(Upper panel) Momentum flux vs bolometric luminosity. Open circles indicate sources from the current sample of Serpens, vertical errorbars correspond to values of the momentum flux for τ = 0 and 1, and horizontal errorbars to the differences in the derived bolometric luminosities for the different Spitzer fluxes in Winston et al. (2007) and Harvey. Arrows and asterisks mark Serpens sources that either F_CO, L_bol, or both are uncertain. The dashed line shows the location of the Class I correlation of Bontemps et al. (1996), and the dot-dashed line the correlation of both low- and high-mass sources of Wu et al. (2004). Filled (red) squares correspond to test sources from the sample that Bontemps et al. (1996) used to control the influence of the new Spitzer derived (red triangles) L_bol to the correlation. (Lower panel) Outflow mechanical luminosity versus the bolometric luminosity for the sample of sources in Serpens; the L_mech − L_bol correlation for the sample of both low- and high- mass sources of Wu et al. (2004) is shown as a dashed line, running through the data points and separating Class 0 and Class I sources.