mcfacts.physics.disk_capture_stars
- mcfacts.physics.disk_capture_stars.distribute_captured_stars(captured_stars_masses, captured_stars_orb_a, timestep_num, timestep_duration_yr)
Distribute captured stars’ masses and orb_a based on how many are captured per timestep
Assumes timesteps are uniform and evenly spaced
- Parameters:
captured_stars_masses (numpy.ndarray) – Masses [Msun] of captured stars, sorted by greatest to least
captured_stars_orb_a (numpy.ndarray) – Semi-major axis [R_{g,SMBH}] of captured stars
timestep_num (int) – Number of timesteps per galaxy
- Returns:
captured_stars – Captured stars’ mass and orb_a values. Dictionary key is timestep they are captured in, and value is a tuple of number of captured stars, array of captured masses, and array of captured orb_a
- Return type:
- mcfacts.physics.disk_capture_stars.setup_captured_stars_masses(captured_star_mass, disk_star_mass_min_init, disk_star_mass_max_init, nsc_imf_star_powerlaw_index)
Generate array of captured star masses, sorted by greatest to least mass
- Parameters:
captured_star_mass (float) – Total stellar mass [Msun] captured by the NSC over the lifetime of the disk
disk_star_mass_min_init (float) – Lower bound [Msun] for stellar IMF
disk_star_mass_max_init (float) – Upper bound [Msun] for stellar IMF
nsc_imf_star_powerlaw_index (float) – Powerlaw index for stellar IMF
- Returns:
star_masses – Captured star masses, sorted from greatest to least
- Return type:
array
- mcfacts.physics.disk_capture_stars.setup_captured_stars_orbs_a(num_stars_captured, disk_lifetime, smbh_mass, disk_surface_density_func, disk_star_mass_min_init, disk_star_mass_max_init, nsc_imf_star_powerlaw_index)
Generate array of orb_a values for captured stars
Captured stars are placed in the disk with radial distribution dN/dr propto r^-1/4
- Parameters:
num_stars_captured (int) – Number of stars captured
disk_lifetime (float) – Disk lifetime [yr]
smbh_mass (float) – SMBH mass [Msun]
disk_inner_stable_circ_orb (float) – Disk innermost stable circular radius [R_{g,SMBH}]
disk_radius_outer (float) – Disk outer radius [R_{g,SMBH}]
disk_surface_density_func (lambda function) – Disk surface density
disk_star_mass_min_init (float) – Lower bound [Msun] for stellar IMF
disk_star_mass_max_init (float) – Upper bound [Msun] for stellar IMF
nsc_imf_star_powerlaw_index (float) – Powerlaw index for stellar IMF
- Returns:
captured_star_orb_a – Array of orb_a values for captured stars
- Return type:
array
- mcfacts.physics.disk_capture_stars.stellar_mass_captured_nsc(disk_lifetime, smbh_mass, nsc_density_index_inner, nsc_mass, nsc_ratio_bh_num_star_num, nsc_ratio_bh_mass_star_mass, disk_surface_density_func, disk_star_mass_min_init, disk_star_mass_max_init, nsc_imf_star_powerlaw_index)
Calculate total stellar mass captured from the NSC over the lifetime of the disk
Note from WZL2024: We assume the surface density scales with r^-3/2, which is true for self-gravitating disk models with constant accretion rate
- Parameters:
disk_lifetime (float) – Lifetime of the disk [yr]
smbh_mass (float) – Mass [Msun] of the SMBH
nsc_density_index_inner (float) – Powerlaw index for the NSC density
nsc_mass (float) – Mass of the NSC
nsc_ratio_bh_num_star_num (float) – Ratio of number of BH to number of stars in the NSC
nsc_ratio_bh_mass_star_mass (float) – Ratio of mass of typical BH to typical star in the NSC
disk_surface_density_func (lambda function) – Disk density
disk_star_mass_min_init (float) – Star mass [Msun] lower bound for IMF
disk_star_mass_max_init (float) – Star mass [Msun] upper bound for IMF
nsc_imf_star_powerlaw_index (float) – Powerlaw index for IMF
- Returns:
captured_mass – Amount of stellar mass captured by the NSC in the disk lifetime
- Return type: