Common Envelope Wind Tunnel: The Effects of Binary Mass Ratio and Implications for the Accretion-driven Growth of LIGO Binary Black Holes
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Common Envelope Wind Tunnel : The Effects of Binary Mass Ratio and Implications for the Accretion-driven Growth of LIGO Binary Black Holes. / De, Soumi; MacLeod, Morgan; Everson, Rosa Wallace; Antoni, Andrea; Mandel, Ilya; Ramirez-Ruiz, Enrico.
In: Astrophysical Journal, Vol. 897, No. 2, 130, 01.07.2020.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Common Envelope Wind Tunnel
T2 - The Effects of Binary Mass Ratio and Implications for the Accretion-driven Growth of LIGO Binary Black Holes
AU - De, Soumi
AU - MacLeod, Morgan
AU - Everson, Rosa Wallace
AU - Antoni, Andrea
AU - Mandel, Ilya
AU - Ramirez-Ruiz, Enrico
PY - 2020/7/1
Y1 - 2020/7/1
N2 - We present three-dimensional local hydrodynamic simulations of flows around objects embedded within stellar envelopes using a "wind tunnel" formalism. Our simulations model the common envelope dynamical inspiral phase in binary star systems in terms of dimensionless flow characteristics. We present suites of simulations that study the effects of varying the binary mass ratio, stellar structure, equation of state, relative Mach number of the object's motion through the gas, and density gradients across the gravitational focusing scale. For each model, we measure coefficients of accretion and drag experienced by the embedded object. These coefficients regulate the coupled evolution of the object's masses and orbital tightening during the dynamical inspiral phase of the common envelope. We extrapolate our simulation results to accreting black holes with masses comparable to that of the population of LIGO black holes. We demonstrate that the mass and spin accrued by these black holes per unit orbital tightening are directly related to the ratio of accretion to drag coefficients. We thus infer that the mass and dimensionless spin of initially nonrotating black holes change by of order 1% and 0.05, respectively, in a typical example scenario. Our prediction that the masses and spins of black holes remain largely unmodified by a common envelope phase aids in the interpretation of the properties of the growing observed population of merging binary black holes. Even if these black holes passed through a common envelope phase during their assembly, features of mass and spin imparted by previous evolutionary epochs should be preserved.
AB - We present three-dimensional local hydrodynamic simulations of flows around objects embedded within stellar envelopes using a "wind tunnel" formalism. Our simulations model the common envelope dynamical inspiral phase in binary star systems in terms of dimensionless flow characteristics. We present suites of simulations that study the effects of varying the binary mass ratio, stellar structure, equation of state, relative Mach number of the object's motion through the gas, and density gradients across the gravitational focusing scale. For each model, we measure coefficients of accretion and drag experienced by the embedded object. These coefficients regulate the coupled evolution of the object's masses and orbital tightening during the dynamical inspiral phase of the common envelope. We extrapolate our simulation results to accreting black holes with masses comparable to that of the population of LIGO black holes. We demonstrate that the mass and spin accrued by these black holes per unit orbital tightening are directly related to the ratio of accretion to drag coefficients. We thus infer that the mass and dimensionless spin of initially nonrotating black holes change by of order 1% and 0.05, respectively, in a typical example scenario. Our prediction that the masses and spins of black holes remain largely unmodified by a common envelope phase aids in the interpretation of the properties of the growing observed population of merging binary black holes. Even if these black holes passed through a common envelope phase during their assembly, features of mass and spin imparted by previous evolutionary epochs should be preserved.
KW - Accretion
KW - Hydrodynamics
KW - Hydrodynamical simulations
KW - Close binary stars
KW - Common envelope binary stars
KW - BONDI-HOYLE ACCRETION
KW - NUMERICAL SIMULATIONS
KW - DYNAMICAL FRICTION
KW - EVOLUTION
KW - STARS
KW - OBJECTS
KW - ORIGIN
KW - PULSAR
KW - ENERGY
KW - FLOW
U2 - 10.3847/1538-4357/ab9ac6
DO - 10.3847/1538-4357/ab9ac6
M3 - Journal article
VL - 897
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 130
ER -
ID: 245893655