Like Fig. 2, but for the FWHM of an isothermal self-gravitating cylinder (black line) and sphere (grey line). The dashed line gives the asymptotic behaviour of the FWHM of an isothermal self-gravitating cylinder for high f (Eq. (23)). The vertical dashed-dotted lines mark the mass fraction of the maxima of FWHM (Eq. (25)). The horizontal dotted line shows the FWHM of a critical stable sphere. The FWHM of a cylinder with this overpressure 14.04 (f_cyl = 0.733) is shown as the filled black circle (FWHM_cyl = 0.0812 pc).