Kilonova/Macronova Emission from Compact Binary Mergers Masaomi - - PowerPoint PPT Presentation

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Kilonova/Macronova Emission from Compact Binary Mergers Masaomi Tanaka (Na$onal Astronomical Observatory of Japan) 1 deg ~ 100 galaxies / 1 deg 2 (< 200 Mpc) SDSS 10 deg h:p://www.ligo.org/detec$ons.php Localiza:on ~ 600 deg 2 (~< 10

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Masaomi Tanaka

(Na$onal Astronomical Observatory of Japan)

Kilonova/Macronova Emission from Compact Binary Mergers

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SDSS

1 deg

~ 100 galaxies / 1 deg2 (< 200 Mpc)

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10 deg

h:p://www.ligo.org/detec$ons.php

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Localiza:on ~ 600 deg2 (~< 10 deg2 with Advanced Virgo and KAGRA) Detec:on of electromagne:c (EM) counterparts is essen:al

  • RedshiL (distance)
  • Host galaxy
  • Local environment

Abbo: et al. 2016, ApJ, 826, L13

10 deg

see Samaya Nissanke’s talk

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Degeneracy between inclina:on and distance

Abbo: et al. 2016, PRL, 116, 241102

Local environments

Berger 2014 (for short GRBs)

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  • EM emission from compact binary mergers
  • Kilonova/macronova emission
  • Lessons from past observa@ons and

prospects for EM follow-up observa@ons

Kilonova/Macronova Emission from Compact Binary Mergers

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BH

  • bs

j

Tidal Tail & Disk Wind

Ejecta ISM Shock

Merger Ejecta

v ~ 0.1 0.3 c Optical (hours days)

Kilonova

Optical (t ~ 1 day)

Jet ISM Shock (Afterglow) GRB

(t ~ 0.1 1 s) Radio (weeks years) Radio (years)

Metzger & Berger 2012, ApJ 746, 48

  • On-axis short GRB
  • Radio aLerglow
  • Op:cal/NIR emission

“kilonova” or “macronova”

Electromagne@c signature from compact binary merger

see talks by Nissanke, Piran, Zhang, ...

(NS-NS or BH-NS)

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(C) ESO

Short 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 et al. 2014, ApJ, 780, 118 Visible Not visible

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

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Mass ejec:on from NS mergers

  • :dal disrup:on
  • shock hea:ng

Rosswog 99, 00, Ruffert & Janka 01 Hotokezaka+13, Bauswein+13

M ~ 10-3 - 10-2 Msun v ~ 0.1 - 0.2 c

Hotokezaka+13

see talks by Rezzolla, Janka, Sekiguchi, ...

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200 Mpc

0.001 0.01 0.1 1 10 1 10 100 1000 10000 Fν [mJy] t [day] 150MHz, n=0.1cm-3 jet ( 0°) jet (45°) jet (90°) dynamical breakout 0.001 0.01 0.1 1 10 1 10 100 1000 10000 Fν [mJy] t [day] 150MHz, n=0.01cm-3 jet ( 0°) jet (45°) jet (90°) dynamical breakout

Nakar & Piran 11 Hotokezaka & Piran 15

Radio emission (aLerglow)

  • Delayed by ~> years
  • Too faint?

(low environment density)

150 MHz, n = 0.01 cm-3 150 MHz, n = 0.1 cm-3 0.1 mJy 0.1 mJy

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BH

  • bs

j

Tidal Tail & Disk Wind

Ejecta ISM Shock

Merger Ejecta

v ~ 0.1 0.3 c Optical (hours days)

Kilonova

Optical (t ~ 1 day)

Jet ISM Shock (Afterglow) GRB

(t ~ 0.1 1 s) Radio (weeks years) Radio (years)

Metzger & Berger 2012, ApJ 746, 48

  • On-axis short GRB

strongly beamed (isotropic soL X-ray?)

  • Off-axis radio aLerglow

isotropic delayed by ~> 1 yr

  • Op:cal/NIR emission

“kilonova” or “macronova”

isotropic short delay

Electromagne@c signature from compact binary merger (NS-NS or BH-NS)

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  • EM emission from compact binary mergers
  • Kilonova/macronova emission
  • Lessons from past observa@ons and

prospects for EM follow-up observa@ons

Kilonova/Macronova Emission from Compact Binary Mergers

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Mass ejec:on from NS mergers

  • :dal disrup:on
  • shock hea:ng

Rosswog 99, 00, Ruffert & Janka 01 Hotokezaka+13, Bauswein+13

M ~ 10-3 - 10-2 Msun v ~ 0.1 - 0.2 c

Hotokezaka+13

see talks by Rezzolla, Janka, Sekiguchi, ...

