of gamma-ray burst afterglow emission if magnetic energy is to be supplied only at microphysical length scales. No bursty or explosive energy loss is observed in relativistic MHD turbulence having modest magnetization, which constrains magnetic reconnection models for rapid time variability of GRB prompt emission, blazars, and the Crab nebula.

  4. General relativistic simulations of black-hole-neutron-star mergers: Effects of magnetic fields

    NASA Astrophysics Data System (ADS)

    Etienne, Zachariah B.; Liu, Yuk Tung; Paschalidis, Vasileios; Shapiro, Stuart L.

    2012-03-01

    As a neutron star (NS) is tidally disrupted by a black hole (BH) companion at the end of a black-hole-neutron-star (BHNS) binary inspiral, its magnetic fields will be stretched and amplified. If sufficiently strong, these magnetic fields may impact the gravitational waveforms, merger evolution and mass of the remnant disk. Formation of highly-collimated magnetic field lines in the disk+spinning BH remnant may launch relativistic jets, providing the engine for a short-hard GRB. We analyze this scenario through fully general relativistic, magnetohydrodynamic BHNS simulations from inspiral through merger and disk formation. Different initial magnetic field configurations and strengths are chosen for the NS interior for both nonspinning and moderately spinning (aBH/MBH=0.75) BHs aligned with the orbital angular momentum. Only strong interior (Bmax⁡˜1017G) initial magnetic fields in the NS significantly influence merger dynamics, enhancing the remnant disk mass by 100% and 40% in the nonspinning and spinning BH cases, respectively. However, detecting the imprint of even a strong magnetic field may be challenging for Advanced LIGO. Though there is no evidence of mass outflows or magnetic field collimation during the preliminary simulations we have performed, higher resolution, coupled with longer disk evolutions and different initial magnetic field configurations, may be required to definitively assess the possibility of BHNS binaries as short-hard gamma-ray burst progenitors.

  5. Anisotropic flow and jet quenching in relativistic nuclear collisions

    NASA Astrophysics Data System (ADS)

    Qin, Guang-You

    2015-02-01

    The exploration of the strong-interaction matter under extreme conditions is one of the main goals of relativistic heavy-ion collisions. We provide some of the main results on the novel properties of quark-gluon plasma, with particular focus given to the strong collectivity and the color opaqueness exhibited by such hot and dense matter produced in high-energy nuclear collisions at RHIC and the LHC.

  6. Terahertz radiation generation in magnetized plasma under relativistic effect

    NASA Astrophysics Data System (ADS)

    Malik, Hitendra K.; Gill, Reenu

    2017-08-01

    We have carried out analytical calculations for the emission of Terahertz (THz) radiation in the magnetized and rippled density plasma by beating of two high intensity cosh-Gaussian laser beams, which are capable of creating a relativistic effect in electrons' motion. We find the expression for the THz field achieved during the relativistic laser plasma interaction and study the effect of density of ripples, laser beam width, and magnetic field on the THz field. The role of skewness parameters of the lasers is also discussed in detail for efficient THz radiation.

  7. Relay transport of relativistic flows in extreme magnetic fields of stars

    NASA Astrophysics Data System (ADS)

    Yao, W. P.; Qiao, B.; Xu, Z.; Zhang, H.; Chang, H. X.; Zhou, C. T.; Zhu, S. P.; Wang, X. G.; He, X. T.

    2017-08-01

    We find that the transport of relativistic flows in extreme magnetic fields can be achieved in a relay manner by considering the quantum electromagnetic cascade process, where photons play a key role as a medium. During the transport, the flow emits particle energy into photons via quantum synchrotron radiation, and then gains particles back by magnetic pair creation, forming a "particle-photon-particle" relay. Particle-in-cell simulations demonstrate that forward transport of the flow density is realized by a self-replenishment process with photon-pair cascades, while that of the flow energy is accomplished due to a new coupling path through radiation of photons. This novel transport mechanism is closely associated with jet generation and disk accretion around the neutron star of X-Ray Binaries, offering a potential explanation for the powerful jets observed there.

  8. A mildly relativistic radio jet from the otherwise normal type Ic supernova 2007gr.

    PubMed

    Paragi, Z; Taylor, G B; Kouveliotou, C; Granot, J; Ramirez-Ruiz, E; Bietenholz, M; van der Horst, A J; Pidopryhora, Y; van Langevelde, H J; Garrett, M A; Szomoru, A; Argo, M K; Bourke, S; Paczyński, B

    2010-01-28

    The class of type Ic supernovae have drawn increasing attention since 1998 owing to their sparse association (only four so far) with long duration gamma-ray bursts (GRBs). Although both phenomena originate from the core collapse of a massive star, supernovae emit mostly at optical wavelengths, whereas GRBs emit mostly in soft gamma-rays or hard X-rays. Though the GRB central engine generates ultra-relativistic jets, which beam the early emission into a narrow cone, no relativistic outflows have hitherto been found in type Ib/c supernovae explosions, despite theoretical expectations and searches. Here we report radio (interferometric) observations that reveal a mildly relativistic expansion in a nearby type Ic supernova, SN 2007gr. Using two observational epochs 60 days apart, we detect expansion of the source and establish a conservative lower limit for the average apparent expansion velocity of 0.6c. Independently, a second mildly relativistic supernova has been reported. Contrary to the radio data, optical observations of SN 2007gr indicate a typical type Ic supernova with ejecta velocities approximately 6,000 km s(-1), much lower than in GRB-associated supernovae. We conclude that in SN 2007gr a small fraction of the ejecta produced a low-energy mildly relativistic bipolar radio jet, while the bulk of the ejecta were slower and, as shown by optical spectropolarimetry, mildly aspherical.

  9. Luminosity enhancement in relativistic jets and altered luminosity functions for beamed objects

    NASA Technical Reports Server (NTRS)

    Urry, C. M.; Shafer, R. A.

    1983-01-01

    Due to relativistic effects, the observed emission from relativistic jets is quite different from the rest frame emission. Systematic differences between the observed and intrinsic intensities of sources in which jet phenomena are occurring are discussed. Assuming that jets have a power law luminosity function of a slope B, the observed luminosity distribution as a function of the velocity of the jet, the spectral index of the rest frame emission, and the range of angles of the jets relative to our line of sight are calculated. The results is well-approximated by two power laws, the higher luminosity end having the original power law index X and the lower luminosity end having a flattened exponent independent of B and only slightly greater than 1. A model consisting of beamed emission from a jet and unbeamed emission from a stationary central component is investigated. The luminosity functions for these two-component sources are calculated for two ranges of angles. For sources in which beaming is important, the luminosity function is much flatter. Because of this, the relative numbers of ""beamed'' and ""unbeamed'' sources detected on the sky depend strongly on the luminosity at which the comparison is made.

  10. Kelvin-Helmholtz Instability of Relativistic Jets - the Transition from Linear to Nonlinear Regime

    NASA Astrophysics Data System (ADS)

    Hanasz, M.

    The observed wiggles and knots in astrophysical jets as well as the curvilinear motion of radio emitting features are frequently interpreted as signatures of the Kelvin-Helmholtz (KH) instability (e.g. Hardee 1987). We investigate the KH instability of a hydrodynamic jet composed of a relativistic gas, surrounded by a nonrelativistic external medium and moving with a relativistic bulk speed. We show basic nonlinear effects, which become important for a finite amplitude KH modes. Since the KH instability in supersonic jets involves acoustic waves overreflected on jet boundaries, the basic nonlinear effect relies on the steepening of the acoustic wave fronts, leading to the formation of shocks. It turns out that the shocks appear predominantly in the external nonrelativistic gas, while the internal acoustic waves remain linear for a much longer time. In addition, the external medium "hardens" as soon as the boundary oscillation velocity becomes comparable to the external sound speed. On the other hand, the amplification of internal waves due to the overreflection is limited by a nonlinearity of the Lorentz gamma factor. This implies that the sideral oscillations of the jet boundary, resulting from the K-H instability, are limited to very small amplitudes comparable to a fraction of the jet radius.

  11. Magnetar giant flares and afterglows as relativistic magnetized explosions

    NASA Astrophysics Data System (ADS)

    Lyutikov, Maxim

    2006-04-01

    We propose that giant flares on soft γ-ray repeaters produce relativistic, strongly magnetized, weakly baryon-loaded magnetic clouds, somewhat analogous to solar coronal mass ejection (CME) events. The flares are driven by unwinding of the internal non-potential magnetic field which leads to a slow build-up of magnetic energy outside of the neutron star. For large magnetospheric currents, corresponding to a large twist of the external magnetic field, the magnetosphere becomes dynamically unstable on the Alfvén crossing time-scale of the inner magnetosphere, tA~RNS/c~ 30μs. The dynamic instability leads to the formation of dissipative current sheets through the development of a tearing mode. The released magnetic energy results in the formation of a strongly magnetized, pair-loaded, quasi-spherically expanding flux rope, topologically connected by the magnetic field to the neutron star during the prompt flare emission. The expansion reaches large Lorentz factors, Γ~ 10-20, at distances r~ 1-2 × 107cm, where a leptophotonic load is lost. Beyond this radius plasma is strongly dominated by the magnetic field, though some baryon loading, with M<Magnetic stresses of the tied flux rope lead to a late collimation of the expansion, on time-scales longer than the giant flare duration. Relativistic bulk motion of the expanding magnetic cloud, directed at an angle θ~ 135° to the line of sight (away from the observer), results in a strongly non-spherical forward shock with observed non-relativistic apparent expansion and bulk motion velocities βapp~ cot θ/2 ~ 0.4 at times of the first radio observations, approximately one week after the burst. An interaction with a shell of wind-shocked interstellar medium (ISM) and then with the unshocked ISM leads to a deceleration, to non-relativistic velocities approximately one month after the flare.

  12. Perpendicular propagating modes for weakly magnetized relativistic degenerate plasma

    SciTech Connect

    Abbas, Gohar; Bashir, M. F.; Murtaza, G.

    2012-07-15

    Using the Vlasov-Maxwell system of equations, the dispersion relations for the perpendicular propagating modes (i.e., X-mode, O-mode, and upper hybrid mode) are derived for a weakly magnetized relativistic degenerate electron plasma. By using the density (n{sub 0}=p{sub F}{sup 3}/3{pi}{sup 2} Planck-Constant-Over-Two-Pi {sup 3}) and the magnetic field values for different relativistic degenerate environments, the propagation characteristics (i.e., cutoff points, resonances, dispersions, and band widths in k-space) of these modes are examined. It is observed that the relativistic effects suppress the effect of ambient magnetic field and therefore the cutoff and resonance points shift towards the lower frequency regime resulting in enhancement of the propagation domain. The dispersion relations of these modes for the non-relativistic limit (p{sub F}{sup 2} Much-Less-Than m{sub 0}{sup 2}c{sup 2}) and the ultra-relativistic limit (p{sub F}{sup 2} Much-Greater-Than m{sub 0}{sup 2}c{sup 2}) are also presented.

  13. MAGNETIC FIELD GENERATION AND PARTICLE ENERGIZATION AT RELATIVISTIC SHEAR BOUNDARIES IN COLLISIONLESS ELECTRON-POSITRON PLASMAS

    SciTech Connect

    Liang, Edison; Smith, Ian; Boettcher, Markus E-mail: iansmith@rice.edu

    2013-04-01

    Using particle-in-cell simulations, we study the kinetic physics of relativistic shear flow in collisionless electron-positron (e+e-) plasmas. We find efficient magnetic field generation and particle energization at the shear boundary, driven by streaming instabilities across the shear interface and sustained by the shear flow. Nonthermal, anisotropic high-energy particles are accelerated across field lines to produce a power-law tail turning over just below the shear Lorentz factor. These results have important implications for the dissipation and radiation of jets in blazars and gamma-ray bursts.

  14. A Temporal Analysis Indicates a Mildly Relativistic Compact Jet in GRS 1915+105

    NASA Astrophysics Data System (ADS)

    Punsly, Brian; Rodriguez, Jérôme

    2016-05-01

    Most of our knowledge of the radio morphology and kinematics of X-ray binary partially synchrotron self-absorbed compact jets (hereafter, compact jets) is based on the observations of GRS 1915+105, which has the most prominent compact jet. Yet, the compact jet bulk velocity, v, is poorly constrained in the literature, 0.07\\lt v/c\\lt 0.98. In spite of this uncertainty, compact jets are often unified with relativistic jets in active galactic nuclei. We estimated v as part of a temporal analysis of GRS 1915+105 jets in “high plateau states” (HPS). We define HPS as a state showing a hard X-ray spectrum and low level of long-term (\\gt 10 s) X-ray activity associated with 15 GHz flux density \\gt 70 mJy for \\gt 7 consecutive days. The radio emission is associated with compact jet emission. Two HPS were monitored at 15 GHz during their termination with e-folding times of 3.8 and 8.6 hr. We combine this timescale with the scale of the spatial variation of the linear source of a Very Large Baseline Array image preceding the fade of one of these HPS in order to estimate the jet speed. Our assumption that the reduction in radio emissivity propagates as an approximate discontinuity down the HPS jet (leaving a weak jet in its wake) indicates 0.17\\lt v/c\\lt 0.43. This agrees closely with the only other existing v estimates that are derived directly from radio images, jet asymmetry produced by Doppler enhancement.

  15. VISCOUS BOUNDARY LAYERS OF RADIATION-DOMINATED, RELATIVISTIC JETS. I. THE TWO-STREAM MODEL

    SciTech Connect

    Coughlin, Eric R.; Begelman, Mitchell C. E-mail: mitch@jila.colorado.edu

    2015-08-10

    Using the relativistic equations of radiation hydrodynamics in the viscous limit, we analyze the boundary layers that develop between radiation-dominated jets and their environments. In this paper we present the solution for the self-similar, 2D, plane-parallel two-stream problem, wherein the jet and the ambient medium are considered to be separate, interacting fluids, and we compare our results to those of previous authors. (In a companion paper we investigate an alternative scenario, known as the free-streaming jet model.) Consistent with past findings, we show that the boundary layer that develops between the jet and its surroundings creates a region of low-density material. These models may be applicable to sources such as super-Eddington tidal disruption events and long gamma-ray bursts.

  16. Multi-wavelength polarimetric studies of relativistic jets in active galactic nuclei

    NASA Astrophysics Data System (ADS)

    Casadio, Carolina

    This Thesis is focussed on the study of relativistic jets, commonly present in multiple astrophysical sites, from active galactic nuclei (AGN), to micro- quasars or gamma-ray bursts (GRBs). In the case of AGN, huge amounts of energy across the whole electromagnetic spectrum are released as a conse- quence of the accretion of material onto a supermassive back hole (SMBH) lurking at their centers. The accretion leads to the formation of a pair of very powerful and highly collimated jets extending far beyond the size of the host galaxy. We analyzed the correlation between the multi-wavelength emission and the radio jet in three powerful AGN, the radio galaxies 3C 120 and M 87, and the quasar CTA 102. The main goal of this Thesis is to obtain a better understanding of the jet dynamics and the role played by the magnetic field, and to determine what are the sites and mechanisms for the production of the γ-ray emission observed in these sources. We have performed multi-wavelength studies of the radio galaxy 3C 120 and the blazar CTA 102 during unprecedented γ-ray flares for both sources. The NASA satellite Fermi registered in September-October 2012 a bright γ-ray flare in CTA 102, and between December 2012 and October 2014 a prolonged γ-ray activity in the radio galaxy 3C 120. In both studies, to determine where the γ-ray emission is produced, the analysis of Fermi data has been compared with a detailed study of the morphology and evolution of the parsec scale jet through a series of extremely-high angular resolution Very Long Baseline Array (VLBA) images at 43 GHz from the Boston University blazar monitoring program, in which our research group is actively participating. In the case of 3C 120 we have also collected 15 GHz VLBA data from the MOJAVE monitoring program, extending our study of the radio jet from June 2008 to May 2014. For the study of CTA 102 a total of 80 VLBA images at 43 GHz have been analyzed and compared with observations across the whole

  17. Baryon Loading Efficiency and Particle Acceleration Efficiency of Relativistic Jets: Cases for Low Luminosity BL Lacs

    NASA Astrophysics Data System (ADS)

    Inoue, Yoshiyuki; Tanaka, Yasuyuki T.

    2016-09-01

    Relativistic jets launched by supermassive black holes, so-called active galactic nuclei (AGNs), are known as the most energetic particle accelerators in the universe. However, the baryon loading efficiency onto the jets from the accretion flows and their particle acceleration efficiencies have been veiled in mystery. With the latest data sets, we perform multi-wavelength spectral analysis of quiescent spectra of 13 TeV gamma-ray detected high-frequency-peaked BL Lacs (HBLs) following one-zone static synchrotron self-Compton (SSC) model. We determine the minimum, cooling break, and maximum electron Lorentz factors following the diffusive shock acceleration (DSA) theory. We find that HBLs have {P}B/{P}e˜ 6.3× {10}-3 and the radiative efficiency {ɛ }{{rad,jet}}˜ 6.7× {10}-4, where P B and P e is the Poynting and electron power, respectively. By assuming 10 leptons per one proton, the jet power relates to the black hole mass as {P}{{jet}}/{L}{{Edd}}˜ 0.18, where {P}{{jet}} and {L}{{Edd}} is the jet power and the Eddington luminosity, respectively. Under our model assumptions, we further find that HBLs have a jet production efficiency of {η }{{jet}}˜ 1.5 and a mass loading efficiency of {ξ }{{jet}}≳ 5× {10}-2. We also investigate the particle acceleration efficiency in the blazar zone by including the most recent Swift/BAT data. Our samples ubiquitously have particle acceleration efficiencies of {η }g˜ {10}4.5, which is inefficient to accelerate particles up to the ultra-high-energy-cosmic-ray (UHECR) regime. This implies that the UHECR acceleration sites should not be the blazar zones of quiescent low power AGN jets, if one assumes the one-zone SSC model based on the DSA theory.

  18. Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars?

    NASA Technical Reports Server (NTRS)

    Sikora, Marek; Begelman, Mitchell C.; Rees, Martin J.

    1994-01-01

    Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

  19. Comptonization of diffuse ambient radiation by a relativistic jet: The source of gamma rays from blazars?

    NASA Technical Reports Server (NTRS)

    Sikora, Marek; Begelman, Mitchell C.; Rees, Martin J.

    1994-01-01

    Recent Energy Gamma Ray Experiment Telescope (EGRET) observations of blazars have revealed strong, variable gamma-ray fluxes with no signatures of gamma-ray absorption by pair production. This radiation probably originates from the inner parts of relativistic jets which are aimed nearly toward us. On sub-parsec scales, the jet will be pervaded by radiation from the broad-line region, as well as by photons from the central continuum source (some of which will be scattered by thermal plasma). In a frame moving with the relativistic outflow, the energy of this ambient radiation would be enhanced. This radiation would be Comptonized by both cold and relativistic electrons in the jet, yielding (in the observer's frame) a collimated beam of X-rays and gamma rays. On the assumption that this process dominates self-Comptonization of synchrotron radiation, we develop a self-consistent model for variable gamma-ray emission, involving a single population of relativistic electrons accelerated by a disturbance in the jet. The spectral break between the X-ray and gamma-ray band, observed in 3C 279 and deduced for other blazars, results from inefficient radiative cooling of lower energy electrons. The existence of such a break strongly favors a model involving Comptonization of an external radiation field over a synchrotron self-Compton model. We derive constraints on such model parameters as the location and speed of the source, its dimensions and internal physical parameters, the maximum photon energies produced in the source, and the density and distribution of ambient radiation. Finally, we discuss how observations might discriminate between our model and alternative ones invoking Comptonization of ambient radiation.

  20. Artificial γ-ray imaging of a galactic, relativistic astrophysical jet

    NASA Astrophysics Data System (ADS)

    Smponias, T.; Kosmas, T. S.

    2013-02-01

    The jet in a microquasar stellar system is simulated with a relativistic hydrocode (PLUTO) and then it is imaged, in the γ-rays wave band, with a line-of-sight method, including both emission and self-absorption. A synthetic image is produced which allows to better estimate the system's physical properties. The calculation procedure in our method has been simplified by exploiting the ability to de-couple the hydrodynamical from the radiative quantities in the computations.

  1. Role of the Kelvin-Helmholtz instability in the evolution of magnetized relativistic sheared plasma flows.

    PubMed

    Hamlin, Nathaniel D; Newman, William I

    2013-04-01

    We explore, via analytical and numerical methods, the Kelvin-Helmholtz (KH) instability in relativistic magnetized plasmas, with applications to astrophysical jets. We solve the single-fluid relativistic magnetohydrodynamic (RMHD) equations in conservative form using a scheme which is fourth order in space and time. To recover the primitive RMHD variables, we use a highly accurate, rapidly convergent algorithm which improves upon such schemes as the Newton-Raphson method. Although the exact RMHD equations are marginally stable, numerical discretization renders them unstable. We include numerical viscosity to restore numerical stability. In relativistic flows, diffusion can lead to a mathematical anomaly associated with frame transformations. However, in our KH studies, we remain in the rest frame of the system, and therefore do not encounter this anomaly. We use a two-dimensional slab geometry with periodic boundary conditions in both directions. The initial unperturbed velocity peaks along the central axis and vanishes asymptotically at the transverse boundaries. Remaining unperturbed quantities are uniform, with a flow-aligned unperturbed magnetic field. The early evolution in the nonlinear regime corresponds to the formation of counter-rotating vortices, connected by filaments, which persist in the absence of a magnetic field. A magnetic field inhibits the vortices through a series of stages, namely, field amplification, vortex disruption, turbulent breakdown, and an approach to a flow-aligned equilibrium configuration. Similar stages have been discussed in MHD literature. We examine how and to what extent these stages manifest in RMHD for a set of representative field strengths. To characterize field strength, we define a relativistic extension of the Alfvénic Mach number M(A). We observe close complementarity between flow and magnetic field behavior. Weaker fields exhibit more vortex rotation, magnetic reconnection, jet broadening, and intermediate turbulence

  2. Evolution of relativistic jets from XTE J1550-564 and the environment of microquasars

    NASA Astrophysics Data System (ADS)

    Zhang, Shuang Nan; Hao, Jing Fang

    2008-10-01

    Two relativistic X-ray jets have been detected with the Chandra X-ray observatory in the black hole X-ray transient XTE J1550-564. We report a full analysis of the evolution of the two jets with a gamma-ray burst external shock model. A plausible scenario suggests a cavity outside the central source and the jets first travelled with constant velocity and then are slowed down by the interactions between the jets and the interstellar medium (ISM). The best fitted radius of the cavity is ~0.36 pc on the eastern side and ~0.46 pc on the western side, and the densities also show asymmetry, of ~0.015 cm-3 on the east to ~0.21 cm-3 on the west. Large scale low density region is also found in another microquasar system, H 1743-322. These results are consistent with previous suggestions that the environment of microquasars should be rather vacuous, compared to the normal Galactic environment. A generic scenario for microquasar jets is proposed, classifying the observed jets into three main categories, with different jet morphologies (and sizes) corresponding to different scales of vacuous environments surrounding them.

  3. Simulation of Relativistic Shocks and Associated Radiation from Turbulent Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Nishikawa, K.; Niemiec, J.; Medvedev, M.; Zhang, B.; Hardee, P.; Mizuno, Y.; Nordlund, A.; Frederiksen, J.; Sol, H.; Pohl, M.; Oka, M.; Hartmann, D. H.; Fishman, J. F.

    2009-01-01

    Plasma instabilities (e.g., Buneman, Weibel and other two-stream instabilities) excited in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a new 3-D relativistic particle-in-cell code, we have investigated the particle acceleration and shock structure associated with an unmagnetized relativistic electron-positron jet propagating into an unmagnetized electron-positron plasma. The simulation has been performed using a long simulation system in order to study the nonlinear stages of the Weibel instability, the particle acceleration mechanism, and the shock structure. Cold jet electrons are thermalized and slowed while the ambient electrons are swept up to create a partially developed hydrodynamic (HD) like shock structure. In the leading shock, electron density increases by a factor of <_ 3.5 in the simulation frame. Strong electromagnetic fields are generated in the trailing shock and provide an emission site. We discuss the possible implication of our simulation results within the AGN and GRB context. We have calculated the time evolution of the spectrum from two electrons propagating in a uniform parallel magnetic field to verify the technique. The same technique will be used to calculate radiation from accelerated electrons (positrons) in turbulent magnetic fields generated by Weibel instability.

  4. Jet Magnetically Accelerated from Advection Dominated Accretion Flow

    NASA Astrophysics Data System (ADS)

    Gong, Xiao-Long; Jiang, Zhi-Xiong

    2014-08-01

    A jet model for the jet power arising from a steady, optically thin, advection dominated accretion flow (ADAF) around a Kerr black hole (BH) is proposed. We investigate the typical numerical solutions of ADAF, and calculate the jet power from an ADAF using a general relativistic version of electronic circuit theory. It is shown that the jet power concentrates in the inner region of the accretion flow, and the higher the degree to which the flow advection-dominated is, the lower the jet power from the ADAF is.

  5. VLBI MERLIN and VLA Observations of the Blazar 1156+295 - a Bending Relativistic Jet

    NASA Astrophysics Data System (ADS)

    McHardy, I. M.; Marscher, A. P.; Gear, W. K.; Muxlow, T.; Lehto, H. J.; Abraham, R. G.

    1990-09-01

    We present VLBI maps at 18, 6, 2.8 and 1.35 cm of the blazar 1156 + 295 which show a jet emerging from the core along position angle (PA) ~20^deg^ and bending to larger PA further out. Maps at 6 cm from 1987 May and 1988 November show different structure, indicating the probable movement from the core of a component with a very high apparent transverse velocity (~15 h^-1^ c where H_0_ = 100 h km s^-1^ Mpc^-1^ and q_0_ = 0.5). The 2.8- and 1.35-cm maps are consistent with this hypothesis. We also present MERLIN and VLA total intensity and polarization maps at 18, 6 and 2 cm which show a 2-arcsec jet emerging from the core in PA - 19^deg^. We show how a bending relativistic jet can also explain the variability seen in this source.

  6. Stability of hydrodynamical relativistic planar jets. II. Long-term nonlinear evolution

    NASA Astrophysics Data System (ADS)

    Perucho, M.; Martí, J. M.; Hanasz, M.

    2004-11-01

    In this paper we continue our study of the Kelvin-Helmholtz (KH) instability in relativistic planar jets following the long-term evolution of the numerical simulations which were introduced in Paper I. The models have been classified into four classes (I to IV) with regard to their evolution in the nonlinear phase, characterized by the process of jet/ambient mixing and momentum transfer. Models undergoing qualitatively different non-linear evolution are clearly grouped in well-separated regions in a jet Lorentz factor/jet-to-ambient enthalpy diagram. Jets with a low Lorentz factor and small enthalpy ratio are disrupted by a strong shock after saturation. Those with a large Lorentz factor and enthalpy ratio are unstable although the process of mixing and momentum exchange proceeds to a longer time scale due to a steady conversion of kinetic to internal energy in the jet. In these cases, the high value of the initial Lorentz seems to prevent transversal velocity from growing far enough to generate the strong shock that breaks the slower jets. Finally, jets with either high Lorentz factors and small enthalpy ratios or low Lorentz factors and large enthalpy ratios appear as the most stable. In the long term, all the models develop a distinct transversal structure (shear/transition layers) as a consequence of KH perturbation growth. The properties of these shear layers are analyzed in connection with the parameters of the original jet models. Appendix A is only available in electronic form at http://www.edpsciences.org

  7. Searches for relativistic magnetic monopoles in IceCube

    NASA Astrophysics Data System (ADS)

    Aartsen, M. G.; Abraham, K.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Ahrens, M.; Altmann, D.; Anderson, T.; Ansseau, I.; Archinger, M.; Arguelles, C.; Arlen, T. C.; Auffenberg, J.; Bai, X.; Barwick, S. W.; Baum, V.; Bay, R.; Beatty, J. J.; Tjus, J. Becker; Becker, K.-H.; Beiser, E.; Benabderrahmane, M. L.; Berghaus, P.; Berley, D.; Bernardini, E.; Bernhard, A.; Besson, D. Z.; Binder, G.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Börner, M.; Bos, F.; Bose, D.; Böser, S.; Botner, O.; Braun, J.; Brayeur, L.; Bretz, H.-P.; Buzinsky, N.; Casey, J.; Casier, M.; Cheung, E.; Chirkin, D.; Christov, A.; Clark, K.; Classen, L.; Coenders, S.; Cowen, D. F.; Cruz Silva, A. H.; Daughhetee, J.; Davis, J. C.; Day, M.; de André, J. P. A. M.; De Clercq, C.; del Pino Rosendo, E.; Dembinski, H.; De Ridder, S.; Desiati, P.; de Vries, K. D.; de Wasseige, G.; de With, M.; DeYoung, T.; Díaz-Vélez, J. C.; di Lorenzo, V.; Dumm, J. P.; Dunkman, M.; Eberhardt, B.; Ehrhardt, T.; Eichmann, B.; Euler, S.; Evenson, P. A.; Fahey, S.; Fazely, A. R.; Feintzeig, J.; Felde, J.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Fösig, C.-C.; Fuchs, T.; Gaisser, T. K.; Gaior, R.; Gallagher, J.; Gerhardt, L.; Ghorbani, K.; Gier, D.; Gladstone, L.; Glagla, M.; Glüsenkamp, T.; Goldschmidt, A.; Golup, G.; Gonzalez, J. G.; Góra, D.; Grant, D.; Griffith, Z.; Groß, A.; Ha, C.; Haack, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hansen, E.; Hansmann, B.; Hanson, K.; Hebecker, D.; Heereman, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hignight, J.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Holzapfel, K.; Homeier, A.; Hoshina, K.; Huang, F.; Huber, M.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; In, S.; Ishihara, A.; Jacobi, E.; Japaridze, G. S.; Jeong, M.; Jero, K.; Jurkovic, M.; Kappes, A.; Karg, T.; Karle, A.; Kauer, M.; Keivani, A.; Kelley, J. L.; Kemp, J.; Kheirandish, A.; Kiryluk, J.; Kläs, J.; Klein, S. R.; Kohnen, G.; Koirala, R.; Kolanoski, H.; Konietz, R.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krings, K.; Kroll, G.; Kroll, M.; Krückl, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Lanfranchi, J. L.; Larson, M. J.; Lesiak-Bzdak, M.; Leuermann, M.; Leuner, J.; Lu, L.; Lünemann, J.; Madsen, J.; Maggi, G.; Mahn, K. B. M.; Mandelartz, M.; Maruyama, R.; Mase, K.; Matis, H. S.; Maunu, R.; McNally, F.; Meagher, K.; Medici, M.; Meli, A.; Menne, T.; Merino, G.; Meures, T.; Miarecki, S.; Middell, E.; Mohrmann, L.; Montaruli, T.; Morse, R.; Nahnhauer, R.; Naumann, U.; Neer, G.; Niederhausen, H.; Nowicki, S. C.; Nygren, D. R.; Obertacke Pollmann, A.; Olivas, A.; Omairat, A.; O'Murchadha, A.; Palczewski, T.; Pandya, H.; Pankova, D. V.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pfendner, C.; Pieloth, D.; Pinat, E.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Pütz, J.; Quinnan, M.; Raab, C.; Rädel, L.; Rameez, M.; Rawlins, K.; Reimann, R.; Relich, M.; Resconi, E.; Rhode, W.; Richman, M.; Richter, S.; Riedel, B.; Robertson, S.; Rongen, M.; Rott, C.; Ruhe, T.; Ryckbosch, D.; Sabbatini, L.; Sander, H.-G.; Sandrock, A.; Sandroos, J.; Sarkar, S.; Schatto, K.; Scheriau, F.; Schimp, M.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönwald, A.; Schulte, L.; Schumacher, L.; Seckel, D.; Seunarine, S.; Soldin, D.; Song, M.; Spiczak, G. M.; Spiering, C.; Stahlberg, M.; Stamatikos, M.; Stanev, T.; Stasik, A.; Steuer, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Ström, R.; Strotjohann, N. L.; Sullivan, G. W.; Sutherland, M.; Taavola, H.; Taboada, I.; Tatar, J.; Ter-Antonyan, S.; Terliuk, A.; Tešić, G.; Tilav, S.; Toale, P. A.; Tobin, M. N.; Toscano, S.; Tosi, D.; Tselengidou, M.; Turcati, A.; Unger, E.; Usner, M.; Vallecorsa, S.; Vandenbroucke, J.; van Eijndhoven, N.; Vanheule, S.; van Santen, J.; Veenkamp, J.; Vehring, M.; Voge, M.; Vraeghe, M.; Walck, C.; Wallace, A.; Wallraff, M.; Wandkowsky, N.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whelan, B. J.; Wiebe, K.; Wiebusch, C. H.; Wille, L.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, D. L.; Xu, X. W.; Xu, Y.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zoll, M.

    2016-03-01

    Various extensions of the Standard Model motivate the existence of stable magnetic monopoles that could have been created during an early high-energy epoch of the Universe. These primordial magnetic monopoles would be gradually accelerated by cosmic magnetic fields and could reach high velocities that make them visible in Cherenkov detectors such as IceCube. Equivalently to electrically charged particles, magnetic monopoles produce direct and indirect Cherenkov light while traversing through matter at relativistic velocities. This paper describes searches for relativistic (vge 0.76c) and mildly relativistic (vge 0.51c) monopoles, each using one year of data taken in 2008/2009 and 2011/2012, respectively. No monopole candidate was detected. For a velocity above 0.51 c the monopole flux is constrained down to a level of 1.55 × 10^{-18} text {cm}^{-2} text {s}^{-1} text {sr}^{-1}. This is an improvement of almost two orders of magnitude over previous limits.

  8. Search for relativistic magnetic monopoles with IceCube

    NASA Astrophysics Data System (ADS)

    Abbasi, R.; Abdou, Y.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Baum, V.; Bay, R.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker Tjus, J.; Becker, K.-H.; Bell, M.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brayeur, L.; Brown, A. M.; Bruijn, R.; Brunner, J.; Buitink, S.; Carson, M.; Casey, J.; Casier, M.; Chirkin, D.; Christy, B.; Clevermann, F.; Cohen, S.; Cowen, D. F.; Cruz Silva, A. H.; Danninger, M.; Daughhetee, J.; Davis, J. C.; De Clercq, C.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; DeYoung, T.; Díaz-Vélez, J. C.; Dreyer, J.; Dumm, J. P.; Dunkman, M.; Eagan, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Flis, S.; Franckowiak, A.; Franke, R.; Frantzen, K.; Fuchs, T.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Góra, D.; Grant, D.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Hanson, K.; Heereman, D.; Heimann, P.; Heinen, D.; Helbing, K.; Hellauer, R.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, R.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Jlelati, O.; Kappes, A.; Karg, T.; Karle, A.; Kiryluk, J.; Kislat, F.; Kläs, J.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, C.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Krasberg, M.; Kroll, G.; Kunnen, J.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lesiak-Bzdak, M.; Lünemann, J.; Madsen, J.; Maruyama, R.; Mase, K.; Matis, H. S.; McNally, F.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Mohrmann, L.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Naumann, U.; Nowicki, S. C.; Nygren, D. R.; Obertacke, A.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pepper, J. A.; Pérez de los Heros, C.; Pieloth, D.; Pirk, N.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rädel, L.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Riedel, B.; Rodrigues, J. P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Ruzybayev, B.; Ryckbosch, D.; Saba, S. M.; Salameh, T.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Scheel, M.; Scheriau, F.; Schmidt, T.; Schmitz, M.; Schoenen, S.; Schöneberg, S.; Schönherr, L.; Schönwald, A.; Schukraft, A.; Schulte, L.; Schulz, O.; Seckel, D.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Smith, M. W. E.; Soiron, M.; Soldin, D.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stasik, A.; Stezelberger, T.; Stokstad, R. G.; Stößl, A.; Strahler, E. A.; Ström, R.; Sullivan, G. W.; Taavola, H.; Taboada, I.; Tamburro, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Usner, M.; van der Drift, D.; van Eijndhoven, N.; Van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Wasserman, R.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Ziemann, J.; Zilles, A.; Zoll, M.

    2013-01-01

    We present the first results in the search for relativistic magnetic monopoles with the IceCube detector, a subsurface neutrino telescope located in the South Polar ice cap containing a volume of 1km3. This analysis searches data taken on the partially completed detector during 2007 when roughly 0.2km3 of ice was instrumented. The lack of candidate events leads to an upper limit on the flux of relativistic magnetic monopoles of Φ90%C.L.˜3×10-18cm-2sr-1s-1 for β≥0.8. This is a factor of 4 improvement over the previous best experimental flux limits up to a Lorentz boost γ below 107. This result is then interpreted for a wide range of mass and kinetic energy values.

  9. Relativistic magnetic reconnection driven by intense lasers in preformed plasma

    NASA Astrophysics Data System (ADS)

    Campbell, Paul; Raymond, A.; McKelvey, A.; Maksimchuk, A.; Nees, J.; Yanovsky, V.; Krushelnick, K.; Dong, C. F.; Fox, W.; Zulick, C.; Wei, M. S.; Chen, H.; Chvykov, V.; Mileham, C.; Nilson, P. M.; Stoeckl, C.; Thomas, A. G. R.; Willingale, L.

    2016-10-01

    Experiments were performed with the OMEGA EP laser system focusing the two short pulse beams to high intensities on foil targets. Relativistic electrons drive fast reconnection self-generated magnetic fields. To investigate the effects of a preformed plasma on this relativistic magnetic reconnection, a long pulse UV beam was used to ablate the front surface of layered targets. The density and reconnection dynamics in the preformed copper or CH plasma were diagnosed with a 4 ω optical probe. A spherically bent crystal imaged characteristic copper Kα emission induced by fast electrons accelerated into the target in the reconnection diffusion region. This work was supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0002727.

  10. VISCOUS BOUNDARY LAYERS OF RADIATION-DOMINATED, RELATIVISTIC JETS. II. THE FREE-STREAMING JET MODEL

    SciTech Connect

    Coughlin, Eric R.; Begelman, Mitchell C. E-mail: mitch@jila.colorado.edu

    2015-08-10

    We analyze the interaction of a radiation-dominated jet and its surroundings using the equations of radiation hydrodynamics in the viscous limit. In a previous paper we considered the two-stream scenario, which treats the jet and its surroundings as distinct media interacting through radiation viscous forces. Here we present an alternative boundary layer model, known as the free-streaming jet model—where a narrow stream of fluid is injected into a static medium—and present solutions where the flow is ultrarelativistic and the boundary layer is dominated by radiation. It is shown that these jets entrain material from their surroundings and that their cores have a lower density of scatterers and a harder spectrum of photons, leading to observational consequences for lines of sight that look “down the barrel of the jet.” These jetted outflow models may be applicable to the jets produced during long gamma-ray bursts and super-Eddington phases of tidal disruption events.

  11. Cosmic jets

    NASA Technical Reports Server (NTRS)

    Rees, M. J.

    1986-01-01

    The evidence that active galactic nuclei produce collimated plasma jets is summarised. The strongest radio galaxies are probably energised by relativistic plasma jets generated by spinning black holes interacting with magnetic fields attached to infalling matter. Such objects can produce e(+)-e(-) plasma, and may be relevant to the acceleration of the highest-energy cosmic ray primaries. Small-scale counterparts of the jet phenomenon within our own galaxy are briefly reviewed.

  12. The high-efficiency jets magnetically accelerated from a thin disk in powerful lobe-dominated FRII radio galaxies

    SciTech Connect

    Li, Shuang-Liang

    2014-06-10

    A maximum jet efficiency line R ∼ 25 (R = L {sub jet}/L {sub bol}), found in FRII radio galaxies by Fernandes et al., was extended to cover the full range of jet power by Punsly. Recent general relativistic magnetohydrodynamic simulations of jet formation have mainly focused on the enhancement of jet power. In this work, we suggest that the jet efficiency could be very high even for conventional jet power if the radiative efficiency of disks was much smaller. We adopt the model of a thin disk with magnetically driven winds to investigate the observational high-efficiency jets in FRII radio galaxies. It is found that the structure of a thin disk can be significantly altered by the feedback of winds. The temperature of a disk gradually decreases with increasing magnetic field; the disk density, surface density, and pressure also change enormously. The lower temperature and higher surface density in the inner disk result in the rapid decrease of radiative efficiency. Thus, the jet efficiency is greatly improved even if the jet power is conventional. Our results can explain the observations quite well. The theoretical maximum jet efficiency of R ∼ 1000 suggested by our calculations is large enough to explain all of the high jet efficiency in observations, even considering the episodic activity of jets.

  13. Relativistic electron vortex beams in a constant magnetic field

    NASA Astrophysics Data System (ADS)

    Rajabi, Ahmad; Berakdar, Jamal

    2017-06-01

    We present solutions for the Dirac equation in the form of Bessel or Laguerre-Gaussian beams for, respectively, a free electron or an electron subject to a longitudinal constant magnetic field. We calculate the probability and the current distributions and find a strong dependence on the spin angular momentum and the orbital angular momentum of the relativistic electron beam. The role of the intrinsic spin-orbital coupling is investigated.

