The nozzle shock in tidal disruption events
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The nozzle shock in tidal disruption events. / Bonnerot, Clement; Lu, Wenbin.
In: Monthly Notices of the Royal Astronomical Society, Vol. 511, No. 2, 11.02.2022, p. 2147-2169.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The nozzle shock in tidal disruption events
AU - Bonnerot, Clement
AU - Lu, Wenbin
PY - 2022/2/11
Y1 - 2022/2/11
N2 - Tidal disruption events (TDEs) occur when a star gets torn apart by the strong tidal forces of a supermassive black hole, which results in the formation of a debris stream that partly falls back towards the compact object. This gas moves along inclined orbital planes that intersect near pericentre, resulting in a so-called 'nozzle shock'. We perform the first dedicated study of this interaction, making use of a two-dimensional simulation that follows the transverse gas evolution inside a given section of stream. This numerical approach circumvents the lack of resolution encountered near pericentre passage in global three-dimensional simulations using particle-based methods. As it moves inward, we find that the gas motion is purely ballistic, which near pericentre causes strong vertical compression that squeezes the stream into a thin sheet. Dissipation takes place at the resulting nozzle shock, inducing a rise in pressure that causes the collapsing gas to bounce back, although without imparting significant net expansion. As it recedes to larger distances, this matter continues to expand while remaining thin despite the influence of pressure forces. This gas evolution specifies the strength of the subsequent self-crossing shock, which we find to be more affected by black hole spin than previously estimated. We also evaluate the impact of general relativistic effects, viscous dissipation, magnetic fields, and radiative processes on the nozzle shock. This study represents an important step forward in the theoretical understanding of TDEs, bridging the gap between our robust knowledge of the fallback rate and the more complex following stages, during which most of the emission occurs.
AB - Tidal disruption events (TDEs) occur when a star gets torn apart by the strong tidal forces of a supermassive black hole, which results in the formation of a debris stream that partly falls back towards the compact object. This gas moves along inclined orbital planes that intersect near pericentre, resulting in a so-called 'nozzle shock'. We perform the first dedicated study of this interaction, making use of a two-dimensional simulation that follows the transverse gas evolution inside a given section of stream. This numerical approach circumvents the lack of resolution encountered near pericentre passage in global three-dimensional simulations using particle-based methods. As it moves inward, we find that the gas motion is purely ballistic, which near pericentre causes strong vertical compression that squeezes the stream into a thin sheet. Dissipation takes place at the resulting nozzle shock, inducing a rise in pressure that causes the collapsing gas to bounce back, although without imparting significant net expansion. As it recedes to larger distances, this matter continues to expand while remaining thin despite the influence of pressure forces. This gas evolution specifies the strength of the subsequent self-crossing shock, which we find to be more affected by black hole spin than previously estimated. We also evaluate the impact of general relativistic effects, viscous dissipation, magnetic fields, and radiative processes on the nozzle shock. This study represents an important step forward in the theoretical understanding of TDEs, bridging the gap between our robust knowledge of the fallback rate and the more complex following stages, during which most of the emission occurs.
KW - black hole physics
KW - hydrodynamics
KW - galaxies: nuclei
KW - BLACK-HOLES
KW - STELLAR DISRUPTION
KW - DISC FORMATION
KW - SELF-GRAVITY
KW - STARS
KW - EVOLUTION
KW - STREAM
KW - SIMULATIONS
KW - DYNAMICS
KW - DEBRIS
U2 - 10.1093/mnras/stac146
DO - 10.1093/mnras/stac146
M3 - Journal article
VL - 511
SP - 2147
EP - 2169
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
SN - 0035-8711
IS - 2
ER -
ID: 303685663