Far and extreme UV radiation feedback in molecular clouds and its influence on the mass and size of star clusters

We study the formation of star clusters in molecular clouds by performing three-dimensional radiation hydrodynamics simulations with far ultraviolet (FUV; $6 ~{\rm eV} \leqq h \nu 13.6 eV}$) and extreme (EUV; $h\nu \geqq 13.6~{\rm radiative feedback. find that FUV feedback significantly suppresses diffuse initial surface densities $\Sigma_{\rm cl} \lesssim \rm 50~M_{\odot} \; pc^{-2}$. In cases \sim 100-200~M_{\odot} pc^{-2}$, EUV plays a main role decrease efficiencies less than $0.3$. show thermal pressure from PDRs or H{\sc ii} regions disrupts makes size larger. Consequently, mass $M_{\rm 10^{5}~\rm M_{\odot}$ density 200~\rm M_{\odot}\; pc^{-2}$ remain stellar $\sim 100~\rm pc^{-3}$ nicely match observed open Milky Way. If are massive ($M_{\rm \gtrsim M_{\odot}$) compact ($\Sigma 400~\rm pc^{-2}$), is not effective they form dense cluster 10^{4}~\rm like globular young clusters. Thus, we suggest conditions key factors inducing variety