pyds.cosmonom

• Calculate cosmological variables under the given parameters: Hubble constant(H0), Omega_Lambda, Omega_m

• All equations and coding were referred to Paper-and-pencil cosmological calculator in Pilipenko (2013): http://adsabs.harvard.edu/abs/2013arXiv1303.5961P

from pyds.cosmonom import cosmonom as cosmo

# H0: Hubble Constant, OL: Omega Lambda, Om: Omega M, zmin: minimun z, zmax: maximum z
# in order to avoid infinity value in the calculation, the minimum z is redefined as
# the value of min(zmax*0.1, 0.1) when zmin is zero

a = cosmo(H0=67.15,OL=0.683,Om=0.317,zmin=0.,zmax=20.)

# Calculate the scaled-values with the given red-shift

zz = 2.

print("when z = %.1f:"%zz)
print('H = %f, r_comov = %f, dm = %f, age = %f, \ntime = %f, size 1" = %f kpc, angle 1kpc = %f"' \
      %(a.Hz(zz), a.rz(zz), a.dmz(zz), a.age_z(zz), a.age0-a.age_z(zz), a.size_z(zz), a.angle_z(zz)))

when z = 2.0:
H = 204.140418, r_comov = 5323.038697, dm = 46.016404, age = 3.275071,
time = 10.547657, size 1" = 8.602265 kpc, angle 1kpc = 0.116248"

print(help(a))

Help on cosmonom in module pyds.cosmonom.cosmonom object:

class cosmonom(builtins.object)
 |  cosmonom(H0=67.15, OL=0.683, Om=0.317, zmin=0.0, zmax=20.0)
 |
 |  Calculate cosmological variables under the given parameters:
 |  Hubble constant(H0), Omega_Lambda, Omega_m
 |
 |  All equations and coding were referred to Paper-and-pencil cosmological calculator in Pilipenko (2013):
 |  http://adsabs.harvard.edu/abs/2013arXiv1303.5961P
 |
 |  keywords -- H0: Hubble constants in km/s/Mpc (default= 67.15)
 |              OL: Omega Lambda (default= 0.683)
 |              Om: Omega M (default=0.317)
 |              zmin: minimum value of red-shift (default=0.)
 |              zmax: maximum value of red-shift (default=20.)
 |
 |  outputs   -- self.zext: extremum value of z
 |               self.age0: self.age_z(0.)   in Gyr
 |  functions -- self.Hz: H(z) in km/s/Mpc    <->  self.zH: z(H)
 |               self.rz: r(z) in Mpc   <->  self.zr: z(r)   - comoving radius
 |               self.dmz: dm(z)  <->  self.zdm: z(dm)
 |               self.size_z: 1" size(z) in kpc <->  self.zSize1, self.zSize2 - z(size) for z<zext, z>zext, respectively.
 |               self.angle_z: 1 kpc angle(z) in arcsec <-> self.zAngle1, self.zAngle2 - z(angle) for z<zext, z>zext, respectively.
 |               self.age_z: age(z)  in Gyr <-> self.zage: z(age)
 |               self.zt : self.zage(self.age0-t) - z for the corresponding lookback time in Gyr
 |
 |  Methods defined here:
 |
 |  __init__(self, H0=67.15, OL=0.683, Om=0.317, zmin=0.0, zmax=20.0)
 |      Initialize self.  See help(type(self)) for accurate signature.
 |
 |  draw(self, **keywords)
 |      Draw the scaled axes for the cosmological variables
 |
 |      **keywords -- out: if given, the plot will be saved to the designated output file (type = string)
 |                      z: if given, it will draw the horizontal line for the value of z so that it
 |                         helps catching the corresponding variables. (type = float)
 |
 |  ----------------------------------------------------------------------
 |  Data descriptors defined here:
 |
 |  __dict__
 |      dictionary for instance variables (if defined)
 |
 |  __weakref__
 |      list of weak references to the object (if defined)

None

import os
%matplotlib inline

#figdir = os.environ["PYTHONFIG"]
figdir = './example_data'
a.draw(out=os.path.join(figdir,"cosmonom.png"))

z_extremum: 1.585763
size(zext): 8.718340, angle(zext): 0.114701

saved to ./example_data\cosmonom.png

""" draw horizontal line for the given value of z """
import os
%matplotlib inline

#figdir = os.environ["PYTHONFIG"]
figdir = './example_data'
a.draw(out=os.path.join(figdir,"cosmonom.eps"), z=2.)

z_extremum: 1.585763
size(zext): 8.718340, angle(zext): 0.114701
z: 2.000000
H(z) = 204.140418 km/s/Mpc
comoving radius r(z) = 5323.038697 Mpc
1 arcsec size(z) = 8.602265 kpc
angle 1kpc(z) = 0.116248 arcsec
age(z) = 3.275071 Gyr
lookback time(z) = 10.547657 Gyr

saved to ./example_data\cosmonom.eps