Mul6-messenger signature of compact binary coalescence Masaomi - PowerPoint PPT Presentation

Mul6-messenger signature of compact binary coalescence Masaomi Tanaka (Tohoku University)

Mul6-messenger signature of compact binary coalescence • Electromagne-c signals from neutron star merger • Mul--messenger observa-ons of GW170817 • Open issues and future prospects

Mul6-messenger from neutron star merger jet => gamma-ray merge neutron star (NS) NS or Black hole (BH) Gravita6onal wave (GW) Mass ejec-on => nucleosynthesis => op-cal/infrared Electromagne6c (EM) wave

Short-dura6on gamma-ray burst (GRBs) Visible Opening angle ~ 10 deg Not visible => probability ~ a few % 20 18 Long 16 Short 14 12 Number 10 8 6 4 2 0 0 5 10 15 20 25 30 35 Opening Angle θ j (degrees) (C) ESO Fong+14

Mass ejec6on from neutron star merger Top view Side view Sekiguchi+15, 16 M ~ 10 -3 - 10 -2 Msun v ~ 0.1 - 0.2 c

Neutron capture process to synthesize elements beyond Fe proton neutron + radioac6ve Ni56 decay - proton 28 - neutron 28

Rapid neutron capture process (r-process) in NS merger Fe (C) Nobuya Nishimura

Origin of heavy (r-process) elements Supernova NS merger NASA M. Weiss Well known event rate Robust r-process Unknown event rate 
 Difficult to have r-process? and ejec6on per event

Timescales of NS mergers Radioac6ve r-process Chemical Merger decay nucleosynthesis enrichment => kilonova Mass Jet forma6on? ejec6on < 1 sec ~> days > Myr ~< 100 ms MT & Hotoke 13 hXp://www.aei.mpg.de/comp-rel-astro

Radioac6ve decay of r-process nuclei β decay + α decay + fission β decay 1 day 10 day ~ t -1.3 Wanajo 18

Radioac6ve decays => “Kilonova” Li & Paczynski 98, Kulkarni 05, Metgzer+10 Β decay (γ, β), α decay, fission =>Heats up ejected material ρ ~ 10 -14 - 10 -13 g cm -3 Time Τ ~ 5,000-10,000 K Bound-bound transi6on of � 1 / 2 � 3 κ M ej When t peak = heavy elements (I, II, III, IV) 4 π cv photons can � 1 / 2 � v � 1 / 2 escape? � � � 1 / 2 � M ej κ 8 . 4 days � 10 cm 2 g � 1 0 . 01 M � 0 . 1 c

Light curves of kilonova Kasen+13, Barnes & Kasen 13, MT & Hotokezaka 13 -16 Infrared g r Op-cal i -15 z J Infrared H -14 L ~ 10 40 -10 41 erg s -1 K Absolute magnitude t ~ weeks -13 NIR > Op6cal -12 -11 Op6cal -10 -9 0 5 10 15 Days after the merger Model: MT+17a

λ = hc 5 ∆ E open s shell 4 open p-shell 3 E (eV) 2 open d-shell 1 5 Fe II 0 4 3 E (eV) 2 Nh Mc Ts Og 1 Nd II 0 open f shell

Bound-bound opacity 10 3 Infrared Op6cal 10 2 Nd (Z = 60, f shell) Opacity (cm 2 g − 1 ) 10 1 10 0 Fe (Z = 26, d shell) 10 − 1 Ru (Z = 44, d shell) Te (Z = 52, p shell) 10 − 2 0 5000 10000 15000 20000 25000 Wavelength (Å) MT, Kato, Gaigalas, Ryunkun, Radzuite et al. 2018, ApJ, 852, 109

Mul6-messenger signature of compact binary coalescence • Mul--messenger signals from neutron star merger • Mul--messenger observa-ons of GW170817 • Open issues and future prospects

2017 Aug 17 The first GW detec6on from 
 neutron stars merger Electromagne6c wave Observa6ons LIGO Scien-fic Collabora-on and Virgo Collabora-on, 2017, PRL

Gamma-ray (Fermi & INTEGRAL) 1.7 sec aqer the merger Weaker than short GRB by a factor of > 10 3 Off-axis line of sight (~30 deg, from GWs) LIGO Scien-fic Collabora-on and Virgo Collabora-on, 2017, ApJ � � Î Î Î � � + Î � � � -

