The Death of Massive Stars: Core-Collapse Supernovae and their - PowerPoint PPT Presentation

The Death of Massive Stars: Core-Collapse Supernovae and their Signature in Gravitational Waves Christian David Ott cott@tapir.caltech.edu TAPIR , California Institute of Technology, Pasadena, CA, USA Niels Bohr International Academy, Niels Bohr Institute, Copenhagen, Denmark Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA

The Supernova Problem R  100 – 200 km 2 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

The Supernova Problem R  100 – 200 km What is the Mechanism of shock revival? 3 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

Blowing up Massive Stars: Core-Collapse SN Mechanisms [Colgate & White 1966, Arnett 1966, Neutrino Wilson 1985, Bethe & Wilson 1985, recent : Buras et al. 2006, Kitaura et al. 2006, Mechanism Marek & Janka 2009 , Ott et al. 2008] Magnetorotational [LeBlanc & Wilson ‘70, Bisnovatyi-Kogan et al. ‘76, Meier et al. ‘76, Symbalisty 1984, Mechanism recent : Burrows et al. 2007] Acoustic [proposed by Burrows et al. 2006, 2007; Mechanism not confirmed by other groups/codes] 4 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

[Ott 2009, arXiv:0905.2797] 5 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

[Ott 2009, arXiv:0905.2797] Multi-D Dynamics • Convection / Turbulence • SASI • Rotation • PNS pulsations 6 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

Using GWs to Study the Supernova Mechanism [Review: Ott, CQG 26, 063001 (2009)] • Only GWs and Neutrinos can provide direct “live” information from the supernova engine deep inside the star. • GWs : Direct probe of the ubiquitous multi-D dynamics in the postshock region and in the protoneutron star (PNS). 7 C. D. Ott @ UC Irvine 02/03/2009

Using GWs to Study the Supernova Mechanism [Review: Ott, CQG 26, 063001 (2009)] • Only GWs and Neutrinos can provide direct “live” information from the supernova engine deep inside the star. • GWs : Direct probe of the ubiquitous multi-D dynamics in the postshock region and in the protoneutron star (PNS). • GW emission processes in stellar collapse and core-collapse SNe: • Rotating core collapse and core bounce • Aspherical outflows • Dynamical rotational 3D instabilities • BH formation • Convection and the Standing Accretion • Anisotropic neutrino emission • Magnetic stresses Shock Instability (SASI) • Protoneutron star core pulsations 8 C. D. Ott @ UC Irvine 02/03/2009

GWs from Stellar Collapse and Core-Collapse SNe [Review: Ott, CQG 26, 063001 (2009)] Rotating Core Nonaxisymmetric Convection & Collapse and Rotational Standing Accretion Bounce Instabilities Shock Instability Protoneutron Star Asymmetric Aspherical Pulsations Neutrino Emission Outflows 9 C. D. Ott @ UC Irvine 02/03/2009

Rotating Core Collapse and Bounce • Collapse: Angular momentum conservation leads to spin up & rotational deformation of inner core. • At core bounce: Very large accelerations -> rapidly changing mass quadrupole moment. • Most extensively studied GW emission in core collapse • Always axisymmetric: ONLY h + • Simplest GW emission process: Rotation + Gravity + Stiffening of EOS . 10 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

New Extended 2D GR Model Set [ Dimmelmeier, Ott, Marek, and Janka 2008 , Ott 2009, Dimmelmeier et al. 2007ab, Ott et al. 2007] • >140 2D GR models with Y e ( ρ ). 6 pre-SN stellar models. • Slow to rapid rotation. • Uniform to moderately differential rotation. • Shen and LS-EOS. • GW signature of rotating collapse multi-degenerate. WARNING: • Key parameters:  99% of massive stars are  Precollapse central Ω . probably slowly rotating!  Iron-core mass/entropy. [ Ott 2009 ] 11 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

GWs from Stellar Collapse and Core-Collapse SNe [Review: Ott, CQG 26, 063001 (2009)] Rotating Core Nonaxisymmetric Convection & Collapse and Rotational Standing Accretion Bounce Instabilities Shock Instability Protoneutron Star Asymmetric Aspherical Pulsations Neutrino Emission Outflows 12 C. D. Ott @ UC Irvine 02/03/2009

PNS Spin and Rotational Instabilities [Dimmelmeier et al. 2008, Ott et al. 2007, Ott et al. 2006] • Classical picture: High T/|W| instabilities . Azimuthalmodes  exp(im  ). m=2 “bar - modes” (T/|W|) dynamical = 0.27, (T/|W|) secular  0.14. [e.g., Chandrasekhar 1969] Numbers hold roughly in GR and moderate differential rotation . [e.g., Baiotti et al. 2007] • Can a real PNS reach such high T/|W|? [Ott et al. ‘07, 3+1 GR simulations] [Shibata et al. 2000, 3+1 GR NS simulations] 13 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

