Input file parameters

Input file parameters#

As described in How to use section, BowshockPy can be run from the terminal, specifying with the --read flag an input file that contains all the parameters needed to perform the modeling of the bowshock(s):

$ bowshockpy --read inputfile.py

In the following there is a description of each parameter that should be included in the input file. We suggest to download one of the examples of input files and check this page as a reference, so the user can modify the parameters according to their scientific goals.

Specification of the desired outputs#

These parameters define the desired outputs:

modelname (str)

Folder name where the outputs of the modeling are going to be stored. If it does not exist, it will be created automatically.

outcubes (dict)

Dictionary indicating the desired output spectral cubes and the operations performed over them. The keys of the dictionary are strings indicating the quantities of the desired cubes. These are the available quantities of the spectral cubes:

  • “mass”: Total mass of molecular hydrogen in solar mass

  • “total_column_density”: Total (H2 + heavier components) column density in cm-2.

  • “emitting_molecule_column_density”: Column density of the emitting molecule in cm-2.

  • “intensity”: Intensity in Jy/beam.

  • “tau”: Opacities.

The values of the dictionary are lists of strings indicating the operations to be performed over the cube. These are the available operations:

  • “add_source”: Add a point source at the reference pixel.

  • “add_noise”: Add Gaussian noise, defined by maxcube2noise parameter.

  • “convolve”: Convolve with a Gaussian defined by the parameters bmaj, bmin, and pabeam.

  • “moments_and_pv”: Computes the moments 0, 1, 2, the maximum intensity, and the PV diagram.

The operations will be performed following the order of the strings in the list (from left to right). The list can be left empty if no operations are desired.

For example, the following dictionary for the outcubes parameter,

outcubes = {
    "intensity": ["add_noise", "convolve", "moments_and_pv"],
    "opacity": [],
    "total_column_density": ["convolve"],
    "mass": [],
}

will save 4 spectral cubes in fits format. The first one are the intensities with Gaussian noise added, it will be convolved, and the moments and PV diagrams will be computed; the second cube will be the opacity; the third will be the total_column_density (column density of molecular hydrogen), which will be convolved; and the forth cube will be the masses. The first spectral cube will be named I_nc.fits, the second tau.fits, the third Ntot_c.fits, and the fourth m.fits. See outputs section for a full description of the outputs and the abbreviations used in the filenames of each fits file.

verbose (bolean)

Set True to verbose messages about the computation.

Observer parameters#

The following parameters define the observer properties:

distpc (float)

Source distance to the observer [pc].

vsys (float)

Systemic velocity of the source [km/s].

ra_source_deg (float)

Source right ascension [deg].

dec_source_deg (float)

Source declination [deg].

Bowshock parameters#

The next parameters are common to all the bowshocks that are going to be generated:

nbowshocks (int)

Number of bowshocks to model.

J (int)

Upper level of the rotational transition (e.g. 3 for the “J=3->2” transition).

nu (float)

Frequency of the transition [GHz].

abund (float)

Abundance relative to the molecular hydrogen.

meanmolmass (float)

Mean molecular mass per hydrogen molecule.

mu (float)

Permanent dipole moment of the molecule [D].

Tex (float)

Excitation temperature [K].

Tbg (float)

Background temperature [K].

BowshockPy allows to model several bowshocks in the same spectral cube. The number of bowshocks are given by nbowshocks parameter. The following parameters should be defined for each bowshock, substituting “n” with the bowshock index (e.g., if 4 bowshocks are included in the model, the user should define vj_1, vj_2, vj_3, and vj_4, and similarly with the rest of parameters).

i_n (float)

Inclination angle of the bowshock symmetry axis with respect to the line of sight. If i>90, the bowshock is redshifted, if i<90, it will be blueshifted [degrees].

L0_n (float)

Characteristic length scale [arcsec].

zj_n (float)

Distance between the internal working surface and the source [arcsec].

vj_n (float)

Jet velocity [km/s].

va_n (float)

Ambient (or surrounding wind) velocity [km/s].

v0_n (float)

Velocity at which the material is ejected sideways from the internal working surface [km/s].

rbf_obs_n (float)

Final radius of the bowshock [arcsec]. Set None if you want to end the bowshock model at the theoretical final radius (see eq. 11 from Tabone et al. 2018).

mass_n (float)

Total mass of the bowshock [solar masses].

pa_n (float)

Position angle [deg].

