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The Critical Neutrino Luminosity and its Observational Signatures

This study explores the critical neutrino luminosity in supernova explosions and its implications for thermodynamic properties, explosion dynamics, and remnant properties. Factors such as rotation, convection, equation of state, and different heating/cooling functions are considered. The study also investigates progenitor dependence, neutron star masses, and constraints from observations. Synthetic supernovae models are used to compare with observations and determine the explosion mechanism.

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The Critical Neutrino Luminosity and its Observational Signatures

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  1. The Critical Neutrino Luminosity and its Observational Signatures Ondřej Pejcha with Todd Thompson, Christopher Kochanek, Basudeb Dasgupta Department of Astronomy, Ohio State University, USA (now Hubble Fellow at Princeton University)

  2. Critical neutrino luminosity • Neutrino mechanism: heating due to neutrinos from the PNS, the shock is revived when L > Lcrit (Burrows & Goshy 1993) • Why does Lcrit exist? What are its implications for thermodynamic properties of the flow? Burrows & Goshy (1993)

  3. Isothermal supernova Version of Bondi accretion - Ṁfixed, varycT(Pejcha & Thompson 2012)

  4. Isothermal supernova

  5. Isothermal supernova

  6. Isothermal supernova

  7. Isothermal supernova

  8. Isothermal supernova

  9. Isothermal supernova

  10. Isothermal supernova

  11. Isothermal supernova

  12. Isothermal supernova

  13. Isothermal supernova

  14. Isothermal supernova

  15. Isothermal supernova

  16. Isothermal supernova antesonic condition

  17. Antesonic condition More realistic calculation (EOS, neutrino heating & cooling, Ye, dL/dr) – proved equivalence to isothermal supernova Pejcha & Thompson (2012) 0.193 ± 0.009 for a wide range of Ṁ, M, r, microphysics Investigated in time-dependent calculations (Couch 2012; Murphy & Meakin 2011; Dolence et al. 2012; Müller et al. 2012; Takiwaki et al. 2012; Ott et al. 2013 and others)

  18. Properties of Lcrit • Sensitivity of the neutrino mechanism to physical effects • Rotation, convection and equation of state (Yamasaki & Yamada 2005, 2006; Couch 2013; Suwa et al. 2013) • Different heating & cooling functions, accretion luminosity (Pejcha & Thompson 2012) • Collective neutrino oscillations (Pejcha, Dasgupta & Thompson 2012) • Parameters of the problem with more realistic calculation Ṁ, M, r(Pejcha & Thompson 2012) • Systematics of Ṁ(t), M(t), r(t) – which stars explode? What are the explosion and remnant properties? (Pejcha & Thompson, in preparation)

  19. Synthetic supernovae • Evolution of Ṁ(t), M(t), r(t), Lcore(t) for each progenitor • Determine Lcrit(t) as a sequence of steady-state models • Introduced parameterized artificial explosions • Determine remnant masses, explosion energy (gain region mass), explosion time & neutrino luminosity • Compare with observations Pejcha & Thompson (in preparation)

  20. Progenitor dependence of neutrino mechanism Pejcha & Thompson (in preparation)

  21. Constraints from observations • Neutron star masses immediately comparable to observations – Pejcha, Thompson & Kochanek (2012)

  22. Double neutron stars probe supernova mechanism • Bayesian comparison of supernova explosion models • Double neutron stars → birth masses • Piston-driven explosion models of Zhang, Woosley & Heger (2008) – piston at S/NA = 4 kB and iron core • No SN progenitors subject to binary evolution • Progenitors independent/correlated with uniform/twin P(q) • Fallback/no fallback Pejcha, Thompson & Kochanek (2012)

  23. Example: best model no fallback NS mass = iron core mass

  24. Double neutron stars probe supernova mechanism • Explosion initiated at iron core • No fallback • Implications for nucleosynthesis, explosion energies etc.

  25. Conclusions • Understanding of core-collapse supernova mechanism important for nucleosynthesis, explosion dynamics, remnant properties and their connection – observationally testable! • Revival of steady-state accretion shock by neutrinos – Lcrit • Isothermal supernova explains Lcrit and gives antesonic condition – diagnostic of explosion (Pejcha & Thompson 2012) • Physical effects quantified through Lcrit (Pejcha & Thompson 2012; Pejcha, Dasgupta & Thompson 2012) • Lcrit convolved with progenitor structure gives testable predictions • Double neutron stars constrain the explosion mechanism (Pejcha, Thompson & Kochanek 2012)

  26. Backup slides

  27. Which stars explode? Smartt (2009)

  28. Mass cut separating remnant and ejecta Iron core low NS mass high NS mass

  29. Stalled accretion shock L Janka (2001)

  30. Example: bad model with fallback

  31. Critical neutrino luminosity • 1D steady-state calculation between PNS surface and shock (Burrows & Goshy 1993, Yamasaki & Yamada 2005, 2007) • Reason for existence of Lcrit unknown • Relation ofLcritto quantities measurable in simulations unknown

  32. What are the properties of the explosions? ? ? Smartt (2009), Janka (2012)

  33. What are the properties of the remnants and the nucleosynthetic yields?

  34. What are the properties of neutron stars and black holes? Özel et al. (2012)

  35. What is the mechanism of core-collapse supernova explosion? Parameterized 3D simulation of Nordhaus et al. (2010)

  36. Collective neutrino oscillations • Three neutrino flavors emanating from PNS • Little absorption of x in the important region • Possibility of self-induced flavor conversion and enhanced heating rate Suppressed by matter effects (interaction with e+/e-) Pejcha, Dasgupta & Thompson (2012)

  37. Dynamical effects 1D time-dependent calculation (Fernandez 2012) – explosions before Lcrit Yamasaki & Yamada (2005): stable for L ≤ Lcrit Yamasaki & Yamada (2007): overstable modes below Lcrit

  38. Antesonic condition antesonic condition useful diagnostic of proximity to explosion Couch (2012) – evaluated at maximal shock radii, antesonic ratio normalized to expected value Murphy & Meakin (2011), Dolence et al. (2012), Müller et al. (2012), Takiwaki et al. (2012)

  39. Critical sound speed • For fixed parameters, there is critical cT above which accretion with shock impossible, because boundary condition cannot be satisfied • Coordinates of the critical point calculated analytically – antesonic condition

  40. A more realistic calculation • 1D steady-state accretion shock problem • Optically-thin heating & cooling • Equation of state: relativistic electrons and positrons with chemical potential and nonrelativistic free protons and neutrons • Boundary value problem for a system of 1st order nonlinear differential equations with one boundary free (shock radius is eigenvalue) • Boundary conditions • Two shock jump conditions • Ṁ fixed everywhere • Ye = 26/56 at shock • L = Lcore at the neutrinosphere

  41. Core collapse Many simulations fail to revive the shock wave Buras et al. (2006)

  42. Multi-dimensional effects

  43. Accretion luminosity Up to ~25% reduction of Lcrit

  44. Multi-dimensional effects 1D, 2D and 3D from Nordhaus et al. (2010) Murphy & Burrows (2008), Nordhaus et al. (2010), Hanke et al. (2011), Couch (2012)

  45. Time dependence and explosions • Time dependence – Fernández (2012) • Systematics with Ṁ(t), M(t), r(t) – which stars explode? What are the explosion and remnant properties? • Lcrit – systematic way for making observable predictions of the neutrino mechanism • How are progenitors different? Pejcha & Thompson (in preparation)

  46. Progenitor dependence of neutrino mechanism Woosley, Heger & Weaver (2002) progenitors

  47. Progenitor dependence of neutrino mechanism L Janka (2001)

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