A MODEL FOR GRAVITATIONAL WAVE EMISSION FROM NEUTRINO-DRIVEN CORE-COLLAPSE SUPERNOVAE

By J. Murphy, Christian D. Ott, Adam Burrows. 2009

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Using a suite of progenitor models, neutrino luminosities, and two-dimensional simulations, we investigate the matter gravitational wave (GW) emission from postbounce phases of neutrino-driven core-collapse supernovae. These phases include prompt and steady-state convection, the standing accretion shock instability (SASI), and asymmetric explosions. For the stages before explosion, we propose a model for the source of GW emission. Downdrafts of the postshock-convection/SASI region strike the protoneutron star “surface” with large speeds and are decelerated by buoyancy forces. We find that the GW amplitude is set by the magnitude of deceleration and, by extension, the downdraft's speed and the vigor of postshock-convective/SASI motions. However, the characteristic frequencies, which evolve from ∼100 Hz after bounce to ∼300–400 Hz, are practically independent of these speeds (and turnover timescales). Instead, they are set by the deceleration timescale, which is in turn set by the buoyancy frequency at the lower boundary of postshock convection. Consequently, the characteristic GW frequencies are dependent upon a combination of core structure attributes, specifically the dense-matter equation of state (EOS) and details that determine the gradients at the boundary, including the accretion-rate history, the EOS at subnuclear densities, and neutrino transport. During explosion, the high frequency signal wanes and is replaced by a strong low frequency, ∼10s of Hz, signal that reveals the general morphology of the explosion (i.e., prolate, oblate, or spherical). However, current and near-future GW detectors are sensitive to GW power at frequencies ≳50 Hz. Therefore, the signature of explosion will be the abrupt reduction of detectable GW emission.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2b57c61978a2fe56dab03c02b838ed67ec22571e

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Citations in the corpus

A NEW MULTI-DIMENSIONAL GENERAL RELATIVISTIC NEUTRINO HYDRODYNAMICS CODE OF CORE-COLLAPSE SUPERNOVAE. III. GRAVITATIONAL WAVE SIGNALS FROM SUPERNOVA EXPLOSION MODELS (2012, methodology): “Contrary to what more energetic explosion models (Murphy et al. 2009; Yakunin et al. 2010) might suggest, strong GW emission in the high-frequency band late in the explosion phase appears to be possible for underenergetic supernovae.”
SASI ACTIVITY IN THREE-DIMENSIONAL NEUTRINO-HYDRODYNAMICS SIMULATIONS OF SUPERNOVA CORES (2013, background): “Moreover, large-amplitude SASI motions were found to stir strong g-mode activity in the neutron star surface, which leads to gravitational-wave emission (Marek et al. 2009; Murphy et al. 2009).”
Gravitational wave signals from 3D neutrino hydrodynamics simulations of core-collapse supernovae (2016, methodology): “This is in contrast to previous studies in 2D (Murphy et al. 2009; M¨uller et al. 2013) where shock expansion is typically followed by an increase in the high-frequency emission band.”
IS STRONG SASI ACTIVITY THE KEY TO SUCCESSFUL NEUTRINO-DRIVEN SUPERNOVA EXPLOSIONS? (2011, methodology): “As a consequence, we had to replace an exponential factore−τeff , which was introduced in an ad hoc way by Murphy et al. (2009) and Nordhaus et al. (2010) to damp the neutrino source terms at high optical depthsτeff , by e−τeff/2.7 in order to reproduce the minimum luminosity found to yield…”
Characterizing the Gravitational Wave Signal from Core-collapse Supernovae (2018, background): “…of 2D (axisymmetric) simulations (Finn & Evans 1990; Dimmelmeier et al. 2002, 2007; Shibata & Sekiguchi 2004; Kotake et al. 2009; Marek et al. 2009; Murphy et al. 2009; Cerdá-Durán et al. 2013; Mueller et al. 2013; Abdikamalov et al. 2014; Yakunin et al. 2015; Morozova et al. 2018; Pan et al.…”
GENERAL-RELATIVISTIC SIMULATIONS OF THREE-DIMENSIONAL CORE-COLLAPSE SUPERNOVAE (2012, background): “In this phase, the GW emission transitions to higher frequencies, indicating that emission from deceleration of downflows at the steep density gradient at the edge of the protoneutron star (as first pointed out by Murphy et al. 2009) and convection in the protoneutron star play an increasing role.”
The Gravitational Wave Signal from Core-collapse Supernovae (2018, methodology): “The dependence of the CCSN GW signal on the progenitor mass was previously studied in a number of works (Murphy et al. 2009; Müller et al. 2013; Yakunin et al. 2015).”
SELF-SUSTAINED ASYMMETRY OF LEPTON-NUMBER EMISSION: A NEW PHENOMENON DURING THE SUPERNOVA SHOCK-ACCRETION PHASE IN THREE DIMENSIONS (2014, background): “…2013) and spins (Blondin & Mezzacappa 2007; Rantsiou et al. 2011; Guilet & Fernández 2014), quasi-periodic neutrino-emission modulations (Marek et al. 2009; Lund et al. 2010; Tamborra et al. 2013), and SN gravitational-wave signals (Marek et al. 2009; Murphy et al. 2009; Müller et al. 2013).”