TeV blazar variability: the firehose instability?

Subramanian, Prasad; Shukla, Amit; Becker, Peter A.

doi:10.1111/j.1365-2966.2012.20991.x

Cited by 16 publications

(12 citation statements)

References 32 publications

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“…In this case the A-EFH develops faster, with maximum growth rates much higher than P-EFH (Li & Habbal 2000;Gary & Nishimura 2003;Camporeale & Burgess 2008;Hellinger et al 2014), and may play the main role in reducing, eventually, the free energy, and leading to enhanced fluctuations which may scatter the electrons and limit their anisotropy. It is also known that firehose instability may influence macroscopic plasma properties, like viscous heating and thermal conduction, with implications for plasma dynamics at the magnetic field reconnection sites in the heliosheath (Schoeffler et al 2011), and at larger scales in intracluster medium and accretion disks plasmas (Sharma et al 2006), and may cause disruptions in the large-scale plasma jets triggering radiative fields (Subramanian et al 2012).…”

Section: Introductionmentioning

confidence: 99%

Firehose instabilities triggered by the solar wind suprathermal electrons

Shaaban

Lazar

Lopez

et al. 2019

Monthly Notices of the Royal Astronomical Society

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In collision-poor plasmas from space, e.g., solar wind, terrestrial magnetospheres, kinetic instabilities are expected to play a major role in constraining the temperature anisotropy of plasma particles, but a definitive answer can be given only after ascertaining their properties in these environments. Present study describes the full spectrum of electron firehose instabilities in the presence of suprathermal electron populations which are ubiquitous in space plasmas. Suprathermal electrons stimulate both the periodic and aperiodic branches, remarkable being the effects shown by the aperiodic mode propagating obliquely to the ambient magnetic field which markedly exceeds the growth rates of the parallel (periodic) branch reported recently in Lazar et al. (2017a, MNRAS 464, 564). Derived exclusively in terms of the plasma parameters, the anisotropy thresholds of this instability are also lowered in the presence of suprathermal electrons, predicting an enhanced effectiveness in the solar wind conditions. These results may also be relevant in various other astrophysical contexts where the firehose instabilities involve, e.g., solar flares, sites of magnetic field reconnection, accretion flows or plasma jets leading to shocks and co-rotating interactions in heliosphere, interstellar medium and galaxy clusters.

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Section: Introductionmentioning

confidence: 99%

Firehose instabilities triggered by the solar wind suprathermal electrons

Shaaban

Lazar

Lopez

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Begelman et al (2008)), misaligned minijets inside the main jet (e.g. Giannios et al (2010)), jet deceleration (Georganopoulos & Kazanas 2003;Levinson 2007), wiggles in an anisotropic electron beam directed along the jet (Ghisellini et al 2009), relativistic plasma blob inside the jet (blob-in-jet model; (Katarzyński et al 2001)) and plasma instability such as firehose (Subramanian et al 2012) caused by anisotropic electron beam. Some fundamental questions regarding this source such as the content of its jet, location and mechanism of γ-ray emission and the origin of observed variability are still not answered unambiguously.…”

Section: Introductionmentioning

confidence: 99%

MULTI-FREQUENCY, MULTI-EPOCH STUDY OF Mrk 501: HINTS FOR A TWO-COMPONENT NATURE OF THE EMISSION

Shukla

Chitnis

Singh

et al. 2014

ApJ

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Since the detection of very high energy (VHE) γ-rays from Mrk 501, its broad band emission of radiation was mostly and quite effectively modeled using one zone emission scenario. However, broadband spectral and flux variability studies enabled by the multiwavelength campaigns carried out during the recent years have revealed rather complex behavior of Mrk 501. The observed emission from Mrk 501 could be due to a complex superposition of multiple emission zones.Moreover new evidences of detection of very hard intrinsic γ-ray spectra obtained from Fermi-LAT observations have challenged the theories about origin of VHE γ-rays. Our studies based on Fermi-LAT data indicate the existence of two separate components in the spectrum, one for low energy γ-rays and the other for high energy γ-rays. Using multiwaveband data from several ground and space based instruments, in addition to HAGAR data, the spectral energy distribution of Mrk 501 is obtained for various flux states observed during 2011. In the present work, this observed broadband spectral energy distribution is reproduced with a leptonic, multi-zone Synchrotron Self-Compton model.

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“…The high energy γ-ray photons which are emitted within the BLR, at the distance of ∼0.1 pc from the central engine, are expected to be absorbed by the UV photons emitted by H-Ly α and continuum emission of a quasar with an accretion disk luminosity above 10 45 ergs/sec. The observed rapid variability warrant more sophisticated scenarios, e.g., turbulence, multi-zone emission, or magnetic reconnection, emission from the magnetosphere of black holes [162,163,164,165].…”

Section: Mjd [Days]mentioning

confidence: 99%

Galactic and Extragalactic Sources of Very High Energy Gamma-rays

Bose,

Chitnis,

Majumdar

et al. 2022

Preprint

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Very high energy γ-rays are one of the most important messengers of the non-thermal Universe. The major motivation of very high energy γ-ray astronomy is to find sources of high energy cosmic rays. Several astrophysical sources are known to accelerate cosmic rays to very high energies under extreme conditions. Very high energy γ-rays are produced at these astrophysical sites or near through interactions of cosmic rays in the surrounding medium close to the sources. Gamma-rays, being neutral, travel in a straight line and thus give us valuable information about the cosmic ray sources and their surroundings. Additionally, very high energy γ-ray astronomy can probe many fundamental physics questions. Ground-based γ-ray astronomy began its journey in 1989 when Whipple telescope detected TeV γ-rays from the Crab, a pulsar wind nebula in the Milky Way. In the last two decades, technological improvements have facilitated the development of the latest generation of very high energy detectors and telescopes which have delivered exciting new results. Until now over two hundred very high energy γ-ray sources, both galactic and extra-galactic has been detected. These observations have provided a deeper insight into a large number of important questions in high energy astrophysics and astroparticle physics. This review article is an attempt to enumerate the most important results in the exciting and rapidly developing field of very high energy γ-ray astronomy.

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TeV blazar variability: the firehose instability?

Cited by 16 publications

References 32 publications

Firehose instabilities triggered by the solar wind suprathermal electrons

Firehose instabilities triggered by the solar wind suprathermal electrons

MULTI-FREQUENCY, MULTI-EPOCH STUDY OF Mrk 501: HINTS FOR A TWO-COMPONENT NATURE OF THE EMISSION

Galactic and Extragalactic Sources of Very High Energy Gamma-rays

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