scispace - formally typeset
Search or ask a question
Journal ArticleDOI

A model for gravitational wave emission from neutrino-driven core-collapse supernovae

TL;DR: In this article, a suite of progenitor models, neutrino luminosities, and two-dimensional simulations were used to investigate the matter gravitational wave (GW) emission from postbounce phases of neutrinos-driven core-collapse supernovae.
Abstract: 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.

Content maybe subject to copyright    Report

Citations
More filters
Journal ArticleDOI
TL;DR: The neutrino-heating mechanism, aided by nonradial flows, drives explosions, albeit low-energy ones, of O-Ne-Mg-core and some Fe-core progenitors as mentioned in this paper.
Abstract: Supernova theory, numerical and analytic, has made remarkable progress in the past decade. This progress was made possible by more sophisticated simulation tools, especially for neutrino transport, improved microphysics, and deeper insights into the role of hydrodynamic instabilities. Violent, large-scale nonradial mass motions are generic in supernova cores. The neutrino-heating mechanism, aided by nonradial flows, drives explosions, albeit low-energy ones, of O-Ne-Mg-core and some Fe-core progenitors. The characteristics of the neutrino emission from newborn neutron stars were revised, new features of the gravitational-wave signals were discovered, our notion of supernova nucleosynthesis was shattered, and our understanding of pulsar kicks and explosion asymmetries was significantly improved. But simulations also suggest that neutrino-powered explosions might not explain the most energetic supernovae and hypernovae, which seem to demand magnetorotational driving. Now that modeling is being advanced from...

971 citations

Journal ArticleDOI
TL;DR: In this paper, the standing accretion shock instability (SASI) was shown to develop in 3D simulations with detailed neutrino transport despite the presence of convection, and it was shown that the SASI amplitudes, shock asymmetry, and nonradial kinetic energy in three dimensions can exceed those of the corresponding 2D case during extended periods of the evolution.
Abstract: The relevance of the standing accretion shock instability (SASI) compared to neutrino-driven convection in three-dimensional (3D) supernova-core environments is still highly controversial. Studying a 27 M ☉ progenitor, we demonstrate, for the first time, that violent SASI activity can develop in 3D simulations with detailed neutrino transport despite the presence of convection. This result was obtained with the PROMETHEUS-VERTEX code with the same sophisticated neutrino treatment so far used only in one-dimensional and two-dimensional (2D) models. While buoyant plumes initially determine the nonradial mass motions in the postshock layer, bipolar shock sloshing with growing amplitude sets in during a phase of shock retraction and turns into a violent spiral mode whose growth is only quenched when the infall of the Si/SiO interface leads to strong shock expansion in response to a dramatic decrease of the mass accretion rate. In the phase of large-amplitude SASI sloshing and spiral motions, the postshock layer exhibits nonradial deformation dominated by the lowest-order spherical harmonics (l = 1, m = 0, ±1) in distinct contrast to the higher multipole structures associated with neutrino-driven convection. We find that the SASI amplitudes, shock asymmetry, and nonradial kinetic energy in three dimensions can exceed those of the corresponding 2D case during extended periods of the evolution. We also perform parameterized 3D simulations of a 25 M ☉ progenitor, using a simplified, gray neutrino transport scheme, an axis-free Yin-Yang grid, and different amplitudes of random seed perturbations. They confirm the importance of the SASI for another progenitor, its independence of the choice of spherical grid, and its preferred growth for fast accretion flows connected to small shock radii and compact proto-neutron stars as previously found in 2D setups.

280 citations


Cites background from "A model for gravitational wave emis..."

  • ...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)....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors explore the viability of the neutrino-heating explosion mechanism's dependence on the spatial dimension and find that the average entropy of matter in the gain layer hardly depends on the dimension and thus is not a good diagnostic quantity for the readiness to explode.
Abstract: Following a simulation approach of recent publications, we explore the viability of the neutrino-heating explosion mechanism's dependence on the spatial dimension. Our results disagree with previous findings. While we also observe that two-dimensional (2D) models explode for lower driving neutrino luminosity than spherically symmetric (1D) models, we do not find that explosions in 3D occur easier and earlier than in 2D. Moreover, we find that the average entropy of matter in the gain layer hardly depends on the dimension and thus is not a good diagnostic quantity for the readiness to explode. Instead, mass, integrated entropy, total neutrino-heating rate, and non-radial kinetic energy in the gain layer are higher when models are closer to explosion. Coherent, large-scale mass motions as typically associated with the standing accretion-shock instability (SASI) are observed to be supportive for explosions because they drive strong shock expansion and thus enlarge the gain layer. While 2D models with better angular resolution clearly explode more easily, the opposite trend is seen in 3D. We interpret this as a consequence of the turbulent energy cascade, which transports energy from small to large spatial scales in 2D, thus fostering SASI activity. In contrast, the energy flow in 3D is in the opposite direction, feeding fragmentation and vortex motions on smaller scales and thus making the 3D evolution with finer grid resolution more similar to 1D. More favorable conditions for explosions in 3D may therefore be tightly linked to efficient growth of low-order SASI modes including nonaxisymmetric ones.

