FaucherSpiral#

class gammapy.astro.population.FaucherSpiral[source]#

Bases: gammapy.astro.population.spatial.LogSpiral

Milky way spiral arm used in Faucher et al (2006).

Reference: https://ui.adsabs.harvard.edu/abs/2006ApJ…643..332F

Attributes Summary

k

r_0

spiralarms

theta_0

Methods Summary

__call__(radius[, blur, random_state])

Draw random position from spiral arm distribution.

radius(theta, spiralarm_index)

Radius for a given angle.

theta(radius, spiralarm_index)

Angle for a given radius.

xy_position([theta, radius, spiralarm_index])

Compute (x, y) position for a given angle or radius.

Attributes Documentation

k = <Quantity [4.25, 4.25, 4.89, 4.89] rad>#
r_0 = <Quantity [3.48, 3.48, 4.9 , 4.9 ] kpc>#
spiralarms = array(['Norma', 'Carina Sagittarius', 'Perseus', 'Crux Scutum'],       dtype='<U18')#
theta_0 = <Quantity [1.57, 4.71, 4.09, 0.95] rad>#

Methods Documentation

__call__(radius, blur=True, random_state='random-seed')[source]#

Draw random position from spiral arm distribution.

Returns the corresponding angle theta[rad] to a given radius[kpc] and number of spiral arm. Possible numbers are:

  • Norma = 0,

  • Carina Sagittarius = 1,

  • Perseus = 2

  • Crux Scutum = 3.

Parameters
random_state{int, ‘random-seed’, ‘global-rng’, RandomState}

Defines random number generator initialisation. Passed to get_random_state. Default is ‘random-seed’.

Returns
Returns dx and dy, if blurring= true.
radius(theta, spiralarm_index)#

Radius for a given angle.

Parameters
thetaQuantity

Angle (deg).

spiralarm_indexint

Spiral arm index.

Returns
radiusndarray

Radius (kpc).

theta(radius, spiralarm_index)#

Angle for a given radius.

Parameters
radiusQuantity

Radius (kpc).

spiralarm_indexint

Spiral arm index.

Returns
thetandarray

Angle (deg).

xy_position(theta=None, radius=None, spiralarm_index=0)#

Compute (x, y) position for a given angle or radius.

Parameters
thetaQuantity, optional

Angle (deg). Default is None.

radiusQuantity, optional

Radius (kpc). Default is None.

spiralarm_indexint, optional

Spiral arm index. Default is 0.

Returns
x, yndarray

Position (x, y).