def nbody_integrator(Ncl,
mcl,
rcl,
t_end,
n_steps,
algorithm=BHTree,
timestep=None):
converter = nbody_system.nbody_to_si(mcl, rcl)
bodies = new_plummer_model(Ncl, convert_nbody=converter)
verbose = False # For AMUSE functions this is called redirection.
algorithm_name = str(algorithm).split('.')[-1][:-2]
# Allow selecting Stellar Dynamics code trough a function argument.
try:
if algorithm_name == 'Hermite':
gravity = algorithm(converter, number_of_workers=4)
else:
gravity = algorithm(converter)
except Exception, e: # Too generic, but I don't know what Error to expect.
# raise Exception
print "Failure for {0}".format(algorithm_name)
print Exception, e
print traceback.format_exc()
return None
def cluster_init(N, mMin, mMax, alpha, mCluster, rCluster):
converter = nbody_system.nbody_to_si(mCluster, rCluster)
cluster = new_plummer_model(N, convert_nbody=converter)
mZAMS = new_powerlaw_mass_distribution(N, mMin, mMax, alpha)
cluster.mass = mZAMS
cluster.scale_to_standard(converter)
return cluster
def main(N=10):
figure(figsize=(5,5))
bodies = new_plummer_model(N)
scatter(bodies.x, bodies.y)
xlim(-1, 1)
ylim(-1, 1)
xlabel("X")
ylabel("Y")
show()
def main(N=10):
figure(figsize=(5, 5))
bodies = new_plummer_model(N)
scatter(bodies.x, bodies.y)
xlim(-1, 1)
ylim(-1, 1)
xlabel("X")
ylabel("Y")
show()
def evolve_cluster_in_galaxy(N, W0, Rinit, tend, timestep, M, R):
R_galaxy = 0.1 | units.kpc
M_galaxy = 1.6e10 | units.MSun
converter = nbody_system.nbody_to_si(M_galaxy, R_galaxy)
galaxy = new_plummer_model(10000, convert_nbody=converter)
print "com:", galaxy.center_of_mass().in_(units.kpc)
print "comv:", galaxy.center_of_mass_velocity().in_(units.kms)
print len(galaxy)
galaxy_code = BHTree(converter, number_of_workers=2)
galaxy_code.parameters.epsilon_squared = (0.01 | units.kpc)**2
channe_to_galaxy = galaxy_code.particles.new_channel_to(galaxy)
channe_to_galaxy.copy()
galaxy_code.particles.add_particles(galaxy)
inner_stars = galaxy.select(lambda r: r.length() < Rinit, ["position"])
Minner = inner_stars.mass.sum()
print "Minner=", Minner.in_(units.MSun)
print "Ninner=", len(inner_stars)
vc_inner = (constants.G * Minner / Rinit).sqrt()
converter = nbody_system.nbody_to_si(Mcluster, Rcluster)
stars = new_king_model(N, W0, convert_nbody=converter)
masses = new_powerlaw_mass_distribution(N, 0.1 | units.MSun,
100 | units.MSun, -2.35)
stars.mass = masses
stars.scale_to_standard(converter)
stars.x += Rinit
stars.vy += 0.8 * vc_inner
cluster_code = ph4(converter, number_of_workers=2)
cluster_code.particles.add_particles(stars)
channel_to_stars = cluster_code.particles.new_channel_to(stars)
system = bridge(verbose=False)
system.add_system(cluster_code, (galaxy_code, ))
system.add_system(galaxy_code, (cluster_code, ))
system.timestep = 0.1 * timestep
times = quantities.arange(0 | units.Myr, tend, timestep)
for i, t in enumerate(times):
print "Time=", t.in_(units.Myr)
channe_to_galaxy.copy()
channel_to_stars.copy()
inner_stars = galaxy.select(lambda r: r.length() < Rinit, ["position"])
print "Minner=", inner_stars.mass.sum().in_(units.MSun)
system.evolve_model(t, timestep=timestep)
plot_galaxy_and_stars(galaxy, stars)
galaxy_code.stop()
cluster_code.stop()
def evolve_cluster_in_galaxy(N, W0, Rinit, tend, timestep, M, R):
R_galaxy=0.1 | units.kpc
M_galaxy=1.6e10 | units.MSun
converter=nbody_system.nbody_to_si(M_galaxy, R_galaxy)
galaxy=new_plummer_model(10000,convert_nbody=converter)
print "com:", galaxy.center_of_mass().in_(units.kpc)
print "comv:", galaxy.center_of_mass_velocity().in_(units.kms)
print len(galaxy)
galaxy_code = BHTree(converter, number_of_workers=2)
galaxy_code.parameters.epsilon_squared = (0.01 | units.kpc)**2
channe_to_galaxy = galaxy_code.particles.new_channel_to(galaxy)
