EPoS Contribution
EPoS Contribution
Impact of episodic outflow feedback on the star formation efficiency and stellar multiplicity

Paul Rohde
U Koeln, Cologne, DE
The evolution of young protostars is accompanied by the launching of outflows. Observations show that accretion, as well as outflows, are episodic. However, the effects of episodic outflow feedback on core-scale are not well understood. We perform 88 hydrodynamic SPH simulations of Mcore = 1 Msun turbulent dense cores to study the effects of outflow feedback on the star formation efficiency (SFE) and stellar multiplicity. Protostars are represented by sink particles, which use a sub-grid model to capture stellar evolution, episodic accretion and the launching of outflows. By comparing simulations with and without episodic outflow feedback, we show that simulations without outflow feedback overproduce binary systems while ejecting single from higher-order multiple systems (S; B; T; Q) = (0.60; 0.31; 0.07; 0.02). Outflow feedback forces later stars to form in rotationally supported orbits and thus supports the formation of long-lived higher-order multiple systems (0.59; 0.23; 0.12; 0.5). The fraction of equal mass "Twin Binaries" is about four times higher when outflows are present. Moreover, we find that outflows are highly self-regulated and their strength scales with the SFE, thereby halving the SFE compared to simulations without outflow feedback.
Caption: (Left) Distribution of mass ratios between secondary and primary, q = Mstar-s/Mstar-p, of all binary systems of the outflow (orange) and reference sample (blue) at t = t0 + 5 tff, normalised to the total number of binary systems in each sample. The total number of binaries in the outflow sample is Nbin-tot-of = 35 and in the reference sample Nbin-tot-rf = 44. Both samples are peaked at high q-ratios with a tail towards lower q-ratios. Outflow feedback enhances the formation of so-called "Twin Binaries" with q > 0.95 (dashed grey line). (Right) Total stellar mass from the outflow sample simulation against the corresponding reference sample simulation for each simulation pair at t = t0 + 5 tff. The ratios scatter around the mean value Mbar,star rel = 0.54 with a standard deviation of σrel = 0.16. Outflow feedback halves the SFE for a broad variety of cores.
Collaborators:
S. Walch, U Koeln, DE
A.P. Whitworth, U Cardiff, UK
D. Seifried, U Koeln, DE
S.D. Clarke, U Koeln, DE
Key publication

Suggested Session: Cores