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Korobkin+12

Nucleosynthesis in NS merger

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(C) NASA

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mass number abundance 50 100 150 200 250 10-8 10-7 10-6 10-5 10-4 10-3 10-2 mass-averaged solar r-abundance

=> solar abundances

Ye mass fraction 0.0 0.1 0.2 0.3 0.4 0.5 10-4 10-3 10-2 10-1 100 100

0.1 0.4 0.2 0.3 higher T higher Ye ν νe + n -> p + e- n + e+ -> νe + p (e.g., Wanajo+14, Just+15, Wu+16)

Nucleosynthesis in NS merger

see talks by Janka, Sekiguchi, ...

Ye = ne np + nn = np np + nn

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NS merger as a possible origin of r-process elements

Event rate

RNSM ~ 10-4 event/yr/Galaxy ~ 103 Gpc-3 yr-1 ~ 40 GW events yr-1 (w/ Adv. detectors, < 200 Mpc) Mej(r-process) ~ 10-2 Msun Enough to explain the r-process abundance in our Galaxy

Ejec@on per event

GW EM

(e.g., Piran+14, Ma:eucci+14, Tsujimoto+14, Cescue+15)

M(Galaxy, r-process) ~ Mej(r) x (RNSM x tG) ~ 10-2 x 10-4 x 1010 ~ 104 Msun

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LIGO O1: Limit to the NS merger rate RNSM ~< 104 Gpc-3 yr-1

100 101 102 103 104

BNS Rate (Gpc−3yr−1)

aLIGO 2010 rate compendium Kim et al. pulsar Fong et al. GRB Siellez et al. GRB Coward et al. GRB Petrillo et al. GRB Jin et al. kilonova Vangioni et al. r-process de Mink & Belczynski pop syn Dominik et al. pop syn

O1 O2 O3

Abbo: et al. (arXiv:1607.07456)

see Laura Nulall’s talk

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Metzger+10, MNRAS, 406, 2650

Supernova 1 10 100 days NS merger

Radioac@ve energy => op@cal emission

see also Wanajo+14, Lippuner+15, Barnes+16

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Supernova (Type Ia) NS merger Mass 1.4 Msun 0.01 Msun Velocity 10,000 km/s 30,000-60,000 km/s Kine:c energy 1051 erg (1-5) x 1050 erg Composi:on Fe-group, Si, S, C, O r-process elements Power source

56Ni

r-process elements

> < > ~

Supernova vs NS merger

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~ 19-20 mag @200 Mpc (=> 1m telescope)

“kilonova/macronova”

Li & Paczynski 98, Metzger+10, Kasen+13, Barnes & Kasen 13 MT & Hotokezaka 13, MT+14 energy deposi:on energy deposi:on Goriely+11

*Opacity of Fe is assumed (b-b transi:ons)

Luminosity (erg/s) 1042 1041 1040 1039

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600,000 b-b transi$ons for 90 elements

3D frequency-dependent radia:ve transfer for NS merger

MT & Hotokezaka 2013, ApJ, 775, 113

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0.001 0.01 0.1 1 10 100 1000 5000 10000 15000 κ (cm2 g-1) Wavelength (A)

NSM-all NSM-Fe

r-process Fe

Similar conclusions by Kasen+13 and Barnes & Kasen 13 with different opacity database (more complete table for a few elements)

MT & Hotokezaka 2013

Lpeak 2 1041 erg s−1

Mej 0.01M

0.35

v 0.1c

0.65

κ 0.1 cm2 g1

−0.65

10 1 x 1040 Opacity

=3

tpeak 0.8 days

  • Mej

0.01M 1/2 v 0.1c 1/2 κ 0.1 cm2 g1 1/2

10 8

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C = Πi gi! ni!(gi − ni)!,

Kasen+13 Lanthanide

Lanthanide => high opacity

has g = 2(2l + 1) number of states in a

n: number of electrons g: number of sublevels

“Complexity” Number of lines ~ C2

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Luminosity

Barnes & Kasen 13

previous expecta:on (Fe opacity)

Fe opacity r-process opacity

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previous expecta:on (Fe opacity)

