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culinary_services [2014/06/05 14:57]
warren
culinary_services [2014/06/05 15:07]
warren
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  {{ ::​cassa.png?​nolink&​200 | Observation of Cassiopeia A.  Green shows <​sup>​44</​sup>​Ti distribution,​ blue is <​sup>​28</​sup>​Si,​ and the red shows the Fe distribution. ​ (From Grefenstette et al 2014)}}  {{ ::​cassa.png?​nolink&​200 | Observation of Cassiopeia A.  Green shows <​sup>​44</​sup>​Ti distribution,​ blue is <​sup>​28</​sup>​Si,​ and the red shows the Fe distribution. ​ (From Grefenstette et al 2014)}}
  
-Using simulations,​ we can use these observations to gain insight into the supernova environment. ​ By matching observed abundances, we can gain insight into the environment in which this nucleosynthesis must have taken place and in turn, the details of the explosion mechanism. ​ However, most core-collapse supernova simulations do not include sufficiently large reaction networks to simulate this nucleosynthesis.  This makes post-processing a necessary step.+Using simulations,​ we can use these observations to gain insight into the supernova environment. ​ By matching observed abundances, we can gain insight into the environment in which this nucleosynthesis must have taken place and in turn, the details of the explosion mechanism. ​ However, most core-collapse supernova simulations do not include sufficiently large reaction networks to simulate this nucleosynthesis.
  
 If the shock heating is sufficient, the material will be in Nuclear Statistical Equilibrium (NSE). ​ The isotopic abundances will be set by the thermodynamic environment (i.e. temperature and density). If the shock heating is sufficient, the material will be in Nuclear Statistical Equilibrium (NSE). ​ The isotopic abundances will be set by the thermodynamic environment (i.e. temperature and density).
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 ===Simulations=== ===Simulations===
  
-We have chosen to do a parameter space study in peak temperature,​ density, and electron fraction, tarting with a set parameter space of peak temperatures [T<​sub>​9</​sub>​ = 4 - 7] and densities [$\rho$ = 10<​sup>​5</​sup>​ - 10<​sup>​7</​sup>​ g/​cm<​sup>​3</​sup>​]. ​ This parameter space roughly corresponds with the shock heated region in simulations of Cassiopeia A-like supernovae (Young & Fryer 2007).+We have chosen to do a parameter space study in peak temperature,​ density, and electron fraction, tarting with a set parameter space of peak temperatures [T<​sub>​9</​sub>​ = 4 - 7] and densities [$\rho$ = 10<​sup>​5</​sup>​ - 10<​sup>​7</​sup>​ g/​cm<​sup>​3</​sup>​] for three values of the electron fraction [Y<​sub>​e</​sub>​ = 0.45, 0.50, 0.55].  This parameter space roughly corresponds with the shock heated region in simulations of Cassiopeia A-like supernovae (Young & Fryer 2007).
  
 We use analytic adiabatic freeze-out trajectories (Hoyle et al. 1964; Fowler & Hoyle 1964) which satisfy the differential equations: We use analytic adiabatic freeze-out trajectories (Hoyle et al. 1964; Fowler & Hoyle 1964) which satisfy the differential equations:
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 Where $\tau$ is some static free-fall timescale. Where $\tau$ is some static free-fall timescale.
-This **obviously** ​leads to:+This leads to temperature and density trajectories:
  
 \begin{equation} \begin{equation}
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 where $T_0$ and $\rho_0$ are the peak temperature and density in the supernova. ​ where $T_0$ and $\rho_0$ are the peak temperature and density in the supernova. ​
  
-Then you run the code, and it doesn'​t work(nevermind, it does work.)+We used the [[https://​wikihost.nscl.msu.edu/​talent/​lib/​exe/​fetch.php?​media=xnet_public.zip|XNet]] reaction network ​code.  Our code included 447 isotopes ranging from hydrogen through germanium. ​ We took the reaction rates from the [[https://​groups.nscl.msu.edu/​jina/​reaclib/​db/​library.php?​action=viewsnapshots|JINA Reaclib database]]. ​ We set the threshold temperature for NSE to be 5 GK.
  
 ===Results=== ===Results===
  
 **REFERENCES** \\ **REFERENCES** \\
-[[http://​iopscience.iop.org/​0067-0049/​191/​1/​66|Trends in 44Ti and 56Ni from Core-Collapse Supernovae (Magkotsios et al (2010))]]\\ +[[http://​iopscience.iop.org/​0067-0049/​191/​1/​66|Trends in 44Ti and 56Ni from Core-Collapse Supernovae (Magkotsios et al 2010)]]\\ 
-[[http://​iopscience.iop.org/​0004-637X/​504/​1/​500|Nuclear Reactions Governing the Nucleosynthesis of 44Ti (The et al (1998))]]\\ +[[http://​iopscience.iop.org/​0004-637X/​504/​1/​500|Nuclear Reactions Governing the Nucleosynthesis of 44Ti (The et al 1998)]]\\ 
-[[http://​www.sciencedirect.com/​science/​article/​pii/​S1387647303002707|X-ray and gamma-ray ​observations ​of Cas A]]+[[http://​www.sciencedirect.com/​science/​article/​pii/​S1387647303002707|X-ray and gamma-ray ​studies ​of Cas A (Vink 2004)]]
culinary_services.txt · Last modified: 2014/06/06 15:52 by long