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

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 signature of compact binary coalescence

Mul6-messenger from neutron star merger

Gravita6onal wave (GW) merge jet => gamma-ray

Mass ejec-on => nucleosynthesis => op-cal/infrared

Electromagne6c (EM) wave

NS or Black hole (BH) neutron star (NS)

(C) ESO

Short-dura6on gamma-ray burst (GRBs)

5 10 15 20 25 30 35 2 4 6 8 10 12 14 16 18 20

Short Long

Opening Angle θj (degrees) Number

Fong+14 Visible Not visible

Opening angle ~ 10 deg => probability ~ a few %

Mass ejec6on from neutron star merger

Sekiguchi+15, 16

M ~ 10-3 - 10-2 Msun v ~ 0.1 - 0.2 c Top view Side view

Neutron capture process to synthesize elements beyond Fe

proton neutron Ni56

• proton 28
• neutron 28

+

radioac6ve decay

Rapid neutron capture process (r-process) in NS merger

(C) Nobuya Nishimura

Fe

Supernova NS merger

• M. Weiss

NASA

Origin of heavy (r-process) elements

Difficult to have r-process? Robust r-process Unknown event rate 
 and ejec6on per event Well known event rate

Merger r-process nucleosynthesis Radioac6ve decay => kilonova

< 1 sec ~> days ~< 100 ms

Mass ejec6on

MT & Hotoke 13 hXp://www.aei.mpg.de/comp-rel-astro

Chemical enrichment

> Myr Timescales of NS mergers

Jet forma6on?

Wanajo 18

Radioac6ve decay of r-process nuclei 1 day 10 day

~ t-1.3

β decay β decay + α decay + fission

Radioac6ve decays => “Kilonova”

Β decay (γ, β), α decay, fission =>Heats up ejected material

When photons can escape?

tpeak = 3κMej 4πcv 1/2

• 8.4 days
• Mej

0.01M 1/2 v 0.1c 1/2 κ 10 cm2 g1 1/2

Bound-bound transi6on of heavy elements (I, II, III, IV)

Time

ρ ~ 10-14 - 10-13 g cm-3 Τ ~ 5,000-10,000 K

Li & Paczynski 98, Kulkarni 05, Metgzer+10

L ~ 1040-1041 erg s-1 t ~ weeks NIR > Op6cal

• 16
• 15
• 14
• 13
• 12
• 11
• 10
• 9

5 10 15 Absolute magnitude Days after the merger g r i z J H K

Infrared Op6cal

Model: MT+17a

Light curves of kilonova

Kasen+13, Barnes & Kasen 13, MT & Hotokezaka 13

Infrared Op-cal

Nh Mc Ts

Og

• pen s shell
• pen p-shell
• pen d-shell
• pen f shell

1 2 3 4 5 E (eV)

Fe II

1 2 3 4 5 E (eV)

Nd II

λ = hc ∆E

Bound-bound opacity

10−2 10−1 100 101 102 103 5000 10000 15000 20000 25000 Opacity (cm2 g−1) Wavelength (Å)

Nd (Z = 60, f shell) Fe (Z = 26, d shell) Ru (Z = 44, d shell) Te (Z = 52, p shell) MT, Kato, Gaigalas, Ryunkun, Radzuite et al. 2018, ApJ, 852, 109

Infrared Op6cal

• Mul--messenger signals from neutron star merger
• Mul--messenger observa-ons of GW170817
• Open issues and future prospects

Mul6-messenger signature of compact binary coalescence

LIGO Scien-fic Collabora-on and Virgo Collabora-on, 2017, PRL

The first GW detec6on from 
 neutron stars merger 2017 Aug 17 Electromagne6c wave Observa6ons

• Î
• Î
• +
• Î
• Î
• Gamma-ray

(Fermi & INTEGRAL) 1.7 sec aqer the merger

LIGO Scien-fic Collabora-on and Virgo Collabora-on, 2017, ApJ

Weaker than short GRB by a factor of > 103 Off-axis line of sight (~30 deg, from GWs)

High-resolu6on radio observa6ons => superluminal mo6on!

Mooley+18

75 days (2017/11) 230 days (2018/4)

Smoking gun for rela6vis6c jet

4.5 GHz

hXps://www.ligo.org/science/Publica-on-GW170817MMA/images/Fig1.png

~30 deg2

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

Op6cal (z) near IR (H) near IR (Ks) Electromagne6c counterpart of GW170817 @ 40 Mpc

Utsumi, MT+17

Day 1 Day 7

GW170817: op6cal/infrared light curves

Arcavi+17, Cowperthwaite+17, Diaz+17, Drout+17,Evans+17, 
 Kasliwal+17,Pian+17, SmarX+17, Tanvir+17, Troja+17, Utsumi, MT+17, Valen-+17

16 17 18 19 20 21 22 5 10 15

• 17
• 16
• 15
• 14
• 13
• 12
• 11

Observed magnitude Absolute magnitude Days after GW170817 g r i z J H K

Op6cal

Iden6fica6on of “kilonova” => signature of r-process nucleosynthesis

Infrared

Rosswog+17, Hotokezaka+15, 18

Constraints from the total amount in our Galaxy

Supernova rate GW Kilonova

• Mul--messenger signals from neutron star merger
• Mul--messenger observa-ons of GW170817
• Open issues and future prospects

Mul6-messenger signature of compact binary coalescence

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?

Possible element features in the spectra?? => Not conclusive yet

n es

0.5 1.0 1.5 2.0 2.5 Flux 5,000 10,000 15,000 20,000 25,000 Wavelength (Å) 0818 0819 0820 0821 0822 0823 0824 0825 0826 0827 0818 0819 0820 0821 0822 0823 0824 0825 0826 0827

Pian+17 Chornock+17 MT+17

Model Obs Obs Model Large Doppler velocity Lack of atomic data

Accurate and complete atomic calcula6ons for element iden6fica6on

Gaigalas, Kato, Rynkun, Radziute, MT 2019, ApJS

1000 1500 2000 2500 3000 1000 1500 2000 2500 3000 λB (5s) (A) λexp (A) Nd IV

10 % accuracy for energy levels 20 % accuracy for transi6on wavelengths 20 % 10 % experiment Calcula6on Nd II-III with GRASP2K code

Spectroscopic experiments are important

Astrophysics x Nuclear physics x Atomic physics

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?

hXps://www.ligo.org/scien-sts/GWEMalerts.php

TODAY

Mul6-messenger observa6ons are ongoing

90 Mpc 135 Mpc 55 Mpc

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)

hXps://gracedb.ligo.org/superevents/S190425z/

GW170817: 30 deg2

e.g., Hosseinzadeh+19

No convincing counterpart was iden6fied so far

hXps://gracedb.ligo.org/superevents/S190814bv/

S190814bv: Candidate of BH-NS merger (~270 Mpc) No convincing counterpart was iden6fied so far

e.g., MT+14, Kawaguchi+16, Huang+18, Barbieri+19 e.g., Gomez+19

kilonova proper6es depends strongly on BH mass/spin

GW170817: 30 deg2

KAGRA: improvement in localiza6on

https://arxiv.org/pdf/1703.08988.pdf

GW150914

Localiza6on area (real6me analysis) LIGO: 600 deg2 => 300 deg2 LIGO + Virgo: 5.5 deg2 LIGO + Virgo + KAGRA: 1.2 deg2 LIGO+Virgo+KAGRA

Field of view (Subaru)

• Mul6messenger observa6ons of NS merger
• GW detec-on triggers EM observa-ons 

• ver 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

Summary