TAUP2019 in Toyama Impact of GW170817 on the NS-matter equation of state Yuichiro Sekiguchi (Toho Univ.) https://www.youtube.com/watch?v=vTeAFAGpfso&feature=share
Major scientific achievements: GW170817 provided us clues to } NS matter equation of state (EOS) } Tidal deformability extraction } Maximum mass constraint } Short gamma-ray bursts (SGRB) central engine } Origin of heavy elements } r-process nucleosynthesis } kilonova/macronova from decay energy of the synthesized elements } GW as standard siren } Hubble constant
Major scientific achievements: GW170817 provided us clues to Abbott et al. (2017) } NS matter equation of Burst of gamma-rays state (EOS) detected 1.74 sec after GW } Tidal deformability extraction } Maximum mass constraint } Short gamma-ray bursts (SGRB) central engine } Origin of heavy elements } r-process nucleosynthesis } kilonova/macronova from decay energy of the synthesized elements } GW as standard siren } Hubble constant
Major scientific achievements: GW170817 provided us clues to } NS matter equation of state (EOS) } Tidal deformability extraction } Maximum mass constraint } Short gamma-ray bursts (SGRB) central engine } Origin of heavy elements } r-process nucleosynthesis } kilonova/macronova : UV- Infrared from decay energy of the synthesized elements } GW as standard siren } Hubble constant
Major scientific achievements: GW170817 provided us clues to } NS matter equation of state (EOS) } Tidal deformability extraction } Maximum mass constraint } Short gamma-ray bursts (SGRB) central engine } Origin of heavy elements } r-process nucleosynthesis } kilonova/macronova from LIGO&Virgo+ (2017) decay energy of the synthesized elements } GW as standard siren } Hubble constant
Major scientific achievements: GW170817 provided us clues to } NS matter EOS } Tidal deformability extraction } Maximum mass constraint } Short gamma-ray bursts (SGRB) central engine } Origin of heavy elements } r-process nucleosynthesis } kilonova/macronova from decay energy of the synthesized elements } GW as standard siren } Hubble constant
Sekiguchi et al, 2011; Hotokezaka et al. 2013 Gravitational waves from NS merger Numerical relativity simulation modelling GW170817 Oscillation of Tidal Inspiral massive NS or deformation r 3 log [ g/cm ] Chirp signal 10 BH formation Density profile at orbital plane Gravitational Waveform Ø finite size effect Ø BH or NS ⇒ maximum mass Ø point particle approx. Ø NS tidal deformability Ø GWs from massive NS Ø information of binary parameter ( NS mass , etc) Ø ⇒ NS radius ⇒ NS radius of massive NS
Sekiguchi et al, 2011; Hotokezaka et al. 2013 Gravitational waves from NS merger Numerical relativity simulation modelling GW170817 Oscillation of Tidal Inspiral massive NS or deformation r 3 log [ g/cm ] Chirp signal 10 BH formation Density profile at orbital plane Gravitational Waveform Ø finite size effect Ø BH or NS ⇒ maximum mass Ø point particle approx. Ø NS tidal deformability Ø GWs from massive NS Ø information of binary parameter ( NS mass , etc) Ø ⇒ NS radius ⇒ NS radius of massive NS
Mass determination by the chirp signal } S/N = 33.0 (signal to noise ratio) Assumption/setup of data analysis � } } NS is not rotating rapidly like BH Using the EM counterpart SSS17a/AT2017gfo for the } source localization Using distance indicated by the red-shift of the host } galaxy NGC 4993 } Chirp mass : ! " ! # $/& '..../ 0 ⊙ ! " '! # "/& = 1.186 -..../ } Total mass : 2.740 ⨀ (1%) } Mass ratio : 6 / /6 7 = 0.7 − 1.0 '=.:> ? ⊙ } Primary mass (m1) : :. ;< -=.:= '=.=A ? ⊙ } Secondary (m2) : :. >@ -=.=A '/. Mpc } Luminosity distance to the source : 40 -/. LIGO-Virgo Collaboration GWTC-1 paper See also Abbott et al. PRL 119, 161101 (2017); arXiv:1805.11579
Tidal deformability } Tidal Love number : ! } Response of quadrupole moment " #$ to external tidal field % #$ = - l Q E ij ij Stiffer NS EOS } ( − * ⇒ NS Gravity can be supported with } less contraction ⇒ larger NS radius } ⇒ larger ! } ⇒ larger deviation from point particle } GW waveform } } Tidal deformability (non-dim.) � Λ C L GM 5 = l = 5 C R � 2 c R G ( − + Compactness parameter Lackey et al. PRD 91, 043002(2015)
Soft EOS � Smaller NS radius � Effect of tidal deformation is not prominent orbit Point particle Effect of tidal deformation on GWs Tidal deformation GW waveform Point particle Tidal deformation Stiff EOS � larger NS radius � Deviation from point particle approximation can be clearly seen
