SSPs & IFU cubes#

MILES SSPs#

class popkinmocks.milesSSPs(lmd_min=4700, lmd_max=6500, age_lim=None, z_lim=None, thin_age=1, thin_z=1)#

MILES SSP models

MILES models (Vazdekis et al. 2010) with BaSTI isochrones for base alpha-content (Pietrinferni et al. 2004) and a Chabrier (2003) IMF.

Parameters

  • lmd_min (float) – min wavelength (Angstrom)

  • lmd_min – max wavelength (Angstrom)

  • age_lim (tuple) – (min, max) ages to keep (Gyr)

  • z_lim (tuple) – (min, max) metallicities to keep [M/H]

  • thin_age (int) – only use every thin_age-th age in SSP grid

  • thin_z (int) – only use every thin_z-th metallicity in SSP grid

get_light_weights()#

Calculate light weights L(t,z) = int_lmd S(lmd;t,z) d lmd

Sets the result to self.light_weights

get_ssp(ssp_id, spacing='wavelength')#

Get a single SSP model indexed by ssp_id

Parameters

  • ssp_id (int) – index of the SSP to be returned

  • spacing (string, optional) – either ‘wavelength’ or ‘log-wavelength’

set_tick_positions(t_ticks=None, z_ticks=None)#

Set tick positions for use in plotting

These ticks positions are used when plotting SSPs variables (t,z) in discrete units when using cube.plot(…, spacing=’discrete’) or when using cube.imshow.

Parameters

  • t_ticks (list) – ages where you would like a tick (Gyr)

  • z_ticks (list) – metallicities where you’d like a tick [M/H]

IFUCube#

class popkinmocks.ifu_cube.IFUCube(ssps=None, nx1=300, nx2=299, nv=200, x1rng=(- 1, 1), x2rng=(- 1, 1), vrng=(- 1000, 1000))#

The integral field unit (IFU) datacube

Parameters

  • ssps – SSP templates in a pkm.model_grids.milesSSPs object

  • nx1 (int) – number of pixels in x1

  • nx2 (int) – number of pixels in x2

  • nv (int) – number of velocity bins

  • x1rng (tuple) – start/end co-ordinates in x1 (arbitrary units)

  • x2rng (tuple) – start/end co-ordinates in x2 (arbitrary units)

  • vrng (tuple) – start/end velocities in km/s

construct_volume_element(which_dist)#

Construct volume element for converting densities to probabilties

Parameters

which_dist (string) – which distribution to evaluate volume element for e.g. ‘vz’ returns dv*dz, ‘t_x’ returns dt

Returns

The volume element shaped compatibly with which_dist

Return type

array

get_axis_label(which_dist)#

Get axis labels for plotting

Parameters

which_variable (string) – which variable, one of (t, v, x1, x2, z)

Returns

to be used in ax.set_label

Return type

string

get_distribution_shape(which_dist)#

Get shape of a distribution given its string

Parameters

which_dist (string) – a valid distribution string.

Returns

the shape of an array representing this distribution

Return type

array

get_variable_edges(which_variable)#

Get discretization bin edges of the variable v, x1, x2, t or z.

Parameters

which_variable (string) – one of (t, v, x1, x2, z)

Returns

the discretisation bin edges used for this variable

Return type

array

get_variable_size(which_variable)#

Get size of variable array

Parameters

which_variable (string) – one of (t, v, x1, x2, z)

Returns

the numer of discretisation elements for this variable

Return type

array

get_variable_values(which_variable)#

Get values of the variable v, x1, x2, t or z.

Parameters

which_variable (string) – one of (t, v, x1, x2, z)

Returns

the discretisation values used for this variable

Return type

array

imshow(img, ax=None, label_ax=True, colorbar=True, colorbar_label='', view=['x1', 'x2'], **kwargs)#

Wrapper around plt.imshow to orient image and label axes

Parameters

  • img (array) – 2D image to show

  • ax (matplotlib axis) – optional, axis to plot on

  • label_ax (bool) – whether to show tick marks and labels

  • colorbar (bool) – whether to show colorbar

  • colorbar_label (string) – colorbar label

  • view (list) – list of two strings amongst [‘t’,’v’,’x1’,’x2’,’z’] representing the variables on the x- and y- axes of the image

  • **kwargs – keyword arguments passed to plt.imshow (must not include extent)

Returns

a matplotlib AxesImage object

plot(which_var, arr, *args, ax=None, xspacing='physical', **kwargs)#

Wrapper around plt.plot to plot 1D plots and label axes

Parameters

  • which_var (string) – x-axis variable, one of (t, v, x1, x2, z)

  • arr (array) – y-axis data to plot

  • *args – any extra args passed to plt.plot

  • ax (matplotlib axis) – optional, axis to plot on

  • xspacing (string, optional) – physical or discrete. If physical, x-axis is spaced in physical units, otherwise with equally spaced points per discretization point

  • **kwargs (dict) – any extra kwargs passed to plt.plot

Returns

a matplotlib AxesImage object

plot_spectrum(arr, *args, ax=None, **kwargs)#

Wrapper around plt.plot to plot spectra

Automatically selects if sampled in log-wavelength or wavelength and chooses x-axis values appropriately

Parameters

  • arr (array) – y-axis data to plot

  • *args – any extra

  • ax (matplotlib axis) – optional, axis to plot on

  • **kwargs (dict) – extra keyword parameters passed to plt.plot

Returns

a matplotlib AxesImage object