Does the impulse response curve of y represents economic fluctuations or economic growth in the logarithmic-linearized DSGE model? And how to explain the meaning of impulse response curve of y?
If the model is stationary, then the IRFs represent fluctuations around trend because the model will always return back to steady state. What exactly does your second question refer to?
You can use DSGE models for example for steady state transitions, but you would most probably not employ a linearized model for that and would not look at typical IRFs but rather simulations.
I’m very sorry, perhaps I was inaccurate in describing the problem. My question is whether the DSGE model is used to study economic fluctuations or economic growth?