The first PRL paper : upper limit on ! Λ ! # 4.6 ≲ %&& # < %&& } The analysis uses GW data only, the other constraints such as } causality ( ' ( < ' ), ) *+,,./0 ≳ 2) ⨀ , nuclear experiments } the two NS should obey the same EOS } use of mass distribution of the observed binary pulsar as prior } are NOT taken into account 6 # 4 + ; = + 4=; 4 ; = 6 # = # = 49 ; 4 + 4=; = ; 4 ! (; 4 + ; = ) @ 4:
A summary of NS structure constraint } Extraction of ! from GW data (data analysis) } Abbott et al. (2017) : " # < %&& } De et al. (2018) : GW data with constraints from nuclear experiments 0123 , 4 5./ = 11.5 ,-.- 0-.. ± 0.2 km (3 mass priors considered ) } " Λ = 310 ,-./ } Interpretation of the extracted Λ } Annala et al. (2018) : chiral EFT (up to 1.1ns) + perturbative QCD } 120 ≲ Λ 5./ ≲ 800 , 10 ≲ 4 5./ ≲ 13.6 km } Tews et al. (2018) : chiral EFT (up to 2ns !!) + perturbative QCD } 80 ≲ Λ 5./ ≲ 570 (upper limit from EOS model, not from GW data) } Fattoyev et al. (2018) : GW data with PREX data and small EOS familiy -DE ≳ 0.15 fm) } 400 ≲ Λ ≲ 800 , 12 ≲ 4 5./ ≲ 13.6 km (lower limit from 4 @ABC } See also, Most et al. (2018) and more
Annala et al. (2018) PRL 120, 172703 An interpretation of Λ ".$ < 800 } Interpretation with an EOS model } ( < 1.1( * : Chiral EFT Hebeler et al. (2013) ApJ 773, 11 } + , > 2.6 GeV : NNLO pQCD by Kurkela et al. (2014) PRD 81 } intermediate: A parametrized (piecewise polytrope) EOS with causality constraint } 10 ≲ 1 ".$ ≲ 13.6 km and Λ ".$ ≳ 120 for 4 567 > 24 ⨀ allowed allowed
Abbott et al. PRL 121, 161101 (2018) Update analysis with NR waveform } waveform calibrated by numerical relativity simulations } wider data range 30-2048 Hz ⇒ 23-2048 Hz ( ≈ 1500 cycle added) } source localization from EM counterpart SSS17a/AT2017gfo } the causality and maximum NS mass constraints are also considered # # +,'' $ < &'' $ ≈ ('' )*''
A summary of NS structure constraint Abbott+ Abbott+ (2017) (2018b) excluded Analla+ (2018) Fattoyev+ (2018) De+ (2018)
EOS comparison : GW vs. Heavy Ion Col. Maximum density for GW170817 Tsang et al., arXiv:1811.04888 Neutron star matter Heavy Ion Collision Danielewicz et al. Science (2002)
How to explore the higher densities ?
Massive NS is necessary to explore high density region Gandolfi et al. (2012) PRC 85 032801(R) } core bounce in supernovae mass � 0.5~0.7Msun } ρ c � a few ρ s } } canonical neutron stars mass � 1.35-1.4Msun } ρ c � several ρ s } } massive NS ( > 1.6 Msun) ρ c � > 4ρ s } } massive NSs are necessary to explore higher densities We can use GW from NS-NS } merger remnant: NS with M > 2 Msun }
GW from post-merger phases
Abbott et al. ApJL 851, L16 (2017); arXiv:1805.11579; see also arXiv:1810.02581 No GW from merger remnant detected Need more sensitivity : 2-3 times more sensitive in kHz band than adv. LIGO design sensitivity for an event @ 40Mpc Torres-Rivas et al. (2019) PRD 98 084061
Constraints from EM signals
Meridian plane Orbital plane
Tidal Inspiral deformation Merger r 3 log [ g/cm ] 10 Charp signal H yper M assive NS Density Contour in orbital plane Gravitational Waveform Animation by Hotokezaka Sekiguchi et al. PRL (2011a, 2011b) Kiuchi et al. PRL (2010); Hotokezaka et al. (2013)
Kilonova from NS-NS merger } Ejecta from NS-NS merger is very neutron rich } Rapid (faster than β decay) neutron capture proceeds (r-process) in the ejecta, synthesizing neutron rich nuclei (r-process nucleosynthesis)
Kilonova from NS-NS merger } Ejecta from NS-NS merger is very neutron rich } Rapid (faster than β decay) neutron capture proceeds (r-process) in the ejecta, synthesizing neutron rich nuclei (r-process nucleosynthesis) } Kilonova : Radioactive decay of r-process nuclei will power the ejecta (by gamma-rays and electrons) to shine in UV to IR band (due to the opacity of r-process elements like lanthanides) �
Constraint on ! ,-. from merger modelling and observations of EM counterpart } Condition 1 : BH should not be directly formed : ! "#$% ≳ 2.74! ⨀ } To small mass ejection and observed kilonova cannot be explained } Condition 2 : merger remnant should not be too long-lived : ! ,-.,012 + ∆! #5%,#$6 ≲ 2.74! ⨀ } If long-lived, activities associated with this monster magnetar (merger remnant is strongly magnetized) should have been observed Bartos et al. (2013); Shibata et al. (2005, 2006)
Summary of constraint on NS structure using both GW and EM Shibata+ (2017); Malgarit+ (2017); Rezzolla+ (2018) No long-lived NS, excluded Bauswein+ (2017) No prompt BH Abbott+ Abbott+ (2017) excluded (2018b) excluded Analla+ (2018) Fattoyev+ (2018) De+ (2018)
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