def fitting_function(x, a, b):
    """
    My fitting function to be fit to the v_out to sfr surface density data

    Parameters
    ----------
    x : (vector)
        the SFR surface density

    a, b : (int)
        constants to be fit

    Returns
    -------
    y : (vector)
        the outflow velocity
    """
    return a*(x**b)