3D simulations of microquasar jets in clumpy stellar winds

Abstract

Context. High-mass microquasars consist of a massive star and a compact object, the latter producing jets that will interact with the stellar wind. The evolution of the jets, and ultimately their radiative outcome, could depend strongly on the inhomogeneity of the wind, which calls for a detailed study. Aims. The hydrodynamics of the interaction between a jet and a clumpy wind is studied, focusing on the global wind-and single clump-jet interplay. Methods. We have performed, using the code Ratpenat, three-dimensional numerical simulations of a clumpy wind interacting with a mildly relativistic jet, and of individual clumps penetrating into a jet. Results. For typical wind and jet velocities, filling factors of about > ∼ 0.1 are already enough for the wind to be considered as clumpy. An inhomogeneous wind makes the jet more unstable when crossing the system. Kinetic luminosities ∼10 37 erg/s allow the jet to reach the borders of a compact binary with an O star, as in the smooth wind case, although with a substantially higher degree of disruption. When able to enter into the jet, clumps are compressed and heated during a time of about their size divided by the sound speed in the shocked clump. Then, clumps quickly disrupt, mass-loading and slowing down the jet. Conclusions. We conclude that moderate wind clumpiness makes already a strong difference with the homogeneous wind case, enhancing jet disruption, mass-loading, bending, and likely energy dissipation in the form of emission. All this can have observational consequences at high-energies and also in the large-scale radio jets.

Gamma rays from clumpy wind-jet interactions in high-mass microquasars

“…In that case, the clumps would be surrounded by a very dilute, hot medium of little dynamical impact either for the jet, or the clumps. We adopt here however the more conservative assumption that, even if χ ∼ 10, the wind interacts with the jet forming a relatively smooth region of shocked material that circumvents the jet (see Perucho & Bosch-Ramon 2012; see also Pittard 2007 in the context of colliding wind binaries). This shocked wind can prevent small clumps from reaching the jet, which sets the first condition for clump-jet interaction to occur.…”

A new multiwavelength lepto-hadronic model of astrophysical jet emission

“…The thermal protons of the wind interact with the relativistic protons in the jets, producing γ-ray photons with energy above the GeV range. If the wind is clumpy, the rate of proton-proton interactions may increase temporarily, resulting in γ-ray flares (see e.g., [31,1,35,32]). However, our work focuses on the steady-state emission of an accreting black hole in a weakly accreting state, we thus choose to model the stellar wind of the companion star by a stationary spherically symmetric wind [19].…”

Relativistic stellar jets: dynamics and non-thermal radiation

“…1, several works have been devoted to study numerically the dynamical impact of the external medium on the microquasar jet. In particular, some of these works [17][18][19] studied the jet-medium interaction on the scales of the binary system in high-mass microquasars. This case is particularly clear in what refers to the degree of medium influence, given the powerful winds of massive stars.…”

“…Such perturbations can develop non-linearly until affecting the whole jet dissipating its kinetic energy in the form of heat, shocks, turbulence, and non-thermal particles [see also 18]. As shown in [19], wind inhomogeneity will enhance the jet disruption processes sharpening the perturbations. Note that mass-entrainment due to the wind-jet lateral interaction will make the jet slower and heavier.…”

“…As their extragalactic relatives, relativistic stellar jets are to cover a long way through a complex medium, not only inhomogeneous in density but also with non-negligible velocities. As shown in a series of papers on numerical studies of relativistic stellar jets [4,6,[17][18][19], the stellar winds and the external medium on large spatial scales are expected to have a relevant dynamical role in the propagation and termination of relativistic stellar jets, as well as on their radiative output.…”