273 citations


Cites background or methods or result from "A model for gravitational wave emis..."

  • ...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…...

    [...]

  • ...(4) and (5) is included in Nordhaus et al. (2010), but not in Murphy & Burrows (2008) and Murphy et al. (2009)....

    [...]

  • ...…to ensure close similarity of our results to the 1D models studied by Nordhaus et al. (2010) and Murphy & Burrows (2008), we have to enhance the net cooling of the accreted matter by reducing the eff ctive opacityκeff by a factor of 2.7 compared to the value given in Murphy et al. (2009) and in Eq....

    [...]

  • ...(6) The effective opacityκeff was derived by Janka (2001) and given in Murphy et al. (2009): κeff ≈ 1.5 · 10−7 · Xn,p ( ρ 1010 g cm−3 ) ( Tνe 4 MeV )2 cm−1, (7) whereXn,p = 12 ( Yn + Yp ) accounts for composition averaging....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors proposed the liquid-scintillator detector LENA (Low Energy Neutrino Astronomy) as a multipurpose neutrino observatory.

258 citations

Journal ArticleDOI
TL;DR: In this article, the authors studied the 3D hydrodynamics of the post-core-bounce phase of the collapse of a 27 M_☉ star and paid special attention to the development of the standing accretion shock instability (SASI) and neutrino-driven convection.
Abstract: We study the three-dimensional (3D) hydrodynamics of the post-core-bounce phase of the collapse of a 27 M_☉ star and pay special attention to the development of the standing accretion shock instability (SASI) and neutrino-driven convection. To this end, we perform 3D general-relativistic simulations with a three-species neutrino leakage scheme. The leakage scheme captures the essential aspects of neutrino cooling, heating, and lepton number exchange as predicted by radiation-hydrodynamics simulations. The 27 M_☉ progenitor was studied in 2D by Muller et al., who observed strong growth of the SASI while neutrino-driven convection was suppressed. In our 3D simulations, neutrino-driven convection grows from numerical perturbations imposed by our Cartesian grid. It becomes the dominant instability and leads to large-scale non-oscillatory deformations of the shock front. These will result in strongly aspherical explosions without the need for large-scale SASI shock oscillations. Low-l-mode SASI oscillations are present in our models, but saturate at small amplitudes that decrease with increasing neutrino heating and vigor of convection. Our results, in agreement with simpler 3D Newtonian simulations, suggest that once neutrino-driven convection is started, it is likely to become the dominant instability in 3D. Whether it is the primary instability after bounce will ultimately depend on the physical seed perturbations present in the cores of massive stars. The gravitational wave signal, which we extract and analyze for the first time from 3D general-relativistic models, will serve as an observational probe of the postbounce dynamics and, in combination with neutrinos, may allow us to determine the primary hydrodynamic instability.

208 citations


Cites background or result from "A model for gravitational wave emis..."

  • ...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....

    [...]

  • ...A more detailed investigation of these features must be left to future work, since it would require multiple quadrupole integrals to isolate emission regions as done, e.g., by Murphy et al. (2009)....

    [...]

  • ...…provide important insight into the role and relevance of multi-dimensional fluid instabilities, rotation, the structure of the protoneutron star, and the nuclear EOS (Dimmelmeier et al. 2008; Marek et al. 2009; Yakunin et al. 2010; Murphy et al. 2009; Röver et al. 2009; Ott 2009; Kotake 2011)....

    [...]

  • ...Our typical |h| are also quantitatively consistent with the findings of the simpler 3D simulations of Scheidegger et al. (2010) and Kotake et al. (2009, 2011), but are a factor of a few smaller than predictions from 2D simulations (e.g., Marek et al. 2009; Yakunin et al. 2010; Murphy et al. 2009)....

    [...]

  • ...…prompt convection with frequencies around ∼100 − 200Hz, a subsequent almost quiescent phase, followed by higher-frequency (400 − 1000Hz) emission, whose amplitudes are dominated by the deceleration of undershooting convective plumes at the edge of the protoneutron star (cf. Murphy et al. 2009)....

    [...]