High-resolu6on radio observa6ons 4.5 GHz => superluminal mo6on! 75 days (2017/11) 230 days (2018/4) Mooley+18 Smoking gun for rela6vis6c jet

~30 deg 2 hXps://www.ligo.org/science/Publica-on-GW170817MMA/images/Fig1.png

Coulter+17, Soares-Santos+17, Valen-+17, Movie: Utsumi, MT+17, Tominaga, MT+18 Arcavi+17, Tanvir+17, Lipunov+17

Electromagne6c counterpart of GW170817 @ 40 Mpc Day 1 Day 7 Op6cal (z) near IR (H) near IR (Ks) Utsumi, MT+17

GW170817: op6cal/infrared light curves 16 -17 Infrared g r i 17 -16 z J H Observed magnitude K Absolute magnitude 18 -15 19 -14 20 -13 Op6cal Arcavi+17, Cowperthwaite+17, 21 -12 Diaz+17, Drout+17,Evans+17, 
 Kasliwal+17,Pian+17, SmarX+17, Tanvir+17, Troja+17, 22 -11 0 5 10 15 Utsumi, MT+17, Valen-+17 Days after GW170817 Iden6fica6on of “kilonova” => signature of r-process nucleosynthesis

Constraints from the total amount in our Galaxy GW Kilonova Supernova rate Rosswog+17, Hotokezaka+15, 18

Mul6-messenger signature of compact binary coalescence • Mul--messenger signals from neutron star merger • Mul--messenger observa-ons of GW170817 • Open issues and future prospects

Open issues (related to heavy element produc6on) • Which elements are produced? • How high is the event rate? (element produc-on rate?) • What about different mass ra-os? BH-NS merger?

Large Doppler velocity Possible element features Lack of atomic data in the spectra?? => Not conclusive yet Model 2.5 Obs 2.0 MT+17 0818 0818 0819 0819 Model 0820 0820 1.5 0821 0821 Flux 0822 0822 1.0 0823 0823 0824 0824 0825 0825 0.5 0826 0826 Obs n 0827 0827 Chornock+17 0 es 5,000 10,000 15,000 20,000 25,000 Wavelength (Å) Pian+17

Accurate and complete atomic calcula6ons for element iden6fica6on Astrophysics x Nuclear physics x Atomic physics Gaigalas, Kato, Rynkun, Radziute, MT 2019, ApJS Nd II-III with GRASP2K code Calcula6on 3000 Nd IV 2500 20 % λ B (5s) (A) 10 % 2000 1500 1000 1000 1500 2000 experiment 2500 3000 λ exp (A) 10 % accuracy for energy levels 20 % accuracy for transi6on wavelengths Spectroscopic experiments are important

Open issues (related to heavy element produc6on) • Which elements are produced? • How high is the event rate? (element produc-on rate?) • What about different mass ra-os? BH-NS merger?

Mul6-messenger observa6ons are ongoing TODAY 90 Mpc 135 Mpc 55 Mpc hXps://www.ligo.org/scien-sts/GWEMalerts.php More GW events with neutron stars - Accurate event rate - Variety in NS mass and ejected mass - BH-NS merger

S190425z: 2nd candidate of NS merger (~150 Mpc) GW170817: 30 deg 2 hXps://gracedb.ligo.org/superevents/S190425z/ No convincing counterpart was iden6fied so far e.g., Hosseinzadeh+19

S190814bv: Candidate of BH-NS merger (~270 Mpc) GW170817: 30 deg 2 hXps://gracedb.ligo.org/superevents/S190814bv/ No convincing counterpart was iden6fied so far e.g., Gomez+19 kilonova proper6es depends strongly on BH mass/spin e.g., MT+14, Kawaguchi+16, Huang+18, Barbieri+19

KAGRA: improvement in localiza6on Field of view GW150914 (Subaru) LIGO+Virgo+KAGRA Localiza6on area (real6me analysis) LIGO: 600 deg 2 => 300 deg 2 LIGO + Virgo: 5.5 deg 2 LIGO + Virgo + KAGRA: 1.2 deg 2 https://arxiv.org/pdf/1703.08988.pdf

Summary • Mul6messenger observa6ons of NS merger • GW detec-on triggers EM observa-ons 
 over the wide wavelength range • Short gamma-ray bursts & superluminal mo-on 
 => rela-vis-c jets • Kilonova => r-process nucleosynthesis • Toward understanding the origin of elements • More GW events are coming => event rate • Variety in NS mass, BH-NS merger • Spectral features => Iden-fica-on of element species