This https://github.com/flaresimulations/synthesizer/blob/main/src/synthesizer/particle/gas.py#L139 automatically sets DTM to 0.3 when the dust mass or DTM is not given. Logically there could be instances of where there are no gas particle in a galaxy (or when masked), that setting it automatically does not make sense. Would be best to check if for example the metallicity is None and keep the values as None.
This https://github.com/flaresimulations/synthesizer/blob/main/src/synthesizer/particle/gas.py#L139 automatically sets DTM to 0.3 when the dust mass or DTM is not given. Logically there could be instances of where there are no gas particle in a galaxy (or when masked), that setting it automatically does not make sense. Would be best to check if for example the metallicity is None and keep the values as None.