vice.singlezone.eta¶
Type : real number or <function>
Default : 2.5
The mass loading factor, defined as the ratio of the mass outflow rate to the star formation rate.
\[\eta \equiv \frac{\dot{M}_\text{out}}{\dot{M}_\star}\]
Note
If the attribute smoothing
is nonzero, this relationship
generalizes to
\[\dot{M}_\text{out} = \eta(t)
\langle\dot{M}_\star\rangle_{\tau_\text{s}} =
\Bigg \lbrace {
\frac{\eta(t)}{t}\int_0^t \dot{M}_\star(t') dt'
(t < \tau_\text{s})
\atop
\frac{\eta(t)}{\tau_\text{s}}\int_{t - \tau_\text{s}}^t
\dot{M}_\star(t') dt'\ (t \geq \tau_\text{s})
}\]
where \(\tau_\text{s}\) is the value of the attribute, the outflow smoothing time.
Note also that the time-average is over the star formation rate only, and not the mass-loading factor.
Note
Saving this functional attribute with VICE outputs requires the
package dill, an extension to pickle
in the Python standard
library. It is recommended that VICE user’s install dill
>= 0.2.0.
Example Code¶
>>> import vice
>>> sz = vice.singlezone(name = "example")
>>> sz.eta = 2
>>> def f(t):
if t <= 2:
return 5
else:
return 1
>>> sz.eta = f