Spectral cube parameters#

The following parameters define the properties of the spectral cube of the bowshock(s) model

nzs (int)

Number of points to model along the direction of the symmetry axis (z-axis).

nphis (int)

Number of azimuthal angles to calculate the bowshock solution at each model point in the z-axis.

nc (int)

Number of spectral channel maps.

vch0 (float)

Central velocity of the first channel map [km/s].

vchf (float)

Central velocity of the last channel map [km/s]. If a float is provided, chanwidth input parameter should be None, since chanwidth would be computed internally. If vchf is None, you should provide instead the channel width using chanwidth parameter.

chanwidth (float)

Channel width of the spectral cube [km/s]. If a float is provided, vchf input parameter should be None, since vchf would be computed internally. If chanwidth>0 then vch0<vchf, if chanwidth<0 then vch0>vchf. If None, you should provide instead the central velocity of the last channel map using vchf parameter.

nxs (int)

Number of pixels in the right ascension axis.

nys (int)

Number of pixels in the declination axis.

xpmax (float)

Physical size of the channel maps along the right ascension axis [arcsec].

papv (float)

Position angle used to calculate the PV [degrees].

bmaj (tupple)

Beam major axis [arcsec].

bmin (tupple)

Beam minor axis [arcsec].

pabeam (float)

Beam position angle [degrees].

vt (str or float)

Thermal+turbulent line-of-sight velocity dispersion [km/s] If thermal+turbulent line-of-sight velocity dispersion is smaller than the instrumental spectral resolution, vt should be the spectral resolution. It can be also set to a integer times the channel width (e.g., “2xchannel”).

tolfactor_vt (float)

The masses corresponding to a channel map are spread along the cube in the velocity axis following a Gaussian distribution, being vt parameter the standard deviation of the Gaussian. tolfactor_vt parameter truncates the Gaussian distribution at vt * tolfactor_vt in order to make the computation substantially faster. A low tolfactor_vt can result in a warning reporting an underestimation of the total mass of the model.

cic (bolean)

Set to True to perform 2D Cloud in Cell interpolation along the spatial dimensions. If False, a Nearest Grid Point method will be perform.

refpix (list or None)

Pixel coordinates (zero-based) of the source, i.e., the origin from which the distances are measured. The first index is the right ascension axis, the second is the declination axis [[int, int] or None].

coordcube (“sky” or “offset”)

Set to “sky” in order to set the cube headers in sky coordinates, or “offset” if you prefer them in offsets relative to the origin (the source).

sigma_beforeconv (float)

Standard deviation of the noise of the map, before convolution. Set to None if maxcube2noise is used.

maxcube2noise (float)

Standard deviation of the noise of the map, before convolution, relative to the maximum pixel in the cube. The actual noise will be computed after convolving. This parameter would not be used if sigma_beforeconve is not None.

Moments and PV parameters#

The next parameters control the properties of the moments and the position-velocity diagrams.

savefits (bolean)

Set to True in order save the moments and the PV in fits format.

saveplot (bolean)

Set to True in order to save a figure of the moments and the PV [True/False].

mom1clipping (str)

Clipping for moment 1 as a function of the standard deviation of noise in the image (e.g., “5xsigma”).

mom2clipping (str)

Clipping for moment 2 as a function of the standard deviation of noise in the image (e.g., “4xsigma”).

mom0values (dict)

Dictionary with the maximum, central, and minimum value to show in the plot of the moment 0. If the dictionary value is None for vmax, vcenter, or vmin, then the maximum, central, or the minimum value of the moment image will be considered, respectively. Example: mom0values = {“vmax”: None, “vcenter”: None, “vmin”: 0,}.

mom1values (dict)

Dictionary with the maximum, central, and minimum value to show in the plot of the moment 1. If the dictionary value is None for vmax, vcenter, or vmin, then the maximum, central, or the minimum value of the moment image will be considered, respectively. Example: mom1values = {“vmax”: 60, “vcenter”: 20, “vmin”: 0,}.

mom2values (dict)

Dictionary with the maximum, central, and minimum value to show in the plot of the moment 2. If the dictionary value is None for vmax, vcenter, or vmin, then the maximum, central, or the minimum value of the moment image will be considered, respectively. Example: mom2values = {“vmax”: None, “vcenter”: None, “vmin”: None,}.

maxintensvalues (dict)

Dictionary with the maximum, central, and minimum value to show in the plot of the maximum value along the velocity axis. If the dictionary value is None for vmax, vcenter, or vmin, then the maximum, central, or the minimum value of the moment image will be considered, respectively. Example: maxintensvalues = {“vmax”: None, “vcenter”: None, “vmin”: None,}.

pvvalues (dict)

Set the maximum, central, and minimum value to show in the plot of the moments and PV-diagram along the jet axis. If the dictionary value is None for vmax, vcenter, or vmin, then the maximum, central, or the minimum value of the position velocity diagram will be considered, respectively. Example: pvvalues = {“vmax”: None, “vcenter”: None, “vmin”: None,}.

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