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<div class="section" id="w0wzcdm">
<h1>w0wzCDM<a class="headerlink" href="#w0wzcdm" title="Permalink to this headline">¶</a></h1>
<dl class="class">
<dt id="astropy.cosmology.core.w0wzCDM">
<em class="property">class </em><tt class="descclassname">astropy.cosmology.core.</tt><tt class="descname">w0wzCDM</tt><big>(</big><em>H0</em>, <em>Om0</em>, <em>Ode0</em>, <em>w0=-1.0</em>, <em>wz=0.0</em>, <em>Tcmb0=2.725</em>, <em>Neff=3.04</em>, <em>name='w0wzCDM'</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/cosmology/core.py#L1814" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="reference internal" href="../_modules/astropy/cosmology/core.html#w0wzCDM"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#astropy.cosmology.core.w0wzCDM" title="Permalink to this definition">¶</a></dt>
<dd><p>Bases: <a class="reference internal" href="astropy.cosmology.core.FLRW.html#astropy.cosmology.core.FLRW" title="astropy.cosmology.core.FLRW"><tt class="xref py py-class docutils literal"><span class="pre">astropy.cosmology.core.FLRW</span></tt></a></p>
<p>FLRW cosmology with a variable dark energy equation of state
and curvature.</p>
<p>The equation for the dark energy equation of state uses the
simple form: <span class="math">w(z) = w_0 + w_z z</span>.</p>
<p>This form is not recommended for z > 1.</p>
<p class="rubric">Examples</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">from</span> <span class="nn">astro.cosmology</span> <span class="kn">import</span> <span class="n">wawzCDM</span>
<span class="gp">>>> </span><span class="n">cosmo</span> <span class="o">=</span> <span class="n">wawzCDM</span><span class="p">(</span><span class="n">H0</span><span class="o">=</span><span class="mi">70</span><span class="p">,</span> <span class="n">Om0</span><span class="o">=</span><span class="mf">0.3</span><span class="p">,</span> <span class="n">Ode0</span><span class="o">=</span><span class="mf">0.7</span><span class="p">,</span> <span class="n">w0</span><span class="o">=-</span><span class="mf">0.9</span><span class="p">,</span> <span class="n">wz</span><span class="o">=</span><span class="mf">0.2</span><span class="p">)</span>
</pre></div>
</div>
<p>The comoving distance in Mpc at redshift z:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">dc</span> <span class="o">=</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>
</pre></div>
</div>
<p class="rubric">Attributes Summary</p>
<table border="1" class="longtable docutils">
<colgroup>
<col width="10%" />
<col width="90%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><a class="reference internal" href="#astropy.cosmology.core.w0wzCDM.w0" title="astropy.cosmology.core.w0wzCDM.w0"><tt class="xref py py-obj docutils literal"><span class="pre">w0</span></tt></a></td>
<td>Dark energy equation of state at z=0</td>
</tr>
<tr class="row-even"><td><a class="reference internal" href="#astropy.cosmology.core.w0wzCDM.wz" title="astropy.cosmology.core.w0wzCDM.wz"><tt class="xref py py-obj docutils literal"><span class="pre">wz</span></tt></a></td>
<td>Derivative of the dark energy equation of state w.r.t.</td>
</tr>
</tbody>
</table>
<p class="rubric">Methods Summary</p>
<table border="1" class="longtable docutils">
<colgroup>
<col width="10%" />
<col width="90%" />
</colgroup>
<tbody valign="top">
<tr class="row-odd"><td><a class="reference internal" href="#astropy.cosmology.core.w0wzCDM.de_density_scale" title="astropy.cosmology.core.w0wzCDM.de_density_scale"><tt class="xref py py-obj docutils literal"><span class="pre">de_density_scale</span></tt></a>(z)</td>
<td>Evaluates the redshift dependence of the dark energy density.</td>
</tr>
<tr class="row-even"><td><a class="reference internal" href="#astropy.cosmology.core.w0wzCDM.w" title="astropy.cosmology.core.w0wzCDM.w"><tt class="xref py py-obj docutils literal"><span class="pre">w</span></tt></a>(z)</td>
<td>Returns dark energy equation of state at redshift <tt class="xref py py-obj docutils literal"><span class="pre">z</span></tt>.</td>
</tr>
</tbody>
</table>
<p class="rubric">Attributes Documentation</p>
<dl class="attribute">
<dt id="astropy.cosmology.core.w0wzCDM.w0">
<tt class="descname">w0</tt><a class="reference internal" href="../_modules/astropy/cosmology/core.html#w0wzCDM.w0"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#astropy.cosmology.core.w0wzCDM.w0" title="Permalink to this definition">¶</a></dt>
<dd><p>Dark energy equation of state at z=0</p>
</dd></dl>
<dl class="attribute">
<dt id="astropy.cosmology.core.w0wzCDM.wz">
<tt class="descname">wz</tt><a class="reference internal" href="../_modules/astropy/cosmology/core.html#w0wzCDM.wz"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#astropy.cosmology.core.w0wzCDM.wz" title="Permalink to this definition">¶</a></dt>
<dd><p>Derivative of the dark energy equation of state w.r.t. z</p>
</dd></dl>
<p class="rubric">Methods Documentation</p>
<dl class="method">
<dt id="astropy.cosmology.core.w0wzCDM.de_density_scale">
<tt class="descname">de_density_scale</tt><big>(</big><em>z</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/cosmology/core.py#L1916" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="reference internal" href="../_modules/astropy/cosmology/core.html#w0wzCDM.de_density_scale"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#astropy.cosmology.core.w0wzCDM.de_density_scale" title="Permalink to this definition">¶</a></dt>
<dd><p>Evaluates the redshift dependence of the dark energy density.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>z</strong> : array_like</p>
<blockquote>
<div><p>Input redshifts.</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>I</strong> : ndarray, or float if input scalar</p>
<blockquote class="last">
<div><p>The scaling of the energy density of dark energy with redshift.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
<p class="rubric">Notes</p>
<p>The scaling factor, I, is defined by <span class="math">\rho(z) = \rho_0 I</span>,
and in this case is given by</p>
<div class="math">
<p><span class="math">I = \left(1 + z\right)^{3 \left(1 + w_0 - w_z\right)}
\exp \left(-3 w_z z\right)</span></p>
</div></dd></dl>
<dl class="method">
<dt id="astropy.cosmology.core.w0wzCDM.w">
<tt class="descname">w</tt><big>(</big><em>z</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/cosmology/core.py#L1889" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="reference internal" href="../_modules/astropy/cosmology/core.html#w0wzCDM.w"><span class="viewcode-link">[source]</span></a><a class="headerlink" href="#astropy.cosmology.core.w0wzCDM.w" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns dark energy equation of state at redshift <tt class="xref py py-obj docutils literal"><span class="pre">z</span></tt>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>z</strong> : array_like</p>
<blockquote>
<div><p>Input redshifts.</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>w</strong> : ndarray, or float if input scalar</p>
<blockquote class="last">
<div><p>The dark energy equation of state</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
<p class="rubric">Notes</p>
<p>The dark energy equation of state is defined as
<span class="math">w(z) = P(z)/\rho(z)</span>, where <span class="math">P(z)</span> is the
pressure at redshift z and <span class="math">\rho(z)</span> is the density
at redshift z, both in units where c=1. Here this is given by
<span class="math">w(z) = w_0 + w_z z</span>.</p>
</dd></dl>
</dd></dl>
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