Exploding SNe with jets: time-scales

We perform hydrodynamical simulations of core collapse supernovae (CCSNe) with a cylindrically-symmetrical numerical code (FLASH) to study the inflation of bubbles and the initiation of the explosion within the frame of the jittering-jets model. We study the typical time- scale of the model and compare it to the typical time-scale of the delayed neutrino mechanism. Our analysis shows that the explosion energy of the delayed neutrino mechanism is an order of magnitude less than the required 10^51 erg.Comment: To appear in Death of Massive Stars: Supernovae and Gamma-Ray Bursts, Proceedings IAU Symposium No. 279, 2012, eds. P. Roming, N. Kawai & E. Pia

Exploding Core-Collapse Supernovae with Jittering Jets

We argue that jittering jets, i.e., jets that have their launching direction rapidly change, launched by the newly formed neutron star in a core collapse supernova can explode the star. We show that under a wide range of parameters the fast narrow jets deposit their energy inside the star via shock waves, and form two hot bubbles, that eventually merge, accelerate the rest of the star and lead to the explosion. To prevent the jets from penetrating through the collapsing stellar core and escape with their energy, instead of forming the hot bubbles, the jets should be prevented from drilling a hole through the star. This condition can be met if the jets' axis rapidly changes its direction. This process of depositing jets' energy into the ambient medium is termed the it penetrating jet feedback mechanism. The feedback exists in that the neutron star (or a black hole) at the center of the core collapse supernova shuts off its own growth by exploding the star. The jets deposit their energy at a distance of 1000 km from the center and expel the mass above that radius. In our model, the material near the stalled shock at several hundreds kilometers from the center is not expelled, but it is rather accreted and feed the accretion disk that blows the jets. The neutrinos might influence the accretion flow, but in the proposed model their role in exploding the star is small.Comment: Accepted for publication in MNRA

Nucleosynthesis of r-Process Elements by Jittering Jets in Core-Collapse Supernovae

We calculate the nucleosynthesis inside the hot bubble formed in the jittering-jets model for core collapse supernovae (CCSNe) explosions, and find the formation of several times 10^-4 M_\odot of r-process elements. In the jittering-jets model fast jets launched from a stochastic accretion disk around the newly formed neutron star are shocked at several thousands km, and form hot high-pressure bubbles. These bubbles merge to form a large bubble that explode the star. In the current study we assume a spherically symmetric homogenous bubble, and follow its evolution for about one second during which nuclear reactions take place. The jets last for about one second, their velocity is v_j=0.5c, and their total energy is 10^51 erg. We use jets' neutron enrichment independent on time, and follow the nuclear reactions to the formation of the seed nuclei up to $Z \leq 50$, on which more neutrons will be absorbed to form the r-process elements. Based on the mass of the seed nuclei we find the r-process element mass in our idealized model to be several times 10^-4 M_\odot, which is slightly larger than the value deduced from observations. More realistic calculations that relax the assumptions of a homogenous bubble and constant jets composition might lead to agreement with observations.Comment: Accepted for publication in MNRA

Binary systems and their nuclear explosions

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