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ABSTRACT Relativistic jets, or highly collimated and fast-moving outflows, are endemic to many astrophysical phenomena. The jets produced by gamma-ray bursts (GRBs) and tidal disruption events (TDEs) are accompanied by the accretion of material on to a black hole or neutron star, with the accretion rate exceeding the Eddington limit of the compact object by orders of magnitude. In such systems, radiation dominates the energy–momentum budget of the outflow, and the dynamical evolution of the jet is governed by the equations of radiation hydrodynamics. Here, we show that there are analytical solutions to the equations of radiation hydrodynamics in the viscous (i.e. diffusive) regime that describe structured, relativistic jets, which consist of a fast-moving, highly relativistic core surrounded by a slower moving, less relativistic sheath. In these solutions, the slower moving, outer sheath contains most of the mass, and the jet structure is mediated by local anisotropies in the radiation field. We show that, depending on the pressure and density profile of the ambient medium, the angular profile of the jet Lorentz factor is Gaussian or falls off even more steeply with angle. These solutions have implications for the nature of jet production and evolution in hyperaccreting systems, and demonstrate that such jets – and the corresponding jet structure – can be sustained entirely by radiative processes. We discuss the implications of these findings in the context of jetted TDEs and short and long GRBs.
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Numerical Simulation of Radiatively Driven Transonic Relativistic Jets
Abstract We perform the numerical simulations of axisymmetric, relativistic, optically thin jets under the influence of the radiation field of an accretion disk. We show that starting from a very low injection velocity at the base, jets can be accelerated to relativistic terminal speeds when traveling through the radiation field. The jet gains momentum through the interaction with the radiation field. We use a relativistic equation of state for multispecies plasma, which self-consistently calculates the adiabatic index for the jet material. All the jet solutions obtained are transonic in nature. In addition to the acceleration of the jet to relativistic speeds, our results show that the radiation field also acts as a collimating agent. The jets remain well collimated under the effect of radiation pressure. We also show that if the jet starts with a rotational velocity, the radiation field will reduce the angular momentum of the jet beam.
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- PAR ID:
- 10591202
- Publisher / Repository:
- The Astrophysical Journal
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 971
- Issue:
- 1
- ISSN:
- 0004-637X
- Page Range / eLocation ID:
- 13
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/1538-4357/ad54c0
