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Gravitational waves and neutrino emission from the merger of binary
neutron stars
Kenta KiuchiCollaboration with Y. Sekiguchi, K. Kyutoku, M. Shibata
Ref.) 1105.5035
IntroductionOur research target = high energy astrophysical phenomenae.g., Supernova energy ≈ 1.5*1046J = energy the Sun consumes for 1.2 trillion years !!
SN1054 ( Crab Nebula)
r~ 1000km~ 10km
~ Solar mass
Energy source = gravitational potential energy ∝ r-1
Products of high energy astrophysical phenomena~ 10km ~ 3km( 1 Solar
mass)
✓Density~ 1015g/cm3 (1.41 g/cm3) ⇒ General Relativity, Strong interaction
✓Temperature~ 1011K (15.7×106K)⇒ Weak interaction✓Magnetic fields~ 1015 Gauss (Sunspot: several
thousand Gauss)⇒Electromagnetic force
All of fundamental interaction play an essential role.
Physical aspects of high energy astrophysical phenomena✓Highly dynamical✓No special symmetry, e.g., spherical symmetry⇒Numerical modeling including four kinds of forces
Numerical RelativityFiguring out high energy astrophysical phenomena by numerically solving the Einstein equations
Importance of Numerical Relativity○ Gravitational waves✓imprinting “raw” information of sources✓extremely weak signal, hc 10∼ -22 = the change of (Size of H atoms)/(Distance to Sun)
GW detectorsNeed to prepare theoretical templates of GWs
Today’s topic = Coalescence of binary neutron stars✓Promising source of GWs✓Theoretical candidate of Short-Gamma-Ray Burst✓High-end laboratory for Nuclear theoryA nuclear theory Mass-Radius relation for Neutron Star⇒
Image of GRB Black hole + disk?
Mass-Radius
Overview of binary neutron star merger
NS
G.Ws. imprint only information of mass
G.Ws. imprint information of radius
Rapidly rotating massive NS
BH and torus
Mtotal < Mcrit
Mtotal > Mcrit
✓Mcrit depends on the Equation of State, i.e. Mcrit = 1.2-1.7 Mmax
✓Final massive NS or torus around BH are extremely hot, T O(10) MeV ∼ ⇒Neutrino cooling plays an importance role
Set up of binary neutron star○ Shen or Shen-Hyperon EOS based on RMF theory (Shen+,98, Sumiyoshi+,11) ⇒ Mcrit = 2.8-2.9 Solar mass for Shen, 2.3-2.4 Solar mass for Shen-Hyperon EOS○ Neutrino cooling based on GR leakage scheme (Sekiguchi,10)○ Equal mass model with 1.35 Solar mass, i.e., Mtot=2.7 Solar mass
Observed BNSs (Lattimer & Paraksh 06)Mass-Radius
Observation constraint by PSR J1614-2230
ResultDensity color contour on equatorial (x-y) plane = orbital plane
In units of Kilometer
In units of millisecond
Log10(ρ [g/cc])
Gravitational Waveforms
Shen
Shen-Hyperon
NSs orbit around each other
BH formation
Massive NS oscillates
Gravitational Wave Spectrum
frequency
Ampl
itudeSensitivity curves for GW detectors
ShenShen-Hyperon
GWs could be detected if the merger happens within 30 Mpc.
○ ○ Neutrino cooling timescale ∼ 2-3 second○ Huge luminosity ∼1053 erg/s○ Could be detected if it happened within 10 Mpc for HK
Neutrino Luminosity
Shen
Shen+Hyperon
Anti electron neutrinoElectron neutrino
μ, τ neutrino
BH formation
Summary
○ Binary neutron star merger Numerical Relativity simulations with microphysical process for the first time ○ GWs could be detected if it happened within 30 Mpc○ Neutrino could be detected if it happened within 10 Mpc
⇒ Multi messenger astronomy is coming soon !!
Thanks to SR16000 in YITP
Thank you for your attention