Luminosity

第 巻 第 号

◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆◆

研究奨励賞

物質は多くの中性子を含んでいるため，放出物質 の中では速い中性子捕獲反応（ ）が進 みます

） ‒ ）

． は放射性不安定な原子核 を経由して重元素を合成するプロセスですので， 中性子星合体は不安定な原子核の放射性エネル ギーを使って電磁波で等方的に光るはずです．こ れは 型超新星がニッケル の放射性崩壊で電 磁波で明るく輝くのと似ています． このような電磁波放射のアイデア自体は 年に初めて提唱されていたのですが

）

，詳細な 放射の様子は最近まで明らかになっていませんで した．核分裂やベータ崩壊によって，放射性エネ ルギーが放出物質に蓄えられるところまでは良い のですが，中性子星合体からの放出物質は鉄より 重い元素「のみ」で構成される特殊な系で，放出 物質内部での光の進みにくさ（ ）がわか らなかったためです．そのため長い間， 型超新 星のような鉄族元素で構成される系の （約

－ ）を仮定して電磁波放射の予想が

行われていました． そこで筆者らは， 元素のみで構成さ れる系での現実的な輻射輸送シミュレーションを 行いました

）

．その結果， 元素で構成 される系における が， 型超新星に比べ て約 倍も高い（

－ ）ことがわかりま

した．同時期にアメリカのグループも異なるアプ ローチで同様の結論に到達しています

） ）

．光 がより進みにくいということは，電磁波放射のタ イムスケールが長くなり，放射がより暗くなるこ とを意味します．シミュレーションの結果，中性 子星合体からの電磁波放射は（ ） 週間程度の タイムスケールで， （ ） ‒

－ 程度の

光度をもち（図 ） ， （ ）放射のピークは近赤外 線にくることがわかりました（図 ） ． ちなみに，この電磁波放射現象は英語では“ ”や“ ”などと呼ばれています． 日本語では正式な名前はまだ存在しません．直訳 すると「千新星」 ， 「巨新星」となり，どうもイマ イチです．そこで筆者は，膨張速度が「速い」こ と， 「速い」中性子捕獲反応で明るく輝くことか ら， 「超速新星」と呼ぶことにしました

）

．この 名前が定着するかは極めて不明ですが，本稿では こう呼ばせていただきます． さて，中性子星合体からこのような放射が起き るとすると，ショートガンマ線バーストの残光の 中にこのような放射が足されて観測される可能性 があります．幸運なことに，筆者らがシミュレー ションを行ったのと同じ年の 年，非常に近 傍でショートガンマ線バースト が 発見されました．このガンマ線バーストの赤外線

図 数値シミュレーションで得られた連星中性子 星合体の光度曲線．破線は 太陽質量の 元素による放射性崩壊エネルギー． 図 連星中性子星合体のスペクトルと， 型超新 星，継続時間の長いガンマ線バーストに付随し た超新星（ ）のスペクトルの比較．

Luminosity (erg/s) Days aZer the merger

d e c a y e n e r g y

Type Ia SN NS merger

MT & Hotokezaka 13 MT 16

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Red spectrum (peak at near-infrared) Extremely broad-line (feature-less) spectra

16 18 20 22 24 26 28 4000 6000 8000 10000

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10

Observed magnitude (200 Mpc) Absolute magnitude Wavelength (A)

g r i z

Type Ia SN SN 1998bw NS-NS 1.5 days 5.0 days 10.0 days

MT 2016

Spectrum

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16 18 20 22 24 26 28 5 10 15 20

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10

Observed magnitude (200 Mpc) Absolute magnitude Days after the merger i-band Type Ia SN NS-NS

NS-NS

Type Ia SN 1m 4m 8m

MT 2016

i-band, Mej = 0.01 Msun

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BH-NS Mergers N(<800 Mpc) ~ 10 (0.2-300) / yr

Kyutoku+13

Kawaguchi+16 Poster I-10

  • more massive BH

higher spin Emission can be bluer (higher T) MT+14

see e.g., Shibata & Taniguchi 06, Duez+08, Kyutoku+10,11 Deaton+13, Foucart+14

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Forma:on of the disk around hypermassive NS/BH

Bartos et al. 2012

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Higher Ye => Synthesis of lighter elements

(Fernandez+13, Metzger+ 2014, Just+15, Fernandez & Metzger 16, Wu+16)