PNS Spin and Rotational Instabilities [Dimmelmeier et al. 2008, Ott et al. 2007, Ott et al. 2006] • Classical picture: High T/|W| instabilities . Azimuthalmodes  exp(im  ). m=2 “bar - modes” (T/|W|) dynamical = 0.27, (T/|W|) secular  0.14. [e.g., Chandrasekhar 1969] Numbers hold roughly in GR and moderate differential rotation . [e.g., Baiotti et al. 2007] • Can a real PNS reach such high T/|W|? • Direct numerical simulation: No – collapsing cores hit rotational barrier. [Ott et al. PRL 2007 & CQG 2007, Dimmelmeier et al. 2008 ] • Critical T/|W| (secular/ dynamical) attainable during PNS cooling. • B-fields: rapid spindown (?) 14 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

Low-T/|W| Rotational Instability • Dynamical rotational instability at low T/|W|. [e.g., Centrella et al. 2001, Shibata et al. 2003, Saijo 2003, Saijo & Yoshida 2006, Ott et al. 2005, Ou & Tohline 2006] • Dominant m=1 mode; m={2,3} modes mixed in (radial & temporal variation). • Mechanism: Corotation instability Resonance of unstable mode with background fluid at corotationpoint(s). • Spiral density waves – relationship to accretion and galactic disks? -> angular momentum transport. [Ott et al. 2007, 3+1 GR simulation] 15 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

Equatorial Observer + Polar Observer + Ott et al. 2007, PRL 3+1 GR simulation of Rotating Core Collapse GW Emission, Model s20A2B4 Equatorial Observer x Polar Observer x 16 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

[Ott 2009, arXiv:0905.2797] 17 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

GW Emission vs. Detector Noise • 3D component: lower in amplitude than core-bounce GW spike, but greater in energy! Emission in narrow frequency band around 900 — 930 Hz (  2 x pattern speed of the unstable mode!) models. 18 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

GWs from Stellar Collapse and Core-Collapse SNe [Review: Ott, CQG 26, 063001 (2009)] Rotating Core Nonaxisymmetric Convection & Collapse and Rotational Standing Accretion Bounce Instabilities Shock Instability Protoneutron Star Asymmetric Aspherical Pulsations Neutrino Emission Outflows 19 C. D. Ott @ UC Irvine 02/03/2009

Convection & SASI • Prompt Convection – Negative entropy gradient left by stalling shock drives prompt convection. [e.g., Burrows & Hayes 1992] – Growth and duration (  5-50 ms) strongly dependent on seed perturbations. • Protoneutron Star (PNS) Convection – Negative lepton gradient drives PNS convection. [e.g., Dessart et al. 2005] – Physical scale: 10-50 km. Duration:  1 s. • Neutrino-Driven Convection and SASI [e.g., Herant et al. 1994, Burrows et al. 1995, Blondin et al. 2003, Buras et al. 2006, Burrows et al. 2006, Marek & Janka 2009] – Neutrino heating -> negative entropy gradient behind shock. – Advective-acoustic cycle -> low-mode standing accretion shock instability. – Physical scale: 50-300 km. Duration: until explosion or BH formation. [Burrows et al. 2006] 20

Convection, SASI & Explosion: GW Emission [ Murphy, Ott & Burrows 2009 (in prep.); Marek et al. 2009, Müller et al. 2004, Kotakeet al. 2007, 2009] • Axisymmetric (2D) simulations with the code Bethe-Hydro. [Murphy & Burrows 2008] • Neutrino cooling & parametrized neutrino luminosity and heating. • Core collapse and SN dynamics in nonrotating 12, 15, 20, and 40 M SUN stars. [Woosley & Heger 2007] [ Murphy, Ott & Burrows 2009 ] • Convective/SASI GW signal is broadband , f ≈ 10 – 1000 Hz, and of stochastic nature (governed by turbulent flow/non-linear dynamics). • Largest GW amplitudes emitted by SASI plumes/rapid downflows to small radii. • Aspherical explosion: Secular increase of |h| (positive: prolate, negative: oblate) 21

[Murphy, Ott and Burrows 2009 (in prep.)] 22 C. D. Ott @ TAUP 2009, Rome, 2009/07/02

Detectability;Dependence on Progenitor & ν -Luminosity [ Murphy, Ott & Burrows 2009 (in prep.)] • More massive progenitor -> higher accretion rate -> greater L ν / heating required and longer time to explosion -> stronger GW emission . 23

GWs from Stellar Collapse and Core-Collapse SNe [Review: Ott, CQG 26, 063001 (2009)] Rotating Core Nonaxisymmetric Convection & Collapse and Rotational Standing Accretion Bounce Instabilities Shock Instability Protoneutron Star Asymmetric Aspherical Pulsations Neutrino Emission Outflows 24 C. D. Ott @ UC Irvine 02/03/2009