%0 Generic %1 sharma2014bubble %A Sharma, Prateek %A Roy, Arpita %A Nath, Biman B. %A Shchekinov, Yuri %D 2014 %K feedback superbubble supernovae %T In hot bubble: why superbubble feedback works and isolated supernovae do not? %U http://arxiv.org/abs/1402.6695 %X Most massive stars form in star clusters extending over just few 10s of pc. Fast winds from massive stars and the first supernovae are expected to create a hot, dilute bubble which encompasses the whole star cluster. Thus subsequent supernovae go off in a dilute, non-radiative bubble and power a superwind. Continuous energy injection via successive supernovae going off within the hot bubble maintains a strong termination shock, which keeps the superbubble over-pressured and drives the outer shock well after it becomes radiative. Isolated supernovae, in contrast, do not have further energy injection, become radiative quite early ($0.1$ Myr, 10s of pc), and stall at scales $100$ pc because of radiative and adiabatic losses. While isolated supernovae lose almost all of their mechanical energy by a Myr, superbubbles can retain up to $40\%$ of the input energy in form of mechanical energy over the lifetime of the star cluster (few 10s of Myr). Thus, superbubbles are expected to be more effective feedback agents compared to isolated supernovae. These conclusions are likely to hold even in presence of realistic magnetic fields and thermal conduction. We compare various recipes for implementing supernova feedback in numerical simulations. We show that the supernova energy needs to be deposited over a small volume in order for it to couple to the ISM. We stress upon the importance of thermalization of supernova energy, which forms the basis of our analytic estimates. We verify our analytic scalings with numerical simulations. Individual supernova ejecta needs to thermalize within the termination shock for the appearance of a simple Chevalier & Clegg (CC85) thermal wind within the hot bubble. A steady thermal wind appears only for a large number ($\gtrsim 10^4$) of supernovae.

@misc{sharma2014bubble, abstract = {Most massive stars form in star clusters extending over just few 10s of pc. Fast winds from massive stars and the first supernovae are expected to create a hot, dilute bubble which encompasses the whole star cluster. Thus subsequent supernovae go off in a dilute, non-radiative bubble and power a superwind. Continuous energy injection via successive supernovae going off within the hot bubble maintains a strong termination shock, which keeps the superbubble over-pressured and drives the outer shock well after it becomes radiative. Isolated supernovae, in contrast, do not have further energy injection, become radiative quite early ($\lesssim 0.1$ Myr, 10s of pc), and stall at scales $\lesssim 100$ pc because of radiative and adiabatic losses. While isolated supernovae lose almost all of their mechanical energy by a Myr, superbubbles can retain up to $\sim 40\%$ of the input energy in form of mechanical energy over the lifetime of the star cluster (few 10s of Myr). Thus, superbubbles are expected to be more effective feedback agents compared to isolated supernovae. These conclusions are likely to hold even in presence of realistic magnetic fields and thermal conduction. We compare various recipes for implementing supernova feedback in numerical simulations. We show that the supernova energy needs to be deposited over a small volume in order for it to couple to the ISM. We stress upon the importance of thermalization of supernova energy, which forms the basis of our analytic estimates. We verify our analytic scalings with numerical simulations. Individual supernova ejecta needs to thermalize within the termination shock for the appearance of a simple Chevalier \& Clegg (CC85) thermal wind within the hot bubble. A steady thermal wind appears only for a large number ($\gtrsim 10^4$) of supernovae.}, added-at = {2014-02-28T11:44:29.000+0100}, author = {Sharma, Prateek and Roy, Arpita and Nath, Biman B. and Shchekinov, Yuri}, biburl = {https://www.bibsonomy.org/bibtex/2e8ab2a20a2033338614dc4d005f88f84/miki}, description = {[1402.6695] In hot bubble: why superbubble feedback works and isolated supernovae do not?}, interhash = {04ef85d7002c5020794c6541a220f30a}, intrahash = {e8ab2a20a2033338614dc4d005f88f84}, keywords = {feedback superbubble supernovae}, note = {cite arxiv:1402.6695Comment: 15 pages, 9 figures; abstract abridged; submitted to MNRAS; comments welcome}, timestamp = {2014-02-28T11:44:29.000+0100}, title = {In hot bubble: why superbubble feedback works and isolated supernovae do not?}, url = {http://arxiv.org/abs/1402.6695}, year = 2014 }