def METHOD_NAME(self, x, y, rho0, gamma, center_x=0, center_y=0):
    """Gravitational potential (modulo 4 pi G and rho0 in appropriate units)
    :param x:
    :param y:
    :param rho0:
    :param gamma:
    :param center_x:
    :param center_y:
    :return:
    """
    x_ = x - center_x
    y_ = y - center_y
    r = np.sqrt(x_**2 + y_**2)
    mass_3d = self.mass_3d(r, rho0, gamma)
    pot = mass_3d / r
    return pot