Probing mass-radius relation of protoneutron stars from gravitational-wave asteroseismology

Sotani, Hajime; Kuroda, T.; Takiwaki, Tomoya; Kotake, Kei

doi:10.1103/physrevd.96.063005

Cited by 67 publications

(51 citation statements)

References 64 publications

(118 reference statements)

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“…The circles and diamonds correspond to the results with SFHx and TM1. The normalized frequencies of the w 1 mode gravitational waves are shown as a function of the compactness in the left panel, where the dotted line is the fitting formula given by Equation (1) (Taken from Sotani et al )…”

Section: Asteroseismology In Protoneutron Starsmentioning

confidence: 99%

“…The time evolution of the frequencies of the f and p 1 mode gravitational waves in the left panel. In the right panel, the frequencies of the f mode gravitational wave are shown as a function of the stellar average density, where the solid line is the fitting formula given by Equation (2) (Taken from Sotani et al )…”

Section: Asteroseismology In Protoneutron Starsmentioning

confidence: 99%

“…With

E_{normalT}^{((), w_{1})}

, one can estimate

E_{w_{1}}

via

E_{normalT}^{((), w_{1})} \approx E_{w_{1}} T_{w_{1}} / τ_{w_{1}}

, where

T_{w_{1}}

and

τ_{w_{1}}

denote the duration time and the damping time of the w 1 mode gravitational wave, respectively. In this study, we simply assume that

T_{w_{1}} = 250

ms and

τ_{w_{1}} = 0.1

ms, which is the typical value of

τ_{w_{1}}

for the protoneutron star (Sotani et al ). The resultant effective amplitudes with

E_{normalT}^{((), w_{1})} = 10^{- 4}, 10^{- 5}, 10^{- 6}, 10^{- 7}, and 10^{- 8} M_{⊙}

, and are shown in Figure , together with the sensitivity curve of the current and future gravitational wave detectors, that is, aLIGO, KAGRA, Einstein Telescope (ET), and Cosmic Explorer (CE).…”

Section: Asteroseismology In Protoneutron Starsmentioning

confidence: 99%

“…Then, we focus on the spacetime oscillation, the so‐called w mode, and the fundamental oscillations, the so‐called f mode, and systematically examine those frequencies of gravitational waves. More details of this study can be seen in Sotani et al ().…”

Section: Introductionmentioning

confidence: 99%

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Gravitational waves from protoneutron stars and nuclear equation of state

Sotani

2019

Astron Nachr

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We examine the frequencies of the gravitational waves radiating from the protoneutron star produced via the core-collapse supernova. In a way similar to the cold neutron star, we find that the frequencies of the w 1 and f mode gravitational waves can be, respectively, expressed well as a function of the stellar compactness and the stellar average density at each time step after core bounce. Thus, via the simultaneous detection of both the f and w 1 mode gravitational waves, one can determine the protoneutron star mass and radius at each time step. Unlike the cold neutron star, the protoneutron star mass and radius are changing with time because of the mass accretion and cooling, which enables us to identify the equation of state for the high-density region in principle via only one event of supernova. KEYWORDS equation of state -gravitational waves -stars: neutron INTRODUCTIONOwing to the success of the direct detection of gravitational waves from the compact object binary merger, now, the gravitational waves have become a tool to observe the universe. Due to very high permeability of gravitational waves, one expects to newly observe the object that cannot be observed with electromagnetic waves. It is also proposed that the neutron star properties can be extracted via the observation of the gravitational waves. In particular, the asteroseismology of the compact object is one of possibilities of the application of the gravitational wave detection. In fact, it would be possible to see the stellar mass, radius, and equation of state (Andersson & Kokkotas 1996). Compared to the asteroseismology of cold neutron stars, similar attempts in protoneutron stars produced via core-collapse supernova are very few. This is because of the difficulty in constructing the background model of a protoneutron star. That is, the cold neutron star models can be constructed by integrating the Tolman-Oppenheimer-Volkoff equation with a specific equation of state, while one needs to prepare the distribution of the electron fraction and entropy per baryon for the construction of the protoneutron star models. However, these distributions of electron fraction and entropy per baryon can be determined after the numerical simulation. So, in this study, we adopt the results of the relativistic numerical simulation in three dimensions and produce the protoneutron star models at each time step by averaging the three-dimensional results. Then, we focus on the spacetime oscillation, the so-called w mode, and the fundamental oscillations, the so-called f mode, and systematically examine those frequencies of gravitational waves. More details of this study can be seen in Sotani et al. (2017). PROTONEUTRON STAR MODELSTo prepare the protoneutron star models, we adopt the numerical results in Kuroda et al. (2016), which is carried out with 15M ⊙ progenitor model and with two different equations of state, that is, SFHx and TM1. SFHx and TM1 are, respectively, the soft and stiff equation of state. In addition, we focus on the early phase after core-bounce u...