References
More filters
Journal ArticleDOI
TL;DR: In this article, the authors examined the current understanding of the lives and deaths of massive stars, with special attention to the relevant nuclear and stellar physics, and focused on their post-helium-burning evolution.
Abstract: amount of energy, a tiny fraction of which is sufficient to explode the star as a supernova. The authors examine our current understanding of the lives and deaths of massive stars, with special attention to the relevant nuclear and stellar physics. Emphasis is placed upon their post-helium-burning evolution. Current views regarding the supernova explosion mechanism are reviewed, and the hydrodynamics of supernova shock propagation and ‘‘fallback’’ is discussed. The calculated neutron star masses, supernova light curves, and spectra from these model stars are shown to be consistent with observations. During all phases, particular attention is paid to the nucleosynthesis of heavy elements. Such stars are capable of producing, with few exceptions, the isotopes between mass 16 and 88 as well as a large fraction of still heavier elements made by the r and p processes.

1,981 citations


"A model for gravitational wave emis..." refers background in this paper

  • ...Although core structure follows a general trend with the progenitor’s ZAMS mass, the correlation is known to be somewhat chaotic (Woosley et al. 2002)....

    [...]

Journal ArticleDOI
TL;DR: In this paper, the authors explore the evolution of very rapidly rotating massive stars, including stripped-down helium cores that might result from mergers or mass transfer in a binary, and single stars that rotate unusually rapidly on the main sequence.
Abstract: Those massive stars that give rise to gamma-ray bursts (GRBs) during their deaths must be endowed with an unusually large amount of angular momentum in their inner regions, 1-2 orders of magnitude greater than the ones that make common pulsars. Yet the inclusion of mass loss and angular momentum transport by magnetic torques during the precollapse evolution is known to sap the core of the necessary rotation. Here we explore the evolution of very rapidly rotating massive stars, including stripped-down helium cores that might result from mergers or mass transfer in a binary, and single stars that rotate unusually rapidly on the main sequence. For the highest possible rotation rates (about 400 km s-1), a novel sort of evolution is encountered in which single stars mix completely on the main sequence, never becoming red giants. Such stars, essentially massive "blue stragglers," produce helium-oxygen cores that rotate unusually rapidly. Such stars might comprise roughly 1% of all stars above 10 M☉ and can, under certain circumstances, retain enough angular momentum to make GRBs. Because this possibility is very sensitive to mass loss, GRBs are much more probable in regions of low metallicity.

942 citations


"A model for gravitational wave emis..." refers background in this paper

  • ...However, the rotation rates necessary for GWs with sizeable amplitudes are likely to obtain in only ∼1% of the massive star population (Heger et al. 2005; Hirschi et al. 2004; Woosley & Heger 2006; Ott et al. 2006b)....

    [...]

Journal ArticleDOI
TL;DR: Laser Interferometric Gravitational-Wave Observatory (LIGO) as discussed by the authors is a project to detect and study gravitational waves of astrophysical origin, which holds the promise of testing general relativity in the strong-field regime, providing a new probe of exotic objects such as black hole and neutron stars, and uncovering unanticipated new astrophysics.
Abstract: The goal of the Laser Interferometric Gravitational-Wave Observatory (LIGO) is to detect and study gravitational waves of astrophysical origin. Direct detection of gravitational waves holds the promise of testing general relativity in the strong-field regime, of providing a new probe of exotic objects such as black hole and neutron stars, and of uncovering unanticipated new astrophysics. LIGO, a joint Caltech-MIT project supported by the National Science Foundation, operates three multi-kilometer interferometers at two widely separated sites in the United States. These detectors are the result of decades of worldwide technology development, design, construction, and commissioning. They are now operating at their design sensitivity, and are sensitive to gravitational wave strains smaller than 1 part in 1E21. With this unprecedented sensitivity, the data are being analyzed to detect or place limits on gravitational waves from a variety of potential astrophysical sources.

844 citations

Journal ArticleDOI

843 citations


"A model for gravitational wave emis..." refers background in this paper

  • ...(5) Note that these approximations for heating and cooling by neutrinos (Bethe & Wilson 1985; Janka 2001) depend upon local quantities and predefined parameters....

    [...]

  • ...More than two decades ago, Wilson (1985) and Bethe & Wilson (1985) suggested that a fraction of the neutrinos being emitt d from depth (.100 km) would be recaptured in the gain region (&100 km), reviving the stalled shock into explosion....

    [...]

Journal ArticleDOI
21 May 2006
TL;DR: LIGO as discussed by the authors is a trio of extremely sensitive Michelson interferometers built to detect gravitational waves from space, and the results of their recent observations are described in detail.
Abstract: LIGO is a trio of extremely sensitive Michelson interferometers built to detect gravitational waves from space. We describe predicted sources of gravitational waves, our detectors, and the results of our recent observations.

839 citations