Long-term gravitational wave asteroseismology of supernovae: From core collapse to 20 seconds postbounce

Masamitsu Mori, Yudai Suwa, and Tomoya Takiwaki
Phys. Rev. D 107, 083015 – Published 7 April 2023

Abstract

We use an asteroseismology method to calculate the frequencies of gravitational waves (GWs) in a long-term core-collapse supernova simulation, with a mass of 9.6 solar mass. The simulation, which includes neutrino radiation transport in general relativity is performed from core-collapse, bounce, explosion and cooling of protoneutron stars (PNSs) up to 20 s after the bounce self-consistently. Based on the hydrodynamics background, we calculate eigenmodes of the PNS oscillation through a perturbation analysis on fluid and metric. We classify the modes by the number of nodes and find that there are several eigenmodes. In the early phase before 1 s, there are low-frequency g-modes around 0.5 kHz, midfrequency f-modes around 1 kHz, and high-frequency p-modes above them. Beyond 1 second, the g-modes drop too low in frequency and the p-modes become too high to be detected by ground-based interferometers. However, the f-mode persists at 1 kHz. We present a novel fitting formula for the ramp-up mode, comprising a mixture of g-mode and f-mode, using postbounce time as a fitting parameter. Our approach yields improved results for the long-term simulation compared to prior quadratic formulas. We also fit frequencies using combinations of gravitational mass, M, and radius, R, of the PNS. We test three types of fitting variables: compactness M/R, surface gravity M/R2, and average density M/R3. We present results of the time evolution of each mode and the fitting for three different ranges, from 0.2 s to 1 s, 4 s, and 20 s for each formula. We then compare the deviation of the formulas from the eigenmodes to determine which fitting formula is the best. In conclusion, any combination of M and R fits the eigenmodes well to a similar degree. Comparing three variables in detail, the fitting with compactness is slightly the best among them. We also find that the fitting using less than 1 s of simulation data cannot be extrapolated to the long-term frequency prediction.

  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
  • Figure
1 More
  • Received 2 February 2023
  • Accepted 28 February 2023

DOI:https://doi.org/10.1103/PhysRevD.107.083015

© 2023 American Physical Society

Physics Subject Headings (PhySH)

Gravitation, Cosmology & Astrophysics

Authors & Affiliations

Masamitsu Mori* and Yudai Suwa

  • Department of Earth Science and Astronomy, The University of Tokyo, Tokyo 153-8902, Japan

Tomoya Takiwaki

  • National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo, 181-8588, Japan

  • *masamitsumori@g.ecc.u-tokyo.ac.jp
  • Also at Center for Gravitational Physics and Quantum Information, Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan.

Article Text (Subscription Required)

Click to Expand

References (Subscription Required)

Click to Expand
Issue

Vol. 107, Iss. 8 — 15 April 2023

Reuse & Permissions
Access Options
Author publication services for translation and copyediting assistance advertisement

Authorization Required


×
×

Images

×

Sign up to receive regular email alerts from Physical Review D

Log In

Cancel
×

Search


Article Lookup

Paste a citation or DOI

Enter a citation
×