Nonrelativistic Compton scattering and models of quasars

Katz, J. I.

doi:10.1086/154455

Cited by 93 publications

(47 citation statements)

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“…However, AGN disk luminosity is known to be dominated not in X-ray but in optical (e.g., Elvis et al 1994). X-ray emission is reprocessed optical emission via Comptonization processes in hot accretion disk coronae (e.g., Katz 1976;Pozdniakov et al 1977;Sunyaev & Titarchuk 1980). Moreover, as recent studies suggest that the fundamental plane exist only for low accretion rate BH systems (see e.g.…”

Section: Introductionmentioning

confidence: 99%

Disk–Jet Connection in Active Supermassive Black Holes in the Standard Accretion Disk Regime

Inoue

Doi

Tanaka

et al. 2017

ApJ

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We study the disk-jet connection in supermassive black holes by investigating the properties of their optical and radio emissions utilizing the SDSS-DR7 and the NVSS catalogs. Our sample contains 7017 radio-loud quasars with detection both at 1.4 GHz and SDSS optical spectrum. Using this radioloud quasar sample, we investigate the correlation among the jet power (P jet ), the bolometric disk luminosity (L disk ), and the black hole mass (M BH ) in the standard accretion disk regime. We find that the jet powers correlate with the bolometric disk luminosities as log P jet = (0.96 ± 0.012) log L disk + (0.79 ± 0.55). This suggests that the jet production efficiency of η jet 1.1 +2.6 −0.76 × 10 −2 assuming the disk radiative efficiency of 0.1 implying low black hole spin parameters and/or low magnetic flux for radio-loud quasars. But it can be also due to dependence of the efficiency on geometrical thickness of the accretion flow which is expected to be small for quasars accreting at the disk Eddington ratios 0.01 λ 0.3. This low jet production efficiency does not significantly increase even if we set the disk radiative efficiency of 0.3. We also investigate the fundamental plane in our samples among P jet , L disk , and M BH . We could not find a statistically significant fundamental plane for radio-loud quasars in the standard accretion regime.

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Section: Introductionmentioning

confidence: 99%

Disk–Jet Connection in Active Supermassive Black Holes in the Standard Accretion Disk Regime

Inoue

Doi

Tanaka

et al. 2017

ApJ

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“…The process of incomplete Comptonization in the disks of accreting compact objects is one well-known astrophysical application (e.g. Sunyaev 1970;Katz 1976;Rybicki & Lightman 1993), see Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Active galactic nuclei jets and multiple oblique shock acceleration: starved spectra

Meli¹,

Biermann

2013

A&A

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Context. Shocks in jets and hot spots of active galactic nuclei (AGN) are one prominent class of possible sources of very high-energy cosmic-ray particles (above 10 18 eV). Extrapolating their spectrum to their plausible injection energy from some shock implies an enormous hidden energy for a spectrum of index ∼−2. Some analyses suggest the particles' injection spectrum at source to be as steep as −2.4 to −2.7, which exacerbates the problem, by a factor of 10 6 . Nevertheless, it seems implausible that more than at the very best 1/3 of the jet energy goes into the required flux of energetic particles, thus one would need to allow for the possibility that there is an energy problem, which we would like to address in this work. Aims. Sequences of consecutive oblique shock features, or conical shocks, have been theoretically predicted and eventually observed in many AGN jets. Based on that, we use by analogy the Comptonization effect and propose a scenario of a single injection of particles consecutively accelerated by several oblique shocks along the axis of an AGN jet. Methods. We developed a test-particle approximation Monte Carlo simulations to calculate particle spectra by acceleration at such a shock pattern while monitoring the efficiency of acceleration by calculating differential spectra. Results. We find that the first shock of a sequence of oblique shocks establishes a low-energy power-law spectrum with ∼E −2.7 . The following consecutive shocks push the spectrum up in energy, rendering flatter distributions with steep cut-offs, and characteristic depletion at low energies, which could explain the puzzling apparent extra source power. Conclusions. Our numerical calculations show a variation of spectral indices, a general spectral flattening, and starved spectra, which connect to the relativistic nature of the shocks, the multiple shock acceleration conditions, and the steepness of the magnetic field to the shock normal. This helps in understanding the jet-magnetic field geometry and the irregular or flat spectra observed in many AGN jets (e.g., CenA, 3C 279, PKS 1510-089). Furthermore, the E −2.4 − E −2.7 ultra-high-energy cosmic-ray injected source spectra claimed by many authors might be explained by the superposition of several, perhaps many, emission sources, all of which end their particle shock-acceleration sequence with flatter, starved spectra produced by two or more consecutive oblique shocks along their jets. It might also imply a mixed component of the accelerated particles above 10 19 eV. Moreover, the present acceleration model can explain the variability of inverted gamma-ray spectra observed in high redshifted flaring extragalactic sources.

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“…A few special cases are of particular interest: a) Source of cool photons surrounded by hot electrons. Such models have been proposed to represent spectral formation in compact binary syste ms (Shapiro et al 1976) and active galactic nuclei (Katz 1976). In this case the emergent spectrum develops a high energy tail whose form is independent of the source spectrum but depends on the optical depth, T o , of the electron distribution.…”

Section: Com Tonizationmentioning

confidence: 99%