  14. JET ROTATION DRIVEN BY MAGNETOHYDRODYNAMIC SHOCKS IN HELICAL MAGNETIC FIELDS

    SciTech Connect

    Fendt, Christian

    2011-08-10

    In this paper, we present a detailed numerical investigation of the hypothesis that a rotation of astrophysical jets can be caused by magnetohydrodynamic (MHD) shocks in a helical magnetic field. Shock compression of the helical magnetic field results in a toroidal Lorentz force component that will accelerate the jet material in the toroidal direction. This process transforms magnetic angular momentum (magnetic stress) carried along the jet into kinetic angular momentum (rotation). The mechanism proposed here only works in a helical magnetic field configuration. We demonstrate the feasibility of this mechanism by axisymmetric MHD simulations in 1.5 and 2.5 dimensions using the PLUTO code. In our setup, the jet is injected into the ambient gas with zero kinetic angular momentum (no rotation). We apply different dynamical parameters for jet propagation such as the jet internal Alfven Mach number and fast magnetosonic Mach number, the density contrast of the jet to the ambient medium, and the external sonic Mach number of the jet. The mechanism we suggest should work for a variety of jet applications, e.g., protostellar or extragalactic jets, and internal jet shocks (jet knots) or external shocks between the jet and the ambient gas (entrainment). For typical parameter values for protostellar jets, the numerically derived rotation feature looks consistent with the observations, i.e., rotational velocities of 0.1%-1% of the jet bulk velocity.

  15. Jet Rotation Driven by Magnetohydrodynamic Shocks in Helical Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Fendt, Christian

    2011-08-01

    In this paper, we present a detailed numerical investigation of the hypothesis that a rotation of astrophysical jets can be caused by magnetohydrodynamic (MHD) shocks in a helical magnetic field. Shock compression of the helical magnetic field results in a toroidal Lorentz force component that will accelerate the jet material in the toroidal direction. This process transforms magnetic angular momentum (magnetic stress) carried along the jet into kinetic angular momentum (rotation). The mechanism proposed here only works in a helical magnetic field configuration. We demonstrate the feasibility of this mechanism by axisymmetric MHD simulations in 1.5 and 2.5 dimensions using the PLUTO code. In our setup, the jet is injected into the ambient gas with zero kinetic angular momentum (no rotation). We apply different dynamical parameters for jet propagation such as the jet internal Alfvén Mach number and fast magnetosonic Mach number, the density contrast of the jet to the ambient medium, and the external sonic Mach number of the jet. The mechanism we suggest should work for a variety of jet applications, e.g., protostellar or extragalactic jets, and internal jet shocks (jet knots) or external shocks between the jet and the ambient gas (entrainment). For typical parameter values for protostellar jets, the numerically derived rotation feature looks consistent with the observations, i.e., rotational velocities of 0.1%-1% of the jet bulk velocity.

  16. Propagation of Relativistic, Hydrodynamic, Intermittent Jets in a Rotating, Collapsing GRB Progenitor Star

    NASA Astrophysics Data System (ADS)

    Geng, Jin-Jun; Zhang, Bing; Kuiper, Rolf

    2016-12-01

    The prompt emission of gamma-ray bursts (GRBs) is characterized by rapid variabilities, which may be a direct reflection of the unsteady central engine. We perform a series of axisymmetric 2.5-dimensional simulations to study the propagation of relativistic, hydrodynamic, intermittent jets through the envelope of a GRB progenitor star. A realistic rapidly rotating star is incorporated as the background of jet propagation, and the star is allowed to collapse due to the gravity of the central black hole. By modeling the intermittent jets with constant-luminosity pulses with equal on and off durations, we investigate how the half period, T, affects the jet dynamics. For relatively small T values (e.g., 0.2 s), the jet breakout time t bo depends on the opening angle of the jet, with narrower jets more penetrating and reaching the surface at shorter times. For T ≤ 1 s, the reverse shock (RS) crosses each pulse before the jet penetrates through the stellar envelope. As a result, after the breakout of the first group of pulses at t bo, several subsequent pulses vanish before penetrating the star, causing a quiescent gap. For larger half periods (T = 2.0 and 4.0 s), all the pulses can successfully penetrate through the envelope, since each pulse can propagate through the star before the RS crosses the shell. Our results may interpret the existence of a weak precursor in some long GRBs, given that the GRB central engine injects intermittent pulses with a half period T ≤ 1 s. The observational data seem to be consistent with such a possibility.

  17. Binary Black Holes, Accretion Disks and Relativistic Jets: Photocenters of Nearby AGN and Quasars

    NASA Technical Reports Server (NTRS)

    Wehrle, Ann E.; Jones, Dayton L.; Meier, David L.; Piner, B. Glenn; Unwin, Stephen C.

    2004-01-01

    One of the most challenging questions in astronomy today is to understand the origin, structure, and evolution of the central engines in the nuclei of quasars and active galaxies (AGNs). The favoured theory involves the activation of relativistic jets from the fueling of a supermassive black hole through an accretion disk. In some AGN an outer optically thick, dusty torus is seen orbiting the black hole system. This torus is probably related to an inner accretion disk - black hole system that forms the actual powerhouse of the AGN. In radio-loud AGN two oppositely-directed radio jets are ejected perpendicular to the torus/disk system. Although there is a wealth of observational data on AGN, some very basic questions have not been definitively answered. The Space Interferometry Mission (SIM) will address the following three key questions about AGN. 1) Does the most compact optical emission from an AGN come from an accretion disk or from a relativistic jet? 2) Does the separation of the radio core and optical photocenter of the quasars used for the reference frame tie, change on the timescales of their photometric variability, or is the separation stable at the level of a few microarcseconds? 3) Do the cores of galaxies harbor binary supermassive black holes remaining from galaxy mergers? It is not known whether such mergers are common, and whether binaries would persist for a significant time.

  18. Statistical Effects of Doppler Beaming on Flux Limited Samples of Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Lister, M. L.; Marscher, A. P.

    1996-05-01

    We use Monte Carlo simulations to examine the effects of Doppler beaming on flux-limited samples of compact radio sources representative of relativistic jets found in active galactic nuclei (AGN). The canonical jets in our model have intrinsic (unbeamed) synchrotron luminosities L = Gamma (xi ) l, where the bulk Lorentz factors (Gamma ) of the parent population are distributed according to a power law. Such a relation between the intrinsic synchrotron luminosity and Gamma (with xi < 0) is predicted by relativistic jet models based on hydrodynamics such as that of Blandford & Rees (1974; MNRAS, 169, 395). Studies of Doppler beaming to date have considered only the case where xi = 0 and have not included an intrinsic luminosity function for the parent population. We discuss and compare the predicted apparent velocity, redshift, and flux density distributions of the xi = 0 and xi < 0 models to the combined Pearson & Readhead/Caltech-Jodrell (PR/CJ) survey (Vermeulen 1995, Proc. Natl. Acad. Sci., 92, 11385) of flat-spectrum AGN selected on the basis of 5 GHz flux density. We also examine the effects of the xi parameter and intrinsic Lorentz factor distribution on the viewing angles, Doppler factors, and other observable properties of flux-limited samples of compact radio sources.

  19. LAUNCHING AND QUENCHING OF BLACK HOLE RELATIVISTIC JETS AT LOW ACCRETION RATE

    SciTech Connect

    Pu, Hung-Yi; Chang, Hsiang-Kuang; Hirotani, Kouichi

    2012-10-20

    Relativistic jets are launched from black hole (BH) X-ray binaries and active galactic nuclei when the disk accretion rate is below a certain limit (i.e., when the ratio of the accretion rate to the Eddingtion accretion rate, m-dot , is below about 0.01) but quenched when above. We propose a new paradigm to explain this observed coupling between the jet and the accretion disk by investigating the extraction of the rotational energy of a BH when it is surrounded by different types of accretion disk. At low accretion rates (e.g., when m-dot {approx}<0.1), the accretion near the event horizon is quasi-spherical. The accreting plasmas fall onto the event horizon in a wide range of latitudes, breaking down the force-free approximation near the horizon. To incorporate the plasma inertia effect, we consider the magnetohydrodynamical (MHD) extraction of the rotational energy from BHs by the accreting MHD fluid, as described by the MHD Penrose process. It is found that the energy extraction operates, and hence a relativistic jet is launched, preferentially when the accretion disk consists of an outer Shakura-Sunyaev disk (SSD) and an inner advection-dominated accretion flow. When the entire accretion disk type changes into an SSD, the jet is quenched because the plasmas bring more rest-mass energy than what is extracted from the hole electromagnetically to stop the extraction. Several other issues related to observed BH disk-jet couplings, such as why the radio luminosity increases with increasing X-ray luminosity until the radio emission drops, are also explained.

  20. Magnetized plasma jets in experiment and simulation

    NASA Astrophysics Data System (ADS)

    Schrafel, Peter; Greenly, John; Gourdain, Pierre; Seyler, Charles; Blesener, Kate; Kusse, Bruce

    2013-10-01

    This research focuses on the initial ablation phase of a thing (20 micron) Al foil driven on the 1 MA-in-100 ns COBRA through a 5 mm diameter cathode in a radial configuration. In these experiments, ablated surface plasma (ASP) on the top of the foil and a strongly collimated axial plasma jet can be observed developing midway through current-rise. Our goal is to establish the relationship between the ASP and the jet. These jets are of interest for their potential relevance to astrophysical phenomena. An independently pulsed 200 μF capacitor bank with a Helmholtz coil pair allows for the imposition of a slow (150 μs) and strong (~1 T) axial magnetic field on the experiment. Application of this field eliminates significant azimuthal asymmetry in extreme ultraviolet emission of the ASP. This asymmetry is likely a current filamentation instability. Laser-backlit shadowgraphy and interferometry confirm that the jet-hollowing is correlated with the application of the axial magnetic field. Visible spectroscopic measurements show a doppler shift consistent with an azimuthal velocity in the ASP caused by the applied B-field. Computational simulations with the XMHD code PERSEUS qualitatively agree with the experimental results.

  1. Particle acceleration, magnetization and radiation in relativistic shocks

    NASA Astrophysics Data System (ADS)

    Derishev, Evgeny V.; Piran, Tsvi

    2016-08-01

    The mechanisms of particle acceleration and radiation, as well as magnetic field build-up and decay in relativistic collisionless shocks, are open questions with important implications to various phenomena in high-energy astrophysics. While the Weibel instability is possibly responsible for magnetic field build-up and diffusive shock acceleration is a model for acceleration, both have problems and current particle-in-cell simulations show that particles are accelerated only under special conditions and the magnetic field decays on a very short length-scale. We present here a novel model for the structure and the emission of highly relativistic collisionless shocks. The model takes into account (and is based on) non-local energy and momentum transport across the shock front via emission and absorption of high-energy photons. This leads to a pre-acceleration of the fluid and pre-amplification of the magnetic fields in the upstream region. Both have drastic implications on the shock structure. The model explains the persistence of the shock-generated magnetic field at large distances from the shock front. The dissipation of this magnetic field results in a continuous particle acceleration within the downstream region. A unique feature of the model is the existence of an `attractor', towards which any shock will evolve. The model is applicable to any relativistic shock, but its distinctive features show up only for sufficiently large compactness. We demonstrate that prompt and afterglow gamma-ray bursts' shocks satisfy the relevant conditions, and we compare their observations with the predictions of the model.

  2. Resolving the Geometry of the Innermost Relativistic Jets in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Algaba, J. C.; Nakamura, M.; Asada, K.; Lee, S. S.

    2017-01-01

    In the current paradigm, it is believed that the compact VLBI radio core of radio-loud active galactic nuclei (AGNs) represents the innermost upstream regions of relativistic outflows. These regions of AGN jets have generally been modeled by a conical outflow with a roughly constant opening angle and flow speed. Nonetheless, some works suggest that a parabolic geometry would be more appropriate to fit the high energy spectral distribution properties and it has been recently found that, at least in some nearby radio galaxies, the geometry of the innermost regions of the jet is parabolic. We compile here multi-frequency core sizes of archival data to investigate the typically unresolved upstream regions of the jet geometry of a sample of 56 radio-loud AGNs. Data combined from the sources considered here are not consistent with the classic picture of a conical jet starting in the vicinity of the super-massive black hole (SMBH), and may exclude a pure parabolic outflow solution, but rather suggest an intermediate solution with quasi-parabolic streams, which are frequently seen in numerical simulations. Inspection of the large opening angles near the SMBH and the range of the Lorentz factors derived from our results support our analyses. Our result suggests that the conical jet paradigm in AGNs needs to be re-examined by millimeter/sub-millimeter VLBI observations.

  3. Simulations of Magnetically Driven Astrophysical Jets

    NASA Astrophysics Data System (ADS)

    Gisler, Galen; Barnes, Daniel; Gerwin, Richard; Lovelace, Richard

    1992-12-01

    Bipolar outflows in protostellar objects may be field-line-twisted magnetohydrodynamic jets. A poloidal magnetic field threading a conducting accretion disk is twisted by the rotation of the disk. The resulting magnetic tension in the axial direction drives material perpendicularly away from the disk, carrying energy, mass, and angular momentum away from the inner regions of the system. Detailed analytical calculations of twisted-field outflows exist already, and we present here realistic magnetohydrodynamic simulations of such jets. We use the semi-implicit code FLX, which was developed for magnetic fusion energy applications, in an (r,z) geometry. The boundary representing the disk is set rotating, and an Alfven pulse propagates along the axial direction. Dissipative boundary regions at the other end allow the outflow to exit the computational box unimpeded. The disk rotation may be Keplerian or solid-body, and the poloidal magnetic field may be either uniform or a distributed dipole. These are the first jet simulations done without specifying an axial velocity as a boundary condition. The axial velocity is determined by the rotation of the disk and the strength of the magnetic field, and the values achieved are in agreement with velocities observed in outflows from protostellar objects. Over much of the simulation domain the component of the current parallel to the magnetic field dominates over the perpendicular current, indicating that the system is evolving toward a helical force-free configuration. Even in the distributed dipole diverging field, the outflow remains fairly well collimated out to hundreds of stellar radii.

  4. TWO-FLUID MAGNETOHYDRODYNAMIC SIMULATIONS OF RELATIVISTIC MAGNETIC RECONNECTION

    SciTech Connect

    Zenitani, Seiji; Hesse, Michael; Klimas, Alex

    2009-05-10

    We investigate the large-scale evolution of a relativistic magnetic reconnection in an electron-positron pair plasma by a relativistic two-fluid magnetohydrodynamic (MHD) code. We introduce an interspecies friction force as an effective resistivity to dissipate magnetic fields. We demonstrate that magnetic reconnection successfully occurs in our two-fluid system, and that it involves Petschek-type bifurcated current layers in a later stage. We further observe a quasi-steady evolution thanks to an open boundary condition, and find that the Petschek-type structure is stable over the long time period. Simulation results and theoretical analyses exhibit that the Petschek outflow channel becomes narrower when the reconnection inflow contains more magnetic energy, as previously claimed. Meanwhile, we find that the reconnection rate goes up to {approx}1 in extreme cases, which is faster than previously thought. The role of the resistivity, implications for reconnection models in the magnetically dominated limit, and relevance to kinetic reconnection works are discussed.

  5. Baryons in the relativistic jets of the stellar-mass black-hole candidate 4U 1630-47.

    PubMed

    Trigo, María Díaz; Miller-Jones, James C A; Migliari, Simone; Broderick, Jess W; Tzioumis, Tasso

    2013-12-12

    Accreting black holes are known to power relativistic jets, both in stellar-mass binary systems and at the centres of galaxies. The power carried away by the jets, and, hence, the feedback they provide to their surroundings, depends strongly on their composition. Jets containing a baryonic component should carry significantly more energy than electron-positron jets. Energetic considerations and circular-polarization measurements have provided conflicting circumstantial evidence for the presence or absence of baryons in jets, and the only system in which they have been unequivocally detected is the peculiar X-ray binary SS 433 (refs 4, 5). Here we report the detection of Doppler-shifted X-ray emission lines from a more typical black-hole candidate X-ray binary, 4U 1630-47, coincident with the reappearance of radio emission from the jets of the source. We argue that these lines arise from baryonic matter in a jet travelling at approximately two-thirds the speed of light, thereby establishing the presence of baryons in the jet. Such baryonic jets are more likely to be powered by the accretion disk than by the spin of the black hole, and if the baryons can be accelerated to relativistic speeds, the jets should be strong sources of γ-rays and neutrino emission.

  6. HYDJET++ for ultra-relativistic HIC’s: A hot cocktail of hydrodynamics, resonances and jets

    SciTech Connect

    Bravina, L. V.; Johansson, B. H. Brusheim; Crkovska, J.; Eyyubova, G. Kh.; Korotkikh, V. L.; Lokhtin, I. P.; Petrushanko, S. V.; Snigirev, A. M.; Malinina, L. V.; Zabrodin, E. E.

    2016-01-22

    An ultra-relativistic heavy-ion collision at LHC energies is a mixture of soft and hard processes. For comparison with data we employ the HYDJET++ model, which combines the description of soft processes with the treatment of hard partons propagating hot and dense nuclear medium. Importance of the interplay of ideal hydrodynamics, final state interactions and jets for the description of harmonics of the anisotropic flow is discussed. Jets are found to be the main source of violation of the number-of-constituent-quark (NCQ) scaling at LHC energies. Many features of higher flow harmonics and dihadron angular correlations, including ridge, can be described by the interference of elliptic and triangular flows.

  7. Relativistic jet meets target - The gamma-rays from 3C 273

    NASA Technical Reports Server (NTRS)

    Morrison, P.; Sadun, A.; Roberts, D.

    1984-01-01

    Gamma-rays dominate the emission from quasar 3C 273, although they cannot arise in its active center. Their origin is ascribed to a relativistic beam which entrains and clumps ambient cluster gas. Secondary electrons from nuclear collisions lead to bremsstrahlung gamma-rays and ultimately to a double radio source. This model requires a great deal of clumping of jet and target matter to get sufficient reactions to occur. The clumping required is consistent with the Liouville theorem, given the high collimation of the beam, which suggests that the process, however unexpected, is at least thermodynamically permitted. The present model is experimentally distinguishable from other models through its location of the X-ray source in the extended optical jet region, and through a number of detailed spectral features.

  8. Magnetized laboratory plasma jets: experiment and simulation.

    PubMed

    Schrafel, Peter; Bell, Kate; Greenly, John; Seyler, Charles; Kusse, Bruce

    2015-01-01

    Experiments involving radial foils on a 1 MA, 100 ns current driver can be used to study the ablation of thin foils and liners, produce extreme conditions relevant to laboratory astrophysics, and aid in computational code validation. This research focuses on the initial ablation phase of a 20 μm Al foil (8111 alloy), in a radial configuration, driven by Cornell University's COBRA pulsed power generator. In these experiments ablated surface plasma (ASP) on the top side of the foil and a strongly collimated axial plasma jet are observed developing midway through the current rise. With experimental and computational results this work gives a detailed description of the role of the ASP in the formation of the plasma jet with and without an applied axial magnetic field. This ∼1 T field is applied by a Helmholtz-coil pair driven by a slow, 150 μs current pulse and penetrates the load hardware before arrival of the COBRA pulse. Several effects of the applied magnetic field are observed: (1) without the field extreme-ultraviolet emission from the ASP shows considerable azimuthal asymmetry while with the field the ASP develops azimuthal motion that reduces this asymmetry, (2) this azimuthal motion slows the development of the jet when the field is applied, and (3) with the magnetic field the jet becomes less collimated and has a density minimum (hollowing) on the axis. PERSEUS, an XMHD code, has qualitatively and quantitatively reproduced all these experimental observations. The differences between this XMHD and an MHD code without a Hall current and inertial effects are discussed. In addition the PERSEUS results describe effects we were not able to resolve experimentally and suggest a line of future experiments with better diagnostics.

  9. On the structure and stability of magnetic tower jets

    SciTech Connect

    Huarte-Espinosa, M.; Frank, A.; Blackman, E. G.; Ciardi, A.; Hartigan, P.; Lebedev, S. V.; Chittenden, J. P.

    2012-09-05

    Modern theoretical models of astrophysical jets combine accretion, rotation, and magnetic fields to launch and collimate supersonic flows from a central source. Near the source, magnetic field strengths must be large enough to collimate the jet requiring that the Poynting flux exceeds the kinetic energy flux. The extent to which the Poynting flux dominates kinetic energy flux at large distances from the engine distinguishes two classes of models. In magneto-centrifugal launch models, magnetic fields dominate only at scales <~ 100 engine radii, after which the jets become hydrodynamically dominated (HD). By contrast, in Poynting flux dominated (PFD) magnetic tower models, the field dominates even out to much larger scales. To compare the large distance propagation differences of these two paradigms, we perform three-dimensional ideal magnetohydrodynamic adaptive mesh refinement simulations of both HD and PFD stellar jets formed via the same energy flux. We also compare how thermal energy losses and rotation of the jet base affects the stability in these jets. For the conditions described, we show that PFD and HD exhibit observationally distinguishable features: PFD jets are lighter, slower, and less stable than HD jets. Here, unlike HD jets, PFD jets develop current-driven instabilities that are exacerbated as cooling and rotation increase, resulting in jets that are clumpier than those in the HD limit. Our PFD jet simulations also resemble the magnetic towers that have been recently created in laboratory astrophysical jet experiments.

  10. On the structure and stability of magnetic tower jets

    DOE PAGES

    Huarte-Espinosa, M.; Frank, A.; Blackman, E. G.; ...

    2012-09-05

    Modern theoretical models of astrophysical jets combine accretion, rotation, and magnetic fields to launch and collimate supersonic flows from a central source. Near the source, magnetic field strengths must be large enough to collimate the jet requiring that the Poynting flux exceeds the kinetic energy flux. The extent to which the Poynting flux dominates kinetic energy flux at large distances from the engine distinguishes two classes of models. In magneto-centrifugal launch models, magnetic fields dominate only at scales <~ 100 engine radii, after which the jets become hydrodynamically dominated (HD). By contrast, in Poynting flux dominated (PFD) magnetic tower models,more » the field dominates even out to much larger scales. To compare the large distance propagation differences of these two paradigms, we perform three-dimensional ideal magnetohydrodynamic adaptive mesh refinement simulations of both HD and PFD stellar jets formed via the same energy flux. We also compare how thermal energy losses and rotation of the jet base affects the stability in these jets. For the conditions described, we show that PFD and HD exhibit observationally distinguishable features: PFD jets are lighter, slower, and less stable than HD jets. Here, unlike HD jets, PFD jets develop current-driven instabilities that are exacerbated as cooling and rotation increase, resulting in jets that are clumpier than those in the HD limit. Our PFD jet simulations also resemble the magnetic towers that have been recently created in laboratory astrophysical jet experiments.« less

  11. Different Paths to Some Fundamental Physical Laws: Relativistic Polarization of a Moving Magnetic Dipole

    ERIC Educational Resources Information Center

    Kholmetskii, Alexander L.; Yarman, T.

    2010-01-01

    In this paper we consider the relativistic polarization of a moving magnetic dipole and show that this effect can be understood via the relativistic generalization of Kirchhoff's first law to a moving closed circuit with a steady current. This approach allows us to better understand the law of relativistic transformation of four-current density…

  12. Different Paths to Some Fundamental Physical Laws: Relativistic Polarization of a Moving Magnetic Dipole

    ERIC Educational Resources Information Center

    Kholmetskii, Alexander L.; Yarman, T.

    2010-01-01

    In this paper we consider the relativistic polarization of a moving magnetic dipole and show that this effect can be understood via the relativistic generalization of Kirchhoff's first law to a moving closed circuit with a steady current. This approach allows us to better understand the law of relativistic transformation of four-current density…

  13. Relativistic Electron Enhancements at GEO: Magnetic Storms vs. Substorms

    NASA Astrophysics Data System (ADS)

    Lyons, L. R.; Kim, H. J.; Pinto, V. A.; Wang, C. P.; Kim, K. C.

    2015-12-01

    We find evidence that magnetic storms are not only unnecessary for relativistic electron enhancements at geosynchronous orbit (GEO) but also not directly relevant to the electron enhancements at GEO even if the enhancements are accompanied by magnetic storms. What is crucial for electron enhancements at GEO are sustained south-oriented or north-south fluctuating IMF Bz that drives sufficiently large substorm activity and small solar wind density Nsw that likely leads to low loss rate of relativistic electrons to the ionosphere and/or to the magnetopause for an extended time period. Specifically, almost all the abrupt, large electron increases in our data set took place under the condition of average AE > 235 nT and average Nsw ≤ 5 cm-3. Examination of detailed time profiles clearly shows that electron flux at GEO starts to increase quite immediately with arrival of the right IMF and solar wind conditions, regardless of a magnetic storm, leaving the accompanied magnetic storms merely co-incident, while the prolonged, intense substorms are critical.

  14. TWO-DIMENSIONAL NUMERICAL STUDY FOR RAYLEIGH-TAYLOR AND RICHTMYER-MESHKOV INSTABILITIES IN RELATIVISTIC JETS

    SciTech Connect

    Matsumoto, Jin; Masada, Youhei

    2013-07-20

    We study the stability of a non-rotating single-component jet using two-dimensional special relativistic hydrodynamic simulations. By assuming translational invariance along the jet axis, we exclude the destabilization effect by Kelvin-Helmholtz mode. The nonlinear evolution of the transverse structure of the jet with a normal jet velocity is highlighted. An intriguing finding in our study is that Rayleigh-Taylor and Richtmyer-Meshkov type instabilities can destroy cylindrical jet configuration as a result of spontaneously induced radial oscillating motion. This is powered by in situ energy conversion between the thermal and bulk kinetic energies. The effective inertia ratio of the jet to the surrounding medium {eta} determines a threshold for the onset of instabilities. The condition {eta} < 1 should be satisfied for the transverse structure of the jet being persisted.

  15. Estimate of the maximum induced magnetic field in relativistic shocks

    NASA Astrophysics Data System (ADS)

    Ghorbanalilu, M.; Sadegzadeh, S.

    2017-01-01

    The proton-driven Weibel instability is a crucial process for amplifying the generated magnetic fields in gamma-ray bursts. An expression for the saturation level of magnetic fields is estimated in a relativistic shock consisting of electron-proton plasmas. Within the shock transition layer, the plasma is modelled with the waterbag and Maxwell-Jüttner distribution functions for asymmetric counter-propagating proton beams and isotropic background electrons, respectively. The proton-driven Weibel-type instability in the linear phase is investigated thoroughly and then the instability conditions and the stabilization mechanisms are considered in details just after the shutdown of the electron Weibel instability. The growth rate of the instability and the saturated magnetic field strength are obtained in terms of the effective proton beam Mach number, asymmetry parameter, and the background electron temperature. In this paper, fully relativistic kinetic treatment is used to formulate the dispersion relation for the proton Weibel-type instability. Then, by using the magnetic trapping criteria, the saturated magnetic field strength is computed. In the present scenario, the instability includes two stages: in the first stage the electron Weibel instability evolves very rapidly, but in the second one because of the free energy stored in the slow counter-propagating proton beams, the instability is further amplified in the context of electrons with an isotropic distribution function. Increment of the growth rate and saturated magnetic field by increasing (decreasing) the effective proton beam Mach number (the asymmetry parameter) is deduced from the results. It is shown that at the temperatures around 108 K a maximum magnetic field up to around 56 G can be detected by this mechanism after the saturation time.

  16. Nonthermal Particle Acceleration in 3D Relativistic Magnetic Reconnection in Pair Plasma

    NASA Astrophysics Data System (ADS)

    Werner, Gregory R.; Uzdensky, Dmitri A.

    2017-07-01

    As a fundamental process converting magnetic to plasma energy in high-energy astrophysical plasmas, relativistic magnetic reconnection is a leading explanation for the acceleration of particles to the ultrarelativistic energies that are necessary to power nonthermal emission (especially X-rays and gamma-rays) in pulsar magnetospheres and pulsar wind nebulae, coronae and jets of accreting black holes, and gamma-ray bursts. An important objective of plasma astrophysics is therefore the characterization of nonthermal particle acceleration (NTPA) effected by reconnection. Reconnection-powered NTPA has been demonstrated over a wide range of physical conditions using large 2D kinetic simulations. However, its robustness in realistic 3D reconnection—in particular, whether the 3D relativistic drift-kink instability (RDKI) disrupts NTPA—has not been systematically investigated, although pioneering 3D simulations have observed NTPA in isolated cases. Here, we present the first comprehensive study of NTPA in 3D relativistic reconnection in collisionless electron-positron plasmas, characterizing NTPA as the strength of 3D effects is varied systematically via the length in the third dimension and the strength of the guide magnetic field. We find that, while the RDKI prominently perturbs 3D reconnecting current sheets, it does not suppress particle acceleration, even for zero guide field; fully 3D reconnection robustly and efficiently produces nonthermal power-law particle spectra closely resembling those obtained in 2D. This finding provides strong support for reconnection as the key mechanism powering high-energy flares in various astrophysical systems. We also show that strong guide fields significantly inhibit NTPA, slowing reconnection and limiting the energy available for plasma energization, yielding steeper and shorter power-law spectra.

  17. Non-thermal emission from standing relativistic shocks: an application to red giant winds interacting with AGN jets

    NASA Astrophysics Data System (ADS)

    Bosch-Ramon, V.

    2015-03-01

    Context. Galactic and extragalactic relativistic jets are surrounded by rich environments that are full of moving objects, such as stars and dense medium inhomogeneities. These objects can enter into the jets and generate shocks and non-thermal emission. Aims: We characterize the emitting properties of the downstream region of a standing shock formed due to the interaction of a relativistic jet with an obstacle. We focus on the case of red giants interacting with an extragalactic jet. Methods: We perform relativistic axisymmetric hydrodynamical simulations of a relativistic jet meeting an obstacle of very large inertia. The results are interpreted in the framework of a red giant whose dense and slow wind interacts with the jet of an active galactic nucleus. Assuming that particles are accelerated in the standing shock generated in the jet as it impacts the red giant wind, we compute the non-thermal particle distribution, the Doppler boosting enhancement, and the non-thermal luminosity in gamma rays. Results: The available non-thermal energy from jet-obstacle interactions is potentially enhanced by a factor of ~100 when accounting for the whole surface of the shock induced by the obstacle, instead of just the obstacle section. The observer gamma-ray luminosity, including the effective obstacle size, the flow velocity and Doppler boosting effects, can be ~300 (γj/10)2 times higher than when the emitting flow is assumed at rest and only the obstacle section is considered, where γj is the jet Lorentz factor. For a whole population of red giants inside the jet of an active galactic nucleus, the predicted persistent gamma-ray luminosities may be potentially detectable for a jet pointing approximately to the observer. Conclusions: Obstacles interacting with relativistic outflows, for instance clouds and populations of stars for extragalactic jets, or stellar wind inhomogeneities in microquasar jets and in winds of pulsars in binaries, should be taken into account when

  18. The magnet system of the Relativistic Heavy Ion Collider (RHIC)

    SciTech Connect

    Greene, A.; Anerella, M.; Cozzolino, J.

    1995-07-01

    The Relativistic Heavy Ion Collider now under construction at Brookhaven National Laboratory (BNL) is a colliding ring accelerator to be completed in 1999. Through collisions of heavy ions it is hoped to observe the creation of matter at extremely high temperatures and densities, similar to what may have occurred in the original ``Big Bang.`` The collider rings will consist of 1740 superconducting magnet elements. Some of elements are being manufactured by industrial partners (Northrop Grumman and Everson Electric). Others are being constructed or assembled at BNL. A description is given of the magnet designs, the plan for manufacturing and test results. In the manufacturing of the magnets, emphasis has been placed on uniformity of their performance and on quality. Results so far indicate that this emphasis has been very successful.

  19. Relativistic Killingbeck energy states under external magnetic fields

    NASA Astrophysics Data System (ADS)

    Eshghi, M.; Mehraban, H.; Ikhdair, S. M.

    2016-07-01

    We address the behavior of the Dirac equation with the Killingbeck radial potential including the external magnetic and Aharonov-Bohm (AB) flux fields. The spin and pseudo-spin symmetries are considered. The correct bound state spectra and their corresponding wave functions are obtained. We seek such a solution using the biconfluent Heun's differential equation method. Further, we give some of our results at the end of this study. Our final results can be reduced to their non-relativistic forms by simply using some appropriate transformations. The spectra, in the spin and pseudo-spin symmetries, are very similar with a slight difference in energy spacing between different states.

  20. Relativistic electron precipitation during magnetic storm main phase

    NASA Technical Reports Server (NTRS)

    Thorne, R. M.; Kennel, C. F.

    1970-01-01

    Relativistic electrons can have cyclotron resonances with electromagnetic cyclotron waves. The resonant energy is generally well above 1 MeV throughout the magnetosphere, but it can fall to 1 MeV just within the plasmapause. This also corresponds to the region where ring current (10 to 50 keV) protons are expected to be strongly unstable. The resulting ion cyclotron wave amplitudes necessary to precipitate ring current protons leads to electron lifetimes near the strong diffusion limit ( 100 sec). Thus, 1 MeV electrons whose drift orbits intersect the stormtime plasmapause should rapidly be precipitated in the region 3 L 5 during the initial phase of a magnetic storm.

  1. Parametric decays in relativistic magnetized electron-positron plasmas with relativistic temperatures

    SciTech Connect

    Lopez, Rodrigo A.; Munoz, Victor; Asenjo, Felipe A.; Alejandro Valdivia, J.

    2012-08-15

    The nonlinear evolution of a circularly polarized electromagnetic wave in an electron-positron plasma propagating along a constant background magnetic field is considered, by studying its parametric decays. Relativistic effects, of the particle motion in the wave field and of the plasma temperature, are included to obtain the dispersion relation of the decays. The exact dispersion relation of the pump wave has been previously calculated within the context of a relativistic fluid theory and presents two branches: an electromagnetic and an Alfven one. We investigate the parametric decays for the pump wave in these two branches, including the anomalous dispersion zone of the Alfven branch where the group velocity is negative. We solve the nonlinear dispersion relation for different pump wave amplitudes and plasma temperatures, finding various resonant and nonresonant wave couplings. We are able to identify these couplings and study their behavior as we modify the plasma parameters. Some of these couplings are suppressed for larger amplitudes or temperatures. We also find two kinds of modulational instabilities, one involving two sideband daughter waves and another involving a forward-propagating electroacoustic mode and a sideband daughter wave.

  2. Beaming of Particles and Synchrotron Radiation in Relativistic Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Kagan, Daniel; Nakar, Ehud; Piran, Tsvi

    2016-08-01

    Relativistic reconnection has been invoked as a mechanism for particle acceleration in numerous astrophysical systems. According to idealized analytical models, reconnection produces a bulk relativistic outflow emerging from the reconnection sites (X-points). The resulting radiation is therefore highly beamed. Using two-dimensional particle-in-cell simulations, we investigate particle and radiation beaming, finding a very different picture. Instead of having a relativistic average bulk motion with an isotropic electron velocity distribution in its rest frame, we find that the bulk motion of the particles in X-points is similar to their Lorentz factor γ, and the particles are beamed within ˜ 5/γ . On the way from the X-point to the magnetic islands, particles turn in the magnetic field, forming a fan confined to the current sheet. Once they reach the islands they isotropize after completing a full Larmor gyration and their radiation is no longer strongly beamed. The radiation pattern at a given frequency depends on where the corresponding emitting electrons radiate their energy. Lower-energy particles that cool slowly spend most of their time in the islands and their radiation is not highly beamed. Only particles that quickly cool at the edge of the X-points generate a highly beamed fan-like radiation pattern. The radiation emerging from these fast cooling particles is above the burn-off limit (˜100 MeV in the overall rest frame of the reconnecting plasma). This has significant implications for models of gamma-ray bursts and active galactic nuclei that invoke beaming in that frame at much lower energies.

  3. V404 Cyg with NuSTAR: relativistic reflection, jets and spin

    NASA Astrophysics Data System (ADS)

    Walton, Dom; Mooley, Kunal

    2017-08-01

    In summer 2015 the Galactic LMXB V404 Cyg, one of the closest known black hole binary systems, went through its first major outburst in ~25 years, triggering a massive multiwavelength monitoring campaign to cover this remarkable event. In this talk, I will discuss results from the NuSTAR contribution to this campaign, focusing in particular on the data obtained during the height of the outburst activity. These data reveal a variety of extreme behaviour, from intense ~Eddington level flares to strong relativistic reflection. The contemporaneous onset of radio emission strongly suggests that this X-ray flaring is related to jet activity, with the ejected plasma/ base of the jet becoming the source of illumination of the disc. We are able to use the reflection observed to place constraints on the system geometry during these events, finding that the X-ray emitting regions in the jet are located very close to the black hole. In addition, our reflection analysis also allows us to place the first constraints on the black hole spin, and we find that V404 Cyg likely hosts a rapidly rotating black hole.

  4. Lorentz Factor Evolution Patterns within Relativistic Jets of GRBs and AGNs

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Ming; Lin, Da-Bin; Lin, Ting-Ting; Liu, Bao-Rong; Huang, Xiao-Li; Zhong, Shu-Qing; Lu, Rui-Jing; Liang, En-Wei

    The Lorentz factor (Γ) is an important parameter related to the relativistic jet physics. We study the evolution patterns of Γ within gamma-ray burst (GRB) and active galactic nuclear jets for individual GRB 090168, GRB 140508A, and 3C 454.3. By estimating the Γ values for well-separated pulses in GRBs 090618 and 140508A with an empirical relation derived from typical GRBs, we find that the Γ evolution pattern in the two GRBs are different. The increasing-to-coasting evolution pattern of Γ in GRB 090618 likely indicates that the GRB fireball is still being accelerated in the prompt phase. The clear decrease evolution pattern of Γ in GRB 140508A suggests the deceleration of the fireball components. By deriving the Γ value through fitting their spectral energy distribution in different flares of 3C 454.3, a pattern of Γ-tracking-γ-ray flux is clearly found, likely indicating that the observed gamma-ray flares are being due to the Doppler boosting effect to the jet emission.

  5. Search for relativistic magnetic monopoles with the ANTARES neutrino telescope

    NASA Astrophysics Data System (ADS)

    Adrián-Martínez, S.; Aguilar, J. A.; Al Samarai, I.; Albert, A.; André, M.; Anghinolfi, M.; Anton, G.; Anvar, S.; Ardid, M.; Assis Jesus, A. C.; Astraatmadja, T.; Aubert, J.-J.; Baret, B.; Basa, S.; Bertin, V.; Biagi, S.; Bigongiari, C.; Bogazzi, C.; Bou-Cabo, M.; Bouhou, B.; Bouwhuis, M. C.; Brunner, J.; Busto, J.; Camarena, F.; Capone, A.; Cârloganu, C.; Carminati, G.; Carr, J.; Cecchini, S.; Charif, Z.; Charvis, Ph.; Chiarusi, T.; Circella, M.; Costantini, H.; Coyle, P.; Curtil, C.; Decowski, M. P.; Dekeyser, I.; Deschamps, A.; Distefano, C.; Donzaud, C.; Dornic, D.; Dorosti, Q.; Drouhin, D.; Eberl, T.; Emanuele, U.; Enzenhöfer, A.; Ernenwein, J.-P.; Escoffier, S.; Fermani, P.; Ferri, M.; Flaminio, V.; Folger, F.; Fritsch, U.; Fuda, J.-L.; Galatà, S.; Gay, P.; Giacomelli, G.; Giordano, V.; Gómez-González, J. P.; Graf, K.; Guillard, G.; Halladjian, G.; Hallewell, G.; van Haren, H.; Hartman, J.; Heijboer, A. J.; Hello, Y.; Hernández-Rey, J. J.; Herold, B.; Hößl, J.; Hsu, C. C.; de Jong, M.; Kadler, M.; Kalekin, O.; Kappes, A.; Katz, U.; Kavatsyuk, O.; Kooijman, P.; Kopper, C.; Kouchner, A.; Kreykenbohm, I.; Kulikovskiy, V.; Lahmann, R.; Lamare, P.; Larosa, G.; Lattuada, D.; Lefèvre, D.; Lim, G.; Lo Presti, D.; Loehner, H.; Loucatos, S.; Mangano, S.; Marcelin, M.; Margiotta, A.; Martínez-Mora, J. A.; Meli, A.; Montaruli, T.; Morganti, M.; Moscoso, L.; Motz, H.; Neff, M.; Nezri, E.; Palioselitis, D.; Păvălaş, G. E.; Payet, K.; Payre, P.; Petrovic, J.; Piattelli, P.; Picot-Clemente, N.; Popa, V.; Pradier, T.; Presani, E.; Racca, C.; Reed, C.; Riccobene, G.; Richardt, C.; Richter, R.; Rivière, C.; Robert, A.; Roensch, K.; Rostovtsev, A.; Ruiz-Rivas, J.; Rujoiu, M.; Russo, G. V.; Salesa, F.; Sapienza, P.; Schöck, F.; Schuller, J.-P.; Schüssler, F.; Seitz, T.; Shanidze, R.; Simeone, F.; Spies, A.; Spurio, M.; Steijger, J. J. M.; Stolarczyk, Th.; Sánchez-Losa, A.; Taiuti, M.; Tamburini, C.; Toscano, S.; Vallage, B.; Van Elewyck, V.; Vannoni, G.; Vecchi, M.; Vernin, P.; Wagner, S.; Wijnker, G.; Wilms, J.; de Wolf, E.; Yepes, H.; Zaborov, D.; Zornoza, J. D.; Zúñiga, J.