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Section: Asteroseismology In Protoneutron Starsmentioning

confidence: 99%

Section: Asteroseismology In Protoneutron Starsmentioning

confidence: 99%

“…With

E_{normalT}^{((), w_{1})}

, one can estimate

E_{w_{1}}

via

E_{normalT}^{((), w_{1})} \approx E_{w_{1}} T_{w_{1}} / τ_{w_{1}}

, where

T_{w_{1}}

and

τ_{w_{1}}

denote the duration time and the damping time of the w 1 mode gravitational wave, respectively. In this study, we simply assume that

T_{w_{1}} = 250

ms and

τ_{w_{1}} = 0.1

ms, which is the typical value of

τ_{w_{1}}

for the protoneutron star (Sotani et al ). The resultant effective amplitudes with

E_{normalT}^{((), w_{1})} = 10^{- 4}, 10^{- 5}, 10^{- 6}, 10^{- 7}, and 10^{- 8} M_{⊙}

, and are shown in Figure , together with the sensitivity curve of the current and future gravitational wave detectors, that is, aLIGO, KAGRA, Einstein Telescope (ET), and Cosmic Explorer (CE).…”

Section: Asteroseismology In Protoneutron Starsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravitational waves from protoneutron stars and nuclear equation of state

Sotani

2019

Astron Nachr

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“…The possibilities for obtaining the interior information of source objects with the asteroseismology have been already pointed out for cold neutron stars (e.g., [1][2][3][4]). On the other hand, the analyses on the protoneutron stars are very few [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Protoneutron Star Properties via Gravitational Wave Asteroseismology

Sotani

2018

Proceedings of the Workshop on Quarks and Compact Stars 2017 (QCS2017)

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We examine the f -and p 1 -modes of gravitational waves from the protoneutron stars formed just after the core bounce of core-collapse supernovae. As a result, we find that the frequencies of fand p 1 -modes are almost independent of the choice of the radial distribution of the electron fraction and entropy per baryon. We also find that the frequencies of the f -and p 1 -modes can be expressed well the average density of protoneutron stars. In particular, we are successful to derive the universal relation between the frequencies and the square root of the average density independently of the equation of state. Since the dependence on the stellar properties is different from that for the known gmode frequencies, one can determine the mass and radius of protoneutron star via careful observation of the gravitational wave variation.

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Effect of stellar rotation on the development of post-shock instabilities during core-collapse supernovae

Buellet¹,

Foglizzo²,

Guilet³

et al. 2023

A&A

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Context. The growth of hydrodynamical instabilities is key to triggering a core-collapse supernova explosion during the phase of stalled accretion shock, immediately after the birth of a proto-neutron star (PNS). Stellar rotation is known to affect the standing accretion shock instability (SASI) even for small rotation rates, but its effect on the onset of neutrino-driven convection is still poorly known. Aims. We assess the effect of stellar rotation on SASI when neutrino heating is taken into account as well as the effect of rotation on neutrino-driven convection. The interplay of rotation with these two instabilities affects the frequency of the mode m = 2, which can be detected with gravitational waves at the onset of a supernova explosion. Methods. We used a linear stability analysis to study the dynamics of the accreting gas in the equatorial plane between the surface of the PNS and the stationary shock. We explored rotation effects on the relative strength of SASI and convection by considering a large range of specific angular momenta and neutrino luminosities. Results. The nature of the dominant non-axisymmetric instability developing in the equatorial post-shock region depends on both the convection parameter, χ, and the rotation rate. Equatorial convective modes with χ ≳ 5 are hampered by differential rotation. At smaller χ, however, mixed SASI-convective modes with a large angular scale, m = 1, 2, 3, can take advantage of rotation and become dominant for relatively low rotation rates, at which centrifugal effects are small. For rotation rates exceeding ∼30% of the Keplerian rotation at the PNS surface, a new instability regime is characterised by a frequency that, when measured in units of the post-shock velocity and radius, vsh/rsh, is nearly independent of the convection parameter, χ. A strong prograde m = 2 spiral dominates over a large parameter range and is favorable to the production of gravitational waves. In this regime, a simple linear relation exists between the oscillation frequency of the dominant mode and the specific angular momentum of the accreted gas. Conclusions. Three different regimes of post-shock instabilities can be distinguished depending on the rotation rate. For low rotation rates (less than 10% of the Keplerian rotation at the PNS surface), differential rotation has a linear destabilising effect on SASI and a quadratic stabilising or destabilising effect on the purely convective equatorial modes depending on their azimuthal wavenumber. Intermediate rotation rates (10% to 30% of the Keplerian rotation) lead to the emergence of mixed SASI-convection-rotation modes that involve large angular scales. Finally, strong rotation erases the influence of the buoyancy and heating rate on the instability. This independence allows for a reduction in the parameter space, which can be helpful for gravitational wave analysis.

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Probing mass-radius relation of protoneutron stars from gravitational-wave asteroseismology

Cited by 67 publications

References 64 publications

Gravitational waves from protoneutron stars and nuclear equation of state

Gravitational waves from protoneutron stars and nuclear equation of state

Protoneutron Star Properties via Gravitational Wave Asteroseismology

Effect of stellar rotation on the development of post-shock instabilities during core-collapse supernovae

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