345 research outputs found
Dynamic Boundaries of Event Horizon Magnetospheres
This Letter analyzes 3-dimensional simulations of Kerr black hole
magnetospheres that obey the general relativistic equations of perfect
magnetohydrodynamics (MHD). Particular emphasis is on the event horizon
magnetosphere (EHM) which is defined as the the large scale poloidal magnetic
flux that threads the event horizon of a black hole (This is distinct from the
poloidal magnetic flux that threads the equatorial plane of the ergosphere,
which forms the ergospheric disk magnetosphere). Standard MHD theoretical
treatments of Poynting jets in the EHM are predicated on the assumption that
the plasma comprising the boundaries of the EHM plays no role in producing the
Poynting flux. The energy flux is electrodynamic in origin and it is
essentially conserved from the horizon to infinity, this is known as the
Blandford-Znajek (B-Z) mechanism. To the contrary, within the 3-D simulations,
the lateral boundaries are strong pistons for MHD waves and actually inject
prodigious quantities of Poynting flux into the EHM. At high black hole spin
rates, strong sources of Poynting flux adjacent to the EHM from the ergospheric
disk will actually diffuse to higher latitudes and swamp any putative B-Z
effects. This is in contrast to lower spin rates, which are characterized by
much lower output powers and modest amounts of Poynting flux are injected into
the EHM from the accretion disk corona.Comment: To appear in MNRAS Letters. A high resolution version can be found
at: http://85.20.11.14/hosting/punsly/MNRAS%20Letter7.20.07
The Jet Power and Emission Line Correlations of Radio Loud Optically Selected Quasars
In this Letter, the properties of the extended radio emission form SDSS DR7
quasars with is studied. This low redshift sample is useful since
any corresponding FIRST radio observations are sensitive enough to detect
extended flux in even the weakest FR II radio sources. In the sample, 2.7% of
the sources have detectable extended emission on larger than galactic scales
( 20 - 30 kpc). The frequency of quasars with FR II level extended radio
emission is and of quasars have FR I level extended
radio emission. The lower limit simply reflects the flux density limit of the
survey. The distribution of the long term time averaged jet powers of these
quasars, , has a broad peak ergs/sec that turns
over below below ergs/sec and sources above ergs/sec are
extremely rare. It is found that the correlation between the bolometric (total
thermal) luminosity of the accretion flow, , and is not
strong. The correlation of with narrow line luminosity is stronger
than the correlation with broad line luminosity and the continuum luminosity.
It is therefore concluded that previous interpretations of correlations of
with narrow line strengths in radio galaxies as a direct correlation
of jet power and accretion power have been overstated. It is explained why this
interpretation mistakenly overlooks the sizeable fraction of sources with weak
accretion luminosity and powerful jets discovered by Ogle et al (2006).Comment: To appear in ApJ Letter
Kinetically Dominated FRII Radio Sources
The existence of FR II objects that are kinetically dominated, the jet
kinetic luminosity, , is larger than the total thermal luminosity (IR to
X-ray) of the accretion flow, , is of profound theoretical interest.
Such objects are not expected in most theoretical models of the central engine
of radio loud AGN. Thus, establishing such a class of objects is an important
diagnostic for filtering through the myriad of theoretical possibilities. This
paper attempts to establish a class of quasars that have existed in a state of
kinetic dominance, , at some epoch, . It is
argued that the 10 quasars in this article with a long term time average
, , that exceed are likely to have satisfied the
condition either presently or in the past based on the rarity of
quasars. Finally, the existence of these sources is discussed
in the context of the theory of the central engine.Comment: To appear in MNRAS Letter
A New Solution to the Plasma Starved Event Horizon Magnetosphere: Application to the Forked Jet in M87
© 2018 ESO. Reproduced with permission from Astronomy & Astrophysics. Content in the UH Research Archive is made available for personal research, educational, and non-commercial purposes only. Unless otherwise stated, all content is protected by copyright, and in the absence of an open license, permissions for further re-use should be sought from the publisher, the author, or other copyright holder.Very Long Baseline Interferometry observations at 86 GHz reveal an almost hollow jet in M87 with a forked morphology. The detailed analysis presented here indicates that the spectral luminosity of the central spine of the jet in M87 is a few percent of that of the surrounding hollow jet 200-400 μ as from the central black hole. Furthermore, recent jet models indicate that a hollow "tubular" jet can explain a wide range of plausible broadband spectra originating from jetted plasma located within ~30 μ as of the central black hole, including the 230 GHz correlated flux detected by the Event Horizon Telescope. Most importantly, these hollow jets from the inner accretion flow have an intrinsic power capable of energizing the global jet out to kiloparsec scales. Thus motivated, this paper considers new models of the event horizon magnetosphere (EHM) in low luminosity accretion systems. Contrary to some models, the spine is not an invisible powerful jet. It is an intrinsically weak jet. In the new EHM solution, the accreted poloidal magnetic flux is weak and the background photon field is weak. It is shown how this accretion scenario naturally results in the dissipation of the accreted poloidal magnetic flux in the EHM not the accumulation of poloidal flux required for a powerful jet. The new solution indicates less large scale poloidal magnetic flux (and jet power) in the EHM than in the surrounding accretion flow and cannot support significant EHM driven jets.Peer reviewe
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