    2012-05-01

    Magnetic monopoles are predicted in various unified gauge models and could be produced at intermediate mass scales. Their detection in a neutrino telescope is facilitated by the large amount of light emitted compared to that from muons. This paper reports on a search for upgoing relativistic magnetic monopoles with the ANTARES neutrino telescope using a data set of 116 days of live time taken from December 2007 to December 2008. The one observed event is consistent with the expected atmospheric neutrino and muon background, leading to a 90% C.L. upper limit on the monopole flux between 1.3 × 10-17 and 8.9 × 10-17 cm-2 s-1 sr-1 for monopoles with velocity β ⩾ 0.625.

  6. The role of magnetic reconnection on jet/accretion disk systems

    NASA Astrophysics Data System (ADS)

    de Gouveia Dal Pino, E. M.; Piovezan, P. P.; Kadowaki, L. H. S.

    2010-07-01

    Context. It was proposed earlier that the relativistic ejections observed in microquasars could be produced by violent magnetic reconnection episodes at the inner disk coronal region (de Gouveia Dal Pino & Lazarian 2005). Aims: Here we revisit this model, which employs a standard accretion disk description and fast magnetic reconnection theory, and discuss the role of magnetic reconnection and associated heating and particle acceleration in different jet/disk accretion systems, namely young stellar objects (YSOs), microquasars, and active galactic nuclei (AGNs). Methods: In microquasars and AGNs, violent reconnection episodes between the magnetic field lines of the inner disk region and those that are anchored in the black hole are able to heat the coronal/disk gas and accelerate the plasma to relativistic velocities through a diffusive first-order Fermi-like process within the reconnection site that will produce intermittent relativistic ejections or plasmons. Results: The resulting power-law electron distribution is compatible with the synchrotron radio spectrum observed during the outbursts of these sources. A diagram of the magnetic energy rate released by violent reconnection as a function of the black hole (BH) mass spanning 109 orders of magnitude shows that the magnetic reconnection power is more than sufficient to explain the observed radio luminosities of the outbursts from microquasars to low luminous AGNs. In addition, the magnetic reconnection events cause the heating of the coronal gas, which can be conducted back to the disk to enhance its thermal soft X-ray emission as observed during outbursts in microquasars. The decay of the hard X-ray emission right after a radio flare could also be explained in this model due to the escape of relativistic electrons with the evolving jet outburst. In the case of YSOs a similar magnetic configuration can be reached that could possibly produce observed X-ray flares in some sources and provide the heating at the

  7. DISCOVERY OF SUB- TO SUPERLUMINAL MOTIONS IN THE M87 JET: AN IMPLICATION OF ACCELERATION FROM SUB-RELATIVISTIC TO RELATIVISTIC SPEEDS

    SciTech Connect

    Asada, Keiichi; Nakamura, Masanori; Inoue, Makoto; Doi, Akihiro; Nagai, Hiroshi E-mail: nakamura@asiaa.sinica.edu.tw

    2014-01-20

    The velocity field of the M87 jet from milli-arcsecond (mas) to arcsecond scales is extensively investigated together with new radio images taken from European VLBI Network (EVN) observations. We detected proper motions of components located at between 160 mas from the core and the HST-1 complex for the first time. Newly derived velocity fields exhibit a systematic increase from sub- to superluminal speeds in the upstream of HST-1. If we assume that the observed velocities reflect the bulk flow, here we suggest that the M87 jet may be gradually accelerated through a distance of 10{sup 6} times the Schwarzschild radius of the supermassive black hole. The acceleration zone is co-spatial with the jet parabolic region, which is interpreted as the collimation zone of the jet. The acceleration and collimation take place simultaneously, which we suggest is characteristic of magnetohydrodynamic flows. The distribution of the velocity field has a peak at HST-1, which is considered as the site of over-collimation, and shows a deceleration downstream of HST-1 where the jet is conical. Our interpretation of the velocity map in the M87 jet provides a hypothesis for active galactic nuclei which suggests that the acceleration and collimation zone of relativistic jets extends over the whole scale within the sphere of influence of the supermassive black hole.

  8. Probing transverse momentum broadening via dihadron and hadron-jet angular correlations in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Chen, Lin; Qin, Guang-You; Wei, Shu-Yi; Xiao, Bo-Wen; Zhang, Han-Zhong

    2017-10-01

    Dijet, dihadron, hadron-jet angular correlations have been reckoned as important probes of the transverse momentum broadening effects in relativistic nuclear collisions. When a pair of high-energy jets created in hard collisions traverse the quark-gluon plasma produced in heavy-ion collisions, they become de-correlated due to the vacuum soft gluon radiation associated with the Sudakov logarithms and the medium-induced transverse momentum broadening. For the first time, we employ the systematical resummation formalism and establish a baseline calculation to describe the dihadron and hadron-jet angular correlation data in pp and peripheral AA collisions where the medium effect is negligible. We demonstrate that the medium-induced broadening 〈 p⊥2 〉 and the so-called jet quenching parameter q ˆ can be extracted from the angular de-correlations observed in AA collisions. A global χ2 analysis of dihadron and hadron-jet angular correlation data renders 〈p⊥ 2 〉 ∼13-4+5 GeV2 for a quark jet at RHIC top energy. Further experimental and theoretical efforts along the direction of this work shall significantly advance the quantitative understanding of transverse momentum broadening and help us acquire unprecedented knowledge of jet quenching parameter in relativistic heavy-ion collisions.

  9. Nine Years of Observations of Hard X-Rays from Relativistic Jet Objects with BATSE

    NASA Technical Reports Server (NTRS)

    Fishman, G. J.; Harmon, B. A.; Fishman, G. J.; Six, N. Frank (Technical Monitor)

    2002-01-01

    The observed hard X-ray temporal and spectral characteristics will be displayed for over nine years of BATSE (Burst and Transient Source Experiment) data from the Compton Observatory. These observations were obtained using the Earth occultation technique, a technique that has become increasingly more sensitive and accurate as systematic effects are understood and corrected. The principal objects that are being presented in this study include: GRO J1655-40, GRS 1915+105, Cyg X-3, Cyg X-1, XTE J1550-564, XTE J1859+226, XTE J1748-288, and V4641 Sgr. Light curves and spectral will be presented and discussed in terms of relativistic jet production in these systems.

  10. A possible relativistic jetted outburst from a massive black hole fed by a tidally disrupted star.

    PubMed

    Bloom, Joshua S; Giannios, Dimitrios; Metzger, Brian D; Cenko, S Bradley; Perley, Daniel A; Butler, Nathaniel R; Tanvir, Nial R; Levan, Andrew J; O'Brien, Paul T; Strubbe, Linda E; De Colle, Fabio; Ramirez-Ruiz, Enrico; Lee, William H; Nayakshin, Sergei; Quataert, Eliot; King, Andrew R; Cucchiara, Antonino; Guillochon, James; Bower, Geoffrey C; Fruchter, Andrew S; Morgan, Adam N; van der Horst, Alexander J

    2011-07-08

    Gas accretion onto some massive black holes (MBHs) at the centers of galaxies actively powers luminous emission, but most MBHs are considered dormant. Occasionally, a star passing too near an MBH is torn apart by gravitational forces, leading to a bright tidal disruption flare (TDF). Although the high-energy transient Sw 1644+57 initially displayed none of the theoretically anticipated (nor previously observed) TDF characteristics, we show that observations suggest a sudden accretion event onto a central MBH of mass about 10(6) to 10(7) solar masses. There is evidence for a mildly relativistic outflow, jet collimation, and a spectrum characterized by synchrotron and inverse Compton processes; this leads to a natural analogy of Sw 1644+57 to a temporary smaller-scale blazar.

  11. Rotating and binary relativistic stars with magnetic field

    NASA Astrophysics Data System (ADS)

    Markakis, Charalampos

    We develop a geometrical treatment of general relativistic magnetohydrodynamics for perfectly conducting fluids in Einstein--Maxwell--Euler spacetimes. The theory is applied to describe a neutron star that is rotating or is orbiting a black hole or another neutron star. Under the hypotheses of stationarity and axisymmetry, we obtain the equations governing magnetohydrodynamic equilibria of rotating neutron stars with poloidal, toroidal or mixed magnetic fields. Under the hypothesis of an approximate helical symmetry, we obtain the first law of thermodynamics governing magnetized equilibria of double neutron star or black hole - neutron star systems in close circular orbits. The first law is written as a relation between the change in the asymptotic Noether charge deltaQ and the changes in the area and electric charge of black holes, and in the vorticity, baryon rest mass, entropy, charge and magnetic flux of the magnetofluid. In an attempt to provide a better theoretical understanding of the methods used to construct models of isolated rotating stars and corotating or irrotational binaries and their unexplained convergence properties, we analytically examine the behavior of different iterative schemes near a static solution. We find the spectrum of the linearized iteration operator and show for self-consistent field methods that iterative instability corresponds to unstable modes of this operator. On the other hand, we show that the success of iteratively stable methods is due to (quasi-)nilpotency of this operator. Finally, we examine the integrability of motion of test particles in a stationary axisymmetric gravitational field. We use a direct approach to seek nontrivial constants of motion polynomial in the momenta---in addition to energy and angular momentum about the symmetry axis. We establish the existence and uniqueness of quadratic constants and the nonexistence of quartic constants for stationary axisymmetric Newtonian potentials with equatorial symmetry

  12. Towards Observational Astronomy of Jets in Active Galaxies from General Relativistic Magnetohydrodynamic Simulations

    NASA Astrophysics Data System (ADS)

    Anantua, Richard; Roger Blandford, Jonathan McKinney and Alexander Tchekhovskoy

    2016-01-01

    We carry out the process of "observing" simulations of active galactic nuclei (AGN) with relativistic jets (hereafter called jet/accretion disk/black hole (JAB) systems) from ray tracing between image plane and source to convolving the resulting images with a point spread function. Images are generated at arbitrary observer angle relative to the black hole spin axis by implementing spatial and temporal interpolation of conserved magnetohydrodynamic flow quantities from a time series of output datablocks from fully general relativistic 3D simulations. We also describe the evolution of simulations of JAB systems' dynamical and kinematic variables, e.g., velocity shear and momentum density, respectively, and the variation of these variables with respect to observer polar and azimuthal angles. We produce, at frequencies from radio to optical, fixed observer time intensity and polarization maps using various plasma physics motivated prescriptions for the emissivity function of physical quantities from the simulation output, and analyze the corresponding light curves. Our hypothesis is that this approach reproduces observed features of JAB systems such as superluminal bulk flow projections and quasi-periodic oscillations in the light curves more closely than extant stylized analytical models, e.g., cannonball bulk flows. Moreover, our development of user-friendly, versatile C++ routines for processing images of state-of-the-art simulations of JAB systems may afford greater flexibility for observing a wide range of sources from high power BL-Lacs to low power quasars (possibly with the same simulation) without requiring years of observation using multiple telescopes. Advantages of observing simulations instead of observing astrophysical sources directly include: the absence of a diffraction limit, panoramic views of the same object and the ability to freely track features. Light travel time effects become significant for high Lorentz factor and small angles between

  13. Magnetic jets from accretion disks : field structure and X-ray emission

    NASA Astrophysics Data System (ADS)

    Memola, Elisabetta

    2002-06-01

    Jets are highly collimated flows of matter. They are present in a large variety of astrophysical sources: young stars, stellar mass black holes (microquasars), galaxies with an active nucleus (AGN) and presumably also intense flashes of gamma-rays. In particular, the jets of microquasars, powered by accretion disks, are probably small-scale versions of the outflows from AGN. Beside observations of astrophysical jet sources, also theoretical considerations have shown that magnetic fields play an important role in jet formation, acceleration and collimation. Collimated jets seem to be systematically associated with the presence of an accretion disk around a star or a collapsed object. If the central object is a black hole, the surrounding accretion disk is the only possible location for a magnetic field generation. We are interested in the formation process of highly relativistic jets as observed from microquasars and AGN. We theoretically investigate the jet collimation region, whose physical dimensions are extremely tiny even compared to radio telescopes spatial resolution. Thus, for most of the jet sources, global theoretical models are, at the moment, the only possibility to gain information about the physical processes in the innermost jet region. For the first time, we determine the global two-dimensional field structure of stationary, axisymmetric, relativistic, strongly magnetized (force-free) jets collimating into an asymptotically cylindrical jet (taken as boundary condition) and anchored into a differentially rotating accretion disk. This approach allows for a direct connection between the accretion disk and the asymptotic collimated jet. Therefore, assuming that the foot points of the field lines are rotating with Keplerian speed, we are able to achieve a direct scaling of the jet magnetosphere in terms of the size of the central object. We find a close compatibility between the results of our model and radio observations of the M87 galaxy innermost jet

  14. IGR J12580+0134: The First Tidal Disruption Event with an Off-beam Relativistic Jet

    NASA Astrophysics Data System (ADS)

    Lei, Wei-Hua; Yuan, Qiang; Zhang, Bing; Wang, Daniel

    2016-01-01

    Supermassive black holes (SMBHs) can capture and tidally disrupt stars or substellar objects orbiting nearby. The detections of Sw J1644+57-like events suggest that at least some TDEs can launch a relativistic jet beaming toward Earth. A natural expectation would be the existence of TDEs with a relativistic jet beaming away from Earth. The nearby TDE candidate IGR J12580+0134 provides new insights into the jet phenomenon. Combining several constraints, we find that the event invokes a 8-40 Jupiter mass object tidally disrupted by a 3× {10}5-1.8× {10}7{M}⊙ SMBH. Recently, a bright radio transient was discovered by Irwin et al. in association with IGR J12580+0134. We perform detailed modeling of the event based on a numerical jet model previously developed for the radio emission of Sw J1644+57. We find that the radio data of IGR J12580+0134 can be interpreted within an external forward shock model in the Newtonian regime. Using Sw J1644+57 as a template and properly correcting for its luminosity, we argue that the observed X-ray flux in early times is too faint to allow an on-beam relativistic jet unless the Lorentz factor is very small. Rather, the X-ray emission is likely from the disk or corona near the black hole. From various constraints, we find that the data are consistent with an off-beam relativistic jet with a viewing angle of {θ }{{obs}}≳ {30}{{o}}, and an initial Lorentz factor of {{{Γ }}}j≳ a few. This scenario can readily be tested in the upcoming very long baseline interferometry observations.

  15. Magnetized and collimated millimeter scale plasma jets with astrophysical relevance

    SciTech Connect

    Brady, Parrish C.; Quevedo, Hernan J.; Valanju, Prashant M.; Bengtson, Roger D.; Ditmire, Todd

    2012-01-15

    Magnetized collimated plasma jets are created in the laboratory to extend our understanding of plasma jet acceleration and collimation mechanisms with particular connection to astrophysical jets. In this study, plasma collimated jets are formed from supersonic unmagnetized flows, mimicking a stellar wind, subject to currents and magnetohydrodynamic forces. It is found that an external poloidal magnetic field, like the ones found anchored to accretion disks, is essential to stabilize the jets against current-driven instabilities. The maximum jet length before instabilities develop is proportional to the field strength and the length threshold agrees well with Kruskal-Shafranov theory. The plasma evolution is modeled qualitatively using MHD theory of current-carrying flux tubes showing that jet acceleration and collimation arise as a result of electromagnetic forces.

  16. Anomalous skin effects in relativistic parallel propagating weakly magnetized electron plasma waves

    SciTech Connect

    Abbas, Gohar; Bashir, M. F.; Murtaza, G.

    2011-10-15

    Fully relativistic analysis of anomalous skin effects for parallel propagating waves in a weakly magnetized electron plasma is presented and general expressions for longitudinal and transverse permittivites are derived. It is found that the penetration depth for R- and L-waves increases as we move from non-relativistic to highly relativistic regime. The ambient magnetic field reduces/enhances the skin effects for R-wave/L-wave as the strength of the field is increased. In general, the weak magnetic field effects are pronounced for the weakly relativistic regime as compared with other relativistic cases. The results are also graphically illustrated. On switching off the magnetic field, previous results for field free case are retrieved [A. F. Alexandrov, A. S. Bogdankevich, and A. A. Rukhadze, Priniples of Plasma Electrodynamics (Springer-Verlag, Berlin, Heidelberg, 1984), Vol. 9, p. 106].

  17. Measurements of Fast Magnetic Reconnection Driven by Relativistic Electrons

    NASA Astrophysics Data System (ADS)

    Raymond, Anthony; McKelvey, Andrew; Zulick, Calvin; Chuanfei, Dong; Maksimchuk, Anatoly; Thomas, Alexander; Yanovsky, Victor; Krushelnick, Karl; Willingale, Louise; Chykov, Vladimir; Nilson, Phil; Chen, Hui; Williams, Gerald; Bhattacharjee, Amitava; Fox, Will

    2015-11-01

    Magnetic reconnection is a process whereby opposing magnetic field lines are forced together and topologically rearrange, resulting in lower magnetic potential energy and in corresponding plasma heating. Such occurrences are ubiquitous in astrophysics as well as appearing in laboratory plasmas such as in ICF in the form of instabilities. We report measurements in the domain of ultra-fast, ultra-intense lasers, in which the mechanism responsible follows from radially expanding surface electrons with v ~ c . Results are compared from two laser facilities (HERCULES and Omega EP), both of which produced two relativistic intensity pulses focused within close proximity onto copper foils. A spherical X-ray crystal was used to image the Kα radiation induced by electron currents, revealing the midplane diffusion region wherein electrons are accelerated into the target by the electric field generated during reconnection. The characteristics of this signal are studied as a function of the focal spot separation, laser energy, and pulse duration. The results are then compared to 3D PIC simulations.

  18. Magnetic Field Generation and Particle Energization in Relativistic Shear Flows

    NASA Astrophysics Data System (ADS)

    Liang, Edison; Boettcher, Markus; Smith, Ian

    2012-10-01

    We present Particle-in-Cell simulation results of magnetic field generation by relativistic shear flows in collisionless electron-ion (e-ion) and electron-positron (e+e-) plasmas. In the e+e- case, small current filaments are first generated at the shear interface due to streaming instabilities of the interpenetrating particles from boundary perturbations. Such current filaments create transverse magnetic fields which coalesce into larger and larger flux tubes with alternating polarity, eventually forming ordered flux ropes across the entire shear boundary layer. Particles are accelerated across field lines to form power-law tails by semi-coherent electric fields sustained by oblique Langmuir waves. In the e-ion case, a single laminar slab of transverse flux rope is formed at the shear boundary, sustained by thin current sheets on both sides due to different drift velocities of electrons and ions. The magnetic field has a single polarity for the entire boundary layer. Electrons are heated to a fraction of the ion energy, but there is no evidence of power-law tail forming in this case.

  19. Relativistic charge currents in oblique electric and magnetic fields

    NASA Astrophysics Data System (ADS)

    Melia, Fulvio; Fatuzzo, Marco

    1991-06-01

    Runaway processes on neutron stars leading to the sudden release of large quantities of energy (up to of order 1040 erg) on time scales as short as a fraction of a second involve plasma heating and particle acceleration in superstrong magnetic fields H (of order 1012 G). These transient events are interesting from a theoretical standpoint because they require knowledge of particle transport properties in low-density plasmas (ɛe 1025 cm-3) threaded by both electric (E) and magnetic fields. The evaluation of matrix elements involving solutions to the Dirac equation for such a field configuration is often difficult and sometimes impossible, since no completely normalized wave function has yet been found. Here it is shown that, in the special case of E/H 10-4, a simplification of the overlap integrals permits an analytical integration that yields explicit expressions for the relativistic charge currents needed in the computation of the anisotropic conductivity tensor when E.H ≠ 0. The application of these results to the evaluation of the conductivity is briefly discussed. Among other things, this work is relevant to a theory of resistive magnetic tearing instabilities in a quantizing field.

  20. Axisymmetric toroidal modes of general relativistic magnetized neutron star models

    SciTech Connect

    Asai, Hidetaka; Lee, Umin E-mail: lee@astr.tohoku.ac.jp

    2014-07-20

    We calculate axisymmetric toroidal modes of magnetized neutron stars with a solid crust in the general relativistic Cowling approximation. We assume that the interior of the star is threaded by a poloidal magnetic field, which is continuous at the surface with an outside dipole field. We examine the cases of the field strength B{sub S} ∼ 10{sup 16} G at the surface. Since separation of variables is not possible for the oscillations of magnetized stars, we employ finite series expansions for the perturbations using spherical harmonic functions. We find discrete normal toroidal modes of odd parity, but no toroidal modes of even parity are found. The frequencies of the toroidal modes form distinct mode sequences and the frequency in a given mode sequence gradually decreases as the number of radial nodes of the eigenfunction increases. From the frequency spectra computed for neutron stars of different masses, we find that the frequency is almost exactly proportional to B{sub S} and is well represented by a linear function of R/M for a given B{sub S}, where M and R are the mass and radius of the star. The toroidal mode frequencies for B{sub S} ∼ 10{sup 15} G are in the frequency range of the quasi-periodic oscillations (QPOs) detected in the soft-gamma-ray repeaters, but we find that the toroidal normal modes cannot explain all the detected QPO frequencies.

  1. What is on Tap? The Role of Spin in Compact Objects and Relativistic Jets

    NASA Astrophysics Data System (ADS)

    King, Ashley L.; Miller, Jon M.; Gültekin, Kayhan; Walton, Dominic J.; Fabian, Andrew C.; Reynolds, Christopher S.; Nandra, Kirpaul

    2013-07-01

    We examine the role of spin in launching jets from compact objects across the mass scale. Our work includes 3 different Seyfert samples with a total of 37 unique Seyferts, as well as 11 stellar-mass black holes, and 13 neutron stars. We find that when the Seyfert reflection lines are modeled with simple Gaussian line features (a crude proxy for inner disk radius and therefore spin), only a slight inverse correlation is found between the Doppler-corrected radio luminosity at 5 GHz (a proxy for jet power) and line width. When the Seyfert reflection features are fit with more relativistically blurred disk reflection models that measure spin, there is a tentative positive correlation between the Doppler-corrected radio luminosity and the spin measurement. Further, when we include stellar-mass black holes in the sample, to examine the effects across the mass scale, we find a slightly stronger correlation with radio luminosity per unit mass and spin, at a marginal significance (2.3σ confidence level). Finally, when we include neutron stars, in order to probe lower spin values, we find a positive correlation (3.3σ confidence level) between radio luminosity per unit mass and spin. Although tentative, these results suggest that spin may have a role in determining the jet luminosity. In addition, we find a slightly more significant correlation (4.4σ and 4.1σ confidence level, respectively) between radio luminosity per bolometric luminosity and spin, as well as radio luminosity corrected for the fundamental plane (i.e., log (\

  2. Characterization of >100 T magnetic fields associated with relativistic Weibel instability in laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Mishra, Rohini; Ruyer, Charles; Goede, Sebastian; Roedel, Christian; Gauthier, Maxence; Zeil, Karl; Schramm, Ulrich; Glenzer, Siegfried; Fiuza, Frederico

    2016-10-01

    Weibel-type instabilities can occur in weakly magnetized and anisotropic plasmas of relevance to a wide range of astrophysical and laboratory scenarios. It leads to the conversion of a significant fraction of the kinetic energy of the plasma into magnetic energy. We will present a detailed numerical study, using 2D and 3D PIC simulations of the Weibel instability in relativistic laser-solid interactions. In this case, the instability develops due to the counter-streaming of laser-heated electrons and the background return current. We show that the growth rate of the instability is maximized near the critical density region on the rear side of the expanded plasma, producing up to 400 MG magnetic fields for Hydrogen plasmas. We have found that this strong field can be directly probed by energetic protons accelerated in rear side of the plasma by Target Normal Sheath Acceleration (TNSA). This allows the experimental characterization of the instability from the analysis of the spatial modulation of the detected protons. Our numerical results are compared with recent laser experiments with Hydrogen jets and show good agreement with the proton modulations observed experimentally. This work was supported by the DOE Office of Science, Fusion Energy Science (FWP 100182).

  3. Magnetic Untwisting in Most Solar X-Ray Jets

    NASA Technical Reports Server (NTRS)

    Moore, Ronald; Sterling, Alphonse; Falconer, David; Robe, Dominic

    2013-01-01

    From 54 X-ray jets observed in the polar coronal holes by Hinode's X-Ray Telescope (XRT) during coverage in movies from Solar Dynamic Observatory's Atmospheric Imaging Assembly (AIA) taken in its He II 304 Å band at a cadence of 12 s, we have established a basic characteristic of solar X-ray jets: untwisting motion in the spire. In this presentation, we show the progression of few of these X-ray jets in XRT images and track their untwisting in AIA He II images. From their structure displayed in their XRT movies, 19 jets were evidently standard jets made by interchange reconnection of the magnetic-arcade base with ambient open field, 32 were evidently blowout jets made by blowout eruption of the base arcade, and 3 were of ambiguous form. As was anticipated from the >10,000 km span of the base arcade in most polar X-ray jets and from the disparity of standard jets and blowout jets in their magnetic production, few of the standard X-ray jets (3 of 19) but nearly all of the blowout X-ray jets (29 of 32) carried enough cool (T is approximately 105 K) plasma to be seen in their He II movies. In the 32 X-ray jets that showed a cool component, the He II movies show 10-100 km/s untwisting motions about the axis of the spire in all 3 standard jets and in 26 of the 29 blowout jets. Evidently, the open magnetic field in nearly all blowout X-ray jets and probably in most standard X-ray jets carries transient twist. This twist apparently relaxes by propagating out along the open field as a torsional wave. High-resolution spectrograms and Dopplergrams have shown that most Type-II spicules have torsional motions of 10-30 km/s. Our observation of similar torsional motion in X-ray jets strengthens the case for Type-II spicules being made in the same way as X-ray jets, by blowout eruption of a twisted magnetic arcade in the spicule base and/or by interchange reconnection of the twisted base arcade with the ambient open field. This work was funded by NASA's Heliophysics Division

  4. Understanding the light curves of the HST-1 knot in M87 with internal relativistic shock waves along its jet

    NASA Astrophysics Data System (ADS)

    Coronado, Y.; López-Corona, O.; Mendoza, S.

    2016-10-01

    Knots or blobs observed in astrophysical jets are commonly interpreted as shock waves moving along them. Long-time observations of the HST-1 knot inside the jet of the galaxy M87 have produced detailed multiwavelength light curves. In this paper, we model these light curves using the semi-analytical approach developed by Mendoza et al. This model was developed to account for the light curves produced by working surfaces (blobs) moving along relativistic jets. These working surfaces are generated by periodic oscillations of the injected flow velocity and mass ejection rates at the base of the jet. Using genetic algorithms to fit the parameters of the model, we are able to explain the outbursts observed in the light curves of the HST-1 knot with an accuracy greater than a 2σ statistical confidence level.

  5. Magnetization Degree at the Jet Base of M87 Derived from the Event Horizon Telescope Data: Testing the Magnetically Driven Jet Paradigm

    NASA Astrophysics Data System (ADS)

    Kino, M.; Takahara, F.; Hada, K.; Akiyama, K.; Nagai, H.; Sohn, B. W.

    2015-04-01

    We explore the degree of magnetization at the jet base of M87 by using the observational data of the event horizon telescope (EHT) at 230 GHz obtained by Doeleman et al. By utilizing the method in Kino et al., we derive the energy densities of the magnetic fields (UB) and electrons and positrons ({{U}+/- }) in the compact region detected by EHT (the EHT region) with its FWHM size 40 μ as. First, we assume that an optically thick region for synchrotron self-absorption (SSA) exists in the EHT region. Then, we find that the SSA-thick region should not be too large, in order to not overproduce the Poynting power at the EHT region. The allowed ranges of the angular size and the magnetic-field strength of the SSA-thick region are 21 μ as≤slant {{θ }thick}≤slant 26.3 μ as and 50 G≤slant {{B}tot}≤slant 124 G, respectively. Correspondingly, {{U}B}\\gg {{U}+/- } is realized in this case. We further examine the composition of plasma and energy density of protons by utilizing the Faraday rotation measurement at 230 GHz obtained by Kuo et al. Then, we find that {{U}B}\\gg {{U}+/- }+{{U}p} still holds in the SSA-thick region. Second, we examine the case when the EHT region is fully SSA-thin. Then, we find that {{U}B}\\gg {{U}+/- } still holds unless protons are relativistic. Thus, we conclude that the magnetically driven jet scenario in M87 is viable in terms of energetics close to the Innermost Stable Circular Orbit scale unless the EHT region is fully SSA-thin and relativistic protons dominated.

  6. Magnetic field modification to the relativistic runaway electron avalanche length

    NASA Astrophysics Data System (ADS)

    Cramer, E. S.; Dwyer, J. R.; Rassoul, H. K.

    2016-11-01

    This paper explores the impact of the geomagnetic field on the relativistic runaway electron avalanche length, λe-. Coleman and Dwyer (2006) developed an analytical fit to Monte Carlo simulations using the Runaway Electron Avalanche Model. In this work, we repeat this process but with the addition of the geomagnetic field in the range of [100,900]/n μT, where n is the ratio of the density of air at altitude to the sea level density. As the ambient electric field approaches the runaway threshold field (Eth≈284 kV/m sea level equivalent), it is shown that the magnetic field has an impact on the orientation of the resulting electron beam. The runaway electrons initially follow the vertically oriented electric field but then are deflected in the v × B direction, and as such, the electrons experience more dynamic friction due to the increase in path length. This will be shown to result in a difference in the avalanche length from the case where B = 0. It will also be shown that the average energy of the runaway electrons will decrease while the required electric field to produce runaway electrons increases. This study is also important in understanding the physics of terrestrial gamma ray flashes (TGFs). Not only will this work impact relativistic feedback rates determined from simulations, it may also be useful in studying spectroscopy of TGFs observed from balloon and aircraft measurements. These models may also be used in determining beaming properties of TGFs originating in the tropical regions seen from orbiting spacecraft.

  7. Moving relativistic large-scale X-ray jets in the microquasar XTE J1550-564

    NASA Astrophysics Data System (ADS)

    Corbel, S.; Fender, R. P.; Tzioumis, A. K.; Tomsick, J. A.; Orosz, J. A.; Miller, J. M.; Wijnands, R.; Kaaret, P.

    2003-10-01

    We have discovered large-scale moving X-ray and radio jets from the microquasar XTE J1550-564. Using X-ray and radio observations performed between 2000 and 2002, we showed that plasma ejected from XTE J1550-564 has been able to travel at relativistic velocities during many years, with evidence for gradual deceleration. The broadband spectrum of the jets is consistent with synchrotron emission from high energy particles accelerated in shocks. Full details can be found in Corbel et al. [Science 298 (2002a) 196], Karret et al. [ApJ 582 (2003) 933] and Tomsick et al. [ApJ (2003) 945].

  8. Moving relativistic large-scale X-ray jets in the microquasar XTE J1550-564

    NASA Astrophysics Data System (ADS)

    Corbel, S.; Fender, R. P.; Tzioumis, A. K.; Tomsick, J. A.; Orosz, J. A.; Miller, J. M.; Wijnands, R.; Kaaret, P.

    We have discovered large-scale moving X-ray and radio jets from the microquasar XTE J1550-564. Using X-ray observations from the Chandra Observatory performed between June 2000 (see also Tomsick et al., these proceedings) and June 2002, we showed that ejected plasma from XTE J1550-564 has been able to travel at relativistic velocities during many years, with evidence for gradual deceleration. The broadband spectrum of the jets is consistent with synchrotron emission from high energy particles accelerated in shocks. Full details can be found in Corbel et al. 2002, Kaaret et al. 2002, Tomsick et al. 2002.

  9. Classical electrodynamics in material media and relativistic transformation of magnetic dipole moment

    NASA Astrophysics Data System (ADS)

    Kholmetskii, A. L.; Missevitch, O. V.; Yarman, T.

    2016-09-01

    We consider the relativistic transformation of the magnetic dipole moment and disclose its physical meaning, shedding light on the related difficulties in the physical interpretation of classical electrodynamics in material media.

  10. Probing the Relativistic Jets of Active Galactic Nuclei with Multiwavelength Monitoring

    NASA Technical Reports Server (NTRS)

    Marscher, Alan P.; Jorstad, Svetlana G.; Aller, Margo

    2005-01-01

    The work completed includes the analysis of observations obtained during Cycle 7 (March 2002-February 2003) of the Rossi X-ray Timing Explorer (RXTE). The project was part of a longer-term, continuing program to study the X-ray emission process in blazars and radio galaxies in collaboration with Dr. Ian McHardy (U. of Southampton, UK) and Prof. Thomas Balonek (Colgate U.). The goals of the program are to study the X-ray emission mechanism in blazars and radio galaxies and the relation of the X-ray emission to changes in the relativistic jet. The program includes contemporaneous brightness and linear polarization monitoring at radio and optical wavelengths, total and polarized intensity imaging at at 43 GHz with a resolution of 0.1 milliarcseconds with the VLBA, and well-sampled X-ray light curves obtained from a series of approved RXTE programs. The objects studied in the time period covered by the grant were 3C 120, 3C 279, PKS 1510-089, and 3C 273, all with radio jets containing bright knots that appear to move at superluminal speeds. During RXTE Cycle 7, the project was awarded RXTE time to monitor PKS 1510-089 two times per week, 3C 273 and 3C 279 three times per week, and 3C 120 four times per week. In addition, 3C273 and 3C 279 were observed several times per day during a ten-day period in April 2002. The X-ray data, including those from earlier cycles, were compared with radio measurements obtained in the centimeter-wave band by the monitoring program of Drs. Margo and Hugh Aller at the University of Michigan Radio Astronomy Observatory, monthly imaging observations with the VLBA at 43 GHz, and optical observations obtained at several telescopes around the world.

  11. The host galaxies of active galactic nuclei with powerful relativistic jets

    NASA Astrophysics Data System (ADS)

    Olguín-Iglesias, A.; León-Tavares, J.; Kotilainen, J. K.; Chavushyan, V.; Tornikoski, M.; Valtaoja, E.; Añorve, C.; Valdés, J.; Carrasco, L.

    2016-08-01

    We present deep near-infrared (NIR) images of a sample of 19 intermediate-redshift (0.3 < z < 1.0) radio-loud active galactic nuclei (AGN) with powerful relativistic jets (L1.4 GHz > 1027 W Hz-1), previously classified as flat-spectrum radio quasars. We also compile host galaxy and nuclear magnitudes for blazars from literature. The combined sample (this work and compilation) contains 100 radio-loud AGN with host galaxy detections and a broad range of radio luminosities L1.4 GHz ˜ 1023.7-1028.3 W Hz-1, allowing us to divide our sample into high-luminosity blazars (HLBs) and low-luminosity blazars (LLBs). The host galaxies of our sample are bright and seem to follow the μe-Reff relation for ellipticals and bulges. The two populations of blazars show different behaviours in the MK,nuclear -MK,bulge plane, where a statistically significant correlation is observed for HLBs. Although it may be affected by selection effects, this correlation suggests a close coupling between the accretion mode of the central supermassive black hole and its host galaxy, which could be interpreted in terms of AGN feedback. Our findings are consistent with semi-analytical models where low-luminosity AGN emit the bulk of their energy in the form of radio jets, producing a strong feedback mechanism, and high-luminosity AGN are affected by galaxy mergers and interactions, which provide a common supply of cold gas to feed both nuclear activity and star formation episodes.

  12. The Relativistic Jet-accretion Flow–Wind Connection in Mrk 231

    NASA Astrophysics Data System (ADS)

    Reynolds, Cormac; Punsly, Brian; Miniutti, Giovanni; O’Dea, Christopher P.; Hurley-Walker, Natasha

    2017-02-01

    Long-term radio monitoring of the broad absorption line (BAL) quasar Mrk 231 at 17.6 GHz detected a strong flare in 2015. This triggered four epochs of Very Long Baseline Array (VLBA) observations from 8.4 to 43 GHz as well as three epochs of X-ray observations with NuSTAR and two with XMM over a 15 week period. Two ejected components were detected by the VLBA observations. A conservative lower bound on the apparent speed of the first ejection is attained by assuming that it was ejected when the flare began, {v}{app}> 3.15c. Serendipitous far-UV Hubble Space Telescope observations combined with our long-term radio monitoring seem to indicate that episodes of relativistic ejections suppress flux that is emitted at wavelengths shortward of the peak of the far-UV spectral energy distribution, similar to what has been observed in radio-loud quasars. Episodes of strong jet production also seem to suppress the high-ionization BAL wind seen in weak jet states. We found a statistically significant increase (∼ 25 % ) of the 3–12 keV flux during the radio flare relative to a quiescent radio state. This is explained by an ultra-fast (∼0.06c) X-ray-absorbing photoionized wind that is significantly detected only in the low-radio state (similar to Galactic black holes). Mrk 231 is becoming more radio loud. We found that the putative parsec-scale radio lobe doubled in brightness in nine years. Furthermore, large flares are more frequent, with three major flares occurring at ∼2 year intervals.

  13. Blazar Variability from Turbulence in Jets Launched by Magnetically Arrested Accretion Flows

    NASA Astrophysics Data System (ADS)

    O' Riordan, Michael; Pe'er, Asaf; McKinney, Jonathan C.

    2017-07-01

    Blazars show variability on timescales ranging from minutes to years, the former being comparable to and in some cases even shorter than the light-crossing time of the central black hole. The observed γ-ray light curves can be described by a power-law power density spectrum (PDS), with a similar index for both BL Lacs and flat-spectrum radio quasars. We show that this variability can be produced by turbulence in relativistic jets launched by magnetically arrested accretion flows (MADs). We perform radiative transport calculations on the turbulent, highly magnetized jet launching region of a MAD with a rapidly rotating supermassive black hole. The resulting synchrotron and synchrotron self-Compton emission, originating from close to the black hole horizon, is highly variable. This variability is characterized by PDS, which is remarkably similar to the observed power-law spectrum at frequencies less than a few per day. Furthermore, turbulence in the jet launching region naturally produces fluctuations in the plasma on scales much smaller than the horizon radius. We speculate that similar turbulent processes, operating in the jet at large radii (and therefore a high bulk Lorentz factor), are responsible for blazar variability over many decades in frequency, including on minute timescales.

  14. FAST X-RAY/IR CROSS-CORRELATIONS AND RELATIVISTIC JET FORMATION IN GRS 1915+105

    SciTech Connect

    Lasso-Cabrera, N. M.; Eikenberry, S. S.

    2013-10-01

    We present cross-correlation analyses of simultaneous X-ray and near-infrared (near-IR) observations of the microquasar GRS 1915+105 during relativistic jet-producing epochs (X-ray class α and β). While previous studies have linked the large amplitude IR flares and X-ray behaviors to jet formation in these states, our new analyses are sensitive to much lower amplitude IR variability, providing more sensitive probes of the jet formation process. The X-ray to IR cross-correlation function (CCF) shows significant correlations that vary in form between the different X-ray states. During low/hard dips in both classes, we find no significant X-ray/IR correlation. During high-variability epochs, we find consistently significant correlations in both α and β classes, but with strong differences in the CCF structure. The high variability α CCF shows strong anti-correlation between X-ray/IR, with the X-ray preceding the IR by ∼13 ± 2 s. The high variability β state shows a time-variable CCF structure, which is statistically significant but without a clearly consistent lag. Our simulated IR light curves, designed to match the observed CCFs, show variably flickering IR emission during the class β high-variability epoch, while class α can be fit by IR flickering with frequencies in the range 0.1-0.3 Hz, strengthening ∼10 s after every X-ray subflare. We interpret these features in the context of the X-ray-emitting accretion disk and IR emission from relativistic jet formation in GRS 1915+105, concluding that the CCF analysis places the origin in a synchrotron-emitting relativistic compact jet at a distance from the compact object of ∼0.02 AU.

