General relativistic stream crossing in tidal disruption events
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General relativistic stream crossing in tidal disruption events. / Batra, Gauri; Lu, Wenbin; Bonnerot, Clement; Phinney, E. Sterl.
In: Monthly Notices of the Royal Astronomical Society, Vol. 520, No. 4, 22.02.2023, p. 5192-5208.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - General relativistic stream crossing in tidal disruption events
AU - Batra, Gauri
AU - Lu, Wenbin
AU - Bonnerot, Clement
AU - Phinney, E. Sterl
PY - 2023/2/22
Y1 - 2023/2/22
N2 - A star is tidally stretched into an elongated stream after being disrupted by a supermassive black hole (BH). Using an approximate tidal equation, we calculate the stream's thickness evolution along its geodesic, during which we treat the effect of nozzle shocks as a perfect bounce. Self-intersection occurs when the closest approach separation is smaller than the stream thickness. We explore a wide parameter space of orbital angular momenta, inclinations, and BH spins to obtain the properties of stream intersection. Two collision modes are identified: in similar to half of the cases, the collision occurs near the pericentre at an angle close to 0(o) ('rear-end' mode) and the other half have collisions far from the pericentre with collision angles close to 180(o) ('head-on' mode). The intersection typically occurs between consecutive half-orbits with a delay time that spans a wide range (from months up to a decade). The intersection radius generally increases with the orbital angular momentum and depends less strongly on the inclination and BH spin. The thickness ratio of the two colliding ends is of order unity and the transverse separation is a small fraction of the sum of the two thicknesses, so a large fraction of the stream's mass is shock heated in an offset collision. Many of the numerical results can be analytically understood in a post-Newtonian picture, where we find the reason for stream collision to be a geometric one. Future hydrodynamic simulations including recombination are needed to understand the long-term effects of pressure forces which are neglected here.
AB - A star is tidally stretched into an elongated stream after being disrupted by a supermassive black hole (BH). Using an approximate tidal equation, we calculate the stream's thickness evolution along its geodesic, during which we treat the effect of nozzle shocks as a perfect bounce. Self-intersection occurs when the closest approach separation is smaller than the stream thickness. We explore a wide parameter space of orbital angular momenta, inclinations, and BH spins to obtain the properties of stream intersection. Two collision modes are identified: in similar to half of the cases, the collision occurs near the pericentre at an angle close to 0(o) ('rear-end' mode) and the other half have collisions far from the pericentre with collision angles close to 180(o) ('head-on' mode). The intersection typically occurs between consecutive half-orbits with a delay time that spans a wide range (from months up to a decade). The intersection radius generally increases with the orbital angular momentum and depends less strongly on the inclination and BH spin. The thickness ratio of the two colliding ends is of order unity and the transverse separation is a small fraction of the sum of the two thicknesses, so a large fraction of the stream's mass is shock heated in an offset collision. Many of the numerical results can be analytically understood in a post-Newtonian picture, where we find the reason for stream collision to be a geometric one. Future hydrodynamic simulations including recombination are needed to understand the long-term effects of pressure forces which are neglected here.
KW - black hole physics
KW - methods: numerical
KW - galaxies: nuclei
KW - transients: tidal disruption events
KW - ROTATING BLACK-HOLES
KW - X-RAY FLARE
KW - DISK ACCRETION
KW - STELLAR
KW - STARS
KW - EVOLUTION
KW - TRANSIENT
KW - DEBRIS
KW - SIMULATIONS
KW - COMPRESSION
U2 - 10.1093/mnras/stad318
DO - 10.1093/mnras/stad318
M3 - Journal article
VL - 520
SP - 5192
EP - 5208
JO - Royal Astronomical Society. Monthly Notices
JF - Royal Astronomical Society. Monthly Notices
SN - 0035-8711
IS - 4
ER -
ID: 342566917