def add_pulsar_parameters(
table,
B_mean=12.05,
B_stdv=0.55,
P_mean=0.3,
P_stdv=0.15,
random_state="random-seed",
):
"""Add pulsar parameters to the table.
For the initial normal distribution of period and logB can exist the following
Parameters: B_mean=12.05[log Gauss], B_stdv=0.55, P_mean=0.3[s], P_stdv=0.15
Parameters
----------
random_state : {int, 'random-seed', 'global-rng', `~numpy.random.RandomState`}
Defines random number generator initialisation.
Passed to `~gammapy.utils.random.get_random_state`.
"""
random_state = get_random_state(random_state)
# Read relevant columns
age = table["age"].quantity
# Draw the initial values for the period and magnetic field
def p_dist(x):
return np.exp(-0.5 * ((x - P_mean) / P_stdv) ** 2)
p0_birth = draw(0, 2, len(table), p_dist, random_state=random_state)
p0_birth = Quantity(p0_birth, "s")
log10_b_psr = random_state.normal(B_mean, B_stdv, len(table))
b_psr = Quantity(10 ** log10_b_psr, "G")
# Compute pulsar parameters
psr = Pulsar(p0_birth, b_psr)
p0 = psr.period(age)
p1 = psr.period_dot(age)
p1_birth = psr.P_dot_0
tau = psr.tau(age)
tau_0 = psr.tau_0
l_psr = psr.luminosity_spindown(age)
l0_psr = psr.L_0
# Add columns to table
table["P0"] = Column(p0, unit="s", description="Pulsar period")
table["P1"] = Column(p1, unit="", description="Pulsar period derivative")
table["P0_birth"] = Column(p0_birth, unit="s", description="Pulsar birth period")
table["P1_birth"] = Column(
p1_birth, unit="", description="Pulsar birth period derivative"
)
table["CharAge"] = Column(tau, unit="yr", description="Pulsar characteristic age")
table["Tau0"] = Column(tau_0, unit="yr")
table["L_PSR"] = Column(l_psr, unit="erg s-1")
table["L0_PSR"] = Column(l0_psr, unit="erg s-1")
table["B_PSR"] = Column(
b_psr, unit="Gauss", description="Pulsar magnetic field at the poles"
)
return table
def make_base_catalog_galactic(
n_sources,
rad_dis="YK04",
vel_dis="H05",
max_age="1e6 yr",
spiralarms=True,
n_ISM="1 cm-3",
random_state="random-seed",
):
"""Make a catalog of Galactic sources, with basic source parameters.
Choose a radial distribution, a velocity distribution, the number
of pulsars n_pulsars, the maximal age max_age[years] and the fraction
of the individual morphtypes. There's an option spiralarms. If set on
True a spiralarm modeling after Faucher&Kaspi is included.
max_age and n_sources effectively correspond to s SN rate:
SN_rate = n_sources / max_age
Parameters
----------
n_sources : int
Number of sources to simulate
rad_dis : callable
Radial surface density distribution of sources
vel_dis : callable
Proper motion velocity distribution of sources
max_age : `~astropy.units.Quantity`
Maximal age of the source
spiralarms : bool
Include a spiralarm model in the catalog?
n_ISM : `~astropy.units.Quantity`
Density of the interstellar medium
random_state : {int, 'random-seed', 'global-rng', `~numpy.random.RandomState`}
Defines random number generator initialisation.
Passed to `~gammapy.utils.random.get_random_state`.
Returns
-------
table : `~astropy.table.Table`
Catalog of simulated source positions and proper velocities
"""
max_age = Quantity(max_age).to_value("yr")
n_ISM = Quantity(n_ISM).to("cm-3")
random_state = get_random_state(random_state)
if isinstance(rad_dis, str):
rad_dis = radial_distributions[rad_dis]
if isinstance(vel_dis, str):
vel_dis = velocity_distributions[vel_dis]
# Draw random values for the age
age = random_state.uniform(0, max_age, n_sources)
age = Quantity(age, "yr")
# Draw spatial distribution
r = draw(
RMIN.to_value("kpc"),
RMAX.to_value("kpc"),
n_sources,
pdf(rad_dis()),
random_state=random_state,
)
r = Quantity(r, "kpc")
if spiralarms:
r, theta, spiralarm = FaucherSpiral()(r, random_state=random_state)
else:
theta = Quantity(random_state.uniform(0, 2 * np.pi, n_sources), "rad")
spiralarm = None
x, y = astrometry.cartesian(r, theta)
z = draw(
ZMIN.to_value("kpc"),
ZMAX.to_value("kpc"),
n_sources,
Exponential(),
random_state=random_state,
)
z = Quantity(z, "kpc")
# Draw values from velocity distribution
v = draw(
VMIN.to_value("km/s"),
VMAX.to_value("km/s"),
n_sources,
vel_dis(),
random_state=random_state,
)
v = Quantity(v, "km/s")
# Draw random direction of initial velocity
theta = Quantity(random_state.uniform(0, np.pi, x.size), "rad")
phi = Quantity(random_state.uniform(0, 2 * np.pi, x.size), "rad")
# Compute new position
dx, dy, dz, vx, vy, vz = astrometry.motion_since_birth(v, age, theta, phi)
# Add displacement to birth position
x_moved = x + dx
y_moved = y + dy
z_moved = z + dz
table = Table()
table["age"] = Column(age, unit="yr", description="Age of the source")
table["n_ISM"] = Column(n_ISM, description="Interstellar medium density")
if spiralarms:
table["spiralarm"] = Column(spiralarm, description="Which spiralarm?")
table["x_birth"] = Column(x, description="Galactocentric x coordinate at birth")
table["y_birth"] = Column(y, description="Galactocentric y coordinate at birth")
table["z_birth"] = Column(z, description="Galactocentric z coordinate at birth")
table["x"] = Column(x_moved.to("kpc"), description="Galactocentric x coordinate")
table["y"] = Column(y_moved.to("kpc"), description="Galactocentric y coordinate")
table["z"] = Column(z_moved.to("kpc"), description="Galactocentric z coordinate")
table["vx"] = Column(vx, description="Galactocentric velocity in x direction")
table["vy"] = Column(vy, description="Galactocentric velocity in y direction")
table["vz"] = Column(vz, description="Galactocentric velocity in z direction")
table["v_abs"] = Column(v, description="Galactocentric velocity (absolute)")
return table