  15. Relativistic jet activity from the tidal disruption of a star by a massive black hole.

    PubMed

    Burrows, D N; Kennea, J A; Ghisellini, G; Mangano, V; Zhang, B; Page, K L; Eracleous, M; Romano, P; Sakamoto, T; Falcone, A D; Osborne, J P; Campana, S; Beardmore, A P; Breeveld, A A; Chester, M M; Corbet, R; Covino, S; Cummings, J R; D'Avanzo, P; D'Elia, V; Esposito, P; Evans, P A; Fugazza, D; Gelbord, J M; Hiroi, K; Holland, S T; Huang, K Y; Im, M; Israel, G; Jeon, Y; Jeon, Y-B; Jun, H D; Kawai, N; Kim, J H; Krimm, H A; Marshall, F E; P Mészáros; Negoro, H; Omodei, N; Park, W-K; Perkins, J S; Sugizaki, M; Sung, H-I; Tagliaferri, G; Troja, E; Ueda, Y; Urata, Y; Usui, R; Antonelli, L A; Barthelmy, S D; Cusumano, G; Giommi, P; Melandri, A; Perri, M; Racusin, J L; Sbarufatti, B; Siegel, M H; Gehrels, N

    2011-08-24

    Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two decades in the form of sparsely sampled, slowly fading emission from distant galaxies, but the onset of the stellar disruption event has not hitherto been observed. Here we report observations of a bright X-ray flare from the extragalactic transient Swift J164449.3+573451. This source increased in brightness in the X-ray band by a factor of at least 10,000 since 1990 and by a factor of at least 100 since early 2010. We conclude that we have captured the onset of relativistic jet activity from a supermassive black hole. A companion paper comes to similar conclusions on the basis of radio observations. This event is probably due to the tidal disruption of a star falling into a supermassive black hole, but the detailed behaviour differs from current theoretical models of such events.

  16. RECOLLIMATION AND RADIATIVE FOCUSING OF RELATIVISTIC JETS: APPLICATIONS TO BLAZARS AND M87

    SciTech Connect

    Bromberg, Omer; Levinson, Amir

    2009-07-10

    Recent observations of M87 and some blazars reveal violent activity in small regions located at relatively large distances from the central engine. Motivated by these considerations, we study the hydrodynamic collimation of a relativistic cooling outflow using a semianalytical model developed earlier. We first demonstrate that radiative cooling of the shocked outflow layer can lead to a focusing of the outflow and its reconfinement in a region having a very small cross-sectional radius. Such a configuration can produce rapid variability at large distances from the central engine via reflections of the converging recollimation shock. Possible applications of this model to TeV blazars are discussed. We then apply our model to M87. The low radiative efficiency of the M87 jet renders focusing unlikely. However, the shallow profile of the ambient medium pressure inferred from observations results in extremely good collimation that can explain the reported variability of the X-ray flux emitted from the HST-1 knot.

  17. Magnetic energy dissipation in force-free jets

    NASA Technical Reports Server (NTRS)

    Choudhuri, Arnab Rai; Konigl, Arieh

    1986-01-01

    It is shown that a magnetic pressure-dominated, supersonic jet which expands or contracts in response to variations in the confining external pressure can dissipate magnetic energy through field-line reconnection as it relaxes to a minimum-energy configuration. In order for a continuous dissipation to occur, the effective reconnection time must be a fraction of the expansion time. The dissipation rate for the axisymmetric minimum-energy field configuration is analytically derived. The results indicate that the field relaxation process could be a viable mechanism for powering the synchrotron emission in extragalactic jets if the reconnection time is substantially shorter than the nominal resistive tearing time in the jet.

  18. Magnetic energy dissipation in force-free jets

    NASA Technical Reports Server (NTRS)

    Choudhuri, Arnab Rai; Konigl, Arieh

    1986-01-01

    It is shown that a magnetic pressure-dominated, supersonic jet which expands or contracts in response to variations in the confining external pressure can dissipate magnetic energy through field-line reconnection as it relaxes to a minimum-energy configuration. In order for a continuous dissipation to occur, the effective reconnection time must be a fraction of the expansion time. The dissipation rate for the axisymmetric minimum-energy field configuration is analytically derived. The results indicate that the field relaxation process could be a viable mechanism for powering the synchrotron emission in extragalactic jets if the reconnection time is substantially shorter than the nominal resistive tearing time in the jet.

  19. The role of magnetic reconnection on astrophysical jets launching and particle acceleration

    NASA Astrophysics Data System (ADS)

    De Gouveia Dal Pino, Elisabete

    2012-07-01

    Magnetic reconnection events like those associated to solar flares can be also a very powerful mechanism operating on accretion disk/jet systems. We have recently found that the magnetic power released in fast reconnection flares is more than sufficient to accelerate relativistic plasmons and produce the observed radio luminosity of the nuclear jets associated both to galactic stellar mass black holes and low luminous active galactic nuclei (AGNs). The famous observed correlation between the radio luminosity and the black hole mass of these sources, spanning ^10^9 orders of magnitude in mass, can be naturally explained in this model as simply due to the magnetic reconnection activity at the jet launching region of the accretion disk coronae of these sources. A similar process may explain the observed x-ray flares in young stars (YSOs) as well. In this talk, we review this mechanism and show results of numerical MHD tests of its validity. Also, particle acceleration in the magnetic reconnection sites of these sources can be rather efficient . In this talk, we will also discuss this acceleration process showing the energy distribution evolution of several thousands of test particles injected in a three-dimensional MHD domain of magnetic reconnection with embedded turbulence. The particle acceleration rate, which depends on the reconnection rate, is highly enhanced in this case. This is because reconnection becomes fast and independent of magnetic resistivity in the presence of turbulence and allows the formation of a thick volume in the current sheet filled with multiple, simultaneously reconnecting magnetic fluxes. The particles trapped within this volume then suffer several head-on scatterings with the contracting magnetic fluctuations in a first-order Fermi process. Particles are thus exponentially accelerated to energies which are several orders of magnitude larger than their injected energy.

  20. Magnetic field induced by strong transverse plasmons in ultra-relativistic electron-positron plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Li, X. Q.; Liu, S. Q.

    2012-08-01

    Context. We investigated the generation of localized magnetic fields in an ultra-relativistic non-isothermal electron-positron plasma by strong electromagnetic plasmons. Aims: The results obtained can be used to explain the origin of small-scale magnetic fields in the internal shock region of gamma-ray bursts with ultra-relativistic electron positron plasmas. Methods: The generation of magnetic fields was investigated with kinetic Vlasov Maxwell equations. Results: The self-generated magnetic field will collapse for modulation instability, leading to spatially highly intermittent magnetic fluxes, whose characteristic scale is much larger than relativistic plasma skin depth, which in turn is conducive to the generation of the long-life small-scale magnetic fields in the internal shock region of gamma-ray bursts.

  1. Tidal disruption and magnetic flux capture: powering a jet from a quiescent black hole

    NASA Astrophysics Data System (ADS)

    Kelley, Luke Zoltan; Tchekhovskoy, Alexander; Narayan, Ramesh

    2014-12-01

    The transient Swift J1644+57 is believed to have been produced by an unlucky star wandering too close to a supermassive black hole (BH) leading to a tidal disruption event. This unusual flare displayed highly super-Eddington X-ray emission which likely originated in a relativistic, collimated jet. This presents challenges to modern accretion and jet theory as upper limits of prior BH activity, which we obtain from the radio afterglow of this event, imply that both the pre-disruption BH and stellar magnetic fluxes fall many orders of magnitude short of what is required to power the observed X-ray luminosity. We argue that a pre-existing, `fossil' accretion disc can contain a sufficient reservoir of magnetic flux and that the stellar debris stream is capable of dragging this flux into the BH. To demonstrate this, we perform local, 3D magnetohydrodynamic simulations of the disc-stream interaction and demonstrate that the interface between the two is unstable to mixing. This mixing entrains a sufficient amount of fossil disc magnetic flux into the infalling stellar debris to power the jet. We argue that the interaction with the fossil disc can have a pronounced effect on the structure and dynamics of mass fallback and likely the resulting transient. Finally, we describe possible ramifications of these interactions on unresolved problems in tidal disruption dynamics, in particular, the efficiency of debris circularization, and effects of the disruption on the pre-existing BH system.

  2. Double Compton and Cyclo-Synchrotron in Super-Eddington Discs, Magnetized Coronae, and Jets

    NASA Astrophysics Data System (ADS)

    McKinney, Jonathan C.; Chluba, Jens; Wielgus, Maciek; Narayan, Ramesh; Sadowski, Aleksander

    2017-01-01

    Black hole accretion discs accreting near the Eddington rate are dominated by bremsstrahlung cooling, but above the Eddington rate the double Compton process can dominate in radiation-dominated regions while the cyclo-synchrotron can dominate in strongly-magnetized regions like in a corona or jet. We present an extension to the general relativistic radiation magnetohydrodynamic code HARMRAD to account for emission and absorption by thermal cyclo-synchrotron, double Compton, bremsstrahlung, low-temperature OPAL opacities as well as Thomson and Compton scattering. We approximate the radiation field as a Bose-Einstein distribution and evolve it using the radiation number-energy-momentum conservation equations in order to track photon hardening. We perform various simulations to study how these extensions affect the radiative properties of magnetically-arrested discs accreting at Eddington to super-Eddington rates. We find that double Compton dominates bremsstrahlung in the disc within a radius of r ˜ 15rg (gravitational radii) at a hundred times the Eddington accretion rate, and within smaller radii at lower accretion rates. Double Compton and cyclo-synchrotron regulate radiation and gas temperatures in the corona, while cyclo-synchrotron regulates temperatures in the jet. Interestingly, as the accretion rate drops to Eddington, an optically thin corona develops whose gas temperature of T ˜ 109K is ˜100 times higher than the disc's black body temperature. Our results show the importance of double Compton and synchrotron in super-Eddington discs, magnetized coronae, and jets.

  3. Helical magnetic field models for parsec-scale radio jets

    NASA Astrophysics Data System (ADS)

    Papageorgiou, A.

    2006-10-01

    Total intensity and polarization structure of extragalactic radio jets are presented in support of models that jets are threaded by helical magnetic fields. Helical magnetic field models predict the following features i) asymmetric distribution in both or either the total and polarized intensity across the jet, ii)displacement between the maxima of total and polarized intensity distributions, iii) abrupt rotation (90 degrees) of the magnetic field position angle (MVPA) and iv) edge brightening in polarization and total intensity. VLBI observations of parsec-scale jets are presented, showing examples of the above predicted features; in one case all four predicted features are present in one source (1055+018).%T GPS studies during the ENIGMA era

  4. Self-compression of intense short laser pulses in relativistic magnetized plasma

    SciTech Connect

    Olumi, M.; Maraghechi, B.

    2014-11-15

    The compression of a relativistic Gaussian laser pulse in a magnetized plasma is investigated. By considering relativistic nonlinearity and using non-linear Schrödinger equation with paraxial approximation, a second-order differential equation is obtained for the pulse width parameter (in time) to demonstrate the longitudinal pulse compression. The compression of laser pulse in a magnetized plasma can be observed by the numerical solution of the equation for the pulse width parameter. The effects of magnetic field and chirping are investigated. It is shown that in the presence of magnetic field and negative initial chirp, compression of pulse is significantly enhanced.

  5. THE DYNAMICS, APPEARANCE, AND DEMOGRAPHICS OF RELATIVISTIC JETS TRIGGERED BY TIDAL DISRUPTION OF STARS IN QUIESCENT SUPERMASSIVE BLACK HOLES

    SciTech Connect

    De Colle, Fabio; Guillochon, James; Naiman, Jill; Ramirez-Ruiz, Enrico E-mail: jfg@ucolick.org E-mail: enrico@ucolick.org

    2012-12-01

    We examine the consequences of a model in which relativistic jets can be triggered in quiescent massive black holes when a geometrically thick and hot accretion disk forms as a result of the tidal disruption of a star. To estimate the power, thrust, and lifetime of the jet, we use the mass accretion history onto the black hole as calculated by detailed hydrodynamic simulations of the tidal disruption of stars. We go on to determine the states of the interstellar medium in various types of quiescent galactic nuclei, and describe how this external matter can affect jets propagating through it. We use this information, together with a two-dimensional hydrodynamic model of the structure of the relativistic flow, to study the dynamics of the jet, the propagation of which is regulated by the density stratification of the environment and by its injection history. The breaking of symmetry involved in transitioning from one to two dimensions is crucial and leads to qualitatively new phenomena. At early times, as the jet power increases, the high pressure of the cocoon collimates the jet, increasing its shock velocity as compared to that of spherical models. We show that small velocity gradients, induced near or at the source, steepen into internal shocks and provide a source of free energy for particle acceleration and radiation along the jet's channel. The jets terminate at a working surface where they interact strongly with the surrounding medium through a combination of shock waves and instabilities; a continuous flow of relativistic fluid emanating from the nucleus supplies this region with mass, momentum, and energy. Information about the t {sup -5/3} decrease in power supply propagates within the jet at the internal sound speed. As a result, the internal energy at the jet head continues to accumulate until long after the peak feeding rate is reached. An appreciable time delay is thus expected between peaks in the short-wavelength radiation emanating near the jet

  6. Searching for Soft Relativistic Jets in Core-Collapse Supernovae with the IceCube Optical Follow-up Program

    NASA Technical Reports Server (NTRS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K. -H.; Benabderrahmane, M. L.; BenZvi, S.; Berdermann, J.; Stamatikos, M.

    2011-01-01

    Context. Transient neutrino sources such as Gamma-Ray Bursts (GRBs) and Supernovae (SNe) are hypothesized to emit bursts of high-energy neutrinos on a time-scale of < or approx.100 s. While GRB neutrinos would be produced in high relativistic jets, core-collapse SNe might host soft-relativistic jets, which become stalled in the outer layers of the progenitor star leading to an efficient production of high-energy neutrinos. Aims. To increase the sensitivity to these neutrinos and identify their sources, a low-threshold optical follow-up program for neutrino multiplets detected with the IceCube observatory has been implemented. Methods. If a neutrino multiplet, i.e. two or more neutrinos from the same direction within 100 s, is found by IceCube a trigger is sent to the Robotic Optical Transient Search Experiment, ROTSE. The 4 ROTSE telescopes immediately start an observation program of the corresponding region of the sky in order to detect an optical counterpart to the neutrino events. Results. No statistically significant excess in the rate of neutrino multiplets has been observed and furthermore no coincidence with an optical counterpart was found. Conclusions. The search allows, for the first time, to set stringent limits on current models predicting a high-energy neutrino flux from soft relativistic hadronic jets in core-collapse SNe. We conclude that a sub-population of SNe with typical Lorentz boost factor and jet energy of 10 and 3 x 10(exp 51) erg, respectively, does not exceed 4:2% at 90% confidence.

  7. Searching for soft relativistic jets in core-collapse supernovae with the IceCube optical follow-up program

    NASA Astrophysics Data System (ADS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Ackermann, M.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Allen, M. M.; Altmann, D.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bindig, D.; Bissok, M.; Blaufuss, E.; Blumenthal, J.; Boersma, D. J.; Bohm, C.; Bose, D.; Böser, S.; Botner, O.; Brown, A. M.; Buitink, S.; Caballero-Mora, K. S.; Carson, M.; Chirkin, D.; Christy, B.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; Cruz Silva, A. H.; D'Agostino, M. V.; Danninger, M.; Daughhetee, J.; Davis, J. C.; de Clercq, C.; Degner, T.; Demirörs, L.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Dunkman, M.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Fedynitch, A.; Feintzeig, J.; Feusels, T.; Filimonov, K.; Finley, C.; Fischer-Wasels, T.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Góra, D.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Haj Ismail, A.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Heinen, D.; Helbing, K.; Hellauer, R.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Hoffmann, B.; Homeier, A.; Hoshina, K.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobi, E.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Kampert, K.-H.; Kappes, A.; Karg, T.; Karle, A.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Kopper, S.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Kroll, G.; Kurahashi, N.; Kuwabara, T.; Labare, M.; Laihem, K.; Landsman, H.; Larson, M. J.; Lauer, R.; Lünemann, J.; Madsen, J.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Miarecki, S.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Richman, M.; Rodrigues, J. P.; Rothmaier, F.; Rott, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schmidt, T.; Schönwald, A.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stezelberger, T.; Stokstad, R. G.; Stössl, A.; Strahler, E. A.; Ström, R.; Stüer, M.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Vehring, M.; Voge, M.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Wood, T. R.; Woschnagg, K.; Xu, C.; Xu, D. L.; Xu, X. W.; Yanez, J. P.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.; Zoll, M.; IceCube Collaboration; Akerlof, C. W.; Pandey, S. B.; Yuan, F.; Zheng, W.; ROTSE Collaboration

    2012-03-01

    Context. Transient neutrino sources such as gamma-ray bursts (GRBs) and supernovae (SNe) are hypothesized to emit bursts of high-energy neutrinos on a time-scale of ≲100 s. While GRB neutrinos would be produced in high relativistic jets, core-collapse SNe might host soft-relativistic jets, which become stalled in the outer layers of the progenitor star leading to an efficient production of high-energy neutrinos. Aims: To increase the sensitivity to these neutrinos and identify their sources, a low-threshold optical follow-up program for neutrino multiplets detected with the IceCube observatory has been implemented. Methods: If a neutrino multiplet, i.e. two or more neutrinos from the same direction within 100 s, is found by IceCube a trigger is sent to the Robotic Optical Transient Search Experiment, ROTSE. The 4 ROTSE telescopes immediately start an observation program of the corresponding region of the sky in order to detect an optical counterpart to the neutrino events. Results: No statistically significant excess in the rate of neutrino multiplets has been observed and furthermore no coincidence with an optical counterpart was found. Conclusions: The search allows, for the first time, to set stringent limits on current models predicting a high-energy neutrino flux from soft relativistic hadronic jets in core-collapse SNe. We conclude that a sub-population of SNe with typical Lorentz boost factor and jet energy of 10 and 3 × 1051 erg, respectively, does not exceed 4.2% at 90% confidence.

  8. The Evolutionary Pathways of Tidal Disruption Events: From Stars to Debris Streams, Accretion Disks, and Relativistic Jets

    NASA Astrophysics Data System (ADS)

    Coughlin, E. R.

    Tidal disruption events, which occur when a star is destroyed by the gravitational field of a supermassive black hole, are unique probes of the inner regions of galaxies. In this thesis we explore various stages of the tidal disruption process, in an attempt to relate the observable signatures of tidal disruption events to the properties of the disrupted star and the black hole. We use numerical techniques to study the long-term evolution of the debris streams produced from tidal disruption events, showing that they can be gravitationally unstable and, as a result of the instability, fragment into small-scale, localized clumps. The implications of this finding are discussed, and we investigate how the thermodynamic properties of the gas comprising the stream affect the nature of the instability. We derive an analytic model for the structure of tidally-disrupted, stellar debris streams, and we compare the predictions of our model to numerical results. We present a model for the accretion disk that forms from a tidal disruption event when the accretion rate surpasses the Eddington limit of the supermassive black hole, showing that these disks are puffed up into quasispherical envelopes that are threaded by bipolar, relativistic jets. We compare the predictions of this model to observations of the jetted tidal disruption event Swift J1644+57. Finally, we derive, from the relativistic Boltzmann equation, the general relativistic equations of radiation hydrodynamics in the viscous limit, which characterize the interaction between radiation and matter when changes in the fluid over the photon mean free path are small. Our results demonstrate that, in contrast to previous works, a radiation-dominated fluid does in fact possess a finite bulk viscosity and a correction to the comoving energy density. Using the general relativistic equations of radiation hydrodynamics in the viscous limit, we present two models to describe the interaction between a relativistic jet launched

  9. PHOTOSPHERE EMISSION FROM A HYBRID RELATIVISTIC OUTFLOW WITH ARBITRARY DIMENSIONLESS ENTROPY AND MAGNETIZATION IN GRBs

    SciTech Connect

    Gao, He; Zhang, Bing E-mail: zhang@physics.unlv.edu

    2015-03-10

    In view of the recent Fermi observations of gamma-ray burst (GRB) prompt emission spectra, we develop a theory of photosphere emission of a hybrid relativistic outflow with a hot fireball component (defined by dimensionless entropy η) and a cold Poynting-flux component (defined by magnetization σ{sub 0} at the central engine). We consider the scenarios both without and with sub-photospheric magnetic dissipations. Based on a simplified toy model of jet dynamics, we develop two approaches: a 'bottom-up' approach to predict the temperature (for a non-dissipative photosphere) and luminosity of the photosphere emission and its relative brightness for a given pair of (η, σ{sub 0}); and a 'top-down' approach to diagnose central engine parameters (η and σ{sub 0}) based on the observed quasi-thermal photosphere emission properties. We show that a variety of observed GRB prompt emission spectra with different degrees of photosphere thermal emission can be reproduced by varying η and σ{sub 0} within the non-dissipative photosphere scenario. In order to reproduce the observed spectra, the outflows of most GRBs need to have a significant σ, both at the central engine and at the photosphere. The σ value at 10{sup 15} cm from the central engine (a possible non-thermal emission site) is usually also greater than unity, so that internal-collision-induced magnetic reconnection and turbulence (ICMART) may be the mechanism to power the non-thermal emission. We apply our top-down approach to GRB 110721A and find that the temporal evolution behavior of its blackbody component can be well interpreted with a time-varying (η, σ{sub 0}) at the central engine, instead of invoking a varying engine base size r {sub 0} as proposed by previous authors.

  10. Photosphere Emission from a Hybrid Relativistic Outflow with Arbitrary Dimensionless Entropy and Magnetization in GRBs

    NASA Astrophysics Data System (ADS)

    Gao, He; Zhang, Bing

    2015-03-01

    In view of the recent Fermi observations of gamma-ray burst (GRB) prompt emission spectra, we develop a theory of photosphere emission of a hybrid relativistic outflow with a hot fireball component (defined by dimensionless entropy η) and a cold Poynting-flux component (defined by magnetization σ0 at the central engine). We consider the scenarios both without and with sub-photospheric magnetic dissipations. Based on a simplified toy model of jet dynamics, we develop two approaches: a "bottom-up" approach to predict the temperature (for a non-dissipative photosphere) and luminosity of the photosphere emission and its relative brightness for a given pair of (η, σ0) and a "top-down" approach to diagnose central engine parameters (η and σ0) based on the observed quasi-thermal photosphere emission properties. We show that a variety of observed GRB prompt emission spectra with different degrees of photosphere thermal emission can be reproduced by varying η and σ0 within the non-dissipative photosphere scenario. In order to reproduce the observed spectra, the outflows of most GRBs need to have a significant σ, both at the central engine and at the photosphere. The σ value at 1015 cm from the central engine (a possible non-thermal emission site) is usually also greater than unity, so that internal-collision-induced magnetic reconnection and turbulence (ICMART) may be the mechanism to power the non-thermal emission. We apply our top-down approach to GRB 110721A and find that the temporal evolution behavior of its blackbody component can be well interpreted with a time-varying (η, σ0) at the central engine, instead of invoking a varying engine base size r 0 as proposed by previous authors.

  11. The role of Magnetic Reconnection in Compact Sources and Jet Acceleration

    NASA Astrophysics Data System (ADS)

    Singh, Chandra Bahadur; De Gouveia Dal Pino, Elisabete; Kadowaki, Luis H. S.

    Almost a decade ago de Gouveia Dal Pino and Lazarian (2005) proposed a model for producing jet plasmons and particle acceleration by magnetic reconnection events in the surrounds of accretion disks around black holes with magnetospheres. Although this model predicts that the amount of magnetic power released by reconnection is more than sufficient to explain observed flares from black hole mass sources in different scales (from microquasars to low luminous active galactic nuclei; see de Gouveia Dal Pino et al. 2010), it still requires refinement and numerical testing. In this work, we take into account relativistic effects by introducing a Pseudo Newtonian approach to the model and also present the results of 2D MHD numerical simulations under this approach.

  12. Magnetic Resonance Velocimetry analysis of an angled impinging jet

    NASA Astrophysics Data System (ADS)

    Irhoud, Alexandre; Benson, Michael; Verhulst, Claire; van Poppel, Bret; Elkins, Chris; Helmer, David

    2016-11-01

    Impinging jets are used to achieve high heat transfer rates in applications ranging from gas turbine engines to electronics. Despite the importance and relative simplicity of the geometry, simulations historically fail to accurately predict the flow behavior in the vicinity of the flow impingement. In this work, we present results from a novel experimental technique, Magnetic Resonance Velocimetry (MRV), which measures three-dimensional time-averaged velocity without the need for optical access. The geometry considered in this study is a circular jet angled at 45 degrees and impinging on a flat plate, with a separation of approximately seven jet diameters between the jet exit and the impingement location. Two flow conditions are considered, with Reynolds numbers of roughly 800 and 14,000. Measurements from the MRV experiment are compared to predictions from Reynolds Averaged Navier Stokes (RANS) simulations, thus demonstrating the utility of MRV for validation of numerical analyses of impinging jet flow.

  13. Weakly relativistic quantum kinetic theory for electrostatic wave modes in magnetized plasmas

    SciTech Connect

    Hussain, Azhar; Stefan, Martin; Brodin, Gert

    2014-03-15

    We have derived the electrostatic dispersion relation in a magnetized plasma using a recently developed quantum kinetic model based on the Dirac equation. The model contains weakly relativistic spin effects such as Thomas precession, the polarization currents associated with the spin and the spin-orbit coupling. It turns out that for strictly electrostatic perturbations the non-relativistic spin effects vanish, and the modification of the classical dispersion relation is solely associated with the relativistic terms. Several new wave modes appear due the electron spin effects, and an example for astrophysical plasmas are given.

  14. Spatiotemporal evolution of high power laser pulses in relativistic magnetized inhomogeneous plasmas

    SciTech Connect

    Bokaei, B.; Niknam, A. R. Imani, E.

    2015-09-15

    In this work, the spatiotemporal evolution of Gaussian laser pulse propagated through a plasma is investigated in the presence of an external axial magnetic field. The coupled equations of self-focusing and self-compression are obtained via paraxial approximation by taking into account the relativistic nonlinearity. The effect of axial magnetic field on simultaneously relativistic self-focusing and self-compression of the laser pulse is studied for homogeneous and inhomogeneous plasmas. The results show that the simultaneous use of both axial magnetic field and density ramp-up leads to generate pulses with the smallest spot size and shortest compression length.

  15. Dynamics of Laboratory Astrophysical Jets with Magnetized Helical Flows

    NASA Astrophysics Data System (ADS)

    von der Linden, Jens; You, Setthivoine

    2014-10-01

    A triple electrode planar plasma gun (MOCHI LabJet) designed to study the dynamics of magnetized helical flows in plasma jets provides boundary conditions and dimensionless numbers relevant to astrophysical jets. The goal is to observe the effect of current and flow profiles on the collimation and stability of jets to address the questions: why are jets collimated and long? How are jet irregularities related to plasma instabilities? The current and azimuthal flow profiles of the jets are tailored by biasing the electrodes at different potentials. High-speed camera images, high-resolution Ḃ probe measurements, and 3D vector tomography of plasma flows will map a stability space for varying current and flow profiles. An analytical stability space is derived with Newcomb's variational analysis applied to collimated magnetic flux tubes with skin and core currents. Two numerical stability spaces are also computed by integrating the Euler-Lagrange equation and applying a shooting method to the ideal MHD eigenvalue problem. The eigenvalue problem is generalized to include azimuthal flows and computed with a monotonicity condition for minimizing the required scanning of the complex eigenvalue space. This work was sponsored in part by the US DOE Grant DE-SC0010340.

  16. Accretion-ejection models for AGN jets

    NASA Astrophysics Data System (ADS)

    Zanni, C.

    2008-10-01

    It is likely that jets from Active Galactic Nuclei derive their energy from accretion onto the central black hole. It is actually possible to fuel the jets by extracting energy and angular momentum from the accretion disk and/or the rotating black hole via the action of large-scale magnetic fields. In this talk I will first present results of analytical and numerical models of the launching process of jets from magnetized accretion disks: I will show that, although a sizeable fraction of the accretion power goes into the jets, these outflows are presumably only mildly relativistic. In the second place, I will therefore suggest that the strongly relativistic components observed at the VLBI scales are accelerated in the innermost parts of the AGNs by Blandford-Znajek and/or Compton-rocket processes. Nonetheless, the non-relativistic disk-wind is needed to collimate the relativistic component and to reproduce the total power of extragalactic jets.

  17. Four-component relativistic theory for nuclear magnetic shielding: magnetically balanced gauge-including atomic orbitals.

    PubMed

    Cheng, Lan; Xiao, Yunlong; Liu, Wenjian

    2009-12-28

    It is recognized only recently that the incorporation of the magnetic balance condition is absolutely essential for four-component relativistic theories of magnetic properties. Another important issue to be handled is the so-called gauge problem in calculations of, e.g., molecular magnetic shielding tensors with finite bases. It is shown here that the magnetic balance can be adapted to distributed gauge origins, leading to, e.g., magnetically balanced gauge-including atomic orbitals (MB-GIAOs) in which each magnetically balanced atomic orbital has its own local gauge origin placed on its center. Such a MB-GIAO scheme can be combined with any level of theory for electron correlation. The first implementation is done here at the coupled-perturbed Dirac-Kohn-Sham level. The calculated molecular magnetic shielding tensors are not only independent of the choice of gauge origin but also converge rapidly to the basis set limit. Close inspections reveal that (zeroth order) negative energy states are only important for the expansion of first order electronic core orbitals. Their contributions to the paramagnetism are therefore transferable from atoms to molecule and are essentially canceled out for chemical shifts. This allows for simplifications of the coupled-perturbed equations.

  18. Method for separating jets and the underlying event in heavy ion collisions at the BNL Relativistic Heavy Ion Collider

    NASA Astrophysics Data System (ADS)

    Hanks, J. A.; Sickles, A. M.; Cole, B. A.; Franz, A.; McCumber, M. P.; Morrison, D. P.; Nagle, J. L.; Pinkenburg, C. H.; Sahlmueller, B.; Steinberg, P.; von Steinkirch, M.; Stone, M.

    2012-08-01

    Reconstructed jets in heavy ion collisions are a crucial tool for understanding the quark-gluon plasma. The separation of jets from the underlying event is necessary particularly in central heavy ion reactions in order to quantify medium modifications of the parton shower and the response of the surrounding medium itself. There have been many methods proposed and implemented for studying the underlying event substructure in proton-proton and heavy ion collisions. In this paper, we detail a method for understanding underlying event contributions in Au+Au collisions at sNN=200 GeV utilizing the HIJING event generator. This method, extended from previous work by the ATLAS collaboration, provides a well-defined association of “truth jets” from the fragmentation of hard partons with “reconstructed jets” using the anti-kT algorithm. Results presented here are based on an analysis of 750M minimum bias HIJING events. We find that there is a substantial range of jet energies and radius parameters where jets are well separated from the background fluctuations (often termed “fake jets”) that make jet measurements at the BNL Relativistic Heavy Ion Collider a compelling physics program.

  19. Jet Interactions with Magnetized Clouds. Preliminary Results from PIC Code and Large-Scale Hydrodynamic Simulations for AGN Jets

    DTIC Science & Technology

    2010-01-01

    rays and neutrinos as it inter- acts with the ambient medium (see Beall and Bednarek, 1999 for a discussion). The plasma instabilities modify the... neutrinos from jet sources would directly suggest an hadronic component at relativistic (i.e. early) stages of jet formation. Such an hypothesis is...consistent with Eichler’s (1979) suggestion of using neutrinos as a probe of AGN. The recent results from the Auger Collaboration (Letessier-Salvon 2009

  20. General Relativistic Simulations of Magnetized Plasmas around Merging Supermassive Black Holes

    NASA Astrophysics Data System (ADS)

    Giacomazzo, Bruno; Baker, John G.; Miller, M. Coleman; Reynolds, Christopher S.; van Meter, James R.

    2012-06-01

    Coalescing supermassive black hole binaries are produced by the mergers of galaxies and are the most powerful sources of gravitational waves accessible to space-based gravitational observatories. Some such mergers may occur in the presence of matter and magnetic fields and hence generate an electromagnetic counterpart. In this Letter, we present the first general relativistic simulations of magnetized plasma around merging supermassive black holes using the general relativistic magnetohydrodynamic code Whisky. By considering different magnetic field strengths, going from non-magnetically dominated to magnetically dominated regimes, we explore how magnetic fields affect the dynamics of the plasma and the possible emission of electromagnetic signals. In particular, we observe a total amplification of the magnetic field of ~2 orders of magnitude, which is driven by the accretion onto the binary and that leads to much stronger electromagnetic signals, more than a factor of 104 larger than comparable calculations done in the force-free regime where such amplifications are not possible.

  1. Relativistic Particle and Relativistic Fluids: Magnetic Moment and Spin-Orbit Interactions

    NASA Astrophysics Data System (ADS)

    Karabali, Dimitra; Nair, V. P.

    2014-11-01

    We consider relativistic charged-particle dynamics and relativistic magnetohydrodynamics using symplectic structures and actions given in terms of coadjoint orbits of the Poincaré group. The particle case is meant to clarify some points such as how minimal coupling (as defined in the text) leads to a gyromagnetic ratio g =2 and to set the stage for fluid dynamics. The general group-theoretic framework is further explained and is then used to set up Abelian magnetohydrodynamics including spin effects. An interesting new physical effect is precession of spin density induced by gradients in pressure and energy density. The Euler equation (the dynamics of the velocity field) is also modified by gradients of the spin density.

  2. External Shock Model for the Large-Scale, Relativistic X-Ray Jets from the Microquasar XTE J1550-564

    NASA Astrophysics Data System (ADS)

    Wang, X. Y.; Dai, Z. G.; Lu, T.

    2003-07-01

    Large-scale, decelerating, relativistic X-ray jets due to material ejected from the black-hole candidate X-ray transient and microquasar XTE J1550-564 have been recently discovered with Chandra by Corbel and coworkers. We find that the dynamical evolution of the eastern jet at the late time is consistent with the well-known Sedov evolutionary phase. A transrelativistic external shock dynamic model by analogy with the evolution of gamma-ray burst remnants is shown to be able to fit the observation data reasonably well. The inferred interstellar medium density around the source is well below the canonical value nISM~1cm-3. We find that the emission from the continuously shocked interstellar medium (forward shock region) decays too slowly to be a viable mechanism for the eastern X-ray jet. However, the rapidly fading X-ray emission can be interpreted as synchrotron radiation from the nonthermal electrons in the adiabatically expanding ejecta. These electrons were accelerated by the reverse shock (moving back into the ejecta), which becomes important when the inertia of the swept external matter leads to an appreciable slowing down of the original ejecta. To ensure the dominance of the emission from the shocked ejecta over that from the forward shock region during the period of the observations, the magnetic field and electron energy fractions in the forward shock region must be far below equipartition. Future continuous, follow-up multiwavelength observations of new ejection events from microquasars up to the significant deceleration phase should provide more valuable insight into the nature of the interaction between the jets and external medium.

  3. Polarization Signatures distinguish the kinetic- and the magnetic-driven blazar jet models

    NASA Astrophysics Data System (ADS)

    Zhang, Haocheng; Li, Hui; Taylor, Gregory B.

    2017-01-01

    Blazars are a type of active galaxies whose jets direct close to our line of sight. They exhibit strong variability across the entire electromagnetic spectrum, from radio up to TeV gamma-rays. The radio to optical polarization signatures, which originate from synchrotron emission in a partially ordered magnetic field, show strong variability as well. Two scenarios have been advanced to explain the blazar variability. The kinetic-driven model argues that the emission region can drain kinetic energy through shocks to accelerate nonthermal particles and generate flares. The magnetic-driven model suggests that the magnetic energy can dissipate through current-driven instabilities to fuel the variability. Both models have their merits in understanding blazar spectra and light curves during flares, thus they cannot be distinguished. We perform comprehensive polarization-dependent radiation modeling of shocks and kink instabilities in the blazar emission region, based on detailed relativistic magnetohydrodynamic (RMHD) simulations. Our approach involves self-consistent magnetic field evolution, nonthermal particle injection based on the energy release from the RMHD simulation, and detailed radiation transfer including all light travel time effects. Hence our method offers the self-consistent time-dependent radiation and polarization signatures from first principles. By comparing the shock and the kink models, we find that while both can interpret the light curves well, the shock model generally produce too strong polarization variations compared to observations. On the other hand, the kink model well fits the general polarization fluctuations and polarization angle swings. We conclude that by coupling first-principle simulations and detailed polarization-dependent radiaiton modeling, polarization signatures can probe the origin of the blazar jet variability, and offer a general diagnostic of the jet physics, including the energy composition, the particle acceleration, and

  4. Three-dimensional dynamics of relativistic flows in pair plasmas with force-free magnetic configuration

    NASA Astrophysics Data System (ADS)

    Sakai, Jun-Ichi; Matsuo, Akira

    2004-06-01

    Dynamics of the relativistic flow in pair plasmas with force-free magnetic configuration is investigated by using a three-dimensional fully relativistic electromagnetic particle-in-cell code. This study is an extension of the work by Haruki and Sakai [Phys. Plasmas 8, 1538 (2001)] that was done in a two-dimensional force-free magnetic configuration. They found that during the early stage of the interaction there occurs the streaming instability, which induces the electromagnetic perturbations associated with generation of quasi-static magnetic field. In the nonlinear stage the force-free magnetic field becomes unstable against the firehose instability and then magnetic islands are formed through magnetic reconnection. The dissipated magnetic field energy is converted to the plasma heating as well as the high-energy particle production. It is found that the three-dimensional configuration could result in completely different dynamics, except for the initial phase where the streaming instability develops. It is also found that the dynamical interaction between the force-free magnetic configuration and the relativistic plasma flows develops sequentially through four different physical processes: (I) The phase of streaming instability, (II) the phase of magnetic reconnection triggered by the first streaming instability, (III) the phase of Alfvén wave excitation through the magnetic reconnection process, and (IV) the phase of dissipation of the Alfvén waves through the magnetic reconnection. It is shown that three-dimensional Alfvén waves with helical magnetic structures can be excited through complicated three-dimensional tearing instability triggered from the streaming instability. During these dynamical processes the pair plasma can be heated through the magnetic reconnection and also the high-energy particles are generated. The interaction process between the force-free collisionless plasmas and the relativistic plasma flows may play an important role for the

  5. Coronal Jets in Closed Magnetic Regions on the Sun

    NASA Astrophysics Data System (ADS)

    Wyper, Peter Fraser; DeVore, C. R.

    2015-04-01

    Coronal jets are dynamic, collimated structures observed in solar EUV and X-ray emission. They appear predominantly in the open field of coronal holes, but are also observed in areas of closed field, especially active regions. A common feature of coronal jets is that they originate from the field above a parasitic polarity of opposite sign to the surrounding field. Some process - such as instability onset or flux emergence - induces explosive reconnection between the closed “anemone” field and the surrounding open field that generates the jet. The lesser number of coronal jets in closed-field regions suggests a possible stabilizing effect of the closed configuration with respect to coronal jet formation. If the scale of the jet region is small compared with the background loop length, as in for example type II spicules, the nearby magnetic field may be treated as locally open. As such, one would expect that if a stabilizing effect exists it becomes most apparent as the scale of the anemone region approaches that of the background coronal loops.To investigate if coronal jets are indeed suppressed along shorter coronal loops, we performed a number of simulations of jets driven by a rotation of the parasitic polarity (as in the previous open-jet calculations by Pariat et. al 2009, 2010, 2015) embedded in a large-scale closed bipolar field. The simulations were performed with the state of the art Adaptively Refined Magnetohydrodynamics Solver. We will report here how the magnetic configuration above the anemone region determines the nature of the jet, when it is triggered, and how much of the stored magnetic energy is released. We show that regions in which the background field and the parasitic polarity region are of comparable scale naturally suppress explosive energy release. We will also show how in the post-jet relaxation phase a combination of confined MHD waves and weak current layers are generated by the jet along the background coronal loops, both of which

  6. Three-dimensional evolution of a relativistic current sheet: triggering of magnetic reconnection by the guide field.

    PubMed

    Zenitani, S; Hoshino, M

    2005-08-26

    The linear and nonlinear evolution of a relativistic current sheet of pair (e(+/-)) plasmas is investigated by three-dimensional particle-in-cell simulations. In a Harris configuration, it is obtained that the magnetic energy is fast dissipated by the relativistic drift kink instability (RDKI). However, when a current-aligned magnetic field (the so-called "guide field") is introduced, the RDKI is stabilized by the magnetic tension force and it separates into two obliquely propagating modes, which we call the relativistic drift-kink-tearing instability. These two waves deform the current sheet so that they trigger relativistic magnetic reconnection at a crossover thinning point. Since relativistic reconnection produces a lot of nonthermal particles, the guide field is of critical importance to study the energetics of a relativistic current sheet.

  7. Jet Formation in Solar Atmosphere due to Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    González-Avilés, J. J.; Guzmán, F. S.; Fedun, V.

