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<h1>Source code for astropy.cosmology.funcs</h1><div class="highlight"><pre>
<span class="c"># Licensed under a 3-clause BSD style license - see LICENSE.rst</span>
<span class="sd">"""</span>
<span class="sd">Convenience functions for `astropy.cosmology`.</span>
<span class="sd">"""</span>
<span class="kn">from</span> <span class="nn">.core</span> <span class="kn">import</span> <span class="n">get_current</span> <span class="k">as</span> <span class="n">_get_current</span>
<div class="viewcode-block" id="kpc_comoving_per_arcmin"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.kpc_comoving_per_arcmin.html#astropy.cosmology.funcs.kpc_comoving_per_arcmin">[docs]</a><span class="k">def</span> <span class="nf">kpc_comoving_per_arcmin</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Separation in transverse comoving kpc corresponding to an</span>
<span class="sd"> arcminute at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> d : ndarray, or float if input scalar</span>
<span class="sd"> The distance in comoving kpc corresponding to an arcmin at each</span>
<span class="sd"> input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">kpc_comoving_per_arcmin</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="kpc_proper_per_arcmin"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.kpc_proper_per_arcmin.html#astropy.cosmology.funcs.kpc_proper_per_arcmin">[docs]</a><span class="k">def</span> <span class="nf">kpc_proper_per_arcmin</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Separation in transverse proper kpc corresponding to an</span>
<span class="sd"> arcminute at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> d : ndarray, or float if input scalar</span>
<span class="sd"> The distance in proper kpc corresponding to an arcmin at each</span>
<span class="sd"> input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">kpc_proper_per_arcmin</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="arcsec_per_kpc_comoving"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.arcsec_per_kpc_comoving.html#astropy.cosmology.funcs.arcsec_per_kpc_comoving">[docs]</a><span class="k">def</span> <span class="nf">arcsec_per_kpc_comoving</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Angular separation in arcsec corresponding to a comoving kpc</span>
<span class="sd"> at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> theta : ndarray, or float if input scalar</span>
<span class="sd"> The angular separation in arcsec corresponding to a comoving kpc</span>
<span class="sd"> at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">arcsec_per_kpc_comoving</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="arcsec_per_kpc_proper"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.arcsec_per_kpc_proper.html#astropy.cosmology.funcs.arcsec_per_kpc_proper">[docs]</a><span class="k">def</span> <span class="nf">arcsec_per_kpc_proper</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Angular separation in arcsec corresponding to a proper kpc at</span>
<span class="sd"> redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> theta : ndarray, or float if input scalar</span>
<span class="sd"> The angular separation in arcsec corresponding to a proper kpc</span>
<span class="sd"> at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">arcsec_per_kpc_proper</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="distmod"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.distmod.html#astropy.cosmology.funcs.distmod">[docs]</a><span class="k">def</span> <span class="nf">distmod</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Distance modulus at redshift `z`.</span>
<span class="sd"> The distance modulus is defined as the (apparent magnitude -</span>
<span class="sd"> absolute magnitude) for an object at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> distmod : ndarray, or float if input scalar</span>
<span class="sd"> Distance modulus at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">distmod</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="H"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.H.html#astropy.cosmology.funcs.H">[docs]</a><span class="k">def</span> <span class="nf">H</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Hubble parameter (km/s/Mpc) at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> H : ndarray, or float if input scalar</span>
<span class="sd"> Hubble parameter at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">H</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="scale_factor"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.scale_factor.html#astropy.cosmology.funcs.scale_factor">[docs]</a><span class="k">def</span> <span class="nf">scale_factor</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Scale factor at redshift `z`.</span>
<span class="sd"> The scale factor is defined as `a = 1 / (1 + z)`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> distmod : ndarray, or float if input scalar</span>
<span class="sd"> Scale factor at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">scale_factor</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="critical_density"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.critical_density.html#astropy.cosmology.funcs.critical_density">[docs]</a><span class="k">def</span> <span class="nf">critical_density</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Critical density in grams per cubic cm at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> critdens : ndarray, or float if input scalar</span>
<span class="sd"> Critical density at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">critical_density</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="lookback_time"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.lookback_time.html#astropy.cosmology.funcs.lookback_time">[docs]</a><span class="k">def</span> <span class="nf">lookback_time</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Lookback time in Gyr to redshift `z`.</span>
<span class="sd"> The lookback time is the difference between the age of the</span>
<span class="sd"> Universe now and the age at redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> t : ndarray, or float if input scalar</span>
<span class="sd"> Lookback time at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">lookback_time</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="comoving_distance"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.comoving_distance.html#astropy.cosmology.funcs.comoving_distance">[docs]</a><span class="k">def</span> <span class="nf">comoving_distance</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Comoving distance in Mpc at redshift `z`.</span>
<span class="sd"> The comoving distance along the line-of-sight between two objects</span>
<span class="sd"> remains constant with time for objects in the Hubble flow.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> codist : ndarray, or float if input scalar</span>
<span class="sd"> Comoving distance at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">comoving_distance</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="angular_diameter_distance"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.angular_diameter_distance.html#astropy.cosmology.funcs.angular_diameter_distance">[docs]</a><span class="k">def</span> <span class="nf">angular_diameter_distance</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Angular diameter distance in Mpc at a given redshift.</span>
<span class="sd"> This gives the proper (sometimes called 'physical') transverse</span>
<span class="sd"> distance corresponding to an angle of 1 radian for an object at</span>
<span class="sd"> redshift `z`.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> angdist : ndarray, or float if input scalar</span>
<span class="sd"> Angular diameter distance at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">angular_diameter_distance</span><span class="p">(</span><span class="n">z</span><span class="p">)</span>
</div>
<div class="viewcode-block" id="luminosity_distance"><a class="viewcode-back" href="../../../_generated/astropy.cosmology.funcs.luminosity_distance.html#astropy.cosmology.funcs.luminosity_distance">[docs]</a><span class="k">def</span> <span class="nf">luminosity_distance</span><span class="p">(</span><span class="n">z</span><span class="p">,</span> <span class="n">cosmo</span><span class="o">=</span><span class="bp">None</span><span class="p">):</span>
<span class="sd">""" Luminosity distance in Mpc at redshift `z`.</span>
<span class="sd"> This is the distance to use when converting between the bolometric</span>
<span class="sd"> flux from an object at redshift `z` and its bolometric luminosity.</span>
<span class="sd"> Parameters</span>
<span class="sd"> ----------</span>
<span class="sd"> z : array_like</span>
<span class="sd"> Input redshifts.</span>
<span class="sd"> Returns</span>
<span class="sd"> -------</span>
<span class="sd"> lumdist : ndarray, or float if input scalar</span>
<span class="sd"> Angular diameter distance at each input redshift.</span>
<span class="sd"> """</span>
<span class="k">if</span> <span class="n">cosmo</span> <span class="ow">is</span> <span class="bp">None</span><span class="p">:</span>
<span class="n">cosmo</span> <span class="o">=</span> <span class="n">_get_current</span><span class="p">()</span>
<span class="k">return</span> <span class="n">cosmo</span><span class="o">.</span><span class="n">luminosity_distance</span><span class="p">(</span><span class="n">z</span><span class="p">)</span></div>
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