channe_to_galaxy.copy()
galaxy_code.particles.add_particles(galaxy)
inner_stars = galaxy.select(lambda r: r.length()<Rinit,["position"])
Minner = inner_stars.mass.sum()
print "Minner=", Minner.in_(units.MSun)
print "Ninner=", len(inner_stars)
vc_inner = (constants.G*Minner/Rinit).sqrt()
converter=nbody_system.nbody_to_si(Mcluster,Rcluster)
stars=new_king_model(N,W0,convert_nbody=converter)
masses = new_powerlaw_mass_distribution(N, 0.1|units.MSun, 100|units.MSun, -2.35)
stars.mass = masses
stars.scale_to_standard(converter)
stars.x += Rinit
stars.vy += 0.8*vc_inner
cluster_code=ph4(converter, number_of_workers=2)
cluster_code.particles.add_particles(stars)
channel_to_stars=cluster_code.particles.new_channel_to(stars)
system=bridge(verbose=False)
system.add_system(cluster_code, (galaxy_code,))
system.add_system(galaxy_code, (cluster_code,))
system.timestep = 0.1*timestep
times = quantities.arange(0|units.Myr, tend, timestep)
for i,t in enumerate(times):
print "Time=", t.in_(units.Myr)
channe_to_galaxy.copy()
channel_to_stars.copy()
inner_stars = galaxy.select(lambda r: r.length()<Rinit,["position"])
print "Minner=", inner_stars.mass.sum().in_(units.MSun)
system.evolve_model(t,timestep=timestep)
plot_galaxy_and_stars(galaxy, stars)
galaxy_code.stop()
cluster_code.stop()
def plummer(mass, radius, N):
conv = nbody_system.nbody_to_si(radius, mass)
pm = new_plummer_model(N, convert_nbody=conv, do_scale=True)
gravity = ph4(conv)
pm.positon = pm.position + ((100, 100, 100) | units.parsec)
pm.velocity = pm.velocity + ((-1000, -1000, -1000) | (units.km / units.s))
lr, mf = pm.LagrangianRadii(unit_converter=conv)
print lr, mf
#print 'position of pm[0] before gravity evolution: ',pm[0].position
#print 'velocity of pm[0] before gravity evolution: ',pm[0].velocity
#while gravity.model_time < 1000000 | units.yr:
#print gravity.particles[0].position
#gravity.evolve_model(gravity.model_time + (100000 | units.yr))
#print 'position of pm[0] after gravity evolution: ',pm[0].position
#print 'velocity of pm[0] after gravity evolution: ',pm[0].velocity
gravity.stop()
def nbody_integrator(Ncl, mcl, rcl, t_end, n_steps, escape_velocity_fraction,
R):
converter = nbody_system.nbody_to_si(mcl, rcl)
bodies = new_plummer_model(Ncl, convert_nbody=converter)
#estimate of milky way mass by "Mass models of the Milky Way", McMillan
blackhole_mass = 1.26e12 | units.MSun
blackhole = Particle(mass=blackhole_mass)
blackhole.position = [0, 0, 0] | units.m
cluster_velocity = [0, 0, 0] | units.m / units.s
cluster_position = [0, 0, 0] | units.parsec
cluster_position[0] = R
G_si = converter.to_si(nbody_system.G)
escape_v = (2 * G_si * blackhole_mass / R).sqrt().as_quantity_in(units.m /
units.s)
V = escape_v * escape_velocity_fraction
cluster_velocity[1] = V
bodies.move_to_center()
bodies.velocity += cluster_velocity
bodies.position += cluster_position
bodies.add_particle(blackhole)
gravity = BHTree(converter)
gravity.particles.add_particles(bodies)
channel_from_gravity_to_framework = gravity.particles.\
new_channel_to(bodies)
time = zero
dt = t_end / float(n_steps)
x = 0
base_path = "encounter_plots/"+str(R.value_in(units.parsec))+"_"+\
str(escape_velocity_fraction)+"_"
while time < t_end:
plot_cluster(bodies, base_path + str(x), time, rcl, V)
time += dt
gravity.evolve_model(time)
channel_from_gravity_to_framework.copy()
x += 1
plot_cluster(bodies, base_path + str(x), time, rcl, V)
gravity.stop()
return V, bodies
def nbody_integrator(Ncl, mcl, rcl, t_end, n_steps, algorithm=BHTree, timestep=None):
converter = nbody_system.nbody_to_si(mcl, rcl)
bodies = new_plummer_model(Ncl, convert_nbody=converter)
verbose = False # For AMUSE functions this is called redirection.