    2017-02-01

    Using numerical simulations, we show that jets with features of type II spicules and cool coronal jets corresponding to temperatures of 104 K can be formed as a result of magnetic reconnection in a scenario with magnetic resistivity. For this, we model the low chromosphere–corona region using the C7 equilibrium solar atmosphere model, assuming that resistive MHD rules the dynamics of the plasma. The magnetic field configurations we analyze correspond to two neighboring loops with opposite polarity. The formation of a high-speed and sharp structure depends on the separation of the loops’ feet. We analyze the cases where the magnetic field strength of the two loops is equal and different. In the first case, with a symmetric configuration the jets rise vertically, whereas in an asymmetric configuration the structure shows an inclination. With a number of simulations carried out under a 2.5D approach, we explore various properties of the excited jets, namely, inclination, lifetime, and velocity. The parameter space involves a magnetic field strength between 20 and 40 G, and the resistivity is assumed to be uniform with a constant value of the order {10}-2{{Ω }}\\cdot m.

  8. MAGNETIC-FIELD AMPLIFICATION BY TURBULENCE IN A RELATIVISTIC SHOCK PROPAGATING THROUGH AN INHOMOGENEOUS MEDIUM

    SciTech Connect

    Mizuno, Yosuke; Nishikawa, Ken-Ichi; Pohl, Martin; Niemiec, Jacek; Zhang, Bing; Hardee, Philip E.

    2011-01-10

    We perform two-dimensional relativistic magnetohydrodynamic simulations of a mildly relativistic shock propagating through an inhomogeneous medium. We show that the postshock region becomes turbulent owing to preshock density inhomogeneity, and the magnetic field is strongly amplified due to the stretching and folding of field lines in the turbulent velocity field. The amplified magnetic field evolves into a filamentary structure in two-dimensional simulations. The magnetic energy spectrum is flatter than the Kolmogorov spectrum and indicates that a so-called small-scale dynamo is occurring in the postshock region. We also find that the amount of magnetic-field amplification depends on the direction of the mean preshock magnetic field, and the timescale of magnetic-field growth depends on the shock strength.

  9. Wave-breaking amplitudes of relativistic upper-hybrid oscillations in a cold magnetized plasma

    SciTech Connect

    Karmakar, Mithun; Chakrabarti, Nikhil

    2016-06-15

    A travelling wave solution is presented for relativistic upper-hybrid oscillations (RUHOs) in a cold magnetized plasma. An expression for the wave-breaking amplitudes of RUHOs is derived. The wave-breaking amplitudes of RUHOs are found to decrease with the increase of the strength of an ambient magnetic field. These results will be of relevance to the laboratory context of particle acceleration by wake-fields in which magnetic field plays a central role.

  10. DRIVING OUTFLOWS WITH RELATIVISTIC JETS AND THE DEPENDENCE OF ACTIVE GALACTIC NUCLEUS FEEDBACK EFFICIENCY ON INTERSTELLAR MEDIUM INHOMOGENEITY

    SciTech Connect

    Wagner, A. Y.; Umemura, M.; Bicknell, G. V.

    2012-10-01

    We examine the detailed physics of the feedback mechanism by relativistic active galactic nucleus (AGN) jets interacting with a two-phase fractal interstellar medium (ISM) in the kpc-scale core of galaxies using 29 three-dimensional grid-based hydrodynamical simulations. The feedback efficiency, as measured by the amount of cloud dispersal generated by the jet-ISM interactions, is sensitive to the maximum size of clouds in the fractal cloud distribution but not to their volume filling factor. Feedback ceases to be efficient for Eddington ratios P{sub jet}/L{sub edd} {approx}< 10{sup -4}, although systems with large cloud complexes {approx}> 50 pc require jets of Eddington ratio in excess of 10{sup -2} to disperse the clouds appreciably. Based on measurements of the bubble expansion rates in our simulations, we argue that sub-grid AGN prescriptions resulting in negative feedback in cosmological simulations without a multi-phase treatment of the ISM are good approximations if the volume filling factor of warm-phase material is less than 0.1 and the cloud complexes are smaller than {approx}25 pc. We find that the acceleration of the dense embedded clouds is provided by the ram pressure of the high-velocity flow through the porous channels of the warm phase, flow that has fully entrained the shocked hot-phase gas it has swept up, and is additionally mass loaded by ablated cloud material. This mechanism transfers 10% to 40% of the jet energy to the cold and warm gas, accelerating it within a few 10 to 100 Myr to velocities that match those observed in a range of high- and low-redshift radio galaxies hosting powerful radio jets.

  11. Afterglow Light Curves from Impulsive Relativistic Jets with an Unconventional Structure

    SciTech Connect

    Granot, J

    2005-04-12

    The jet structure in gamma-ray burst (GRB) sources is still largely an open question. The leading models invoke either (i) a roughly uniform jet with sharp edges, or (ii) a jet with a narrow core and wide wings where the energy per solid angle drops as a power law with the angle {theta} from the jet symmetry axis. Recently, a two component jet model has also been considered, with a narrow uniform jet of initial Lorentz factor {Lambda}{sub 0} {approx}> 100 surrounded by a wider uniform jet with {Lambda}{sub 0} {approx} 10-30. Some models predict more exotic jet profiles, such as a thin uniform ring (i.e. the outflow is bounded by two concentric cones of half opening angle {theta}{sub c} and {theta}{sub c} + {Delta}{theta}, with {Delta}{theta} << {theta}{sub c}) or a fan (a thin outflow with {Delta}{theta} << 1 along the rotational equator, {theta}{sub c} = {pi}/2 + {Delta}{theta}/2). In this paper they calculate the expected afterglow light curves from such jet structures, using a simple formalism that is developed here for this purpose, and could also have other applications. These light curves are qualitatively compared to observations of GRB afterglows. It is shown that the two component jet model cannot produce sharp features in the afterglow model due to the deceleration of the wide jet or the narrow jet becoming visible at lines of sight outside of it. They find that a ''ring'' shaped jet or a ''fan'' shaped jet produce a jet break in the afterglow light curve that is too shallow compared to observations, where the change in the temporal decay index across the jet break is about half of that for a uniform conical jet. For a ''ring'' jet, the break is divided into two distinct and smaller breaks, the first occurring when {gamma}{Delta}{theta} {approx} 1-2 and the second when {gamma}{theta}{sub c} {approx} 1/2.

  12. Effects of the imposed magnetic field on the production and transport of relativistic electron beams

    NASA Astrophysics Data System (ADS)

    Cai, Hong-bo; Zhu, Shao-ping; He, X. T.

    2013-07-01

    The effects of the imposed uniform magnetic field, ranging from 1 MG up to 50 MG, on the production and transport of relativistic electron beams (REBs) in overdense plasmas irradiated by ultraintense laser pulse are investigated with two-dimensional particle-in-cell numerical simulations. This study gives clear evidence that the imposed magnetic field is capable of effectively confining the relativistic electrons in space even when the source is highly divergent since it forces the electrons moving helically. In comparison, the spontaneous magnetic fields, generated by the helically moving electrons interplaying with the current filamentation instability, are dominant in scattering the relativistic electrons. As the imposed magnetic field was increased from 1 MG to 50 MG, overall coupling from laser to the relativistic electrons which have the potential to heat the compressed core in fast ignition was found to increase from 6.9% to 21.3% while the divergence of the REB increases significantly from 64° to 90°. The simulations show that imposed magnetic field of the value of 3-30 MG could be more suitable to fast-ignition inertial fusion.

  13. Relativistic Runaway Electron Avalanches in the Presence of an External Magnetic Field

    NASA Astrophysics Data System (ADS)

    Cramer, E. S.; Dwyer, J. R.; Liu, N.; Rassoul, H.; Briggs, M. S.

    2015-12-01

    Relativistic runaway electron avalanches are known to be produced inside the high electric field regions of thunderstorms. In this work, we include the effects of an external static magnetic field. Previous studies have shown that the magnetic field has a great influence on the electron motion at higher altitudes, e.g. Lehtinen et al., 1997, and Gurevich et al., 1996. This result proves important when studying phenomena such as Terrestrial Gamma-ray Flashes, and their effects on the upper atmosphere. Therefore, electron avalanche rates, feedback rates, and electron energy distribution functions will be analyzed and compared to the results of previous studies that did not include a magnetic field. The runaway electron avalanche model (REAM) is a Monte Carlo code that simulates the generation, interactions, and propagation of relativistic runaway electrons in air [Dwyer, 2003, 2004, 2007]. We use this simulation for varying strengths and angles between the electric and magnetic fields to calculate avalanche lengths and angular distribution functions of the relativistic runaway electrons. We will also show electron distribution functions in momentum space. Finally, we will discuss the important regimes for which the magnetic field becomes significant in studying the properties of runaway electron avalanches and relativistic feedback.

  14. Trends in magnetism of free Rh clusters via relativistic ab-initio calculations.

    PubMed

    Šipr, O; Ebert, H; Minár, J

    2015-02-11

    A fully relativistic ab-initio study on free Rh clusters of 13-135 atoms is performed to identify general trends concerning their magnetism and to check whether concepts which proved to be useful in interpreting magnetism of 3d metals are applicable to magnetism of 4d systems. We found that there is no systematic relation between local magnetic moments and coordination numbers. On the other hand, the Stoner model appears well-suited both as a criterion for the onset of magnetism and as a guide for the dependence of local magnetic moments on the site-resolved density of states at the Fermi level. Large orbital magnetic moments antiparallel to spin magnetic moments were found for some sites. The intra-atomic magnetic dipole Tz term can be quite large at certain sites but as a whole it is unlikely to affect the interpretation of x-ray magnetic circular dichroism experiments based on the sum rules.

  15. Relativistic Effects on Electron Transport in Magnetic Alloys

    NASA Astrophysics Data System (ADS)

    Drchal, Václav; Kudrnovský, Josef; Turek, Ilja

    We study the relativistic effects on electron transport in spin-polarized metals and random alloys on ab initio level using the fully relativistic tight-binding linear muffin-tin-orbital (TB-LMTO) method. We employ a Kubo linear-response approach adapted to disordered multisublattice systems in which the chemical disorder is described in terms of the coherent potential approximation (CPA). The CPA vertex corrections are included. We calculate both the Fermi surface and Fermi sea terms of the full conductivity tensor. We find that in cubic ferromagnetic 3d transition metals (Fe, Co, Ni) and their random binary alloys (Ni-Fe, Fe-Si) the Fermi sea term in the anomalous Hall conductivity is small in comparison with the Fermi surface term, however, in more complicated structures, such as hexagonal Co and selected Co-based Heusler alloys, it becomes important. We find an overall good agreement between the theory and experimental data.

  16. Relativistic effects on the nuclear magnetic shielding in the MF (M=Cu, Ag, Au) series

    SciTech Connect

    David, Jorge; Restrepo, Albeiro

    2007-11-15

    Relativistic effects on the nuclear magnetic shielding {sigma}(M) of the series of diatomics MF (M=Cu, Ag, Au) are calculated and analyzed using the Dirac-Hartree-Fock (DHF) method in the random phase approximation (RPA). Significant differences due to relativistic effects on the shielding constant {sigma}(M) are found in this series of atoms. The high electronegativity of the fluorine atom works in conjunction with the spin-orbit coupling to increase the calculated value for {sigma}(Au). An unusually large diamagnetic contribution to the shielding constant is observed. Nonrelativistic nuclear magnetic shielding [{sigma}{sup NR}(M)] shows very good linear correlation with the nuclear charge (Z) of the metal, while the relativistic shielding [{sigma}{sup rel}(M)] varies as Z{sup 2.26}.

  17. Generalised relativistic Ohm's laws, extended gauge transformations, and magnetic linking

    SciTech Connect

    Pegoraro, F.

    2015-11-15

    Generalisations of the relativistic ideal Ohm's law are presented that include specific dynamical features of the current carrying particles in a plasma. Cases of interest for space and laboratory plasmas are identified where these generalisations allow for the definition of generalised electromagnetic fields that transform under a Lorentz boost in the same way as the real electromagnetic fields and that obey the same set of homogeneous Maxwell's equations.

  18. Generalised relativistic Ohm's laws, extended gauge transformations, and magnetic linking

    NASA Astrophysics Data System (ADS)

    Pegoraro, F.

    2015-11-01

    Generalisations of the relativistic ideal Ohm's law are presented that include specific dynamical features of the current carrying particles in a plasma. Cases of interest for space and laboratory plasmas are identified where these generalisations allow for the definition of generalised electromagnetic fields that transform under a Lorentz boost in the same way as the real electromagnetic fields and that obey the same set of homogeneous Maxwell's equations.

  19. Solar Polar Jets Driven by Magnetic Reconnection, Gravity, and Wind

    NASA Astrophysics Data System (ADS)

    DeVore, C. Richard; Karpen, Judith T.; Antiochos, Spiro K.

    2014-06-01

    Polar jets are dynamic, narrow, radially extended structures observed in solar EUV emission near the limb. They originate within the open field of coronal holes in “anemone” regions, which are intrusions of opposite magnetic polarity. The key topological feature is a magnetic null point atop a dome-shaped fan surface of field lines. Applied stresses readily distort the null into a current patch, eventually inducing interchange reconnection between the closed and open fields inside and outside the fan surface (Antiochos 1996). Previously, we demonstrated that magnetic free energy stored on twisted closed field lines inside the fan surface is released explosively by the onset of fast reconnection across the current patch (Pariat et al. 2009, 2010). A dense jet comprised of a nonlinear, torsional Alfvén wave is ejected into the outer corona along the newly reconnected open field lines. Now we are extending those exploratory simulations by including the effects of solar gravity, solar wind, and expanding spherical geometry. We find that the model remains robust in the resulting more complex setting, with explosive energy release and dense jet formation occurring in the low corona due to the onset of a kink-like instability, as found in the earlier Cartesian, gravity-free, static-atmosphere cases. The spherical-geometry jet including gravity and wind propagates far more rapidly into the outer corona and inner heliosphere than a comparison jet simulation that excludes those effects. We report detailed analyses of our new results, compare them with previous work, and discuss the implications for understanding remote and in-situ observations of solar polar jets.This work was supported by NASA’s LWS TR&T program.

  20. About the magnetic origin of Chromospheric Spicules and Coronal Jets

    NASA Astrophysics Data System (ADS)

    Koutchmy, S.; Filippov, B.; Tavabi, E.

    2012-06-01

    Observations of jet- like phenomena near the solar limb are reported for a long time, first in Hα (Secchi observations of spicules in the 1870 ies), and after, from eclipse high resolution coronal images taken in white-light (1920-1973) as spiky structures. EUV jets were reported in the 70 ies from rocket and space-borne CIV filtergrams and finally X-EUV jets were reported from SXT observations of Yohkoh and from EIT and CDS SoHO observations. There is now little doubt that they are of magnetic origin although no magnetic field measurements exist for these regions and thermo-dynamical models are still work out. New observations of both spicules and jets with the SOT/SXT of Hinode were subjected to an analysis showing the influence of the null point(s) of the magnetic field. The collective behavior of the H CaII SOT(Hinode) time sequences of processed with the Madmax operator images of limb spicules show the torsional effects which were partly suggested before from the interpretation of high resolution limb spectra taken on Russian coronagraphs and the VTT at SacPeak. 100 s and shorter period waves are recorded. We propose a reconnection process occurring at the top of an emerging twisted flux tube for explaining some peculiarities of the spicular eruptions and possibly, as a viable mechanism for explaining the SXR jet eruptions. The result of a numerical 3D modeling illustrates this erupting mechanism although the behavior of the magneto-plasma structure near a null point, as shown by coronal filtergrams, does not necessary imply reconnections, especially the case of jets making a long coronal ray we observed in white-light with Lasco C2.

  1. Hydrogen atom in a strong magnetic field. II. Relativistic corrections for low-lying excited states

    NASA Astrophysics Data System (ADS)

    Poszwa, A.; Rutkowski, A.

    2004-02-01

    The highly accurate solution of the Schrödinger equation in the form of common Landau exponential factor multiplied by a power series in two variables, the sine of the cone angle and radial variable is completed by the first-order relativistic correction calculated within the framework of the relativistic direct perturbation theory (DPT). It is found that in contrast to behavior of relativistic corrections for the ground state and 2p-1(ms=-1/2) excited state, which change sign from negative to positive near B≈1011 G and B≈1010 G, respectively [Z. Chen and S. P. Goldman, Phys. Rev A 45, 1722 (1992)], the relativistic corrections for 2s0(ms=-1/2) and 2p0(ms=-1/2) excited states are negative for the magnetic field varying in range 0relativistic correction significantly mix nonrelativistic states the near-degenerate version of DPT is used. The avoided crossings of relativistic levels with μ=-1/2 and π=-1, evolving from field-free states with principal quantum numbers n=2,3,4 are presented.

  2. Pulsating jet-like structures in magnetized plasma

    SciTech Connect

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-15

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as “radio pulsars.” The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  3. Pressure and Magnetics Measurements of Single and Merged Jets

    NASA Astrophysics Data System (ADS)

    Messer, S.; Case, A.; Brockington, S.; Bomgardner, R.; Witherspoon, F. D.

    2010-11-01

    We present pressure and magnetic data from both a single full scale coaxial gun and from the merging of jets from several minirailguns. The magnetic probes measure all three components of field, and include an array of probes inside the coaxial gun. Magnetic measurements beyond the muzzle of the gun show the scale of currents trapped in the plasma plume. The pressure probe measures adiabatic stagnation pressure and shows how this quantity decreases with distance from the gun as well as the changes in stagnation pressure through the merge process. Stagnation pressure is influenced by density, temperature, and velocity, and serves as a check on spectroscopic and interferometer measurements. Unlike optical measurements, stagnation pressure is taken at a definite location. These guns are early prototypes of guns to be installed on the Plasma Liner eXperiment at LANL. The jet-merging results are reviewed in the context of what is expected for PLX.

  4. Pulsating jet-like structures in magnetized plasma

    NASA Astrophysics Data System (ADS)

    Goncharov, V. P.; Pavlov, V. I.

    2016-08-01

    The formation of pulsating jet-like structures has been studied in the scope of the nonhydrostatic model of a magnetized plasma with horizontally nonuniform density. We discuss two mechanisms which are capable of stopping the gravitational spreading appearing to grace the Rayleigh-Taylor instability and to lead to the formation of stationary or oscillating localized structures. One of them is caused by the Coriolis effect in the rotating frames, and another is connected with the Lorentz effect for magnetized fluids. Magnetized jets/drops with a positive buoyancy must oscillate in transversal size and can manifest themselves as "radio pulsars." The estimates of their frequencies are made for conditions typical for the neutron star's ocean.

  5. Double Compton and Cyclo-Synchrotron in Super-Eddington Discs, Magnetized Coronae, and Jets

    NASA Astrophysics Data System (ADS)

    McKinney, Jonathan C.; Chluba, Jens; Wielgus, Maciek; Narayan, Ramesh; Sadowski, Aleksander

    2017-05-01

    Black hole accretion discs accreting near the Eddington rate are dominated by bremsstrahlung cooling, but above the Eddington rate, the double Compton process can dominate in radiation-dominated regions, while the cyclo-synchrotron can dominate in strongly magnetized regions like a corona or a jet. We present an extension to the general relativistic radiation magnetohydrodynamic code harmrad to account for emission and absorption by thermal cyclo-synchrotron, double Compton, bremsstrahlung, low-temperature opal opacities, as well as Thomson and Compton scattering. The harmrad code and associated analysis and visualization codes have been made open-source and are publicly available at the github repository website. We approximate the radiation field as a Bose-Einstein distribution and evolve it using the radiation number-energy-momentum conservation equations in order to track photon hardening. We perform various simulations to study how these extensions affect the radiative properties of magnetically arrested discs accreting at Eddington to super-Eddington rates. We find that double Compton dominates bremsstrahlung in the disc within a radius of r ˜ 15rg (gravitational radii) at hundred times the Eddington accretion rate, and within smaller radii at lower accretion rates. Double Compton and cyclo-synchrotron regulate radiation and gas temperatures in the corona, while cyclo-synchrotron regulates temperatures in the jet. Interestingly, as the accretion rate drops to Eddington, an optically thin corona develops whose gas temperature of T ˜ 109K is ˜100 times higher than the disc's blackbody temperature. Our results show the importance of double Compton and synchrotron in super-Eddington discs, magnetized coronae and jets.

  6. Probing the innermost regions of AGN jets and their magnetic fields: LBA

    NASA Astrophysics Data System (ADS)

    Anderson, James M.; Lobanov, Andrei; Perez Torres, Miguel Angel; Ros, Eduardo; Alberdi, Antxon; Taylor, Greg; Zensus, Anton; Cawthorne, Tim; Kovalev, Yuri; Krichbaum, Thomas P.; Savolainen, Tuomas; Gomez, Jose Luis; Bach, Uwe; Bernhart, Simone; Clausen-Brown, Eric; Eilek, Jean; Fromm, Christian

    2013-10-01

    RadioAstron provides the first true full-polarization capabilities for space-VLBI. As part of our RadioAstron key science project to study magnetic fields in AGNs, we propose that the LBA participates in two global VLBI imaging observations (10 to 20 hours of total observing time) at K-band from a list of possible imaging targets (including OJ~287, 3C~273, 3C~279, and 3C~454.3 for the LBA) and sessions in the timerange 2013 October through 2014 April currently under consideration by other global VLBI stations. These measurements will exploit the unprecedented high-angular resolution polarization capabilities of RadioAstron to probe the innermost regions of AGN jets and their magnetic fields. Our initial target sample contains bright, strongly polarized AGN jets for which we confidently expect to measure polarization and be able to perform Faraday rotation synthesis analysis that will allow us to construct 3D maps of the magnetic field structure and strength in the vicinity of the central black hole. Comparison with 3D relativistic-MHD and emission simulations will allow us to obtain a better understanding of the jet formation and high-energy emission mechanisms. Perigee imaging with RadioAstron requires support from a truly global VLBI array that can co-observe for the full RadioAstron track. As very sensitive stations are required at all times to locate and track fringes to the weak RadioAstron K-band system, the LBA, including DSS-43, the ATCA, and Parkes, is crucial for the far eastern latitude region of the global array.

  7. Two-jet astrosphere model: effect of azimuthal magnetic field

    NASA Astrophysics Data System (ADS)

    Golikov, E. A.; Izmodenov, V. V.; Alexashov, D. B.; Belov, N. A.

    2017-01-01

    Opher et al., Drake, Swisdak and Opher have shown that the heliospheric magnetic field results in formation of two-jet structure of the solar wind flow in the inner heliosheath, i.e. in the subsonic region between the heliospheric termination shock (TS) and the heliopause. In this scenario, the heliopause has a tube-like topology as compared with a sheet-like topology in the most models of the global heliosphere. In this paper, we explore the two-jet scenario for a simplified astrosphere in which (1) the star is at rest with respect to the circumstellar medium, (2) radial magnetic field is neglected as compared with azimuthal component and (3) the stellar wind outflow is assumed to be hypersonic (both the Mach number and the Alfvénic Mach number are much greater than unity at the inflow boundary). We have shown that the problem can be formulated in dimensionless form, in which the solution depends only on one dimensionless parameter ε that is reciprocal of the Alfvénic Mach number at the inflow boundary. This parameter is proportional to stellar magnetic field. We present the numerical solution of the problem for various values of ε. Three first integrals of the governing ideal magnetohydrodynamic equations are presented, and we make use of them in order to get the plasma distribution in the jets. Simple relations between distances to the TS, astropause and the size of the jet are established. These relations allow us to determine the stellar magnetic field from the geometrical pattern of the jet-like astrosphere.

  8. Wave dispersion in a counterstreaming, relativistic thermal, magnetized, electron-positron plasma.

    PubMed

    Verdon, M W; Melrose, D B

    2011-05-01

    The dispersion equation is analyzed for waves in a strongly magnetized, electron-positron plasma in which counterstreaming electrons and positrons have a relativistic thermal distribution in their respective rest frames, for propagation parallel to the magnetic field. We derive the response tensor for the medium, demonstrate the dispersion curves for different temperatures, and discuss the differences from the cold-plasma case. Application to the case of pulsar magnetospheres is discussed. © 2011 American Physical Society

  9. Generation and evolution of magnetic field in the relativistic plasma following q-nonextensive distribution

    NASA Astrophysics Data System (ADS)

    Lin, Fu-Jun; Chen, Zong-Hua; Li, Xiao-Qing; Liao, Jing-Jing; Zhu, Yun

    2017-02-01

    A GigaGauss quasi-steady magnetic field can be generated in astrophysical plasmas and laser-produced plasmas with high-frequency electromagnetic radiation through wave-wave and wave-particle interactions. A set of governing equations for this field are obtained in the plasma consisting of ultra-relativistic electrons following q-nonextensive distribution. The numerical results show that the initial field is unstable and can collapse to generate various spatially intermittent magnetic flux tubes. It can also be found that the behavior of the magnetic field is greatly dependent on the nonextensive index q, which may be helpful in understanding the magnetic turbulence.

  10. Plasma waves in a relativistic, strongly anisotropic plasma propagated along a strong magnetic field

    NASA Technical Reports Server (NTRS)

    Onishchenko, O. G.

    1980-01-01

    The dispersion properties of plasma waves in a relativistic homogeneous plasma propagated along a strong magnetic field are studied. It is shown that the non-damping plasma waves exist in the frequency range omega sub p or = omega or = omega sub L. The values of omega sub p and omega sub L are calculated for an arbitrary homogeneous relativistic function of the particle distribution. In the case of a power ultrarelativistic distribution, it is shown that, if the ultrarelativistic tail of the distribution drops very rapidly, slightly damping plasma waves are possible with the phase velocity (omega/K)c.

  11. On the perpendicular propagating modes in the ultra-relativistic weakly magnetized plasma

    SciTech Connect

    Abbas, Gohar; Iqbal, Z.; Murtaza, G.

    2015-03-15

    The dispersion relations for the weakly magnetized perpendicular propagating modes (O-mode, X-mode, and upper hybrid mode) based on the ultra-relativistic Fermi-Dirac distribution function with chemical potential are derived using the Vlasov–Maxwell model. The results are presented in terms of Polylog functions without making any approximation. It is found that as the ratio μ/T is increased, the cutoff points shift downward. A comparison is also performed with the previously derived results for ultra-relativistic Maxwellian distribution.

  12. Detecting Relativistic X-Ray Jets in High-redshift Quasars

    NASA Astrophysics Data System (ADS)

    McKeough, Kathryn; Siemiginowska, Aneta; Cheung, C. C.; Stawarz, Łukasz; Kashyap, Vinay L.; Stein, Nathan; Stampoulis, Vasileios; van Dyk, David A.; Wardle, J. F. C.; Lee, N. P.; Harris, D. E.; Schwartz, D. A.; Donato, Davide; Maraschi, Laura; Tavecchio, Fabrizio

    2016-12-01

    We analyze Chandra X-ray images of a sample of 11 quasars that are known to contain kiloparsec scale radio jets. The sample consists of five high-redshift (z ≥ 3.6) flat-spectrum radio quasars, and six intermediate redshift (2.1 < z < 2.9) quasars. The data set includes four sources with integrated steep radio spectra and seven with flat radio spectra. A total of 25 radio jet features are present in this sample. We apply a Bayesian multi-scale image reconstruction method to detect and measure the X-ray emission from the jets. We compute deviations from a baseline model that does not include the jet, and compare observed X-ray images with those computed with simulated images where no jet features exist. This allows us to compute p-value upper bounds on the significance that an X-ray jet is detected in a pre-determined region of interest. We detected 12 of the features unambiguously, and an additional six marginally. We also find residual emission in the cores of three quasars and in the background of one quasar that suggest the existence of unresolved X-ray jets. The dependence of the X-ray to radio luminosity ratio on redshift is a potential diagnostic of the emission mechanism, since the inverse Compton scattering of cosmic microwave background photons (IC/CMB) is thought to be redshift dependent, whereas in synchrotron models no clear redshift dependence is expected. We find that the high-redshift jets have X-ray to radio flux ratios that are marginally inconsistent with those from lower redshifts, suggesting that either the X-ray emissions are due to the IC/CMB rather than the synchrotron process, or that high-redshift jets are qualitatively different.

  13. Leading-order relativistic effects on nuclear magnetic resonance shielding tensors.

    PubMed

    Manninen, Pekka; Ruud, Kenneth; Lantto, Perttu; Vaara, Juha

    2005-03-15

    We present perturbational ab initio calculations of the nuclear-spin-dependent relativistic corrections to the nuclear magnetic resonance shielding tensors that constitute, together with the other relativistic terms reported by us earlier, the full leading-order perturbational set of results for the one-electron relativistic contributions to this observable, based on the (Breit-)Pauli Hamiltonian. These contributions are considered for the H(2)X (X = O,S,Se,Te,Po) and HX (X = F,Cl,Br,I,At) molecules, as well as the noble gas (Ne, Ar, Kr, Xe, Rn) atoms. The corrections are evaluated using the relativistic and magnetic operators as perturbations on an equal footing, calculated using analytical linear and quadratic response theory applied on top of a nonrelativistic reference state provided by self-consistent field calculations. The (1)H and heavy-atom nuclear magnetic shielding tensors are compared with four component, nearly basis-set-limit Dirac-Hartree-Fock calculations that include positronic excitations, as well as available literature data. Besides the easy interpretability of the different contributions in terms of familiar nonrelativistic concepts, the accuracy of the present perturbational scheme is striking for the isotropic part of the shielding tensor, for systems including elements up to Xe.

  14. Nonthermal Particle Acceleration in 3D Relativistic Magnetic Reconnection in Pair Plasma

    NASA Astrophysics Data System (ADS)

    Uzdensky, Dmitri; Werner, Gregory; Zhdankin, Vladimir

    2016-10-01

    Magnetic reconnection is a fundamental plasma process that converts magnetic energy into particle kinetic energy. ``Relativistic'' reconnection is of interest in astrophysical contexts because it can accelerate particles to relativistic energies high enough for synchrotron (or inverse Compton) emission to explain observed high-energy radiation. After several 2D particle-in-cell (PIC) simulations of reconnection in pair plasmas demonstrated power-law electron-energy spectra extending to high energies, a few 3D simulations surprisingly confirmed the robustness of nonthermal particle acceleration, despite fundamental differences, such as the development of the relativistic drift-kink instability (RDKI) in 3D. We present a comprehensive PIC study of 3D relativistic pair-plasma reconnection characterizing the effect of the third dimension. We investigate how reconnection dynamics and particle acceleration depend on guide magnetic field Bz and on the simulation box length Lz in the third dimension. We find that, while the RDKI does indeed grow in 3D reconnection, it does not inhibit particle acceleration, even in the absence of guide field. This work was funded by NSF, DOE, and NASA.

  15. Three-dimensional outflow jets generated in collisionless magnetic reconnection

    NASA Astrophysics Data System (ADS)

    Fujimoto, Keizo

    2016-10-01

    The present study proposes a new theoretical model generating three-dimensional (3-D) outflow jets in collisionless magnetic reconnection by means of a large-scale particle-in-cell simulation. The key mechanism is the formation of 3-D flux ropes arising in the turbulent electron current layer formed around the magnetic x line. The scale of the flux ropes along the current density is determined by the wavelength of an electron flow shear mode which is a macroscopic scale larger than the typical kinetic scales. The 3-D flux ropes are intermittently ejected from the current layer and regulates the outflow jets into three dimensions. The gross reconnection rate is sufficiently large, since reconnection takes place almost uniformly along the x line.

  16. Nonuniform Currents and Spins of Relativistic Electron Vortices in a Magnetic Field

    NASA Astrophysics Data System (ADS)

    van Kruining, Koen; Hayrapetyan, Armen G.; Götte, Jörg B.

    2017-07-01

    We present a relativistic description of electron vortex beams in a homogeneous magnetic field. Including spin from the beginning reveals that spin-polarized electron vortex beams have a complicated azimuthal current structure, containing small rings of counterrotating current between rings of stronger corotating current. Contrary to many other problems in relativistic quantum mechanics, there exists a set of vortex beams with exactly zero spin-orbit mixing in the highly relativistic and nonparaxial regime. The well-defined phase structure of these beams is analogous to simpler scalar vortex beams, owing to the protection by the Zeeman effect. For states that do show spin-orbit mixing, the spin polarization across the beam is nonuniform rendering the spin and orbital degrees of freedom inherently inseparable.

  17. Torque Enhancement, Spin Equilibrium, and Jet Power from Disk-Induced Opening of Pulsar Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Parfrey, Kyle; Spitkovsky, Anatoly; Beloborodov, Andrei M.

    2016-05-01

    The interaction of a rotating star’s magnetic field with a surrounding plasma disk lies at the heart of many questions posed by neutron stars in X-ray binaries. We consider the opening of stellar magnetic flux due to differential rotation along field lines coupling the star and disk, using a simple model for the disk-opened flux, the torques exerted on the star by the magnetosphere, and the power extracted by the electromagnetic wind. We examine the conditions under which the system enters an equilibrium spin state, in which the accretion torque is instantaneously balanced by the pulsar wind torque alone. For magnetic moments, spin frequencies, and accretion rates relevant to accreting millisecond pulsars, the spin-down torque from this enhanced pulsar wind can be substantially larger than that predicted by existing models of the disk-magnetosphere interaction, and is in principle capable of maintaining spin equilibrium at frequencies less than 1 kHz. We speculate that this mechanism may account for the non-detection of frequency increases during outbursts of SAX J1808.4-3658 and XTE J1814-338, and may be generally responsible for preventing spin-up to sub-millisecond periods. If the pulsar wind is collimated by the surrounding environment, the resulting jet can satisfy the power requirements of the highly relativistic outflows from Cir X-1 and Sco X-1. In this framework, the jet power scales relatively weakly with accretion rate, {L}{{j}}\\propto {\\dot{M}}4/7, and would be suppressed at high accretion rates only if the stellar magnetic moment is sufficiently low.

  18. Nanosecond response ''gasket-type'' magnetic loop current monitor for relativistic electron beam current measurements.

    PubMed

    Copeland, R L; Adamski, J L; Doggett, W O; Morrow, D L; Bennett, W H

    1979-02-01

    A fast response magnetic loop current monitor has been developed to measure relativistic electron beam return currents. The monitor has a rise time of about a nanosecond and a high degree of symmetry with moderate sensitivity, variable from about 1 to 10 V/kA. This simple monitor, with a thickness of 0.254 mm or less, is thin enough to be placed between segments of return current path in the diode or drift tube regions, is insensitive to flashover, beam and plasma bombardment, and radiation effects, and measures net current, thus offering some advantages over conventional magnetic probes, since the main components are outside of the vacuum region. Design criteria, an equivalent circuit analysis, and typical calibration waveforms are presented. Experimental current measurements for a pinched electron beam diode configuration using both conventional magnetic probes and ''gasket-type''current monitors with the FX-75 relativistic electron beam accelerator are presented.

  19. Space-charge limiting currents in magnetically focused intense relativistic beams with an ion channel

    SciTech Connect

    Li Jianqing; Mo Yuanlong

    2006-12-15

    The intense relativistic beam propagation through the drift tube filled with background plasma is investigated. The self-consistent differential equations, which describe the laminar-flow equilibria state in magnetically focused relativistic beams with an ion channel, are presented. By solving these equations using the Runge-Kutta method, the azimuthal velocity, the axial velocity, and the electron beam density, which are functions of radial position, can be calculated. Then the space-charge limiting current and the externally applied magnetic field can be obtained for solid beams and hollow beams. In the case of plasma fill, the axial velocity of the laminar flow is a nonuniform radial profile. The simulated results show that the background plasma can increase the space-charge limiting current, reduce the externally applied magnetic field, and improve the electron beam propagation through the drift tube.

  20. Collisionless Electron-ion Shocks in Relativistic Unmagnetized Jet-ambient Interactions: Non-thermal Electron Injection by Double Layer

    NASA Astrophysics Data System (ADS)

    Ardaneh, Kazem; Cai, Dongsheng; Nishikawa, Ken-Ichi

    2016-08-01

    The course of non-thermal electron ejection in relativistic unmagnetized electron-ion shocks is investigated by performing self-consistent particle-in-cell simulations. The shocks are excited through the injection of a relativistic jet into ambient plasma, leading to two distinct shocks (referred to as the trailing shock and leading shock) and a contact discontinuity. The Weibel-like instabilities heat the electrons up to approximately half of the ion kinetic energy. The double layers formed in the trailing and leading edges then accelerate the electrons up to the ion kinetic energy. The electron distribution function in the leading edge shows a clear, non-thermal power-law tail which contains ˜1% of electrons and ˜8% of the electron energy. Its power-law index is -2.6. The acceleration efficiency is ˜23% by number and ˜50% by energy, and the power-law index is -1.8 for the electron distribution function in the trailing edge. The effect of the dimensionality is examined by comparing the results of three-dimensional simulations with those of two-dimensional simulations. The comparison demonstrates that electron acceleration is more efficient in two dimensions.

  1. Magnetic Fields Sculpt Narrow Jets From Dying Star

    NASA Astrophysics Data System (ADS)

    2006-03-01

    Molecules spewed outward from a dying star are confined into narrow jets by a tightly-wound magnetic field, according to astronomers who used the National Science Foundation's Very Long Baseline Array (VLBA) radio telescope to study an old star about 8,500 light-years from Earth. Magnetic Field Around Jet Artist's Conception Shows Tightly-Wound Magnetic Field Confining Jet CREDIT: NRAO/AUI/NSF (Click on image for larger version) The star, called W43A, in the constellation Aquila, is in the process of forming a planetary nebula, a shell of brightly-glowing gas lit by the hot ember into which the star will collapse. In 2002, astronomers discovered that the aging star was ejecting twin jets of water molecules. That discovery was a breakthrough in understanding how many planetary nebulae are formed into elongated shapes. "The next question was, what is keeping this outpouring of material confined into narrow jets? Theoreticians suspected magnetic fields, and we now have found the first direct evidence that a magnetic field is confining such a jet," said Wouter Vlemmings, a Marie Curie Fellow working at the Jodrell Bank Observatory of the University of Manchester in England. "Magnetic fields previously have been detected in jets emitted by quasars and protostars, but the evidence was not conclusive that the magnetic fields were actually confining the jets. These new VLBA observations now make that direct connection for the very first time," Vlemmings added. By using the VLBA to study the alignment, or polarization, of radio waves emitted by water molecules in the jets, the scientists were able to determine the strength and orientation of the magnetic field surrounding the jets. "Our observations support recent theoretical models in which magnetically-confined jets produce the sometimes-complex shapes we see in planetary nebulae," said Philip Diamond, also of Jodrell Bank Observatory. During their "normal" lives, stars similar to our Sun are powered by the nuclear fusion

  2. Bjorken flow in one-dimensional relativistic magnetohydrodynamics with magnetization

    NASA Astrophysics Data System (ADS)

    Pu, Shi; Roy, Victor; Rezzolla, Luciano; Rischke, Dirk H.

    2016-04-01

    We study the one-dimensional, longitudinally boost-invariant motion of an ideal fluid with infinite conductivity in the presence of a transverse magnetic field, i.e., in the ideal transverse magnetohydrodynamical limit. In an extension of our previous work Roy et al., [Phys. Lett. B 750, 45 (2015)], we consider the fluid to have a nonzero magnetization. First, we assume a constant magnetic susceptibility χm and consider an ultrarelativistic ideal gas equation of state. For a paramagnetic fluid (i.e., with χm>0 ), the decay of the energy density slows down since the fluid gains energy from the magnetic field. For a diamagnetic fluid (i.e., with χm<0 ), the energy density decays faster because it feeds energy into the magnetic field. Furthermore, when the magnetic field is taken to be external and to decay in proper time τ with a power law ˜τ-a, two distinct solutions can be found depending on the values of a and χm. Finally, we also solve the ideal magnetohydrodynamical equations for one-dimensional Bjorken flow with a temperature-dependent magnetic susceptibility and a realistic equation of state given by lattice-QCD data. We find that the temperature and energy density decay more slowly because of the nonvanishing magnetization. For values of the magnetic field typical for heavy-ion collisions, this effect is, however, rather small. It is only for magnetic fields about an order of magnitude larger than expected for heavy-ion collisions that the system is substantially reheated and the lifetime of the quark phase might be extended.

