vice.toolkit.J21_sf_law.molecular¶
Calculate the star formation efficiency timescale of molecular gas at a given simulation time.
Signature: x.molecular(time)
Parameters¶
- x
J21_sf_law
An instance of this class.
- time
float
The simulation time in Gyr.
Returns¶
- tau_star_molfloat
The star formation efficiency timescale \(\tau_\star\) for molecular gas only (\(\tau_\text{mol}\)), defined accordingly:
\[\tau_\text{mol} = \tau_{\text{mol},0} \left(\frac{0.5 + t}{t_0}\right)^\gamma\]where \(\tau_{\text{mol},0}\) is the value of \(\tau_\text{mol}\) at the present day, \(t_0\) is the present-day age of the universe (assumed to be 13.7 Gyr), \(\gamma\) is the power-law index, and \(t\) is the parameter
time
passed to this function. A value of 0.5 is added, beacuse the onset of star formation is assumed to occur 0.5 Gyr following the big bang in the Johnson et al. (2021) models [1].The values of \(\tau_{\text{mol},0}\) and \(\gamma\) are controlled by the attributes
present_day_molecular
andmolecular_index
, respectively.
Example Code¶
>>> import vice
>>> mw = vice.milkyway(name = "example")
>>> mw.zones[0].tau_star.molecular(0)
0.6617825960083583
>>> mw.zones[0].tau_star.molecular(5)
1.3776103291490314
>>> mw.zones[0].tau_star.molecular(13.2)
2.0