make_ppv

turbustat.simulator.make_ppv(vel_field, dens_field, los_axis=0, m=<Quantity 2.34167069e-27 kg>, T=<Quantity 100. K>, los_length=<Quantity 1. pc>, vel_disp=None, chan_width=None, v_min=None, v_max=None, threads=1, max_chan=1000, vel_struct_index=0.5, verbose=False, return_hdu=True, pixel_ang_scale=<Quantity 1. arcmin>, restfreq=<Quantity 1.42 GHz>)

Generate a mock, optically-thin HI PPV cube from a given velocity and density field. Currently, the conversion to K assumes the 21-cm column density conversion.

Parameters:

vel_fieldQuantity

Three-dimensional isotropic, velocity field. Must have units of velocity.

dens_fieldQuantity

Three-dimensional isotropic, velocity field. Must have units of number density.

los_axisint, optional

The axis used to produce the PPV cube.

mQuantity, optional

Average particle mass. Defaults to 1.4 time the proton mass, appropriate for the neutral ISM at solar metallicity. Used to calculate the thermal line width.

TQuantity, optional

Temperature of the gas. Defaults to 100 K. Used to calculate the thermal line width.

los_lengthQuantity, optional

Set the total physical length of the density and velocity fields along the line-of-sight. Defaults to 1 pc.

vel_dispQuantity, optional

Velocity dispersion of the 3D velocity field. When none is given, the mean of the projected standard deviation of the velocity field along los_axis is used. Used to set the extent of the velocity channels and estimate the channel widths, when not given.

chan_widthQuantity, optional

Width of a velocity channel. When the width is not given, an estimate is made based on Eq. 12 from Esquivel+2003.

v_minQuantity, optional

Minimum velocity channel. Set to vel_field - 4 * v_lim, where v_lim = sqrt(vel_disp**2 + v_therm**2), when a limit is not given.

v_maxQuantity, optional

Maximum velocity channel. Set to vel_field + 4 * v_lim, where v_lim = sqrt(vel_disp**2 + v_therm**2), when a limit is not given.

threadsint, optional

Number of cores to run on. Defaults to 1.

max_chanint, optional

Sets an upper limit on the number of velocity channels (default of 1000) to avoid using excessive amounts of memory. If the number of channels exceeds this limit, a ValueError is raised.

vel_struct_indexfloat, optional

Index of the velocity field. Used when automatically determining the channel width. Defaults to 0.5.

verbosebool, optional

Print out the min and max velocity extents and the channel width prior to computing the cube.

return_hdubool, optional

Return the cube as a FITS HDU. Enabled by default.

pixel_ang_scaleQuantity, optional

Specify the angular scale of one spatial pixel to set values in the FITS header. Defaults to 1 arcmin.

restfreqQuantity, optional

Rest frequency of the spectral line passed to the FITS header. Defaults to 1.42 GHz, roughly the 21-cm HI rest frequency.

Returns:

cubeQuantity or PrimaryHDU

The PPV cube as an array (return_hdu=False) or a FITS HDU (return_hdu=True).

vel_axisQuantity

When return_hdu=False is returned, the values for the velocity axis are returned.