def test_hubble_parameter_1s( self ):
expected = 75.71*3.24078e-20
actual = astro.hubble_parameter( 0.16946, .702, 0.272, 0.728, units='1/s' )
npt.assert_allclose( expected, actual, rtol=1e-4 )
def test_hubble_parameter( self ):
expected = 75.71
actual = astro.hubble_parameter( 0.16946, .702, 0.272, 0.728 )
npt.assert_allclose( expected, actual, rtol=1e-4 )
def test_hubble_z(self):
self.t_data.redshift = np.array([0., 0.0698467, 0.16946])
expected = np.array([
astro.hubble_parameter(redshift, units='km/s/kpc')
for redshift in self.t_data.redshift
])
actual = self.t_data.hubble_z
npt.assert_allclose(expected, actual)
def get_radial_velocity( self ):
'''Get the radial velocity of particles, relative to the main galaxy.
Returns:
v_r ( [n_particle, n_snap] np.ndarray ) : The radial velocity of
each particle at that redshift, relative to the main galaxy.
'''
# Get the position and velocity of the main galaxy
main_mt_halo_p = self.ahf_reader.get_pos_or_vel(
'pos', self.ptrack_attrs[ 'main_mt_halo_id' ], self.ptrack[ 'snum' ]
)
main_mt_halo_v = self.ahf_reader.get_pos_or_vel(
'vel', self.ptrack_attrs[ 'main_mt_halo_id' ], self.ptrack[ 'snum' ]
)
# Apply cosmological corrections to the position of the main galaxy
main_mt_halo_p *= 1. / \
( 1. + self.ptrack['redshift'][:, np.newaxis] ) / \
self.ptrack_attrs['hubble']
# Loop over each redshift
v_r = []
for i in range(self.n_snap):
v = self.ptrack['V'][:, i] - main_mt_halo_v[i][np.newaxis]
p = self.ptrack['P'][:, i] - main_mt_halo_p[i][np.newaxis]
r_i = np.sqrt( ( p**2. ).sum( axis=1 ) )
v_r_i = ( v * p ).sum( axis=1 )/r_i
# Add the hubble flow.
hubble_factor = astro_tools.hubble_parameter(
self.ptrack['redshift'][i],
h=self.ptrack_attrs['hubble'],
omega_matter=self.ptrack_attrs['omega_matter'],
omega_lambda=self.ptrack_attrs['omega_lambda'],
units='1/s'
)
v_r_i += hubble_factor * r_i * constants.UNITLENGTH_IN_CM / \
constants.UNITVELOCITY_IN_CM_PER_S
v_r.append( v_r_i )
# Format the output
v_r = np.array( v_r ).transpose()
return v_r