General relativistic magnetohydrodynamical simulations of the jet in M 87

Abstract

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 ofṀ ∼ 9 × 10 −3 M yr −1 and a total jet power of P j ∼ 10 43 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 accretion rate. This suggests the possibility that this model could also apply to a wider range of low-luminosity black holes.

The Structure and Propagation of the Misaligned Jet M87

“…This may allow us to determine whether the jet is ultimately launched from the black hole (Blandford-Znajek process; [6]) or from the accretion disk (Blandford-Payne process; [7]). Moreover, the effect of gravitational lensing can enhance the brightness of the counter-jet near the black hole, which might further enable us to constrain the mass loading radius of the jet [8,9]. Along with this situation, the traditional lower-frequency VLBI also gains in importance.…”

Modeling Polarized Emission from Black Hole Jets: Application to M87 Core Jet

“…In combination with radiative transfer model, this finally makes our numerical simulations of accretion flows resemble observations of underluminous accreting black holes [13,14,16,18,31].…”

“…The electron temperatures, T e , are computed assuming that the proton-to-electron coupling depends on plasma magnetization [14,16,18]:…”

“…Until recently, the least understood part of these models was a proper treatment of radiating electrons. Finally, however, this issue has been addressed [13][14][15][16][17][18][19]. With new and more detailed observations, we are beginning to directly compare the numerical simulations of accretion flows to real astronomical systems such as Galactic center Sgr A* and the core of M87 galaxy [20].…”

Jet Signatures in the Spectra of Accreting Black Holes

“…Furthermore, because of the similarities between AGN and the low/hard state in XRBs, we assume that the physics of electron heating and cooling is the same across these systems. We therefore choose a range of values of d  and j  motivated by fitting to Sgr A * and M87, since these are the only sources whose spectra have been fitted to constrain these parameters Mościbrodzka et al 2014;Mościbrodzka & Falcke 2013;Chan et al 2015a;Moscibrodzka et al 2015).…”