algorithm_name = str(algorithm).split('.')[-1][:-2]
# Allow selecting Stellar Dynamics code trough a function argument.
try:
if algorithm_name == 'Hermite':
gravity = algorithm(converter, number_of_workers=4)
else:
gravity = algorithm(converter)
except Exception, e: # Too generic, but I don't know what Error to expect.
# raise Exception
print "Failure for {0}".format(algorithm_name)
print Exception, e
print traceback.format_exc()
return None
def nbody_integrator(Ncl, mcl, rcl, t_end, n_steps, escape_velocity_fraction, R):
converter = nbody_system.nbody_to_si(mcl, rcl)
bodies = new_plummer_model(Ncl, convert_nbody=converter)
#estimate of milky way mass by "Mass models of the Milky Way", McMillan
blackhole_mass = 1.26e12 | units.MSun
blackhole = Particle(mass=blackhole_mass)
blackhole.position = [0,0,0] | units.m
cluster_velocity = [0,0,0] | units.m / units.s
cluster_position = [0,0,0] | units.parsec
cluster_position[0] = R
G_si = converter.to_si(nbody_system.G)
escape_v = (2*G_si*blackhole_mass/R).sqrt().as_quantity_in(units.m/units.s)
V = escape_v * escape_velocity_fraction
cluster_velocity[1] = V
bodies.move_to_center()
bodies.velocity += cluster_velocity
bodies.position += cluster_position
bodies.add_particle(blackhole)
gravity = BHTree(converter)
gravity.particles.add_particles(bodies)
channel_from_gravity_to_framework = gravity.particles.\
new_channel_to(bodies)
time = zero
dt = t_end / float(n_steps)
x = 0
base_path = "encounter_plots/"+str(R.value_in(units.parsec))+"_"+\
str(escape_velocity_fraction)+"_"
while time < t_end:
plot_cluster(bodies, base_path+str(x),time, rcl, V)
time += dt
gravity.evolve_model(time)
channel_from_gravity_to_framework.copy()
x+=1
plot_cluster(bodies, base_path+str(x),time, rcl, V)
gravity.stop()
return V, bodies
return vc
N = 100 # Stars in the cluster
Rv = 1. | al.units.parsec # virial radius of cluster
RSun = 50 | al.units.parsec # Position of cluster in the galaxy
M = al.new_kroupa_mass_distribution(
N,
100. | al.units.MSun) # N samples from Kroupa IMF, with each max. 100 MSun
# Contains the plummer radius and total mass of the plummer distribution
converter = al.nbody_system.nbody_to_si(R_virial_to_plummer(Rv), M.sum())
bodies = al.new_plummer_model(N, converter)
bodies.mass = M
t_end = 2.5 | al.units.Myr # End time
dt = 0.01 | al.units.Myr # Bridge timestep
# Galaxy model with 1.6x10^10 MSun within 1 kpc, and power law scaling with index 1.2
galaxy_gravity = GalacticPotential(1. | al.units.kpc, 1.6E10 | al.units.MSun,
1.2)
# Place cluster in galaxy
bodies.x += RSun
bodies.vy += galaxy_gravity.circular_velocity(RSun)
cluster_gravity = al.ph4(converter)
cluster_gravity.particles.add_particles(bodies)