  3. The inteplanetary magnetic field associated to the propagation of solar relativistic particles

    NASA Astrophysics Data System (ADS)

    Masson, Sophie; Dasso, Sergio; Démoulin, Pasal; Klein, Karl-Ludwig

    2010-05-01

    The origin and the propagation of high energetic solar particles (450 MeV- few GeV) in the interplanetary medium remains a complex topic. These relativistic solar particles, detected at the Earth by neutron monitors (called Ground level enhancement, GLE), have been previously accelerated close to the Sun. In order to be detected at the Earth, these relativistic particles have to travel along an interplanetary magnetic field (IMF) connecting the acceleration site and the Earth. Generally, the nominal Parker spiral (SP), is considered for ensuring the magnetic connection to the Earth. However, in most of GLEs the IMF is highly disturbed, and the active regions (ARs) associated to the GLEs are not always located close to the footprint of the nominal Parker spiral. If the AR is not connected to the Earth by the nominal Parker spiral, which is the IMF connecting the acceleration site and the Earth during the GLEs? A possible explanation of relativistic particles propagation under these circumstances are transient magnetic structures, travelling in the IMF as Interplanetary coronal mass ejections (ICMEs). In order to check this interpretation, we studied in detail the magnetic connection for 10 GLEs of the last solar cycle. Using the magnetic field and the plasma parameter measurements (ACE/MAG and ACE/SWEPAM), we find that relativistic particles associated to ARs located close to the footprint of the nominal Parker spiral tend to propagate along this nominal Parker spiral (2 clear cases) or in a solar wind disturbed by a previous magnetic perturbation (3 cases). Instead, the GLEs associated to ARs which is clearly not-well connected tend to propagate in an interplanetary coronal mass ejection or in the back of a previous ICME. More specifically on the 3 not-well connected cases, two propagate in the back of an ICME and one of them propagates in the ICME. Depending in which IMF particles propagate, the path length can display significant differences. Using the velocity

  4. Giant magnetic fields and relativistic electron transport in dense, hot plasmas created on solid targets

    NASA Astrophysics Data System (ADS)

    Gattamraju, Ravindra Kumar; Shaikh, Moniruzzaman; Lad, Amit; Sarkar, Deep; Jana, Kamalesh; Dey, Indranuj

    2016-10-01

    Intense,femtosecond laser pulses generate relativistic electron pulses,important for many applications. In this paper, we present a femtosecond time-resolved and micrometer space resolved giant magnetic fields generated by 1019 W cm-2, 800 nm, 30 fs, high intensity contrast laser pulses in using pump-probe Cotton Mouton polarimetry. The space and time resolved maps of the magnetic fields at the front and rear of targets reveal turbulence in the magnetic fields. We also present data from shadowgraphy and Cherenkov emission along with model calculations to build up a picture of the transport process. GRK thanks J C Bose Fellowship Grant JCB-37/2010 for partial support.

  5. Exact two-component relativistic theory for nuclear magnetic resonance parameters.

    PubMed

    Sun, Qiming; Liu, Wenjian; Xiao, Yunlong; Cheng, Lan

    2009-08-28

    An exact two-component (X2C) relativistic theory for nuclear magnetic resonance parameters is obtained by first a single block-diagonalization of the matrix representation of the Dirac operator in a magnetic-field-dependent basis and then a magnetic perturbation expansion of the resultant two-component Hamiltonian and transformation matrices. Such a matrix formulation is not only simple but also general in the sense that the various ways of incorporating the field dependence can be treated in a unified manner. The X2C dia- and paramagnetic terms agree individually with the corresponding four-component ones up to machine accuracy for any basis.

  6. Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

    NASA Astrophysics Data System (ADS)

    Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Jörn; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, John E.; Tramper, Frank

    2011-02-01

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states." Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary's focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c 2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus, whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum dependent, none of the broad line fits allow for an inner disk radius that is >40 GM/c 2.

  7. Corona, Jet, and Relativistic Line Models for Suzaku/RXTE/Chandra-HETG Observations of the Cygnus X-1 Hard State

    NASA Technical Reports Server (NTRS)

    Nowak, Michael A.; Hanke, Manfred; Trowbridge, Sarah N.; Markoff, Sera B.; Wilms, Joern; Pottschmidt, Katja; Coppi, Paolo; Maitra, Dipankar; Davis, Jhn E.; Tramper, Frank

    2009-01-01

    Using Suzaku and the Rossi X-ray Timing Explorer (RXTE), we have conducted a series of four simultaneous observations of the galactic black hole candidate Cyg X-1 in what were historically faint and spectrally hard "low states". Additionally, all of these observations occurred near superior conjunction with our line of sight to the X-ray source passing through the dense phases of the "focused wind" from the mass donating secondary. One of our observations was also simultaneous with observations by the Chandra-High Energy Transmission Grating (HETG). These latter spectra are crucial for revealing the ionized absorption due to the secondary s focused wind. Such absorption is present and must be accounted for in all four spectra. These simultaneous data give an unprecedented view of the 0.8-300 keV spectrum of Cyg X-1, and hence bear upon both corona and X-ray emitting jet models of black hole hard states. Three models fit the spectra well: coronae with thermal or mixed thermal/non-thermal electron populations, and jets. All three models require a soft component that we fit with a low temperature disk spectrum with an inner radius of only a few tens of GM/c2. All three models also agree that the known spectral break at 10 keV is not solely due to the presence of reflection, but each gives a different underlying explanation for the augmentation of this break. Thus whereas all three models require that there is a relativistically broadened Fe line, the strength and inner radius of such a line is dependent upon the specific model, thus making premature line-based estimates of the black hole spin in the Cyg X-1 system. We look at the relativistic line in detail, accounting for the narrow Fe emission and ionized absorption detected by HETG. Although the specific relativistic parameters of the line are continuum-dependent, none of the broad line fits allow for an inner disk radius that is > 40 GM/c(sup 2).

  8. Magnetic Field Generation and Electron Acceleration in Relativistic Laser Channel

    SciTech Connect

    I.Yu. Kostyukov; G. Shvets; N.J. Fisch; J.M. Rax

    2001-12-12

    The interaction between energetic electrons and a circularly polarized laser pulse inside an ion channel is studied. Laser radiation can be resonantly absorbed by electrons executing betatron oscillations in the ion channel and absorbing angular momentum from the laser. The absorbed angular momentum manifests itself as a strong axial magnetic field (inverse Faraday effect). The magnitude of this magnetic field is calculated and related to the amount of the absorbed energy. Absorbed energy and generated magnetic field are estimated for the small and large energy gain regimes. Qualitative comparisons with recent experiments are also made.

  9. Particle energization in 3D magnetic reconnection of relativistic pair plasmas

    SciTech Connect

    Liu Wei; Yin Lin; Albright, B. J.; Bowers, K. J.; Liang, Edison P.; Li Hui

    2011-05-15

    We present large scale 3D particle-in-cell simulations to examine particle energization in magnetic reconnection of relativistic electron-positron (pair) plasmas. The initial configuration is set up as a relativistic Harris equilibrium without a guide field. These simulations are large enough to accommodate a sufficient number of tearing and kink modes. Contrary to the non-relativistic limit, the linear tearing instability is faster than the linear kink instability, at least in our specific parameters. We find that the magnetic energy dissipation is first facilitated by the tearing instability and followed by the secondary kink instability. Particles are mostly energized inside the magnetic islands during the tearing stage due to the spatially varying electric fields produced by the outflows from reconnection. Secondary kink instability leads to additional particle acceleration. Accelerated particles are, however, observed to be thermalized quickly. The large amplitude of the vertical magnetic field resulting from the tearing modes by the secondary kink modes further help thermalizing the non-thermal particles generated from the secondary kink instability. Implications of these results for astrophysics are briefly discussed.

  10. Relativistic theory of magnetic inertia in ultrafast spin dynamics

    NASA Astrophysics Data System (ADS)

    Mondal, Ritwik; Berritta, Marco; Nandy, Ashis K.; Oppeneer, Peter M.

    2017-07-01

    The influence of possible magnetic inertia effects has recently drawn attention in ultrafast magnetization dynamics and switching. Here we derive rigorously a description of inertia in the Landau-Lifshitz-Gilbert equation on the basis of the Dirac-Kohn-Sham framework. Using the Foldy-Wouthuysen transformation up to the order of 1 /c4 gives the intrinsic inertia of a pure system through the second order time derivative of magnetization in the dynamical equation of motion. Thus, the inertial damping I is a higher order spin-orbit coupling effect, ˜1 /c4 , as compared to the Gilbert damping Γ that is of order 1 /c2 . Inertia is therefore expected to play a role only on ultrashort timescales (subpicoseconds). We also show that the Gilbert damping and inertial damping are related to one another through the imaginary and real parts of the magnetic susceptibility tensor, respectively.

  11. Fluid-magnetic helicity in axisymmetric stationary relativistic magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Prasad, G.

    2017-10-01

    The present work is intended to gain a fruitful insight into the understanding of the formations of magneto-vortex configurations and their role in the physical processes of mutual exchange of energies associated with fluid's motion and the magnetic fields in an axisymmetric stationary hydromagnetic system subject to strong gravitational field (e.g., neutron star/magnetar). It is found that the vorticity flux vector field associated with vorticity 2-form is a linear combination of fluid's vorticity vector and of magnetic vorticity vector. The vorticity flux vector obeys Helmholtz's flux conservation. The energy equation associated with the vorticity flux vector field is deduced. It is shown that the mechanical rotation of vorticity flux surfaces contributes to the formation of vorticity flux vector field. The dynamo action for the generation of toroidal components of vorticity flux vector field is described in the presence of meridional circulations. It is shown that the stretching of twisting magnetic lines due to differential rotation leads to the breakdown of gravitational isorotation in the absence of meridional circulations. An explicit expression consists of rotation of vorticity flux surface, energy and angular momentum per baryon for the fluid-magnetic helicity current vector is obtained. The conservation of fluid-magnetic helicity is demonstrated. It is found that the fluid-magnetic helicity displays the energy spectrum arising due to the interaction between the mechanical rotation of vorticity flux surfaces and the fluid's motion obeying Euler's equations. The dissipation of a linear combination of modified fluid helicity and magnetic twist is shown to occur due to coupled effect of frame dragging and meridional circulation. It is found that the growing twist of magnetic lines causes the dissipation of modified fluid helicity in the absence of meridional circulations.

  12. Novel Analysis of the Multiwavelength Structure of the Relativistic Jet in Quasar 3C 273

    NASA Astrophysics Data System (ADS)

    Marchenko, Volodymyr; Harris, D. E.; Ostrowski, Michał; Stawarz, Łukasz; Bohdan, Artem; Jamrozy, Marek; Hnatyk, Bohdan

    2017-07-01

    We present a detailed analysis of the best-quality multiwavelength data gathered for the large-scale jet in the core-dominated quasar 3C 273. We analyze all the archival observations of the target with the Chandra X-ray Observatory, the far-ultraviolet observations with the Hubble Space Telescope, and the 8.4 GHz map obtained with the Very Large Array. In our study, we focus on investigating the morphology of the outflow at different frequencies, and therefore we apply various techniques for the image deconvolution, paying particular attention to a precise modeling of the Chandra and Hubble point-spread functions. We find that the prominent brightness enhancements in the X-ray and far-ultraviolet jet of 3C 273—the “knots”—are not point-like, and can be resolved transversely as extended features with sizes of about ≃ 0.5 {kpc}. Also, the radio outflow is wider than the deconvolved X-ray/ultraviolet jet. We have also found circumstantial evidence that the intensity peaks of the X-ray knots are located systematically upstream of the corresponding radio intensity peaks, with the projected spatial offsets along the jet ranging from ≲ 0.2 {kpc} up to ≃ 1 {kpc}. We discuss our findings in the wider context of multi-component models for the emission and structure of large-scale quasar jets, and speculate on the physical processes enabling an efficient acceleration of the emitting ultrarelativistic electrons along the entire jet length that exceeds 100 kpc.

  13. GENERAL RELATIVISTIC SIMULATIONS OF MAGNETIZED PLASMAS AROUND MERGING SUPERMASSIVE BLACK HOLES

    SciTech Connect

    Giacomazzo, Bruno; Baker, John G.; Van Meter, James R.; Coleman Miller, M.; Reynolds, Christopher S.

    2012-06-10

    Coalescing supermassive black hole binaries are produced by the mergers of galaxies and are the most powerful sources of gravitational waves accessible to space-based gravitational observatories. Some such mergers may occur in the presence of matter and magnetic fields and hence generate an electromagnetic counterpart. In this Letter, we present the first general relativistic simulations of magnetized plasma around merging supermassive black holes using the general relativistic magnetohydrodynamic code Whisky. By considering different magnetic field strengths, going from non-magnetically dominated to magnetically dominated regimes, we explore how magnetic fields affect the dynamics of the plasma and the possible emission of electromagnetic signals. In particular, we observe a total amplification of the magnetic field of {approx}2 orders of magnitude, which is driven by the accretion onto the binary and that leads to much stronger electromagnetic signals, more than a factor of 10{sup 4} larger than comparable calculations done in the force-free regime where such amplifications are not possible.

  14. Weibel Instability Growth Rate in Magnetized Plasmas with Quasi-Relativistic Distribution Function

    NASA Astrophysics Data System (ADS)

    Hosseini, Sayed Ahmad; Mahdavi, Mohammad

    2016-12-01

    The mechanism of the Weibel instability is investigated for dense magnetized plasmas. As we know, due to the electron velocity distribution, the Coulomb collision effect of electron-ion and the relativistic properties play an important role in such study. In this study an analytical expression for the growth rate and the condition of restricting the Weibel instability are derived for low-frequency limit. These calculations are done for the oscillation frequency dependence on the electron cyclotron frequency. It is shown that, the relativistic properties of the particle lead to increasing the growth rate of the instability. On the other hand the collision effects and background magnetic field try to decrease the growth rate by decreasing the temperature anisotropy and restricting the particles movement.

  15. Formation of hard power laws in the energetic particle spectra resulting from relativistic magnetic reconnection.

    PubMed

    Guo, Fan; Li, Hui; Daughton, William; Liu, Yi-Hsin

    2014-10-10

    Using fully kinetic simulations, we demonstrate that magnetic reconnection in relativistic plasmas is highly efficient at accelerating particles through a first-order Fermi process resulting from the curvature drift of particles in the direction of the electric field induced by the relativistic flows. This mechanism gives rise to the formation of hard power-law spectra in parameter regimes where the energy density in the reconnecting field exceeds the rest mass energy density σ ≡ B(2)/(4πnm(e)c(2))>1 and when the system size is sufficiently large. In the limit σ ≫ 1, the spectral index approaches p = 1 and most of the available energy is converted into nonthermal particles. A simple analytic model is proposed which explains these key features and predicts a general condition under which hard power-law spectra will be generated from magnetic reconnection.

  16. Nonlinear dynamics of cold magnetized non-relativistic plasma in the presence of electron-ion collisions

    SciTech Connect

    Sahu, Biswajit; Sinha, Anjana; Roychoudhury, Rajkumar

    2015-09-15

    A numerical study is presented of the nonlinear dynamics of a magnetized, cold, non-relativistic plasma, in the presence of electron-ion collisions. The ions are considered to be immobile while the electrons move with non-relativistic velocities. The primary interest is to study the effects of the collision parameter, external magnetic field strength, and the initial electromagnetic polarization on the evolution of the plasma system.

  17. RECURRENT SOLAR JETS INDUCED BY A SATELLITE SPOT AND MOVING MAGNETIC FEATURES

    SciTech Connect

    Chen, Jie; Su, Jiangtao; Yin, Zhiqiang; Priya, T. G.; Zhang, Hongqi; Xu, Haiqing; Yu, Sijie; Liu, Jihong

    2015-12-10

    Recurrent and homologous jets were observed to the west edge of active region NOAA 11513 at the boundary of a coronal hole. We find two kinds of cancellations between opposite polarity magnetic fluxes, inducing the generation of recurrent jets. First, a satellite spot continuously collides with a pre-existing opposite polarity magnetic field and causes recurrent solar jets. Second, moving magnetic features, which emerge near the sunspot penumbra, pass through the ambient plasma and eventually collide with the opposite polarity magnetic field. Among these recurrent jets, a blowout jet that occurred around 21:10 UT is investigated. The rotation of the pre-existing magnetic field and the shear motion of the satellite spot accumulate magnetic energy, which creates the possibility for the jet to experience blowout right from the standard.

  18. On parasupersymmetric oscillators and relativistic vector mesons in constant magnetic fields

    NASA Technical Reports Server (NTRS)

    Debergh, Nathalie; Beckers, Jules

    1995-01-01

    Johnson-Lippmann considerations on oscillators and their connection with the minimal coupling schemes are visited in order to introduce a new Sakata-Taketani equation describing vector mesons in interaction with a constant magnetic field. This new proposal, based on a specific parasupersymmetric oscillator-like system, is characterized by real energies as opposed to previously pointed out relativistic equations corresponding to this interacting context.

  19. Twisting space-time: relativistic origin of seed magnetic field and vorticity.

    PubMed

    Mahajan, S M; Yoshida, Z

    2010-08-27

    We demonstrate that a purely ideal mechanism, originating in the space-time distortion caused by the demands of special relativity, can break the topological constraint (leading to helicity conservation) that would forbid the emergence of a magnetic field (a generalized vorticity) in an ideal nonrelativistic dynamics. The new mechanism, arising from the interaction between the inhomogeneous flow fields and inhomogeneous entropy, is universal and can provide a finite seed even for mildly relativistic flows.

  20. Magnetic and Energy Characteristics of Recurrent Homologous Jets from an Emerging Flux

    NASA Astrophysics Data System (ADS)

    Liu, J.; Wang, Y.; Erdelyi, R.; Liu, R.; Mcintosh, S. W.; Gou, T.; Chen, J.; Liu, K.; Liu, L.; Pan, Z.

    2016-12-01

    We present the detailed analysis of recurrent homologous jets originating from an emerging negative magnetic flux at the edge of an Active Region. Detailed investigation of the related Poynting flux across the photosphere employing the HMI vector magnetic field data confirms the vital role of the emerging flux in accumulating the necessary free magnetic energy for the associated reconnection to initiate jets. The observed jets show multi-thermal features. Their evolution shows high consistence with the characteristic parameters of the emerging flux, suggesting that with more free magnetic energy, the eruptions tend to be more violent, frequent and blowout-like. The average temperature, average electron number density and axial speed are found to be similar for different jets, indicating that they should have been formed by plasmas from similar origins. Statistical analysis of the jets and their footpoint region conditions reveals a strong positive relationship between the footpoint region total 131 Å intensity enhancement and jets' length/width. Stronger linearly positive relationships also exist between the total intensity enhancement/thermal energy of the footpoint regions and jets' mass/kinetic/thermal energy, with higher cross-correlation coefficients. All the above results, together, confirm the direct relationship between the magnetic reconnection and the jets, and validate the important role of magnetic reconnection in transporting large amount of free magnetic energy into jets. It is also suggested that there should be more free energy released during the magnetic reconnection of blowout than of standard jet events.

  1. Effects of magnetic field on plasma evolution in relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Das, Arpan; Dave, Shreyansh S.; Saumia, P. S.; Srivastava, Ajit M.

    2017-09-01

    Very strong magnetic fields can arise in noncentral heavy-ion collisions at ultrarelativistic energies, and may not decay quickly in a conducting plasma. We carry out relativistic magnetohydrodynamics (RMHD) simulations to study the effects of this magnetic field on the evolution of the plasma and on resulting flow fluctuations in the ideal RMHD limit. Our results show that the magnetic field leads to enhancement in elliptic flow for small impact parameters while it suppresses it for large impact parameters (which may provide a signal for the initial stage magnetic field). Interestingly, we find that magnetic field in localized regions can temporarily increase in time as evolving plasma energy density fluctuations lead to reorganization of magnetic flux. This can have important effects on the chiral magnetic effect. The magnetic field has nontrivial effects on the power spectrum of flow fluctuations. For the very strong magnetic field case, one sees a pattern of even-odd difference in the power spectrum of flow coefficients arising from reflection symmetry about the magnetic field direction if initial state fluctuations are not dominant. We discuss the situation of nontrivial magnetic field configurations arising from collision of deformed nuclei and show that it can lead to anomalous elliptic flow. Special (crossed body-body) configurations of deformed nuclei collisions can lead to the presence of a quadrupolar magnetic field, which can have very important effects on the rapidity dependence of transverse expansion (similar to beam focusing from quadrupole fields in accelerators).

  2. Magnetic confinement of the optical jets in young stellar objects

    NASA Astrophysics Data System (ADS)

    Choe, S.-U.; Jones, T. W.

    1993-03-01

    We discuss a model for collimating plasma outflow from a young stellar object via an axial current initiated by collisionally charged dust grains incorporated in the ionized outflow from the central object. The charged grains generate an electric current in response to their greater reaction to the radiation field of the central star and their large mobility with respect to the plasma. This produces a pinching toroidal magnetic field of about 0.001 G in the base flow. A simple self-similar, steady state MHD solution shows that a well-collimated jet can result, provided this pinch is only marginally overbalanced there by the gas pressure and centrifugal acceleration associated with any rotation of the jet.

  3. Analytic theory for betatron radiation from relativistic electrons in ion plasma channels with magnetic field

    SciTech Connect

    Lee, H. C.; Jiang, T. F.

    2010-11-15

    We analytically solve the relativistic equation of motion for an electron in ion plasma channels and calculate the corresponding trajectory as well as the synchrotron radiation. The relativistic effect on a trajectory is strong, i.e., many high-order harmonic terms in the trajectory, when the ratio of the initial transverse velocity (v{sub x0}) to the longitudinal velocity (v{sub z0}) of the electron injected to ion plasma channels is high. Interestingly, these high-order harmonic terms result in a quite broad and intense radiation spectrum, especially at an oblique angle, in contrast to an earlier understanding. As the initial velocity ratio (v{sub x0}:v{sub z0}) decreases, the relativistic effect becomes weak; only the first and second harmonic terms remain in the transverse and longitudinal trajectories, respectively, which coincides with the result of Esarey et al. [Phys. Rev. E 65, 056505 (2002)]. Our formalism also allows the description of electron's trajectory in the presence of an applied magnetic field. Critical magnetic fields for cyclotron motions are figured out and compared with semiclassical results. The cyclotron motion leads to more high-order harmonic terms than the trajectory without magnetic fields and causes an immensely broad spectrum with vastly large radiation amplitude for high initial velocity ratios (v{sub x0}:v{sub z0}). The radiation from hard x-ray to gamma-ray regions can be generated with a broad radiation angle, thus available for applications.

  4. Nonlinear electrostatic excitations in magnetized dense plasmas with nonrelativistic and ultra-relativistic degenerate electrons

    SciTech Connect

    Mahmood, S.; Sadiq, Safeer; Haque, Q.

    2013-12-15

    Linear and nonlinear electrostatic waves in magnetized dense electron-ion plasmas are studied with nonrelativistic and ultra-relativistic degenerate and singly, doubly charged helium (He{sup +}, He{sup ++}) and hydrogen (H{sup +}) ions, respectively. The dispersion relation of electrostatic waves in magnetized dense plasmas is obtained under both the energy limits of degenerate electrons. Using reductive perturbation method, the Zakharov-Kuznetsov equation for nonlinear propagation of electrostatic solitons in magnetized dense plasmas is derived for both nonrelativistic and ultra-relativistic degenerate electrons. It is found that variations in plasma density, magnetic field intensity, different mass, and charge number of ions play significant role in the formation of electrostatic solitons in magnetized dense plasmas. The numerical plots are also presented for illustration using the parameters of dense astrophysical plasma situations such as white dwarfs and neutron stars exist in the literature. The present investigation is important for understanding the electrostatic waves propagation in the outer periphery of compact stars which mostly consists of hydrogen and helium ions with degenerate electrons in dense magnetized plasmas.

  5. Pressure of Degenerate and Relativistic Electrons in a Superhigh Magnetic Field

    NASA Astrophysics Data System (ADS)

    Gao, Zhi Fu; Wang, Na; Peng, Qiu He; Li, Xiang Dong; Du, Yuan Jie

    2013-11-01

    Based on our previous work, we deduce a general formula for pressure of degenerate and relativistic electrons, Pe, which is suitable for superhigh magnetic fields, discuss the quantization of Landau levels of electrons, and consider the quantum electrodynamic (QED) effects on the equations of states (EOSs) for different matter systems. The main conclusions are as follows: Pe is related to the magnetic field B, matter density ρ, and electron fraction Ye; the stronger the magnetic field, the higher the electron pressure becomes; the high electron pressure could be caused by high Fermi energy of electrons in a superhigh magnetic field; compared with a common radio pulsar, a magnetar could be a more compact oblate spheroid-like deformed neutron star (NS) due to the anisotropic total pressure; and an increase in the maximum mass of a magnetar is expected because of the positive contribution of the magnetic field energy to the EOS of the star.

  6. Three-dimensional fast magnetic reconnection driven by relativistic ultraintense femtosecond lasers.

    PubMed

    Ping, Y L; Zhong, J Y; Sheng, Z M; Wang, X G; Liu, B; Li, Y T; Yan, X Q; He, X T; Zhang, J; Zhao, G

    2014-03-01

    Three-dimensional fast magnetic reconnection driven by two ultraintense femtosecond laser pulses is investigated by relativistic particle-in-cell simulation, where the two paralleled incident laser beams are shot into a near-critical plasma layer to form a magnetic reconnection configuration in self-generated magnetic fields. A reconnection X point and out-of-plane quadrupole field structures associated with magnetic reconnection are formed. The reconnection rate is found to be faster than that found in previous two-dimensional Hall magnetohydrodynamic simulations and electrostatic turbulence contribution to the reconnection electric field plays an essential role. Both in-plane and out-of-plane electron and ion accelerations up to a few MeV due to the magnetic reconnection process are also obtained.

  7. The different energy loss mechanisms of inclusive and b-tagged reconstructed jets within ultra-relativistic heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Senzel, F.; Uphoff, J.; Xu, Z.; Greiner, C.

    2017-10-01

    The phenomenon of jet quenching provides essential information about the properties of hot and dense matter created in ultra-relativistic heavy-ion collisions. Recent results from experiments at the Large Hadron Collider (LHC) show evidence for an unexpectedly similar suppression of both light and heavy flavor jets. Furthermore, the role of radiative energy loss of heavy quarks is still under active discussion within the theoretical community. By employing the parton cascade Boltzmann Approach to Multi-Parton Scatterings (BAMPS), which numerically solves the 3 + 1 D Boltzmann equation both for light and heavy flavor partons, we calculate the nuclear modification factor of inclusive and b-tagged reconstructed jets in 0-10% central √{s}LHC = 2.76 A TeV Pb + Pb collisions. Based on perturbative QCD cross sections we find a suppression of both light and heavy flavor jets. While the inclusive jets are slightly too strong suppressed within BAMPS in comparison with data, both elastic + radiative and only elastic interactions lead to a realistic b-tagged jet suppression. To further investigate light and heavy flavor energy loss we predict the R dependence of inclusive and b-tagged jet suppression. Furthermore, we propose the medium modification of b-tagged jet shapes as an observable for discriminating between different heavy quark energy loss scenarios.

  8. High frequency electromagnetic modes in a weakly magnetized relativistic electron plasma

    SciTech Connect

    Abbas, Gohar; Murtaza, G.; Kingham, R. J.

    2010-07-15

    Using the linearized Vlasov-Maxwell model, the polarization tensor for a weakly magnetized electron plasma is derived. For isotropic relativistic Maxwellian velocity distribution function, dispersion relations are obtained for both parallel and perpendicular propagations. The integrals (called Meijer G functions) that arise due to relativistic effects are examined in various limits and dispersion relations are derived for the nonrelativistic, weakly, strongly, and ultrarelativistic Maxwellian velocity distributions. It is generally observed that the propagation domains of the modes are enlarged as one proceeds from the nonrelativistic to the highly relativistic regime. Resultantly, due to the relativistic effects, the Whistler mode is suppressed in the R-wave, the nonpropagation band of X-mode is reduced, and the X-mode itself approaches the O-mode. Further, the results derived in the ultra- and nonrelativistic limits found to be in agreement with the earlier calculations [G. Abbas et al. Phys. Scr. 76, 649 (2007); F. F. Chen, Introduction to Plasma Physics and Controlled Fusion (Plenum, New York, 1984), Vol. 1].

  9. High frequency electromagnetic modes in a weakly magnetized relativistic electron plasma

    NASA Astrophysics Data System (ADS)

    Abbas, Gohar; Murtaza, G.; Kingham, R. J.

    2010-07-01

    Using the linearized Vlasov-Maxwell model, the polarization tensor for a weakly magnetized electron plasma is derived. For isotropic relativistic Maxwellian velocity distribution function, dispersion relations are obtained for both parallel and perpendicular propagations. The integrals (called Meijer G functions) that arise due to relativistic effects are examined in various limits and dispersion relations are derived for the nonrelativistic, weakly, strongly, and ultrarelativistic Maxwellian velocity distributions. It is generally observed that the propagation domains of the modes are enlarged as one proceeds from the nonrelativistic to the highly relativistic regime. Resultantly, due to the relativistic effects, the Whistler mode is suppressed in the R-wave, the nonpropagation band of X-mode is reduced, and the X-mode itself approaches the O-mode. Further, the results derived in the ultra- and nonrelativistic limits found to be in agreement with the earlier calculations [G. Abbas et al. Phys. Scr. 76, 649 (2007); F. F. Chen, Introduction to Plasma Physics and Controlled Fusion (Plenum, New York, 1984), Vol. 1].

  10. Dynamics of Magnetized Plasma Jets and Bubbles Launched into a Background Magnetized Plasma

    NASA Astrophysics Data System (ADS)

    Wallace, B.; Zhang, Y.; Fisher, D. M.; Gilmore, M.

    2016-10-01

    The propagation of dense magnetized plasma, either collimated with mainly azimuthal B-field (jet) or toroidal with closed B-field (bubble), in a background plasma occurs in a number of solar and astrophysical cases. Such cases include coronal mass ejections moving in the background solar wind and extragalactic radio lobes expanding into the extragalactic medium. Understanding the detailed MHD behavior is crucial for correctly modeling these events. In order to further the understanding of such systems, we are investigating the injection of dense magnetized jets and bubbles into a lower density background magnetized plasma using a coaxial plasma gun and a background helicon or cathode plasma. In both jet and bubble cases, the MHD dynamics are found to be very different when launched into background plasma or magnetic field, as compared to vacuum. In the jet case, it is found that the inherent kink instability is stabilized by velocity shear developed due to added magnetic tension from the background field. In the bubble case, rather than directly relaxing to a minimum energy Taylor state (spheromak) as in vacuum, there is an expansion asymmetry and the bubble becomes Rayleigh-Taylor unstable on one side. Recent results will be presented. Work supported by the Army Research Office Award No. W911NF1510480.

  11. Special relativistic magnetohydrodynamic simulation of two-component outflow powered by magnetic explosion on compact stars

    NASA Astrophysics Data System (ADS)

    Matsumoto, Jin; Masada, Youhei; Asano, Eiji; Shibata, Kazunari

    2011-06-01

    The nonlinear dynamics of the outflow driven by magnetic explosion on the surface of compact object is investigated through special relativistic magnetohydrodynamic simulations. We adopt, as an initial equilibrium state, a spherical stellar object embedded in the hydrostatic plasma which has a density ρ(r) ~ r-α and is threaded by a dipole magnetic field. The injection of magnetic energy at the surface of compact star breaks the dynamical equilibrium and triggers two-component outflow. At the early evolutionary stage, the magnetic pressure increases rapidly in time around the stellar surface, initiating a magnetically driven outflow. Then it excites a strong forward shock, shock driven outflow. The expansion velocity of the magnetically driven outflow is characterized by the Alfvén velocity on the stellar surface, and follows a simple scaling relation υmag ~ υA1/2. When the initial density profile declines steeply with radius, the strong shock is accelerated self-similarly to relativistic velocity ahead of the magnetically driven component. We find that the evolution of the strong forward shock can be described by a self-similar relation Γsh ~ rsh, where Γsh is the Lorentz factor of the plasma measured at the shock surface rsh. It should be stressed that the pure hydrodynamic process is responsible for the acceleration of the shock driven outflow. Our two-component outflow model, which is the natural outcome of the magnetic explosion, would deepen the understanding of the magnetic active phenomena on various magnetized stellar objects.

  12. Pair production rates in mildly relativistic, magnetized plasmas

    NASA Technical Reports Server (NTRS)

    Burns, M. L.; Harding, A. K.

    1984-01-01

    Electron-positron pairs may be produced by either one or two photons in the presence of a strong magnetic field. In magnetized plasmas with temperatures kT approximately sq mc, both of these processes may be important and could be competitive. The rates of one-photon and two-photon pair production by photons with Maxwellian, thermal bremsstrahlung, thermal synchrotron and power law spectra are calculated as a function of temperature or power law index and field strength. This allows a comparison of the two rates and a determination of the conditions under which each process may be a significant source of pairs in astrophysical plasmas. It is found that for photon densities n(gamma) or = 10 to the 25th power/cu cm and magnetic field strengths B or = 10 to the 12th power G, one-photon pair production dominates at kT approximately sq mc for a Maxwellian, at kT approximately 2 sq mc for a thermal bremsstrahlung spectrum, at all temperatures for a thermal synchrotron spectrum, and for power law spectra with indices s approximately 4.

  13. Large Hubble Survey Confirms Link between Mergers and Supermassive Black Holes with Relativistic Jets

    NASA Image and Video Library

    2017-09-28

    Tidal disruption event Every galaxy has a black hole at its center. Usually they are quiet, without gas accretions, like the one in our Milky Way. But if a star creeps too close to the black hole, the gravitational tides can rip away the star’s gaseous matter. Like water spinning around a drain, the gas swirls into a disk around the black hole at such speeds that it heats to millions of degrees. As an inner ring of gas spins into the black hole, gas particles shoot outward from the black hole’s polar regions. Like bullets shot from a rifle, they zoom through the jets at velocities close to the speed of light. Astronomers using NASA’s Hubble Space Telescope observed correlations between supermassive black holes and an event similar to tidal disruption, pictured above in the Centaurus A galaxy. Certain galaxies have shining centers, illuminated by heated gas circling around a supermassive black hole. Matter escapes where it can, forming two jets of plasma moving near the speed of light. To learn more about the relationship between galaxies and the black holes at their cores, go to NASA’s Hubble Space Telescope: www.nasa.gov/mission_pages/hubble/main/ -------------------------------- Original caption: A team of astronomers using the Hubble Space Telescope found an unambiguous link between the presence of supermassive black holes that power high-speed, radio-signal-emitting jets and the merger history of their host galaxies. Almost all galaxies with the jets were found to be merging with another galaxy, or to have done so recently. Credit: NASA/ESA/STScI NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  14. The extent of power-law energy spectra in collisionless relativistic magnetic reconnection in pair plasma

    DOE PAGES

    Werner, G. R.; Uzdensky, D. A.; Cerutti, B.; ...

    2015-12-30

    Using two-dimensional particle-in-cell simulations, we characterize the energy spectra of particles accelerated by relativistic magnetic reconnection (without guide field) in collisionless electron–positron plasmas, for a wide range of upstream magnetizations σ and system sizes L. The particle spectra are well-represented by a power lawmore » $${\\gamma }^{-\\alpha }$$, with a combination of exponential and super-exponential high-energy cutoffs, proportional to σ and L, respectively. As a result, for large L and σ, the power-law index α approaches about 1.2.« less

  15. The extent of power-law energy spectra in collisionless relativistic magnetic reconnection in pair plasma

    SciTech Connect

    Werner, G. R.; Uzdensky, D. A.; Cerutti, B.; Nalewajko, K.; Begelman, M. C.

    2015-12-30

    Using two-dimensional particle-in-cell simulations, we characterize the energy spectra of particles accelerated by relativistic magnetic reconnection (without guide field) in collisionless electron–positron plasmas, for a wide range of upstream magnetizations σ and system sizes L. The particle spectra are well-represented by a power law ${\\gamma }^{-\\alpha }$, with a combination of exponential and super-exponential high-energy cutoffs, proportional to σ and L, respectively. As a result, for large L and σ, the power-law index α approaches about 1.2.

  16. On the asymptotic balance between electric and magnetic energies for hydromagnetic relativistic flows

    SciTech Connect

    Núñez, Manuel

    2013-06-15

    In the equations of classical magnetohydrodynamics, the displacement current is considered vanishingly small due to low plasma velocities. For velocities comparable to the speed of light, the full relativistic electromagnetic equations must be used. In the absence of gravitational forcings and with an isotropic Ohm's law, it is proved that for poloidal magnetic field and velocity and toroidal electric field, the electric and magnetic energies tend to be equivalent in average for large times. This represents a partial extension of Cowling's theorem for axisymmetric fields.

  17. Magnetic-Field-Induced Relativistic Properties in Type-I and Type-II Weyl Semimetals

    NASA Astrophysics Data System (ADS)

    Tchoumakov, Serguei; Civelli, Marcello; Goerbig, Mark O.

    2016-08-01

    We investigate Weyl semimetals with tilted conical bands in a magnetic field. Even when the cones are overtilted (type-II Weyl semimetal), Landau-level quantization can be possible as long as the magnetic field is oriented close to the tilt direction. Most saliently, the tilt can be described within the relativistic framework of Lorentz transformations that give rise to a rich spectrum, displaying new transitions beyond the usual dipolar ones in the optical conductivity. We identify particular features in the latter that allow one to distinguish between semimetals of different types.

  18. The interplanetary magnetic field associated with the propagation of solar relativistic particles

    NASA Astrophysics Data System (ADS)

    Masson, Sophie; Dasso, Sergio; Demoulin, Pascal

    The origin and the propagation of relativistic solar particles (450 MeV-few GeV) in the inter-planetary medium remains a complex topic. These particles, detected at the Earth by neutron monitors (called Ground level enhancement, GLE), have been previously accelerated close to the Sun. Before being detected at the Earth, these relativistic particles have to travel along an interplanetary magnetic field (IMF) connecting the acceleration site and the Earth. Generally, the nominal Parker spiral (SP), is considered for ensuring the magnetic connection to the Earth. However, in most GLEs the IMF is highly disturbed, and the active regions (ARs) associated to the GLEs are not always located close to the footprint of the nominal Parker spiral. If it is not the nominal Parker spiral, which IMF connects the acceleration site and the Earth during the GLEs? A possible explanation of relativistic particles propagation under these circumstances are transient magnetic structures, travelling in the IMF as Interplanetary coronal mass ejections (ICMEs). In order to check this interpretation, we studied in detail the interplanetary medium in which 10 GLEs of the last solar cycle propagate. Using the magnetic field and the plasma parameter measurements (ACE/MAG and ACE/SWEPAM), we found widely different IMF configurations. Those included obvious cases of propagation in an ICME, as well as some cases consistent with a Parker Spiral. But, we also found cases correponding to the propagation of relativistic particles in a highly disturbed Parker like IMF. In an independant approach we applied the velocity dispersion method (VDA) to energetic protons measured by SoHO/ERNE and relativistic particles measured by the neutron monitor network. We determined the path length travelled by energetic particles. These lengths are fully consistent with the IMF shape determined previously. Thus, the length associated to particles propagating along the nominal Parker spiral is of the order of 1-1.2 AU

  19. THREE-DIMENSIONAL RELATIVISTIC MAGNETOHYDRODYNAMIC SIMULATIONS OF CURRENT-DRIVEN INSTABILITY WITH A SUB-ALFVENIC JET: TEMPORAL PROPERTIES

    SciTech Connect

    Mizuno, Yosuke; Nishikawa, Ken-Ichi; Hardee, Philip E.

    2011-06-10

    We have investigated the influence of a velocity shear surface on the linear and nonlinear development of the current-driven (CD) kink instability of force-free helical magnetic equilibria in three dimensions. In this study, we follow the temporal development within a periodic computational box and concentrate on flows that are sub-Alfvenic on the cylindrical jet's axis. Displacement of the initial force-free helical magnetic field leads to the growth of CD kink instability. We find that helically distorted density structure propagates along the jet with speed and flow structure dependent on the radius of the velocity shear surface relative to the characteristic radius of the helically twisted force-free magnetic field. At small velocity shear surface radius, the plasma flows through the kink with minimal kink propagation speed. The kink propagation speed increases as the velocity shear radius increases and the kink becomes more embedded in the plasma flow. A decreasing magnetic pitch profile and faster flow enhance the influence of velocity shear. Simulations show continuous transverse growth in the nonlinear phase of the instability. The growth rate of the CD kink instability and the nonlinear behavior also depend on the velocity shear surface radius and flow speed, and the magnetic pitch radial profile. Larger velocity shear radius leads to slower linear growth, makes a later transition to the nonlinear stage, and with larger maximum amplitude than that occuring for a static plasma column. However, when the velocity shear radius is much greater than the characteristic radius of the helical magnetic field, linear and nonlinear development can be similar to the development of a static plasma column.

  20. Dielectric tensor of a weakly relativistic, nonequilibrium, and magnetized plasma

    NASA Technical Reports Server (NTRS)

    Tsai, S. T.; Wu, C. S.; Wang, Y. D.; Kang, S. W.

    1981-01-01

    The dielectric tensor of a magnetized plasma is investigated in order to obtain analytic expressions which can be used to study wave-plasma interactions for the case of wave frequencies lying close to the cyclotron harmonics of ions or electrons. Work on this topic by Trubnikov (1959) and Shkarovsky (1966) is extended to the nonequilibrium cases, in which the particles may have drift motions, thermal anisotropy, and loss-cone-type distributions. Account is taken of these features, and a set of analytic expressions in terms of an integral is derived. The discussion presented is pertinent to the absorption and emission of radiation near the electron cyclotron harmonics.

