The Cosmic Battery in Astrophysical Accretion Disks

Contopoulos, Ioannis; Nathanail, Antonios; Katsanikas, Matthaios

doi:10.1088/0004-637x/805/2/105

Cited by 32 publications

(38 citation statements)

References 40 publications

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“…The central jet current closes along the interface between the core jet and the outer wind, whereas the outer wind electric current closes farther out (not along the inner core jet). This universal configuration of the axial electric current circuit in extragalactic jets, predicted by Contopoulos et al (2009, hereafter CCKG), is unique to the CB mechanism and it was confirmed numerically by the simulations of Christodoulou et al (2008) and Contopoulos et al (2015).…”

Section: The Cosmic Batterysupporting

confidence: 57%

“…azimuthal currents in the inner disks of AGN (Contopoulos & Kazanas 1998;Contopoulos et al 2006Contopoulos et al , 2015Christodoulou et al 2008;Lynden-Bell 2013;Koutsantoniou & Contopoulos 2014). Its most important element is that it supports and maintains a large-scale poloidal magnetic field whose direction is inextricably tied to the rotation of the disk (see also Lynden-Bell 2013).…”

Section: The Cosmic Batterymentioning

confidence: 99%

“…Its most important element is that it supports and maintains a large-scale poloidal magnetic field whose direction is inextricably tied to the rotation of the disk (see also Lynden-Bell 2013). In the vicinity of a 10 8 M black hole, this mechanism can generate a field corresponding to equipartition between the magnetic and relativistic-particle energies on timescales of the order of one billion years (Contopoulos & Kazanas 1998;Contopoulos et al 2015). We call this mechanism the Cosmic Battery (hereafter CB).…”

Section: The Cosmic Batterymentioning

confidence: 99%

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Dominance of outflowing electric currents on decaparsec to kiloparsec scales in extragalactic jets

Christodoulou

Gabuzda

Knuettel

et al. 2016

A&A

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Context. Helical magnetic fields embedded in the jets of active galactic nuclei (AGNs) are required by the broad range of theoretical models that advocate for electromagnetic launching of the jets. In most models, the direction of the magnetic field is random, but if the axial field is generated by a Cosmic Battery generated by current in the direction of rotation in the accretion disk, there is a correlation between the directions of the spin of the AGN accretion disk and of the axial field, which leads to a specific direction for the axial electric current, azimuthal magnetic field, and the resulting observed transverse Faraday-rotation (FR) gradient across the jet, due to the systematic change in the line-of-sight magnetic field. Aims. We consider new observational evidence for the presence of a nested helical magnetic-field structure such as would be brought about by the operation of the Cosmic Battery, and make predictions about the expected behavior of transverse FR gradients observed on decaparsec and kiloparsec scales. Methods. We have jointly considered 27 detections of transverse FR gradients on parsec scales, four reports of reversals in the directions of observed transverse FR gradients observed on parsec-decaparsec scales, and five detections of transverse FR gradients on decaparsec-kiloparsec scales, one reported here for the first time. We also consider seven tentative additional examples of transverse FR gradients on kiloparsec scales, based on an initial visual inspection of published Very Large Array FR maps of 85 extragalactic radio sources, for three of which we have carried out quantitative analyses in order to quantitatively estimate the significances of the gradients. Results. The data considered indicate a predominance of transverse FR gradients in the clockwise direction on the sky (i.e., net axial current flowing inward in the jet) on parsec scales and in the counter-clockwise direction on the sky (i.e., net axial current flowing outward) on scales greater than about 10 pc, consistent with the expectations for the Cosmic Battery. The predominance of counter-clockwise FR gradients on larger scales has been established at the 3σ confidence level. Conclusions. The collected results provide evidence for a reversal in the direction of the net azimuthal magnetic field determining the ordered component of the observed FR images, with distance from the jet base. This can be understood if the dominant azimuthal field on parsec scales corresponds to an axial electric current flowing inward along the jet, whereas the (weaker) dominant azimuthal field on kiloparsec scales corresponds to a outward-flowing current in the outer sheath of the jet and/or an extended disk wind. This is precisely the current/magnetic field structure that should be generated by the Cosmic Battery.

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Section: The Cosmic Batterysupporting

confidence: 57%

Section: The Cosmic Batterymentioning

confidence: 99%

Section: The Cosmic Batterymentioning

confidence: 99%

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Dominance of outflowing electric currents on decaparsec to kiloparsec scales in extragalactic jets

Christodoulou

Gabuzda

Knuettel

et al. 2016

A&A

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“…In order to convince ourselves and the scientific community that the CB operates as described above, we performed in the past several numerical simulations of the process (Contopoulos et al 2006;Christodoulou et al 2008;Contopoulos et al 2015). In all of them, though, the source of radiation has been considered to be isotropic as in eq.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulations of the Cosmic Battery in accretion flows around astrophysical black holes

Contopoulos

Nathanail

Sądowski

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We implement the KORAL code to perform two sets of very long general relativistic radiation magnetohydrodynamic simulations of an axisymmetric optically thin magnetized flow around a non-rotating black hole: one with a new term in the electromagnetic field tensor due to the radiation pressure felt by the plasma electrons on the comoving frame of the electron-proton plasma, and one without. The source of the radiation is the accretion flow itself. Without the new term, the system evolves to a standard accretion flow due to the development of the magneto-rotational instability (MRI). With the new term, however, the system eventually evolves to a magnetically arrested state (MAD) in which a large scale jet-like magnetic field threads the black hole horizon. Our results confirm the secular action of the Cosmic Battery in accretion flows around astrophysical black holes.

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“…Of course, the programmer must decide whether their simulations apply to an electron-ion or to an electron-positron plasma 2 . We have performed in the past several numerical simulations of the Cosmic Battery process [18,[21][22][23]. Our first simulations were performed in Newtonian spacetime and the source of radiation was considered to be isotropic.…”

Section: Gr Radiation Mhd Simulations Of the Cosmic Battery In Actionmentioning

confidence: 99%

Electric Currents along Astrophysical Jets

Contopoulos

2017

Galaxies

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Astrophysical black holes and their surrounding accretion disks are believed to be threaded by grand design helical magnetic fields. There is strong theoretical evidence that the main driver of their winds and jets is the Lorentz force generated by these fields and their associated electric currents. Several researchers have reported direct evidence for large scale electric currents along astrophysical jets. Quite unexpectedly, their directions are not random as would have been the case if the magnetic field were generated by a magnetohydrodynamic dynamo. Instead, in all kpc-scale detections, the inferred electric currents are found to flow away from the galactic nucleus. This unexpected break of symmetry suggests that a battery mechanism is operating around the central black hole. In the present article, we summarize observational evidence for the existence of large scale electric currents and their associated grand design helical magnetic fields in kpc-scale astrophysical jets. We also present recent results of general relativistic radiation magnetohydrodynamic simulations which show the action of the Cosmic Battery in the vicinity of astrophysical black holes.

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The Cosmic Battery in Astrophysical Accretion Disks

Cited by 32 publications

References 40 publications

Dominance of outflowing electric currents on decaparsec to kiloparsec scales in extragalactic jets

Dominance of outflowing electric currents on decaparsec to kiloparsec scales in extragalactic jets

Numerical simulations of the Cosmic Battery in accretion flows around astrophysical black holes

Electric Currents along Astrophysical Jets

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