def get_potential(log_M_h, log_r_s, log_M_n, log_a):
mw_potential = gp.CCompositePotential()
mw_potential['bulge'] = gp.HernquistPotential(m=5E9, c=1., units=galactic)
mw_potential['disk'] = gp.MiyamotoNagaiPotential(m=6.8E10 * u.Msun,
a=3 * u.kpc,
b=280 * u.pc,
units=galactic)
mw_potential['nucl'] = gp.HernquistPotential(m=np.exp(log_M_n),
c=np.exp(log_a) * u.pc,
units=galactic)
mw_potential['halo'] = gp.NFWPotential(m=np.exp(log_M_h),
r_s=np.exp(log_r_s),
units=galactic)
return mw_potential
def morphology(omega,
m_b,
release_every=1,
n_particles=1,
dt=-1,
n_steps=6000):
"""
Takes the pattern speed (with units, in km/s/kpc), and release_every, which controls how
often to release particles, and the bar mass m_b. Creates mock streams,
returns RA, dec to be used for track calculation
"""
S = np.load('../data/Sn9l19m.npy') #expansion coeff.
S = S[:2, :6, :6]
w0 = gd.PhaseSpacePosition(pal5_c.transform_to(galcen_frame).cartesian)
pot = gp.CCompositePotential()
pot['disk'] = default_mw['disk']
pot['halo'] = default_mw['halo']
pot['bar'] = get_bar_model(Omega=omega, Snlm=S, m=m_b)
frame = gp.ConstantRotatingFrame(Omega=[0, 0, -1] * omega, units=galactic)
H = gp.Hamiltonian(
pot, frame) #frame such that we're "moving" with respect to bar
df = gd.FardalStreamDF(random_state=np.random.RandomState(42))
prog_pot = gp.PlummerPotential(pal5_M, 4 * u.pc, units=galactic)
gen = gd.MockStreamGenerator(df=df,
hamiltonian=H,
progenitor_potential=prog_pot)
# gen = gd.MockStreamGenerator(df=df, hamiltonian=H)
stream_data, _ = gen.run(w0,
pal5_M,
dt=dt,
n_steps=n_steps,
release_every=release_every,
n_particles=n_particles)
cache_file = 'BarModels_RL{:d}_Mb{:.0e}_Om{:.1f}.hdf5'.format(
release_every, m_b.value, omega.value)
if path.exists(cache_file):
os.unlink(cache_file)
stream_data.to_hdf5(cache_file)
sim_c = stream_data.to_coord_frame(coord.ICRS,
galactocentric_frame=galcen_frame)
return sim_c
phi = 2. / 4. * np.pi
x_0 = r_0 * np.cos(phi)
y_0 = r_0 * np.sin(phi)
vx_0 = -1. * v_0 * np.sin(phi)
vy_0 = v_0 * np.cos(phi)
z_0 = 4 # kpc
vz_0 = 20 # km/s
M_progenitor = 1e8 # Msun
n_steps = 3e4
########################################
# Set up potential object
pot = gp.CCompositePotential()
# Using 3 Miyamoto-Nagai disc approximation to an exponential disc
# Coefficients here have been calculated using online calculator (http://astronomy.swin.edu.au/~cflynn/expmaker.php)
# but it's fairly straightforward to implement calculation following https://ui.adsabs.harvard.edu/abs/2015MNRAS.448.2934S/abstract
pot['disk1'] = gp.MiyamotoNagaiPotential(m=10E10 * 1.9627 * u.Msun,
a=1.9746 * 5 * u.kpc,
b=1 * u.kpc,
units=galactic)
pot['disk2'] = gp.MiyamotoNagaiPotential(m=10E10 * -1.2756 * u.Msun,
a=4.2333 * 5 * u.kpc,
b=1 * u.kpc,
units=galactic)
nmax = ConfigItem(
6, "Maximum number of radial terms in the SCF expansion "
"of the bar component")
lmax = ConfigItem(6, "Maximum number of spherical hamonic l terms")
Omega = ConfigItem(40., "Bar pattern speed [km/s/kpc]")
bar_mass = ConfigItem(1E10, "Bar mass [Msun]")
# TODO: add other tunable parameters once I decide on the potential...
# ==============================================================================
# Define the potential model up to the bar component
potential_no_bar = gp.CCompositePotential()
potential_no_bar['disk'] = gp.MiyamotoNagaiPotential(m=5E10 * u.Msun,
a=3 * u.kpc,
b=280 * u.pc,
units=galactic)
potential_no_bar['spheroid'] = gp.HernquistPotential(m=4E9 * u.Msun,
c=0.6 * u.kpc,
units=galactic)
potential_no_bar['halo'] = gp.NFWPotential(m=6E11,
r_s=18 * u.kpc,
units=galactic)
def get_hamiltonian(config_file=None):
c = Config()
c.load(config_file)
# Third-party packages
from astropy.coordinates.matrix_utilities import rotation_matrix
import astropy.units as u
from scipy.optimize import minimize
import gala.potential as gp
from gala.units import galactic
default_mw = gp.BovyMWPotential2014()
default_disk_bulge = gp.CCompositePotential()
default_disk_bulge['disk'] = default_mw['disk']
default_disk_bulge['bulge'] = default_mw['bulge']
def corot_func(r_cr, Omega, mw_pot):
vc = mw_pot.circular_velocity([r_cr, 0., 0.])
return abs(vc - Omega * r_cr * u.kpc).decompose().value[0]
def get_bar_model(Omega, Snlm, alpha=-27 * u.deg, m=5e9 * u.Msun, mw_pot=None):
"""Get an SCF bar model with the specified pattern speed.
Parameters
----------
Omega : `~astropy.units.Quantity`
The bar pattern speed.
Snlm : array_like
The expansion coefficients for the bar model.
alpha : `~astropy.units.Quantity`, optional
The initial angle of the bar relative to the x-axis.
m : `~astropy.units.Quantity`, optional
The bar mass.