  1. Modified magnetic field distribution in relativistic magnetron with diffraction output for compact operation

    NASA Astrophysics Data System (ADS)

    Li, Wei; Liu, Yong-gui

    2011-02-01

    A modified magnetic field distribution in relativistic magnetron with diffraction output (MDO) for compact operation is proposed in this paper. The principle of how the modified magnetic field confines electrons drifting out of the interaction space is analyzed. The results of the particle-in-cell (PIC) simulations of the MDO with the modified magnetic field distribution show that the output power of the MDO is improved, and the long cylindrical waveguide used for collecting the drifting electrons can be omitted. The latter measure allows the horn antenna of the MDO to produce more focused energy with better directivity in the far field than it does with the long cylindrical waveguide. The MDO with the modified magnetic field distribution promises to be the real most compact narrow band high power microwave source.

  2. Magnetohydrodynamic Effects in Propagating Relativistic Ejecta: Reverse Shock and Magnetic Acceleration

    NASA Technical Reports Server (NTRS)

    Mizuno, Y.; Nishikawa, K.I.; Zhang, B.; Giacomazzo, B.; Hardee, P.E.; Nagataki, S.; Hartmann, D.H.

    2008-01-01

    We solve the Riemann problem for the deceleration of arbitrarily magnetized relativistic ejecta injected into a static unmagnetized medium. We find that for the same initial Lorentz factor, the reverse shock becomes progressively weaker with increasing magnetization s (the Poynting-to-kinetic energy flux ratio), and the shock becomes a rarefaction wave when s exceeds a critical value, sc, defined by the balance between the magnetic pressure in the ejecta and the thermal pressure in the forward shock. In the rarefaction wave regime, we find that the rarefied region is accelerated to a Lorentz factor that is significantly larger than the initial value. This acceleration mechanism is due to the strong magnetic pressure in the ejecta.

  3. Relativistic wave-induced splitting of the Langmuir mode in a magnetized plasma.

    PubMed

    Robiche, J; Rax, J M

    2008-01-01

    A relativistic effect that occurs in a magnetized plasma irradiated by a circularly polarized wave is identified and analyzed: the usual plasma frequency associated with longitudinal oscillations splits into two new frequencies. We set up a Hamiltonian description of the plasma dynamic in order to identify this effect that results from the coupling between the plasma oscillation and the transverse circular motion driven by both the magnetic and wave fields. Within the small oscillations approximation, we compute for right- and left-handed polarization the two characteristics frequencies of the electron oscillations as functions of the field and wave parameters. We also describe the electron trajectories in the wave, magnetic, and restoring plasma fields. This new class of oscillations is rotational and therefore radiate suggesting a method for the diagnostics of strong static magnetic field in laser-plasma experiments.

  4. Relativistic Particle Population and Magnetic Fields in Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Kushnir, Doron

    2011-08-01

    We derive constrains on the cosmic ray (CR) population and magnetic fields (MF) in clusters of galaxies, based on: 1. The correlation between the radio and the X-ray luminosities: the former emitted by synchrotron of secondary electrons in a strong MF, >˜3 muG; In the core, the CR energy is ˜10^{-3} of the thermal energy; The source of CR is the accretion shock (AS), which accelerate CR with efficiency >˜1%. 2. The HXR luminosity: emitted by IC of CMB photons by electrons accelerated in AS with efficiency >˜1%. The constrains imply that gamma-ray emission from secondaries will be difficult to detect with existing/planned instruments. However, the extended emission from primary electrons might be detected by future HXR (NuStar, Simbol-X) and gamma-ray observations (Fermi, HESS, VERITAS).

  5. Enhancement of threshold electric field for relativistic runaway electrons due to magnetic fluctuation and synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Li, Shucai; Wang, Lu; Chen, Zhongyong; Huang, Duwei; Tong, Ruihai

    2016-10-01

    The dynamics of relativistic electrons are analyzed using the relativistic Fokker-Planck equation including deceleration due to synchrotron radiation (SR) and radial diffusion loss caused by magnetic fluctuation (MF). Threshold electric field for avalanche growth is enhanced, and the growth rate is reduced by the combined effect of MF and SR as compared to the case with only SR. The threshold electric field is determined by the time scales balance between momentum evolution and radial diffusion loss induced by MF, and increased with level of MF. More importantly, the hysteresis behavior of runaway pointed out by does not exist anymore. This is because the ``seed electrons'' cannot be sustained as a result of diffusion loss. This work was supported by NSFC Grant No. 11305071, and the Ministry of Science and technology of China, under Contract Nos. 2013GB112002, 2015GB111002 and 2015GB111001.

  6. Pitch angle scattering of relativistic electrons near electromagnetic ion cyclotron resonances in diverging magnetic fields

    NASA Astrophysics Data System (ADS)

    Eliasson, B.; Papadopoulos, K.

    2017-10-01

    A theoretical study of the propagation of left-hand polarized shear Alfvén waves in spatially decreasing magnetic field geometries near the EMIC resonance, including the spectrum and amplitude of the mode converted EMIC waves and the pitch angle scattering of relativistic electrons transiting the resonant region, is presented. The objective of the paper is to motivate an experimental study of the subject using the UCLA LAPD chamber. The results are relevant in exploring the possibility that shear Alfvén waves strategically injected into the radiation belts using either ionospheric heating from ground based RF transmitters or injected by transmitters based on space platforms can enhance the precipitation rate of trapped relativistic electrons. Effects of multi-ionic composition are also investigated.

  7. GAMMA-RAY BURSTS FROM MAGNETIZED COLLISIONALLY HEATED JETS

    SciTech Connect

    Vurm, Indrek; Beloborodov, Andrei M.; Poutanen, Juri E-mail: juri.poutanen@oulu.fi

    2011-09-01

    Jets producing gamma-ray bursts (GRBs) are likely to carry a neutron component that drifts with respect to the proton component. The neutron-proton collisions strongly heat the jet and generate electron-positron pairs. We investigate radiation produced by this heating using a new numerical code. Our results confirm the recent claim that collisional heating generates the observed Band-type spectrum of GRBs. We extend the model to study the effects of magnetic fields on the emitted spectrum. We find that the spectrum peak remains near 1 MeV for the entire range of the magnetization parameter 0 < {epsilon}{sub B} < 2 that is explored in our simulations. The low-energy part of the spectrum softens with increasing {epsilon}{sub B}, and a visible soft excess appears in the keV band. The high-energy part of the spectrum extends well above the GeV range and can contribute to the prompt emission observed by Fermi/LAT. Overall, the radiation spectrum created by the collisional mechanism appears to agree with observations, with no fine tuning of parameters.

  8. Electron Weibel instability in relativistic counterstreaming plasmas with flow-aligned external magnetic fields.

    PubMed

    Grassi, A; Grech, M; Amiranoff, F; Pegoraro, F; Macchi, A; Riconda, C

    2017-02-01

    The Weibel instability driven by two symmetric counterstreaming relativistic electron plasmas, also referred to as current-filamentation instability, is studied in a constant and uniform external magnetic field aligned with the plasma flows. Both the linear and nonlinear stages of the instability are investigated using analytical modeling and particle-in-cell simulations. While previous studies have already described the stabilizing effect of the magnetic field, we show here that the saturation stage is only weakly affected. The different mechanisms responsible for the saturation are discussed in detail in the relativistic cold fluid framework considering a single unstable mode. The application of an external field leads to a slight increase of the saturation level for large wavelengths, while it does not affect the small wavelengths. Multimode and temperature effects are then investigated. While at high temperature the saturation level is independent of the external magnetic field, at low but finite temperature the competition between different modes in the presence of an external magnetic field leads to a saturation level lower with respect to the unmagnetized case.

  9. Electron Weibel instability in relativistic counterstreaming plasmas with flow-aligned external magnetic fields

    NASA Astrophysics Data System (ADS)

    Grassi, A.; Grech, M.; Amiranoff, F.; Pegoraro, F.; Macchi, A.; Riconda, C.

    2017-02-01

    The Weibel instability driven by two symmetric counterstreaming relativistic electron plasmas, also referred to as current-filamentation instability, is studied in a constant and uniform external magnetic field aligned with the plasma flows. Both the linear and nonlinear stages of the instability are investigated using analytical modeling and particle-in-cell simulations. While previous studies have already described the stabilizing effect of the magnetic field, we show here that the saturation stage is only weakly affected. The different mechanisms responsible for the saturation are discussed in detail in the relativistic cold fluid framework considering a single unstable mode. The application of an external field leads to a slight increase of the saturation level for large wavelengths, while it does not affect the small wavelengths. Multimode and temperature effects are then investigated. While at high temperature the saturation level is independent of the external magnetic field, at low but finite temperature the competition between different modes in the presence of an external magnetic field leads to a saturation level lower with respect to the unmagnetized case.

  10. Investigation of recurrent EUV jets from highly dynamic magnetic field region

    NASA Astrophysics Data System (ADS)

    Joshi, Navin Chandra; Chandra, Ramesh; Guo, Yang; Magara, Tetsuya; Zhelyazkov, Ivan; Moon, Young-Jae; Uddin, Wahab

    2017-01-01

    In this work, we present observations and interpretations of recurrent extreme ultraviolet (EUV) jets that occurred between 2012 July 1 21:00 UT and 2012 July 2 10:00 UT from the western edge of the NOAA active region 11513. Solar Dynamics Observatory/Atmospheric Imaging Assembly ( SDO/AIA), SDO/Helioseismic and Magnetic Imager ( SDO/HMI) and Reuven Ramaty High Energy Solar Spectroscopic Imager ( RHESSI) observations have been used for the present study. Observations as well as potential-field source-surface (PFSS) extrapolation suggest an open field configuration in the vicinity of the jet activity area. 18 EUV jets were observed from the western edge of the active region along the open field channel. All the jet events appeared to be non-homologous and show different morphological properties and evolution. Some of the jets were small and narrow in size while the others were huge and wide. The average speed of these jets ranges from {˜}47 to {˜}308 km s^{-1}. SDO/AIA 171 Å intensity profiles at the base of these jets show bumps corresponding to each jet, which is an evidence of recurrent magnetic reconnections. The magnetic field observation at the foot points of the jets revealed a very complex and dynamic magnetic activity which includes flux emergence, flux cancellation, dynamic motions, merging, separation, etc. We suggest that the recurrent jets are the result of recurrent magnetic reconnections among the various emerging bipolar fields themselves as well as with the open fields.

  11. Two-dimensional relativistic longitudinal Green's function in the presence of a moving planar dielectric-magnetic discontinuity.

    PubMed

    Danov, Tatiana; Melamed, Timor

    2012-03-01

    The current contribution is concerned with obtaining the relativistic two-dimensional (three-dimensional in relativity jargon) Green's function of a time-harmonic line current that is embedded in a moving dielectric-magnetic medium with a planar discontinuity. By applying a plane-wave (PW) spectral representation for the relativistic electromagnetic Green's function of a dielectric-magnetic medium that is moving in a uniform velocity, the exact reflected and transmitted (refracted) fields are obtained in the form of a spectral integral over PWs in the so-called laboratory and comoving frames. We investigate these spectral representations, as well as their asymptotic evaluations, and discuss the associated relativistic wave phenomena of direct reflected/transmitted rays and relativistic head waves (lateral waves).

  12. On the Distribution of Particle Acceleration Sites in Plasmoid-dominated Relativistic Magnetic Reconnection

    NASA Astrophysics Data System (ADS)

    Nalewajko, Krzysztof; Uzdensky, Dmitri A.; Cerutti, Benoît; Werner, Gregory R.; Begelman, Mitchell C.

    2015-12-01

    We investigate the distribution of particle acceleration sites, independently of the actual acceleration mechanism, during plasmoid-dominated, relativistic collisionless magnetic reconnection by analyzing the results of a particle-in-cell numerical simulation. The simulation is initiated with Harris-type current layers in pair plasma with no guide magnetic field, negligible radiative losses, no initial perturbation, and using periodic boundary conditions. We find that the plasmoids develop a robust internal structure, with colder dense cores and hotter outer shells, that is recovered after each plasmoid merger on a dynamical timescale. We use spacetime diagrams of the reconnection layers to probe the evolution of plasmoids, and in this context we investigate the individual particle histories for a representative sample of energetic electrons. We distinguish three classes of particle acceleration sites associated with (1) magnetic X-points, (2) regions between merging plasmoids, and (3) the trailing edges of accelerating plasmoids. We evaluate the contribution of each class of acceleration sites to the final energy distribution of energetic electrons: magnetic X-points dominate at moderate energies, and the regions between merging plasmoids dominate at higher energies. We also identify the dominant acceleration scenarios, in order of decreasing importance: (1) single acceleration between merging plasmoids, (2) single acceleration at a magnetic X-point, and (3) acceleration at a magnetic X-point followed by acceleration in a plasmoid. Particle acceleration is absent only in the vicinity of stationary plasmoids. The effect of magnetic mirrors due to plasmoid contraction does not appear to be significant in relativistic reconnection.

  13. ON THE DISTRIBUTION OF PARTICLE ACCELERATION SITES IN PLASMOID-DOMINATED RELATIVISTIC MAGNETIC RECONNECTION

    SciTech Connect

    Nalewajko, Krzysztof; Cerutti, Benoit; Begelman, Mitchell C.

    2015-12-20

    We investigate the distribution of particle acceleration sites, independently of the actual acceleration mechanism, during plasmoid-dominated, relativistic collisionless magnetic reconnection by analyzing the results of a particle-in-cell numerical simulation. The simulation is initiated with Harris-type current layers in pair plasma with no guide magnetic field, negligible radiative losses, no initial perturbation, and using periodic boundary conditions. We find that the plasmoids develop a robust internal structure, with colder dense cores and hotter outer shells, that is recovered after each plasmoid merger on a dynamical timescale. We use spacetime diagrams of the reconnection layers to probe the evolution of plasmoids, and in this context we investigate the individual particle histories for a representative sample of energetic electrons. We distinguish three classes of particle acceleration sites associated with (1) magnetic X-points, (2) regions between merging plasmoids, and (3) the trailing edges of accelerating plasmoids. We evaluate the contribution of each class of acceleration sites to the final energy distribution of energetic electrons: magnetic X-points dominate at moderate energies, and the regions between merging plasmoids dominate at higher energies. We also identify the dominant acceleration scenarios, in order of decreasing importance: (1) single acceleration between merging plasmoids, (2) single acceleration at a magnetic X-point, and (3) acceleration at a magnetic X-point followed by acceleration in a plasmoid. Particle acceleration is absent only in the vicinity of stationary plasmoids. The effect of magnetic mirrors due to plasmoid contraction does not appear to be significant in relativistic reconnection.

  14. Astrophysical ZeV acceleration in the relativistic jet from an accreting supermassive blackhole

    NASA Astrophysics Data System (ADS)

    Ebisuzaki, Toshikazu; Tajima, Toshiki

    2014-04-01

    An accreting supermassive blackhole, the central engine of active galactic nucleus (AGN), is capable of exciting extreme amplitude Alfven waves whose wavelength (wave packet) size is characterized by its clumpiness. The pondermotive force and wakefield are driven by these Alfven waves propagating in the AGN (blazar) jet, and accelerate protons/nuclei to extreme energies beyond Zetta-electron volt (ZeV=1021 eV). Such acceleration is prompt, localized, and does not suffer from the multiple scattering/bending enveloped in the Fermi acceleration that causes excessive synchrotron radiation loss beyond 1019 eV. The production rate of ZeV cosmic rays is found to be consistent with the observed gamma-ray luminosity function of blazars and their time variabilities.

  15. Aharonov-Bohm scattering of relativistic Dirac particles with an anomalous magnetic moment

    SciTech Connect

    Lin Qionggui

    2005-10-15

    The Aharonov-Bohm scattering of relativistic spin-1/2 particles with an anomalous magnetic moment are studied. The scattering cross sections for unpolarized and polarized particles are obtained by solving the Dirac-Pauli equation. It is somewhat unexpected that the results are in general the same as those for particles without an anomalous magnetic moment. However, when the incident energy takes some special values, the cross section for polarized particles is dramatically changed. In these cases the helicity of scattered particles is not conserved. In particular, the helicity of particles scattered in the backward direction is all reversed. In the nonrelativistic limit, a very simple relation between the polarized directions of the incident and scattered particles is found, for both general and special incident energies. For particles without an anomalous magnetic moment this relation can be drawn from previous results but it appears to be unnoticed.

  16. RICHTMYER-MESHKOV-TYPE INSTABILITY OF A CURRENT SHEET IN A RELATIVISTICALLY MAGNETIZED PLASMA

    SciTech Connect

    Inoue, Tsuyoshi

    2012-11-20

    The linear stability of a current sheet that is subject to an impulsive acceleration due to shock passage with the effect of a guide magnetic field is studied. We find that a current sheet embedded in relativistically magnetized plasma always shows a Richtmyer-Meshkov-type instability, while the stability depends on the density structure in the Newtonian limit. The growth of the instability is expected to generate turbulence around the current sheet, which can induce the so-called turbulent reconnection, the rate of which is essentially free from plasma resistivity. Thus, the instability can be applied as a triggering mechanism for rapid magnetic energy release in a variety of high-energy astrophysical phenomena such as pulsar wind nebulae, gamma-ray bursts, and active galactic nuclei, where the shock wave is thought to play a crucial role.

  17. Search for Ultra-relativistic Magnetic Monopoles with the Pierre Auger Observatory

    SciTech Connect

    Aab, Alexander

    2016-10-03

    In this paper, we present a search for ultra-relativistic magnetic monopoles with the Pierre Auger Observatory. Such particles, possibly a relic of phase transitions in the early universe, would deposit a large amount of energy along their path through the atmosphere, comparable to that of ultrahigh-energy cosmic rays (UHECRs). The air shower profile of a magnetic monopole can be effectively distinguished by the fluorescence detector from that of standard UHECRs. No candidate was found in the data collected between 2004 and 2012, with an expected background of less than 0.1 event from UHECRs. The corresponding 90% confidence level (C.L.) upper limits on the flux of ultra-relativistic magnetic monopoles range from $10^{-19}$ (cm$^{2}$ sr s)$^{-1}$ for a Lorentz factor $\\gamma=10^9$ to $2.5 \\times10^{-21}$ (cm$^{2}$ sr s)$^{-1}$ for $\\gamma=10^{12}$. Lastly, these results - the first obtained with a UHECR detector - improve previously published limits by up to an order of magnitude.

  18. Search for Ultra-relativistic Magnetic Monopoles with the Pierre Auger Observatory

    DOE PAGES

    Aab, Alexander

    2016-10-03

    In this paper, we present a search for ultra-relativistic magnetic monopoles with the Pierre Auger Observatory. Such particles, possibly a relic of phase transitions in the early universe, would deposit a large amount of energy along their path through the atmosphere, comparable to that of ultrahigh-energy cosmic rays (UHECRs). The air shower profile of a magnetic monopole can be effectively distinguished by the fluorescence detector from that of standard UHECRs. No candidate was found in the data collected between 2004 and 2012, with an expected background of less than 0.1 event from UHECRs. The corresponding 90% confidence level (C.L.) upper limits on the flux of ultra-relativistic magnetic monopoles range frommore » $$10^{-19}$$ (cm$$^{2}$$ sr s)$$^{-1}$$ for a Lorentz factor $$\\gamma=10^9$$ to $$2.5 \\times10^{-21}$$ (cm$$^{2}$$ sr s)$$^{-1}$$ for $$\\gamma=10^{12}$$. Lastly, these results - the first obtained with a UHECR detector - improve previously published limits by up to an order of magnitude.« less

  19. Search for relativistic magnetic monopoles with the AMANDA-II neutrino telescope

    NASA Astrophysics Data System (ADS)

    Abbasi, R.; Abdou, Y.; Abu-Zayyad, T.; Adams, J.; Aguilar, J. A.; Ahlers, M.; Andeen, K.; Auffenberg, J.; Bai, X.; Baker, M.; Barwick, S. W.; Bay, R.; Bazo Alba, J. L.; Beattie, K.; Beatty, J. J.; Bechet, S.; Becker, J. K.; Becker, K.-H.; Benabderrahmane, M. L.; Benzvi, S.; Berdermann, J.; Berghaus, P.; Berley, D.; Bernardini, E.; Bertrand, D.; Besson, D. Z.; Bissok, M.; Blaufuss, E.; Boersma, D. J.; Bohm, C.; Böser, S.; Botner, O.; Bradley, L.; Braun, J.; Buitink, S.; Carson, M.; Chirkin, D.; Christy, B.; Clem, J.; Clevermann, F.; Cohen, S.; Colnard, C.; Cowen, D. F.; D'Agostino, M. V.; Danninger, M.; Davis, J. C.; de Clercq, C.; Demirörs, L.; Depaepe, O.; Descamps, F.; Desiati, P.; de Vries-Uiterweerd, G.; Deyoung, T.; Díaz-Vélez, J. C.; Dierckxsens, M.; Dreyer, J.; Dumm, J. P.; Duvoort, M. R.; Ehrlich, R.; Eisch, J.; Ellsworth, R. W.; Engdegård, O.; Euler, S.; Evenson, P. A.; Fadiran, O.; Fazely, A. R.; Feusels, T.; Filimonov, K.; Finley, C.; Foerster, M. M.; Fox, B. D.; Franckowiak, A.; Franke, R.; Gaisser, T. K.; Gallagher, J.; Geisler, M.; Gerhardt, L.; Gladstone, L.; Glüsenkamp, T.; Goldschmidt, A.; Goodman, J. A.; Grant, D.; Griesel, T.; Groß, A.; Grullon, S.; Gurtner, M.; Ha, C.; Hallgren, A.; Halzen, F.; Han, K.; Hanson, K.; Helbing, K.; Herquet, P.; Hickford, S.; Hill, G. C.; Hoffman, K. D.; Homeier, A.; Hoshina, K.; Hubert, D.; Huelsnitz, W.; Hülß, J.-P.; Hulth, P. O.; Hultqvist, K.; Hussain, S.; Ishihara, A.; Jacobsen, J.; Japaridze, G. S.; Johansson, H.; Joseph, J. M.; Kampert, K.-H.; Karg, T.; Karle, A.; Kelley, J. L.; Kemming, N.; Kenny, P.; Kiryluk, J.; Kislat, F.; Klein, S. R.; Knops, S.; Köhne, J.-H.; Kohnen, G.; Kolanoski, H.; Köpke, L.; Koskinen, D. J.; Kowalski, M.; Kowarik, T.; Krasberg, M.; Krings, T.; Kroll, G.; Kuehn, K.; Kuwabara, T.; Labare, M.; Lafebre, S.; Laihem, K.; Landsman, H.; Lauer, R.; Lehmann, R.; Lennarz, D.; Lünemann, J.; Madsen, J.; Majumdar, P.; Marotta, A.; Maruyama, R.; Mase, K.; Matis, H. S.; Matusik, M.; Meagher, K.; Merck, M.; Mészáros, P.; Meures, T.; Middell, E.; Milke, N.; Miller, J.; Montaruli, T.; Morse, R.; Movit, S. M.; Nahnhauer, R.; Nam, J. W.; Naumann, U.; Nießen, P.; Nygren, D. R.; Odrowski, S.; Olivas, A.; Olivo, M.; O'Murchadha, A.; Ono, M.; Panknin, S.; Paul, L.; Pérez de Los Heros, C.; Petrovic, J.; Piegsa, A.; Pieloth, D.; Porrata, R.; Posselt, J.; Price, P. B.; Prikockis, M.; Przybylski, G. T.; Rawlins, K.; Redl, P.; Resconi, E.; Rhode, W.; Ribordy, M.; Rizzo, A.; Rodrigues, J. P.; Roth, P.; Rothmaier, F.; Rott, C.; Roucelle, C.; Ruhe, T.; Rutledge, D.; Ruzybayev, B.; Ryckbosch, D.; Sander, H.-G.; Santander, M.; Sarkar, S.; Schatto, K.; Schlenstedt, S.; Schmidt, T.; Schukraft, A.; Schultes, A.; Schulz, O.; Schunck, M.; Seckel, D.; Semburg, B.; Seo, S. H.; Sestayo, Y.; Seunarine, S.; Silvestri, A.; Slipak, A.; Spiczak, G. M.; Spiering, C.; Stamatikos, M.; Stanev, T.; Stephens, G.; Stezelberger, T.; Stokstad, R. G.; Stoyanov, S.; Strahler, E. A.; Straszheim, T.; Sullivan, G. W.; Swillens, Q.; Taavola, H.; Taboada, I.; Tamburro, A.; Tarasova, O.; Tepe, A.; Ter-Antonyan, S.; Tilav, S.; Toale, P. A.; Toscano, S.; Tosi, D.; Turčan, D.; van Eijndhoven, N.; Vandenbroucke, J.; van Overloop, A.; van Santen, J.; Voge, M.; Voigt, B.; Walck, C.; Waldenmaier, T.; Wallraff, M.; Walter, M.; Weaver, Ch.; Wendt, C.; Westerhoff, S.; Whitehorn, N.; Wiebe, K.; Wiebusch, C. H.; Wikström, G.; Williams, D. R.; Wischnewski, R.; Wissing, H.; Wolf, M.; Woschnagg, K.; Xu, C.; Xu, X. W.; Yodh, G.; Yoshida, S.; Zarzhitsky, P.

    2010-10-01

    We present the search for Cherenkov signatures from relativistic magnetic monopoles in data taken with the AMANDA-II detector, a neutrino telescope deployed in the Antarctic ice cap at the Geographic South Pole. The non-observation of a monopole signal in data collected during the year 2000 improves present experimental limits on the flux of relativistic magnetic monopoles: Our flux limit varies between 3.8×10-17 cm-2 s-1 sr-1 (for monopoles moving at the vacuum speed of light) and 8.8×10-16 cm-2 s-1 sr-1 (for monopoles moving at a speed β= v/ c=0.76, just above the Cherenkov threshold in ice). These limits apply to monopoles that are energetic enough to penetrate the Earth and enter the detector from below the horizon. The limit obtained for monopoles reaching the detector from above the horizon is less stringent by roughly an order of magnitude, due to the much larger background from down-going atmospheric muons. This looser limit is however valid for a larger class of magnetic monopoles, since the monopoles are not required to pass through the Earth.

  20. Search for Ultra-relativistic Magnetic Monopoles with the Pierre Auger Observatory

    SciTech Connect

    Aab, Alexander

    2016-10-03

    In this paper, we present a search for ultra-relativistic magnetic monopoles with the Pierre Auger Observatory. Such particles, possibly a relic of phase transitions in the early universe, would deposit a large amount of energy along their path through the atmosphere, comparable to that of ultrahigh-energy cosmic rays (UHECRs). The air shower profile of a magnetic monopole can be effectively distinguished by the fluorescence detector from that of standard UHECRs. No candidate was found in the data collected between 2004 and 2012, with an expected background of less than 0.1 event from UHECRs. The corresponding 90% confidence level (C.L.) upper limits on the flux of ultra-relativistic magnetic monopoles range from $10^{-19}$ (cm$^{2}$ sr s)$^{-1}$ for a Lorentz factor $\\gamma=10^9$ to $2.5 \\times10^{-21}$ (cm$^{2}$ sr s)$^{-1}$ for $\\gamma=10^{12}$. Lastly, these results - the first obtained with a UHECR detector - improve previously published limits by up to an order of magnitude.

  1. Quantum speed limit for a relativistic electron in a uniform magnetic field

    NASA Astrophysics Data System (ADS)

    Villamizar, D. V.; Duzzioni, E. I.

    2015-10-01

    We analyze the influence of relativistic effects on the minimum evolution time between two orthogonal states of a quantum system. Defining the initial state as a homogeneous superposition between two Hamiltonian eigenstates of an electron in a uniform magnetic field, we obtain a relation between the minimum evolution time and the displacement of the mean radial position of the electron wave packet. The quantum speed limit time is calculated for an electron dynamics described by Dirac and Schrödinger-Pauli equations considering different parameters, such as the strength of magnetic field and the linear momentum of the electron in the axial direction. We highlight that when the electron undergoes a region with extremely strong magnetic field the relativistic and nonrelativistic dynamics differ substantially, so that the description given by the Schrödinger-Pauli equation enables the electron to travel faster than c , which is prohibited by Einstein's theory of relativity. This approach allows a connection between the abstract Hilbert space and the space-time coordinates, besides the identification of the most appropriate quantum dynamics used to describe the electron motion.

  2. Coronal mass ejections, magnetic clouds, and relativistic magnetospheric electron events: ISTP

    SciTech Connect

    Baker, D.N.; Pulkkinen, T.I.; Li, X.; Kanekal, S.G.; Blake, J.B.; Selesnick, R.S.; Henderson, M.G.; Reeves, G.D.; Spence, H.E.

    1998-08-01

    The role of high-speed solar wind streams in driving relativistic electron acceleration within the Earth{close_quote}s magnetosphere during solar activity minimum conditions has been well documented. The rising phase of the new solar activity cycle (cycle 23) commenced in 1996, and there have recently been a number of coronal mass ejections (CMEs) and related {open_quotes}magnetic clouds{close_quotes} at 1 AU. As these CME/cloud systems interact with the Earth{close_quote}s magnetosphere, some events produce substantial enhancements in the magnetospheric energetic particle population while others do not. This paper compares and contrasts relativistic electron signatures observed by the POLAR, SAMPEX, Highly Elliptical Orbit, and geostationary orbit spacecraft during two magnetic cloud events: May 27{endash}29, 1996, and January 10{endash}11, 1997. Sequences were observed in each case in which the interplanetary magnetic field was first strongly southward and then rotated northward. In both cases, there were large solar wind density enhancements toward the end of the cloud passage at 1 AU. Strong energetic electron acceleration was observed in the January event, but not in the May event. The relative geoeffectiveness for these two cases is assessed, and it is concluded that large induced electric fields ({partial_derivative}B/{partial_derivative}t) caused in situ acceleration of electrons throughout the outer radiation zone during the January 1997 event. {copyright} 1998 American Geophysical Union

  3. Interaction of Radio Jets with Magnetic Fields in Clusters of Galaxies

    NASA Astrophysics Data System (ADS)

    Soker, Noam

    1997-10-01

    High Faraday rotation measures in the centers of cooling-flow clusters indicate the presence of strong magnetic fields. We examine the effects of these strong fields on the propagation of radio jets emerging from the central cD galaxies of these clusters, and the deformation of the magnetic fields by the fast-propagating jets. We argue that active regions will develop around these radio jets as a result of the violent response of the strong ambient magnetic fields. The magnetic tension can act back on the jets by influencing the development of Rayleigh-Taylor and Kelvin-Helmholtz instability modes, and by exerting a nonaxisymmetric force on the jets. If the jet propagation direction is not along the magnetic field lines, then the jet will be sharply bent by the magnetic tension. Future MHD numerical simulations that will study these effects more quantitatively should be compared directly with specific clusters. If, indeed, some properties of jets expanding from cD galaxies in cooling-flow clusters will turn out to result from interaction with strong magnetic fields in the intracluster medium at the centers of these clusters, then this will strengthen the cooling-flow model, since it will support the presence of inflow.

  4. Standard map in magnetized relativistic systems: Fixed points and regular acceleration

    SciTech Connect

    Sousa, M. C. de; Steffens, F. M.; Pakter, R.; Rizzato, F. B.

    2010-08-15

    We investigate the concept of a standard map for the interaction of relativistic particles and electrostatic waves of arbitrary amplitudes, under the action of external magnetic fields. The map is adequate for physical settings where waves and particles interact impulsively, and allows for a series of analytical result to be exactly obtained. Unlike the traditional form of the standard map, the present map is nonlinear in the wave amplitude and displays a series of peculiar properties. Among these properties we discuss the relation involving fixed points of the maps and accelerator regimes.

  5. Relativistic, QED, and nuclear mass effects in the magnetic shielding of 3He.

    PubMed

    Rudziński, Adam; Puchalski, Mariusz; Pachucki, Krzysztof

    2009-06-28

    The magnetic shielding sigma of (3)He is studied. The complete relativistic corrections of order O(alpha(2)), leading QED corrections of order O(alpha(3) ln alpha), and finite nuclear mass effects of order O(m/m(N)) are calculated with high numerical precision. The resulting theoretical predictions for sigma = 59.967 43(10)x10(-6) are the most accurate to date among all elements and support the use of (3)He as a NMR standard.

  6. Intense propagation in a magnetized cold plasma: modulational instabilities of fully relativistic electromagnetic waves

    NASA Astrophysics Data System (ADS)

    Kates, Ronald E.; Kaup, D. J.

    1992-08-01

    This paper studies modulational instabilities of intensely propagating, circularly polarized, plane electromagnetic plasma waves in the presence of an external magnetic field pointing exactly in the direction of propagation. By ‘intense propagation’, we mean that eEo/mw (where Eo is the amplitude of the wave's transverse electric field) is comparable to unity, so that the problem is fully nonlinear and cannot be solved by regular perturbation methods. The positive component may consists of either positrons or singly charged ions. The plasma is assumed to be fully ionized and cold. Modulated intensely propagating electromagnetic waves couple (in general) to longitudinal motions via the ponderomotive force. For given wavenumber, the frequency of the wave depends on the amplitude not only via the obvious mechanism of relativistic mass increase but also via the density inhomogeneities induced by the ponderomotive force. This coupling effectively involves derivatives of the envelope, and the effect of longitudinal motions is comparable to that of relativistic nonlinearities. For this reason, a proper expansion procedure requires verification that one has obtained a self-consistent solution of all the field equations up to the appropriate order, including the longitudinal equations. This is best accomplished using the well-known two-timing approach. Modulational instability arises in the case of an ion-electron plasma with relativistic electrons but non-relativistic ions. However, for parameter values appropriate to pulsar magnetospheres, where the electron-cyclotron frequency is much larger than the frequency of the wave, there is no instability on the time scale of a micropulse.

  7. Magnetic Probe to Study Plasma Jets for Magneto-Inertial Fusion

    SciTech Connect

    Martens, Daniel; Hsu, Scott C.

    2012-08-16

    A probe has been constructed to measure the magnetic field of a plasma jet generated by a pulsed plasma rail-gun. The probe consists of two sets of three orthogonally-oriented commercial chip inductors to measure the three-dimensional magnetic field vector at two separate positions in order to give information about the magnetic field evolution within the jet. The strength and evolution of the magnetic field is one of many factors important in evaluating the use of supersonic plasma jets for forming imploding spherical plasma liners as a standoff driver for magneto-inertial fusion.

  8. Correlations between jet-quenching observables at energies available at the BNL Relativistic Heavy Ion Collider

    SciTech Connect

    Jia, J.; Horowitz, W.; Liao, J.

    2011-10-01

    Focusing on four types of correlation plots, R{sub AA} versus v{sub 2}, R{sub AA} versus I{sub AA}, I{sub AA} versus v{sub 2}{sup I{sub AA}}, and v{sub 2} versus v{sub 2}{sup I{sub AA}}, we demonstrate how the centrality dependence of correlations between multiple jet quenching observables provide valuable insight into the energy loss mechanism in a quark-gluon plasma. In particular, we find that a qualitative energy loss model gives a good description of R{sub AA} versus v{sub 2} only when we take {Delta}E-I{sup 3} and a medium geometry generated by a model of the color glass condensate. This same {Delta}E-I{sup 3} model also qualitatively describes the trigger p{sub T} dependence of R{sub AA} versus I{sub AA} data and makes novel predictions for the centrality dependence for this R{sub AA} versus I{sub AA} correlation. Current data suggest, albeit with extremely large uncertainty, that v{sub 2}{sup I{sub AA}} >> v{sub 2}, a correlation that is difficult to reproduce in current energy loss models.

  9. Correlations between jet-quenching observables at energies available at the BNL Relativistic Heavy Ion Collider

    SciTech Connect

    Jia Jiangyong; Horowitz, W. A.; Liao Jinfeng

    2011-09-15

    Focusing on four types of correlation plots, R{sub AA} versus v{sub 2}, R{sub AA} versus I{sub AA}, I{sub AA} versus v{sub 2}{sup I{sub AA}}, and v{sub 2} versus v{sub 2}{sup I{sub AA}}, we demonstrate how the centrality dependence of correlations between multiple jet quenching observables provide valuable insight into the energy loss mechanism in a quark-gluon plasma. In particular, we find that a qualitative energy loss model gives a good description of R{sub AA} versus v{sub 2} only when we take {Delta}E{approx}l{sup 3} and a medium geometry generated by a model of the color glass condensate. This same {Delta}E{approx}l{sup 3} model also qualitatively describes the trigger p{sub T} dependence of R{sub AA} versus I{sub AA} data and makes novel predictions for the centrality dependence for this R{sub AA} versus I{sub AA} correlation. Current data suggest, albeit with extremely large uncertainty, that v{sub 2}{sup I{sub AA}}>>v{sub 2}, a correlation that is difficult to reproduce in current energy loss models.

  10. Generation of Alfvenic Waves and Turbulence in Magnetic Reconnection Jets

    NASA Astrophysics Data System (ADS)

    Hoshino, M.

    2014-12-01

    The magneto-hydro-dynamic (MHD) linear stability for the plasma sheet with a localized bulk plasma flow parallel to the neutral sheet is investigated. We find three different unstable modes propagating parallel to the anti-parallel magnetic field line, and we call them as "streaming tearing'', "streaming sausage'', and "streaming kink'' mode. The streaming tearing and sausage modes have the tearing mode-like structure with symmetric density fluctuation to the neutral sheet, and the streaming kink mode has the asymmetric fluctuation. The growth rate of the streaming tearing mode decreases with increasing the magnetic Reynolds number, while those of the streaming sausage and kink modes do not strongly depend on the Reynolds number. The wavelengths of these unstable modes are of the order of the thickness of plasma sheet, which behavior is almost same as the standard tearing mode with no bulk flow. Roughly speaking the growth rates of three modes become faster than the standard tearing mode. The situation of the plasma sheet with the bulk flow can be realized in the reconnection exhaust with the Alfvenic reconnection jet, and the unstable modes may be regarded as one of the generation processes of Alfvenic turbulence in the plasma sheet during magnetic reconnection.

  11. Nonlinear effects in new magnetic pickup coils for JET

    SciTech Connect

    Quercia, A.; Pomaro, N.; Visone, C.

    2006-10-15

    In the framework of the JET magnetic diagnostic enhancement, a set of pickup coils (UC subsystem) wound on metallic Inconel registered 600 former was manufactured. For cross-validation purposes, two different calibration methods were used. A discrepancy in the range of 3% was observed, which can be explained when considering the dependence of the calibration coefficients on the field strength, which in turn is mostly due to the nonlinear behavior of the Inconel former. For this reason a specimen of Inconel was analyzed by means of a magnetometer, which showed a nonlinear and hysteretic behavior occurring at low field level (below 5 mT). The calibration coefficients are also measured at low field (0.1-2 mT) and so are affected by such peculiar ferromagnetic behavior. Moreover, the ferromagnetic behavior might be sensitive to mechanical and thermal treatments performed during probe manufacturing and testing. Therefore the achievable accuracy for the calibration of coils wound on Inconel formers is limited by the following effects: (i) the field level in operation can be completely different from the field used in the calibration procedure; (ii) measurements of the magnetic properties on Inconel specimens cannot be extrapolated to the former, because of unpredictable effects of mechanical and thermal treatments made on the coil; (iii) residual magnetization; and (iv) temperature variations during operation.

  12. Simulations of ion acceleration at non-relativistic shocks. II. Magnetic field amplification

    SciTech Connect

    Caprioli, D.; Spitkovsky, A.

    2014-10-10

    We use large hybrid simulations to study ion acceleration and generation of magnetic turbulence due to the streaming of particles that are self-consistently accelerated at non-relativistic shocks. When acceleration is efficient, we find that the upstream magnetic field is significantly amplified. The total amplification factor is larger than 10 for shocks with Alfvénic Mach number M = 100, and scales with the square root of M. The spectral energy density of excited magnetic turbulence is determined by the energy distribution of accelerated particles, and for moderately strong shocks (M ≲ 30) agrees well with the prediction of resonant streaming instability, in the framework of quasilinear theory of diffusive shock acceleration. For M ≳ 30, instead, Bell's non-resonant hybrid (NRH) instability is predicted and found to grow faster than resonant instability. NRH modes are excited far upstream by escaping particles, and initially grow without disrupting the current, their typical wavelengths being much shorter than the current ions' gyroradii. Then, in the nonlinear stage, most unstable modes migrate to larger and larger wavelengths, eventually becoming resonant in wavelength with the driving ions, which start diffuse. Ahead of strong shocks we distinguish two regions, separated by the free-escape boundary: the far upstream, where field amplification is provided by the current of escaping ions via NRH instability, and the shock precursor, where energetic particles are effectively magnetized, and field amplification is provided by the current in diffusing ions. The presented scalings of magnetic field amplification enable the inclusion of self-consistent microphysics into phenomenological models of ion acceleration at non-relativistic shocks.

