arXiv subjects

R. Daniel Murphy

Publications and source records attributed to R. Daniel Murphy.

5 recordsLinked to original sources

arXiv2026

Universal relations applied to proto-neutron star generated gravitational waves from three-dimensional core collapse supernova simulations

Using asteroseismology techniques, several relations have been developed that relate the quasi-normal, non-radial oscillation mode frequencies of the proto-neutron star (PNS) to the high frequency component of core collapse supernova (CCSN) generated gravitational waves predicted from simulation. These relations are universal in the sense that they are parameterized entirely by PNS properties, e.g., mean density or surface gravity, and are independent of both progenitor properties, e.g., zero age man sequence (ZAMS) mass or metallicity, and the physics included in CCSN simulations, e.g., nuclear equation of state (EOS). In this work, we apply several externally developed universal relations to PNS evolution data--specifically the mass, M, and radius, R,--generated from both two- and three-dimensional CCSN simulations and compare the resulting PNS oscillation frequencies predicted by the universal relations to the peak gravitational wave frequencies computed directly from the simulation-produced spectrogram. Additionally, we use the gravitational wave spectrogram peak frequencies as input to the universal relations and compare the predicted PNS properties from each relation to the true PNS properties as determined by the simulations. In this way, we show what these universal relations would predict for the PNS properties and their evolution from a real CCSN gravitational wave detection in the best case scenario, i.e., no detector noise. Our results indicate that caution must be exercised when using these universal relations, particularly when interpreting their predictions for PNS evolution from a gravitational wave detection, and that, given the extent to which we do see agreement between asteroseismological predictions and simulation outcomes, further development of universal relations would be beneficial.

gr-qc↗

arXiv2026

GenASiS: General Astrophysical Simulation System. II. Self-gravitating Baryonic Matter

GenASiS (General Astrophysical Simulation System) is a code being developed initially and primarily, though not exclusively, for the simulation of core-collapse supernovae on the world's leading capability supercomputers. This paper -- the second in a series -- documents capabilities for Newtonian self-gravitating fluid dynamics, including tabulated microphysical equations of state treating nuclei and nuclear matter (`baryonic matter'). Computation of the gravitational potential of a spheroid, and simulation of the gravitational collapse of dust and of an ideal fluid, provide tests of self-gravitation against known solutions. In multidimensional computations of the adiabatic collapse, bounce, and explosion of spherically symmetric pre-supernova progenitors -- which we propose become a standard benchmark for code comparisons -- we find that the explosions are prompt and remain spherically symmetric (as expected), with an average shock expansion speed and total kinetic energy that are inversely correlated with the progenitor mass at the onset of collapse and the compactness parameter.

astro-ph.HE↗

arXiv2025

Gravitational Waves as a Probe of Core Collapse Supernova Progenitor Structure

We present the gravitational wave predictions from two-dimensional core collapse supernova (CCSN) simulations initiated from two nearly identical progenitors that have significantly different internal structures due to their late-stage stellar evolution. At the time of collapse, the 15.78 $M_{\odot}$ and 15.79 $M_{\odot}$ progenitors have compactness parameters $\xi_{2.5}$ of 0.136 and 0.206, respectively. We connect several features of the gravitational wave signal from each model to its previously explored explosion dynamics. In particular, the greater accretion onto the PNS of the more compact model is evident in broad-band frequency features with larger amplitude gravitational wave strains and greater gravitational wave energy release when compared to the less compact model. Additionally, the faster contraction rate of the more compact model is reflected in the $\sim$26% greater slope of the $g$-/$f$-mode feature (gfF) evolution of the gravitational wave signal. This work shows that in principle gravitational wave detection may provide information about interior stellar structure.

astro-ph.HE↗

arXiv2025

Core Collapse Supernova Gravitational Wave Sourcing and Characterization based on Three-Dimensional Models

We present for the first time an analysis of high-frequency gravitational wave (GW) emission from proto-neutron stars (PNS) in core collapse supernovae (CCSN) that combines spatial decomposition and modal decomposition to both source and characterize the emission using three-dimensional CCSN simulations. We analyze simulations initiated from 15 and 25 solar mass progenitors with Solar- and zero-metallicity respectively. We decompose the GW strains into five spatial regions and find that strains are initially largest in the PNS surface layers from accretion and later largest from the Ledoux convective and convective overshoot regions of the PNS. We compute the fractional GW luminosity as a function of enclosed radius and observe that most of the luminosity moves from the PNS surface to deep within the PNS at later times. Using a self-consistent perturbative analysis, we investigate the evolution of the oscillation modes of the PNS. We find that the frequency of the evolving high-frequency component of the GW signal is well matched to the eigenfrequency evolution of the ${}^2g_2$-, ${}^2g_1$-, and ${}^2f$-modes over time. We show that the ${}^2g$-modes emit most of their power in GW initially from the PNS surface region, but within a few 100 ms after bounce, it is the convective overshoot region of the PNS that emits the most GW power for the ${}^2g_1$-mode. Eventually, the ${}^2f$-mode is the dominant mode producing GWs, and they are emitted primarily from the convective overshoot region. Thus, we show that, while the GW emission is global, it is possible to source the dominant contributions to it. We find that the source of the high-frequency GW emission from the PNS in CCSN is more complex than assessed by other methods, as well as time dependent, first emitted by ${}^2g$-modes driven by accretion onto the PNS and later emitted by the ${}^2f$-mode driven by sustained Ledoux convection.

astro-ph.HE↗

arXiv2024

Dependence of the Reconstructed Core-Collapse Supernova Gravitational Wave High-Frequency Feature on the Nuclear Equation of State, in Real Interferometric Data

We present an analysis of gravitational wave (GW) predictions from five two-dimensional Core Collapse Supernova (CCSN) simulations that varied only in the Equation of State (EOS) implemented. The GW signals from these simulations are used to produce spectrograms in the absence of noise, and the emergent high-frequency feature (HFF) is found to differ quantitatively between simulations. Below 1 kHz, the HFF is well approximated by a first-order polynomial in time. The resulting slope was found to vary between 10-50% across all models. Further, using real interferometric noise we investigated the current capabilities of GW detectors to resolve these differences in HFF slope for a Galactic CCSN. We find that for distances up to 1 kpc, current detectors can resolve HFF slopes that vary by at least 30%. For further Galactic distances, current detectors are capable of distinguishing the upper and lower bounds of the HFF slope for groupings of our models that varied in EOS. With the higher sensitivity of future GW detectors, and with improved analysis of the HFF, our ability to resolve properties of the HFF will improve for all Galactic distances. This study shows the potential of using the HFF of CCSN produced GWs to provide insight into the physical processes occurring deep within CCSN during collapse, and in particular its potential to further constrain the EOS through GW detection.

astro-ph.HE↗