  13. Chandra and HST Imaging of the Quasars PKS B0106+013 and 3C 345: Inverse Compton X-Rays and Magnetized Jets

    NASA Astrophysics Data System (ADS)

    Kharb, P.; Lister, M. L.; Marshall, H. L.; Hogan, B. S.

    2012-04-01

    energy distribution (SED) modeling of individual jet components in both quasars suggests that the optical emission is from the synchrotron mechanism, while the X-rays are produced via the inverse Compton mechanism from relativistically boosted cosmic microwave background seed photons. The locations of the upstream X-ray termination peaks strongly suggest that the sites of bulk jet deceleration lie upstream (by a few kiloparsecs) of the radio hot spots in these quasars. These regions are also the sites of shocks or magnetic field dissipation, which reaccelerate charged particles and produce high-energy optical and X-ray photons. This is consistent with the best-fit SED modeling parameters of magnetic field strength and electron power-law indices being higher in the jet termination regions compared to the cores. The shocked jet regions upstream of the radio hot spots, the kiloparsec-scale jet wiggles and a "nose cone"-like jet structure in 0106+013, and the V-shaped radio structure in 3C 345, are all broadly consistent with instabilities associated with Poynting-flux-dominated jets. A greater theoretical understanding and more sensitive numerical simulations of jets spanning parsec to kiloparsec scales are needed, however, to make direct quantitative comparisons.

  14. Electric current variations and 3D magnetic configuration of coronal jets

    NASA Astrophysics Data System (ADS)

    Schmieder, Brigitte; Harra, Louise K.; Aulanier, Guillaume; Guo, Yang; Demoulin, Pascal; Moreno-Insertis, Fernando, , Prof

    Coronal jets (EUV) were observed by SDO/AIA on September 17, 2010. HMI and THEMIS measured the vector magnetic field from which we derived the magnetic flux, the phostospheric velocity and the vertical electric current. The magnetic configuration was computed with a non linear force-free approach. The phostospheric current pattern of the recurrent jets were associated with the quasi-separatrix layers deduced from the magnetic extrapolation. The large twisted near-by Eiffel-tower-shape jet was also caused by reconnection in current layers containing a null point. This jet cannot be classified precisely within either the quiescent or the blowout jet types. We will show the importance of the existence of bald patches in the low atmosphere

  15. Motion of relativistic particles in axially symmetric and perturbed magnetic fields in a tokamak

    SciTech Connect

    de Rover, M.; Lopes Cardozo, N.J.; Montvai, A.

    1996-12-01

    An extensive comparison is given between an analytical theory for the computations of particle orbits of relativistic runaway electrons [M. de Rover {ital et} {ital al}., Phys. Plasmas {bold 3}, 4468 (1996)], and numerical simulations. A new numerical scheme is used for the computer simulations of guiding center orbits. Furthermore, simulations of the full particle motion, including the gyration are performed to check the guiding center approximation. The behavior of drift surfaces and particle orbits in axially symmetric magnetic fields, as predicted in the companion paper are confirmed. This includes the smaller minor radius of a drift surface compared to a magnetic flux surface with identical rotational transform, and the decrease of the minor radius of a drift surface with increasing particle energy. Magnetic islands and drift islands appear when the axial symmetry of the magnetic field is broken by harmonic perturbations. In the numerical simulations the amplitudes of the perturbations have been chosen to increase towards the plasma edge. The analytic theory gave predictions of the width of the drift islands that are in good agreement with the numerical simulations. When overlap of the magnetic perturbations introduces stochasticity, the Hamiltonian theory shows that drift islands can exist in the region of stochastic magnetic field lines, which is also confirmed by the numerical simulations. {copyright} {ital 1996 American Institute of Physics.}

  16. Magnetic field amplification and electron acceleration to near-energy equipartition with ions by a mildly relativistic quasi-parallel plasma protoshock

    NASA Astrophysics Data System (ADS)

    Murphy, G. C.; Dieckmann, M. E.; Bret, A.; Drury, L. O'c.

    2010-12-01

    Context. The prompt emissions of gamma-ray bursts (GRBs) are seeded by radiating ultrarelativistic electrons. Kinetic energy dominated internal shocks propagating through a jet launched by a stellar implosion, are expected to dually amplify the magnetic field and accelerate electrons. Aims: We explore the effects of density asymmetry and of a quasi-parallel magnetic field on the collision of two plasma clouds. Methods: A two-dimensional relativistic particle-in-cell (PIC) simulation models the collision with 0.9c of two plasma clouds, in the presence of a quasi-parallel magnetic field. The cloud density ratio is 10. The densities of ions and electrons and the temperature of 131 keV are equal in each cloud, and the mass ratio is 250. The peak Lorentz factor of the electrons is determined, along with the orientation and the strength of the magnetic field at the cloud collision boundary. Results: The magnetic field component orthogonal to the initial plasma flow direction is amplified to values that exceed those expected from the shock compression by over an order of magnitude. The forming shock is quasi-perpendicular due to this amplification, caused by a current sheet which develops in response to the differing deflection of the upstream electrons and ions incident on the magnetised shock transition layer. The electron deflection implies a charge separation of the upstream electrons and ions; the resulting electric field drags the electrons through the magnetic field, whereupon they acquire a relativistic mass comparable to that of the ions. We demonstrate how a magnetic field structure resembling the cross section of a flux tube grows self-consistently in the current sheet of the shock transition layer. Plasma filamentation develops behind the shock front, as well as signatures of orthogonal magnetic field striping, indicative of the filamentation instability. These magnetic fields convect away from the shock boundary and their energy density exceeds by far the

  17. Magnetic Untwisting in Solar Jets that Go into the Outer Corona in Polar Coronal Holes

    NASA Technical Reports Server (NTRS)

    Moore, Ronald L.; Sterling, Alphonse C.; Falconer, David A.

    2014-01-01

    We present results from 14 exceptionally high-reaching large solar jets observed in the polar coronal holes. EUV movies from SDO/AIA show that each jet is similar to many other similar-size and smaller jets that erupt in coronal holes, but each is exceptional in that it goes higher than most other jets, so high that it is observed in the outer corona beyond 2.2 R(sub Sun) in images from the SOHO/LASCO/C2 coronagraph. For these high-reaching jets, we find: (1) the front of the jet transits the corona below 2.2 R(sub Sun) at a speed typically several times the sound speed; (2) each jet displays an exceptionally large amount of spin as it erupts; (3) in the outer corona, most jets display oscillatory swaying having an amplitude of a few degrees and a period of order 1 hour. We conclude that these jets are magnetically driven, propose that the driver is a magnetic-untwisting wave that is grossly a large-amplitude (i.e., nonlinear) torsional Alfven wave that is put into the reconnected open magnetic field in the jet by interchange reconnection as the jet erupts, and estimate from the measured spinning and swaying that the magnetic-untwisting wave loses most of its energy in the inner corona below 2.2 R(sub Sun). From these results for these big jets, we reason that the torsional magnetic waves observed in Type-II spicules should dissipate in the corona in the same way and could thereby power much of the coronal heating in coronal holes.

  18. MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation

    SciTech Connect

    Ivanov, I. A. Arzhannikov, A. V.; Burmasov, V. S.; Popov, S. S.; Postupaev, V. V.; Sklyarov, V. F.; Vyacheslavov, L. N.; Burdakov, A. V.; Sorokina, N. V.; Gavrilenko, D. E.; Kasatov, A. A.; Kandaurov, I. V.; Mekler, K. I.; Rovenskikh, A. F.; Trunev, Yu. A.; Kurkuchekov, V. V.; Kuznetsov, S. A.; Polosatkin, S. V.

    2015-12-15

    There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70–110 keV for the electron energy, 1–10 MW for the beam power and 30–300 μs for its duration. The spectrum was measured in 75–230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.

  19. MM-wave emission by magnetized plasma during sub-relativistic electron beam relaxation

    NASA Astrophysics Data System (ADS)

    Ivanov, I. A.; Arzhannikov, A. V.; Burdakov, A. V.; Burmasov, V. S.; Gavrilenko, D. E.; Kasatov, A. A.; Kandaurov, I. V.; Kurkuchekov, V. V.; Kuznetsov, S. A.; Mekler, K. I.; Polosatkin, S. V.; Popov, S. S.; Postupaev, V. V.; Rovenskikh, A. F.; Sklyarov, V. F.; Sorokina, N. V.; Trunev, Yu. A.; Vyacheslavov, L. N.

    2015-12-01

    There are described electromagnetic spectra of radiation emitted by magnetized plasma during sub-relativistic electron beam in a double plasma frequency band. Experimental studies were performed at the multiple-mirror trap GOL-3. The electron beam had the following parameters: 70-110 keV for the electron energy, 1-10 MW for the beam power and 30-300 μs for its duration. The spectrum was measured in 75-230 GHz frequency band. The frequency of the emission follows variations in electron plasma density and magnetic field strength. The specific emission power on the length of the plasma column is estimated on the level 0.75 kW/cm.

  20. Numerical Simulation of Solar Coronal X-Ray Jets Based on the Magnetic Reconnection Model

    NASA Astrophysics Data System (ADS)

    Yokoyama, Takaaki; Shibata, Kazunari

    1996-04-01

    We performed two-dimensional numerical simulations of solar coronal X-ray jets by solving the resistive magnetohydrodynamic (MHD) equations. The simulations were based on the magnetic reconnection model, in which the plasma of an X-ray jet is accelerated and heated by reconnection between the emerging flux and a pre-existing coronal field. Many observed characteristics of X-ray jets could be successfully reproduced. Morphologically, the two observed types of jets, two-sided-loop type and anemone-jet type, were well reproduced. Here, the two-sided-loop type is a pair of horizontal jets (or loops), which occurs when an emerging flux appears in a quiet region where the coronal field is approximately horizontal. In contrast, the anemone-jet type is a vertical jet, which takes place when an emerging flux appears in a coronal hole where the coronal field is vertical or oblique. Quantitatively, the velocity, temperature, thermal energy, kinetic energy, and other parameters obtained in the simulation are in good agreement with the observations. Furthermore, the simulations reveal new features which might be associated with X-ray jets: (1) A fast-mode MHD shock is produced at the collision site of each reconnection jet with the ambient magnetic field. (2) Reconnection produces a cool jet as well as a hot jet (X-ray jet). The hot and cool jets are adjacent to each other, which is consistent with the observed simultaneous coexistence of X-ray jets and {Hα } surges in the sun.

  1. Four-component relativistic theory for nuclear magnetic shielding constants: critical assessments of different approaches.

    PubMed

    Xiao, Yunlong; Liu, Wenjian; Cheng, Lan; Peng, Daoling

    2007-06-07

    Both formal and numerical analyses have been carried out on various exact and approximate variants of the four-component relativistic theory for nuclear magnetic shielding constants. These include the standard linear response theory (LRT), the full or external field-dependent unitary transformations of the Dirac operator, as well as the orbital decomposition approach. In contrast with LRT, the latter schemes take explicitly into account both the kinetic and magnetic balances between the large and small components of the Dirac spinors, and are therefore much less demanding on the basis sets. In addition, the diamagnetic contributions, which are otherwise "missing" in LRT, appear naturally in the latter schemes. Nevertheless, the definitions of paramagnetic and diamagnetic terms are not the same in the different schemes, but the difference is only of O(c(-2)) and thus vanishes in the nonrelativistic limit. It is shown that, as an operator theory, the full field-dependent unitary transformation approach cannot be applied to singular magnetic fields such as that due to the magnetic point dipole moment of a nucleus. However, the inherent singularities can be avoided by the corresponding matrix formulation (with a partial closed summation). All the schemes are combined with the Dirac-Kohn-Sham ansatz for ground state calculations, and by using virtually complete basis sets a new and more accurate set of absolute nuclear magnetic resonance shielding scales for the rare gases He-Rn have been established.

  2. On the theory of magnetic field generation by relativistically strong laser radiation

    SciTech Connect

    Berezhiani, V.I.; Shatashvili, N.L.; Mahajan, S.M. |

    1996-07-01

    The authors consider the interaction of subpicosecond relativistically strong short laser pulses with an underdense cold unmagnetized electron plasma. It is shown that the strong plasma inhomogeneity caused by laser pulses results in the generation of a low frequency (quasistatic) magnetic field. Since the electron density distribution is determined completely by the pump wave intensity, the generated magnetic field is negligibly small for nonrelativistic laser pulses but increases rapidly in the ultrarelativistic case. Due to the possibility of electron cavitation (complete expulsion of electrons from the central region) for narrow and intense beams, the increase in the generated magnetic field slows down as the beam intensity is increased. The structure of the magnetic field closely resembles that of the field produced by a solenoid; the field is maximum and uniform in the cavitation region, then it falls, changes polarity and vanishes. In extremely dense plasmas, highly intense laser pulses in the self-channeling regime can generate magnetic fields {approximately} 100 Mg and greater.

  3. Experimental study of transport of relativistic electron beams in strong magnetic mirror field

    NASA Astrophysics Data System (ADS)

    Sakata, Shohei; Kondo, Kotaro; Bailly-Grandvaux, Mathiu; Bellei, Claudio; Santos, Joao; Firex Project Team

    2015-11-01

    Relativistic electron beams REB produced by ultra high intense laser pulses have generally a large divergence angle that results in degradation of energy coupling between the REB and a fuel core in the fast ignition scheme. Guiding and focusing of the REB by a strong external magnetic field was proposed to achieve high efficiency. We investigated REB transport through 50 μm or 250 μm thick plastic foils CuI doped under external magnetic fields, in magnetic mirror configurations of 1.2 or 4 mirror ratio. The experiment was carried out at the GEKKO XII and LFEX laser facility. Spatial pattern of the REB was measured by coherent transition radiation and/or Cu Ka x ray emission from the rear surface of the foil targets. Strong collimation of the REB by the external magnetic field was observed with 50 μm thick plastic targets, while the REB scattered in 250 μm thick targets. The experimental results are compared with computer simulations to understand the physical mechanisms of the REB transport in the external magnetic field. This work is supported by NIFS (Japan), MEXT/JSPS KAKENHI (Japan), JSPS Fellowship (Japan), ANR (France) and COST (Europe).

  4. Acoustic solitons in a magnetized quantum electron-positron-ion plasma with relativistic degenerate electrons and positrons pressure

    NASA Astrophysics Data System (ADS)

    Abdikian, A.; Mahmood, S.

    2016-12-01

    The obliquely nonlinear acoustic solitary propagation in a relativistically quantum magnetized electron-positron (e-p) plasma in the presence of the external magnetic field as well as the stationary ions for neutralizing the plasma background was studied. By considering the dynamic of the fluid e-p quantum and by using the quantum hydrodynamics model and the standard reductive perturbation technique, the Zakharov-Kuznetsov (ZK) equation is derived for small but finite amplitude waves and the solitary wave solution for the parameters relevant to dense astrophysical objects such as white dwarf stars is obtained. The numerical results show that the relativistic effects lead to propagate the electrostatic bell shape structures in quantum e-p plasmas like those in classical pair-ion or pair species for relativistic plasmas. It is also observed that by increasing the relativistic effects, the amplitude and width of the e-p acoustic solitary wave will decrease. In addition, the wave amplitude increases as positron density decreases in magnetized e-p plasmas. It is indicated that by increasing the strength of the magnetic field, the width of the soliton reduces and it becomes sharper. At the end, we have analytically and numerically shown that the pulse soliton solution of the ZK equation is unstable and have traced the dependence of the instability growth rate on electron density. It is found that by considering the relativistic pressure, the instability of the soliton pulse can be reduced. The results can be useful to study the obliquely nonlinear propagation of small amplitude localized structures in magnetized quantum e-p plasmas and be applicable to understand the particle and energy transport mechanism in compact stars such as white dwarfs, where the effects of relativistic electron degeneracy become important.

  5. Collimation of magnetic jets by disk winds - the case of M87

    NASA Astrophysics Data System (ADS)

    Levinson, Amir

    2015-08-01

    The interaction of a magnetic jet emerging from the ergosphere of an accreting black hole, with a transonic wind emanating from the accretion flow surrounding the black hole will be discussed. It is found that effective collimation of the polar jet occurs already for modest ratios of the wind and jet powers. The jet is ensheathed by a shocked wind layer that can be a significant source of low energy emission at relatively small radii. It is suggested that a disk wind from the RIAF may be responsible for the collimation of the jet in M87, and that the shocked wind layer may be the source of the radio emission detected by the EHT. The variable TeV emission may originate from a sparking gap at the base of the magnetic jet, as proposed recently.

  6. Numerical Simulations of Solar Spicule Jets at a Magnetic Null-Point

    NASA Astrophysics Data System (ADS)

    Smirnova, V.; Konkol, P. M.; Solov'ev, A. A.; Murawski, K.

    2016-11-01

    Two-dimensional numerical simulations of jet-like structures in the solar atmosphere are performed. These structures result from a pressure pulse that is launched at the null point of a potential magnetic arcade. The plasma jet exhibits a double structure with two components: (a) dense, cool, and short vertical stream and (b) a less dense, hot and tall part of the jet. The upper part of the hot and tall jet may represent a direct response of the system to the pressure pulse launched at the null point, and the second, slower cool and dense part of the jet is formed later through the stretching up of the stream as a result of plasma evacuation from the top of the magnetic arcade. Numerical results show that jet-like structures mimic some properties of both type I and type II spicules, according to the classification provided by De Pontieu et al. ( Publ. Astron. Soc. Japan 59, S655, 2007).

  7. Evolution of the bounded magnetized jet and comparison with Helimak experiments

    NASA Astrophysics Data System (ADS)

    Dahlburg, R. B.; Horton, W.; Rowan, W. L.; Correa, C.; Perez, J. C.

    2009-07-01

    Magnetized jets are important features of many systems of physical interest. To date, most interest has focused on solar and space physics and astrophysical applications, and hence the unbounded magnetized jet, and its cousin, the unbounded magnetized wake, have received the most attention. This work presents calculations of a bounded, magnetized jet for a laboratory experiments in the Helimak device [K. W. Gentle and H. He, Plasma Sci. Technol. 10, 284 (2008)]. The Helimak device has a toroidal magnetic field with a controlled velocity flow that represents jets in bounded systems. Experimental and theoretical features include three spatial dimensions, the inclusion of resistivity and viscosity, and the presence of no-slip walls. The results of the linearized model are computed with a Chebyshev-τ algorithm. The bounding walls stabilize the ideal varicose mode found in unbounded magnetized jets. The ideal sinuous mode persists in the bounded system. A comparison theorem is proved showing that two-dimensional modes are more unstable than the corresponding three-dimensional modes for any given set of system parameters. This result is a generalization of the hydrodynamic Squires theorem. An energy-stress theorem indicates that the Maxwell stress is crucial for the growth of the instability. The results of the analysis are consistent with the observed plasma fluctuations with in the limits of using a simple model for the more complex measured jet velocity flow profile. The working gas is singly ionized argon and the jet velocity profile is accurately measured with Doppler shift spectroscopy.

  8. On the Magnetic and Energy Characteristics of Recurrent Homologous Jets from An Emerging Flux

    NASA Astrophysics Data System (ADS)

    Liu, Jiajia; Wang, Yuming; Erdélyi, Robertus; Liu, Rui; McIntosh, Scott W.; Gou, Tingyu; Chen, Jun; Liu, Kai; Liu, Lijuan; Pan, Zonghao

    2016-12-01

    In this paper, we present the detailed analysis of recurrent homologous jets originating from an emerging negative magnetic flux at the edge of an active region. The observed jets show multithermal features. Their evolution shows high consistence with the characteristic parameters of the emerging flux, suggesting that with more free magnetic energy, the eruptions tend to be more violent, frequent, and blowout-like. The average temperature, average electron number density, and axial speed are found to be similar for different jets, indicating that they should have been formed by plasmas from similar origins. Statistical analysis of the jets and their footpoint region conditions reveals a strong positive relationship between the footpoint region total 131 Å intensity enhancement and jets’ length/width. Stronger linearly positive relationships also exist between the total intensity enhancement/thermal energy of the footpoint regions and jets’ mass/kinetic/thermal energy, with higher cross-correlation coefficients. All the above results together confirm the direct relationship between the magnetic reconnection and the jets and validate the important role of magnetic reconnection in transporting large amounts of free magnetic energy into jets. It is also suggested that there should be more free energy released during the magnetic reconnection of blowout than of standard jet events.

  9. MULTIPLE PLASMA EJECTIONS AND INTERMITTENT NATURE OF MAGNETIC RECONNECTION IN SOLAR CHROMOSPHERIC ANEMONE JETS

    SciTech Connect

    Singh, K. A. P.; Nishida, K.; Shibata, K.; Isobe, H.; Nishizuka, N. E-mail: nishida@kwasan.kyoto-u.ac.jp E-mail: isobe@kwasan.kyoto-u.ac.jp

    2012-11-01

    The recent discovery of chromospheric anemone jets with the Solar Optical Telescope (SOT) on board Hinode has shown an indirect evidence of magnetic reconnection in the solar chromosphere. However, the basic nature of magnetic reconnection in chromosphere is still unclear. We studied nine chromospheric anemone jets from SOT/Hinode using Ca II H filtergrams, and we found multiple bright, plasma ejections along the jets. In most cases, the major intensity enhancements (larger than 30% relative to the background intensity) of the loop correspond to the timing of the plasma ejections. The typical lifetime and size of the plasma ejecta are about 20-60 s and 0.3-1.5 Mm, respectively. The height-time plot of jet shows many sub-structures (or individual jets) and the typical lifetime of the individual jet is about one to five minutes. Before the onset of the jet activity, a loop appears in Ca II H and gradually increases in size, and after few minutes several jets are launched from the loop. Once the jet activity starts and several individual jets are launched, the loop starts shrinking with a speed of {approx}4 km s{sup -1}. In some events, a downward moving blob with a speed of {approx}35 km s{sup -1} was observed, associated with the upward moving plasma along one of the legs of the loop hosting the jets. The upward moving plasma gradually developed into jets. Multiple plasma ejections in chromospheric anemone jet show the strongly time-dependent as well as intermittent nature of magnetic reconnection in the solar chromosphere.

  10. Magnetic Untwisting in Solar Jets that Go into the Outer Corona in Polar Coronal Holes

    NASA Astrophysics Data System (ADS)

    Moore, Ronald L.; Sterling, Alphonse C.; Falconer, David A.

    2015-06-01

    We study 14 large solar jets observed in polar coronal holes. In EUV movies from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA), each jet appears similar to most X-ray jets and EUV jets that erupt in coronal holes; but each is exceptional in that it goes higher than most, so high that it is observed in the outer corona beyond 2.2 R Sun in images from the Solar and Heliospheric Observatory/Large Angle Spectroscopic Coronagraph (LASCO)/C2 coronagraph. From AIA He ii 304 Å movies and LASCO/C2 running-difference images of these high-reaching jets, we find: (1) the front of the jet transits the corona below 2.2 R Sun at a speed typically several times the sound speed; (2) each jet displays an exceptionally large amount of spin as it erupts; (3) in the outer corona, most of the jets display measureable swaying and bending of a few degrees in amplitude; in three jets the swaying is discernibly oscillatory with a period of order 1 hr. These characteristics suggest that the driver in these jets is a magnetic-untwisting wave that is basically a large-amplitude (i.e., nonlinear) torsional Alfvén wave that is put into the reconnected open field in the jet by interchange reconnection as the jet erupts. From the measured spinning and swaying, we estimate that the magnetic-untwisting wave loses most of its energy in the inner corona below 2.2 R Sun. We point out that the torsional waves observed in Type-II spicules might dissipate in the corona in the same way as the magnetic-untwisting waves in our big jets, and thereby power much of the coronal heating in coronal holes.

  11. MAGNETIC UNTWISTING IN SOLAR JETS THAT GO INTO THE OUTER CORONA IN POLAR CORONAL HOLES

    SciTech Connect

    Moore, Ronald L.; Sterling, Alphonse C.; Falconer, David A.

    2015-06-10

    We study 14 large solar jets observed in polar coronal holes. In EUV movies from the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA), each jet appears similar to most X-ray jets and EUV jets that erupt in coronal holes; but each is exceptional in that it goes higher than most, so high that it is observed in the outer corona beyond 2.2 R{sub Sun} in images from the Solar and Heliospheric Observatory/Large Angle Spectroscopic Coronagraph (LASCO)/C2 coronagraph. From AIA He ii 304 Å movies and LASCO/C2 running-difference images of these high-reaching jets, we find: (1) the front of the jet transits the corona below 2.2 R{sub Sun} at a speed typically several times the sound speed; (2) each jet displays an exceptionally large amount of spin as it erupts; (3) in the outer corona, most of the jets display measureable swaying and bending of a few degrees in amplitude; in three jets the swaying is discernibly oscillatory with a period of order 1 hr. These characteristics suggest that the driver in these jets is a magnetic-untwisting wave that is basically a large-amplitude (i.e., nonlinear) torsional Alfvén wave that is put into the reconnected open field in the jet by interchange reconnection as the jet erupts. From the measured spinning and swaying, we estimate that the magnetic-untwisting wave loses most of its energy in the inner corona below 2.2 R{sub Sun}. We point out that the torsional waves observed in Type-II spicules might dissipate in the corona in the same way as the magnetic-untwisting waves in our big jets, and thereby power much of the coronal heating in coronal holes.

  12. Multiple Plasma Ejections and Intermittent Nature of Magnetic Reconnection in Solar Chromospheric Anemone Jets

    NASA Astrophysics Data System (ADS)

    Singh, K. A. P.; Isobe, H.; Nishizuka, N.; Nishida, K.; Shibata, K.

    2012-11-01

    The recent discovery of chromospheric anemone jets with the Solar Optical Telescope (SOT) on board Hinode has shown an indirect evidence of magnetic reconnection in the solar chromosphere. However, the basic nature of magnetic reconnection in chromosphere is still unclear. We studied nine chromospheric anemone jets from SOT/Hinode using Ca II H filtergrams, and we found multiple bright, plasma ejections along the jets. In most cases, the major intensity enhancements (larger than 30% relative to the background intensity) of the loop correspond to the timing of the plasma ejections. The typical lifetime and size of the plasma ejecta are about 20-60 s and 0.3-1.5 Mm, respectively. The height-time plot of jet shows many sub-structures (or individual jets) and the typical lifetime of the individual jet is about one to five minutes. Before the onset of the jet activity, a loop appears in Ca II H and gradually increases in size, and after few minutes several jets are launched from the loop. Once the jet activity starts and several individual jets are launched, the loop starts shrinking with a speed of ~4 km s-1. In some events, a downward moving blob with a speed of ~35 km s-1 was observed, associated with the upward moving plasma along one of the legs of the loop hosting the jets. The upward moving plasma gradually developed into jets. Multiple plasma ejections in chromospheric anemone jet show the strongly time-dependent as well as intermittent nature of magnetic reconnection in the solar chromosphere.

  13. Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

    NASA Astrophysics Data System (ADS)

    Higginson, D. P.; Revet, G.; Khiar, B.; Béard, J.; Blecher, M.; Borghesi, M.; Burdonov, K.; Chen, S. N.; Filippov, E.; Khaghani, D.; Naughton, K.; Pépin, H.; Pikuz, S.; Portugall, O.; Riconda, C.; Riquier, R.; Ryazantsev, S. N.; Skobelev, I. Yu.; Soloviev, A.; Starodubtsev, M.; Vinci, T.; Willi, O.; Ciardi, A.; Fuchs, J.

    2017-06-01

    The collimation of astrophysically-relevant plasma ejecta in the form of narrow jets via a poloidal magnetic field is studied experimentally by irradiating a target situated in a 20 T axial magnetic field with a 40 J, 0.6 ns, 0.7 mm diameter, high-power laser. The dynamics of the plasma shaping by the magnetic field are studied over 70 ns and up to 20 mm from the source by diagnosing the electron density, temperature and optical self-emission. These show that the initial expansion of the plasma is highly magnetized, which leads to the formation of a cavity structure when the kinetic plasma pressure compresses the magnetic field, resulting in an oblique shock [A. Ciardi et al., Phys. Rev. Lett. 110, 025002 (2013)]. The resulting poloidal magnetic nozzle collimates the plasma into a narrow jet [B. Albertazzi et al., Science 346, 325 (2014)]. At distances far from the target, the jet is only marginally magnetized and maintains a high aspect ratio due to its high Mach-number (M ∼ 20) and not due to external magnetic pressure. The formation of the jet is evaluated over a range of laser intensities (1012-1013 W/cm2), target materials and orientations of the magnetic field. Plasma cavity formation is observed in all cases and the viability of long-range jet formation is found to be dependent on the orientation of the magnetic field.

  14. Detailed characterization of laser-produced astrophysically-relevant jets formed via a poloidal magnetic nozzle

    DOE PAGES

    Higginson, D. P.; Revet, G.; Khiar, B.; ...

    2017-02-24

    We report that the collimation of astrophysically-relevant plasma ejecta in the form of narrow jets via a poloidal magnetic field is studied experimentally by irradiating a target situated in a 20 T axial magnetic field with a 40 J, 0.6 ns, 0.7 mm diameter, high-power laser. The dynamics of the plasma shaping by the magnetic field are studied over 70 ns and up to 20 mm from the source by diagnosing the electron density, temperature and optical self-emission. These show that the initial expansion of the plasma is highly magnetized, which leads to the formation of a cavity structure whenmore » the kinetic plasma pressure compresses the magnetic field, resulting in an oblique shock [A. Ciardi et al., Phys. Rev. Lett. 110, 025002 (2013)]. The resulting poloidal magnetic nozzle collimates the plasma into a narrow jet [B. Albertazzi et al., Science 346, 325 (2014)]. At distances far from the target, the jet is only marginally magnetized and maintains a high aspect ratio due to its high Mach-number (M~20) and not due to external magnetic pressure. The formation of the jet is evaluated over a range of laser intensities (1012–1013 W/cm2), target materials and orientations of the magnetic field. Lastly, plasma cavity formation is observed in all cases and the viability of long-range jet formation is found to be dependent on the orientation of the magnetic field.« less

  15. General relativistic models for rotating magnetized neutron stars in conformally flat space-time

    NASA Astrophysics Data System (ADS)

    Pili, A. G.; Bucciantini, N.; Del Zanna, L.

    2017-09-01

    The extraordinary energetic activity of magnetars is usually explained in terms of dissipation of a huge internal magnetic field of the order of 1015-16 G. How such a strong magnetic field can originate during the formation of a neutron star (NS) is still subject of active research. An important role can be played by fast rotation: if magnetars are born as millisecond rotators dynamo mechanisms may efficiently amplify the magnetic field inherited from the progenitor star during the collapse. In this case, the combination of rapid rotation and strong magnetic field determine the right physical condition not only for the development of a powerful jet-driven explosion, manifesting as a gamma-ray burst, but also for a copious gravitational waves emission. Strong magnetic fields are indeed able to induce substantial quadrupolar deformations in the star. In this paper, we analyse the joint effect of rotation and magnetization on the structure of a polytropic and axisymmetric NS, within the ideal magneto-hydrodynamic regime. We will consider either purely toroidal or purely poloidal magnetic field geometries. Through the sampling of a large parameter space, we generalize previous results in literature, inferring new quantitative relations that allow for a parametrization of the induced deformation, that takes into account also the effects due to the stellar compactness and the current distribution. Finally, in the case of purely poloidal field, we also discuss how different prescription on the surface charge distribution (a gauge freedom) modify the properties of the surrounding electrosphere and its physical implications.

  16. Space and time resolved EUV burst associated with magnetic reconnection in magnetically driven plasma jets

    NASA Astrophysics Data System (ADS)

    Chai, Kil-Byoung; Bellan, Paul

    2013-10-01

    We have developed a high-speed EUV movie camera to study magnetic reconnection associated with the Rayleigh-Taylor (RT) instability in the Caltech MHD jet experiment. In order to achieve high speed, a fast, visible-light movie camera is utilized with a fast-decaying YAG:Ce scintillator crystal that converts EUV radiation into visible light. A custom-designed Si/Mo multilayer mirror having central wavelength at 36 nm (34 eV) and 10 nm FWHM is used to focus EUV photons onto the scintillator crystal. After confirming the spatial resolution and field of view of our EUV camera, we have installed it on the plasma chamber and have successfully made EUV movies of the plasma. The EUV images are similar to the visible images when the jet starts kinking but before the kink acceleration drives the RT unstable. The EUV images differ at the instant the RT causes the jet to break off from its source electrode. A small jet segment becomes extremely bright in EUV and the visible light dims somewhat at this location. We plan to study why and how this intense EUV radiation develops.

  17. Nonlinear Amplification of the Whistler Wave in a Magnetized Relativistic Beam-Plasma Interaction

    NASA Astrophysics Data System (ADS)

    Taguchi, Toshihiro; Antonsen, Thomas; Mima, Kunioki

    2015-11-01

    We have been investigating a relativistic electron beam-plasma interaction under a strong magnetic field using a hybrid simulation code. In an initial stage, the electron beam drives a return current in a background plasma and such a two beam state causes a longitudinal two stream instability and a transverse Weibel instability. The application of a strong magnetic field is proposed for the suppression of the beam instabilities. When a sufficiently strong magnetic field is applied along the beam propagation, the Weibel instability is well suppressed and electrons flow laminarly. When the magnetic field strength is not large enough, however, electrons stagnate and the total number of beam electrons is largely reduced. Our detailed analyses show that a strong whistler wave is excited during the interaction and the wave stops the beam electrons. Since the whistler wave is composed of transverse electromagnetic fields, there should be a mechanism to convert the transverse field to a longitudinal one. In order to investigate this problem, we have performed a lot of simulation runs for a simple geometry. Then we found the amplified transverse modulation of the background plasma due to the Weibel instability plays an important role for the amplification of the whistler wave. This work was supported by a Grant-in-Aid for Scientific Research (B), 15H03758.

  18. Magnetic and antimagnetic rotation in 110Cd within tilted axis cranking relativistic mean-field theory

    NASA Astrophysics Data System (ADS)

    Peng, J.; Zhao, P. W.

    2015-04-01

    The self-consistent tilted axis cranking relativistic mean-field (TAC-RMF) theory based on a point-coupling interaction is applied to investigate the observed magnetic and antimagnetic rotations in the nucleus 110Cd . The energy spectra, the relation between the spin and the rotational frequency, the deformation parameters, and the reduced M 1 and E 2 transition probabilities are studied with the various configurations. It is found that the configuration has to be changed to reproduce the energy spectra and the relations between the spin and the rotational frequency for both the magnetic and antimagnetic rotational bands. The shears mechanism for the magnetic rotation and the two-shears-like mechanism for the antimagnetic rotation are examined by investigating the orientation of the neutron and proton angular momenta. The calculated electromagnetic transitions B (M 1 ) and B (E 2 ) are in reasonable agreement with the data, and their tendencies are coincident with the typical characteristics of the magnetic and antimagnetic rotations.

  19. NUMERICAL SIMULATIONS OF CHROMOSPHERIC ANEMONE JETS ASSOCIATED WITH MOVING MAGNETIC FEATURES

    SciTech Connect

    Yang, Liping; He, Jiansen; Tu, Chuanyi; Zhang, Lei; Peter, Hardi; Feng, Xueshang; Zhang, Shaohua

    2013-11-01

    Observations with the space-based solar observatory Hinode show that small-scale magnetic structures in the photosphere are found to be associated with a particular class of jets of plasma in the chromosphere called anemone jets. The goal of our study is to conduct a numerical experiment of such chromospheric anemone jets related to the moving magnetic features (MMFs). We construct a 2.5 dimensional numerical MHD model to describe the process of magnetic reconnection between the MMFs and the pre-existing ambient magnetic field, which is driven by the horizontal motion of the magnetic structure in the photosphere. We include thermal conduction parallel to the magnetic field and optically thin radiative losses in the corona to account for a self-consistent description of the evaporation process during the heating of the plasma due to the reconnection process. The motion of the MMFs leads to the expected jet and our numerical results can reproduce many observed characteristics of chromospheric anemone jets, topologically and quantitatively. As a result of the tearing instability, plasmoids are generated in the reconnection process that are consistent with the observed bright moving blobs in the anemone jets. An increase in the thermal pressure at the base of the jet is also driven by the reconnection, which induces a train of slow-mode shocks propagating upward. These shocks are a secondary effect, and only modulate the outflow of the anemone jet. The jet itself is driven by the energy input due to the reconnection of the MMFs and the ambient magnetic field.

  20. Numerical Simulations of Chromospheric Anemone Jets Associated with Moving Magnetic Features

    NASA Astrophysics Data System (ADS)

    Yang, Liping; He, Jiansen; Peter, Hardi; Tu, Chuanyi; Zhang, Lei; Feng, Xueshang; Zhang, Shaohua

    2013-11-01

    Observations with the space-based solar observatory Hinode show that small-scale magnetic structures in the photosphere are found to be associated with a particular class of jets of plasma in the chromosphere called anemone jets. The goal of our study is to conduct a numerical experiment of such chromospheric anemone jets related to the moving magnetic features (MMFs). We construct a 2.5 dimensional numerical MHD model to describe the process of magnetic reconnection between the MMFs and the pre-existing ambient magnetic field, which is driven by the horizontal motion of the magnetic structure in the photosphere. We include thermal conduction parallel to the magnetic field and optically thin radiative losses in the corona to account for a self-consistent description of the evaporation process during the heating of the plasma due to the reconnection process. The motion of the MMFs leads to the expected jet and our numerical results can reproduce many observed characteristics of chromospheric anemone jets, topologically and quantitatively. As a result of the tearing instability, plasmoids are generated in the reconnection process that are consistent with the observed bright moving blobs in the anemone jets. An increase in the thermal pressure at the base of the jet is also driven by the reconnection, which induces a train of slow-mode shocks propagating upward. These shocks are a secondary effect, and only modulate the outflow of the anemone jet. The jet itself is driven by the energy input due to the reconnection of the MMFs and the ambient magnetic field.

  1. Dynamics and Structure of Three-dimensional Poloidally Magnetized Supermagnetosonic Jets

    NASA Astrophysics Data System (ADS)

    Hardee, Philip E.; Clarke, David A.; Rosen, Alexander

    1997-08-01

    A set of three-dimensional magnetohydrodynamical simulations of supermagnetosonic magnetized jets has been performed. The jets contain an equipartition primarily poloidal magnetic field, and the effect of jet density on jet dynamics and structure is evaluated. The jet is precessed at the origin to break the symmetry and to excite Kelvin-Helmholtz-unstable helical modes. In the linear limit, observed structures are similar in all simulations and can be produced by structures predicted to arise as a result of instability. The amplitude of various unstable modes is evaluated. Most unstable modes do not reach the maximum amplitudes estimated from the linear theory by computing displacement surfaces associated with the modes. Surprisingly, even these large-amplitude distortions are fitted reasonably well by displacement surfaces computed from the linear theory. Large-amplitude helical and elliptical distortions lead to significant differences in the nonlinear development of the jets as a function of the jet density. Jets less dense than the surrounding medium entrain material, lose energy through shock heating, and slow down relatively rapidly once large-amplitude distortions develop as a result of instability. Jets more dense than the surrounding medium lose much less energy as they entrain and accelerate the surrounding medium. The dense jet maintains a high-speed spine that exhibits large-amplitude helical twisting and elliptical distortion over considerable distance without disruption of internal jet structures as happens for the less dense jets. This dense high-speed spine is surrounded by a less dense sheath consisting of slower moving jet fluid and magnetic field mixed with the external medium. Simulated synchrotron intensity and fractional polarization images from these calculations provide a considerably improved connection between simulation results and jet observations than do images made using the fluid variables alone. Intensity structure in the dense jet

  2. Computer simulations of relativistic MIG`s with magnetically compressed beams for high power microwave tubes

    SciTech Connect

    Boers, J.E.

    1994-12-31

    High power microwave tubes require well focused, high energy electron beams. High frequencies cause the rf interaction with the beam to concentrate in the outer edge of the beam, making the center relatively unimportant. The Magnetron Injection Gun (MIG) uses a truncated cone for a cathode and an axial magnetic field to concentrate the electron current in an annulus, eliminating the current in the center of the beam. High power microwave tubes used for rf plasma generation, and for accelerators require these high current, relativistic beams. A theoretical study of Relativistic MIG`s has been carried out using PBGUNS, a digital program for the Poisson simulation of particle beams. The simulations show that there are two types of guns that need to be considered, those with cathodes that are short axially compared with their mean radius from the axis and those whose length are comparable to or longer than the mean radius. Short cathodes are dominated by the axial end conditions which need to be close to the Pierce angle but are little effected by the shape of the accelerating electrode. The longer cathodes are critically dependent on both the end conditions and the accelerating electrode. One or two transition regions are needed; one to transport the beam to its final diameter and a second to turn it axially in such a way that it does not ripple excessively.

  3. Compressible Relativistic Magnetohydrodynamic Turbulence in Magnetically Dominated Plasmas an