Ye

0.2 0.4 0.6

Log {s [kB/nuc]}

0.5 1 1.5 2 2.5 3

2 4 6 8 10 −10 −8 −6 −4 −2 −10 −5 5 10 z [107 cm] x [107 cm]

(b)

M3A8m3a5, t = 50 ms

50 ms Just+15 higher Ye

Mass ejec:on from the disk

Wu+16 10% of disk mass

Disk wind ~ Dynamical ejecta

Poster I-7 by Sho Fujibayashi

(Fernandez+13, Just+15, Kiuchi+14,15)

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Higher Ye => Lower opacity (if Lanthanide free) => Brighter emission at earlier epochs

“Blue kilonova”

Kasen+15 Metzger & Fernandez 14

Emission proper:es depend on

  • life:me of hypermassive neutron star (<= EOS)
  • presence of preceding ejecta (Lanthanide rich)

red blue NIR

  • p@cal > NIR

(Metzger & Fernandez 14, Kasen+15, Fernandez & Metzger 16)

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16 18 20 22 24 26 28 5 10 15 20

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10

Observed magnitude (200 Mpc) Absolute magnitude Days after the merger i-band Type Ia SN NS-NS BH-NS Wind

NS-NS Disk wind (lower opacity) BH-NS (higher T)

Type Ia SN

i-band, Mej = 0.01 Msun

1m 4m 8m

MT 2016

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  • EM emission from compact binary mergers
  • Kilonova/macronova emission
  • Lessons from past observa@ons and

prospects for EM follow-up observa@ons

Kilonova/Macronova Emission from Compact Binary Mergers

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Test with short GRBs

(C) ESO

GRB kilonova

Kann+11 SN 1998bw x 0.01 NS-NS 0.01 Msun

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21 1 10 X-ray F606W F160W 22 23 AB magnitude 24 25 26 27 104 105 10–11 10–12 10–13 10–14 106 28 29 Time since GRB 130603B (s) Time since GRB 130603B (d) X-ray fux (erg s–1 cm–2)

Very red source (R-H > 2.5 mag) consistent with theore:cal models (mass ejec:on of ~0.02-0.06 Msun)

NIR source

GRB 130603B

Tanvir+13, Berger+13 NIR

  • p:cal

z=0.356

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Possible probe of NS radius (EOS)

0.01 0.1 1 10 0.13 0.14 0.15 0.16 0.17 0.18 0.19 0.2 Mej/10-2Msun Mtot/2R1.35

APR4 SLy ALF2 H4 MS1

small R large R

R1.35 11.1 km 13.6 km 12.4 km 14.4 km 11.4 km

Mej (10-2 Msun) Compactness (M/2R)

GRB 130603B

soL EOS (smaller NS radius) => stronger shock => brighter emission

Hotokezaka+13

*NOTE: contribu:on from disk wind is NOT taken into account

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GRB 060614

Yang+15, Jin+15 see also Jin+16 for possible excess in GRB 050709

23 24 25 26 27 28 2 4 6 8 10 20 40 Vega magnitude Time since burst (days)

VLT R excess VLT I excess HST F606W excess HST F814W excess

20 21 22 23 24 25 26 27 28 29 10-14 10-13 10-12 10-11 Vega magnitude X-ray flux (0.3-10keV) (erg cm-2 s-1)

VLT V VLT R VLT I HST F606W HST F814W X-ray

Mej ~0.1 Msun

  • Disk wind?
  • BH-NS?
  • Different mechanism

associated X-ray emission?? (Kisaka+15a,15b) GRB160821b @ z = 0.16!!

z=0.125 z=0.16

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200 Mpc shallow deep

GRB 150101B Previous sGRBs

Rest-frame Time after Burst (days) Optical Luminosity λLλ (erg s-1) 10

  • 1

10 10

1

10

38

10

39

10

40

10

41

10

42

10

43

10

44

Near-IR Luminosity λL (erg s-1)

Fong+16

24 mag 21 mag @ 200 Mpc

Constraints from short GRBs

1m telescopes >4m telescopes

Barnes & Kasen 2013 Tanaka+ 2014 (NS-NS) Tanaka+ 2014 (NS-BH) Kasen+ 2015

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16 18 20 22 24 26 28 5 10 15 20

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10

Observed magnitude (200 Mpc) Absolute magnitude Days after the merger i-band Type Ia SN NS-NS BH-NS Wind

NS-NS Disk wind (lower opacity) BH-NS (higher T)

Type Ia SN

i-band, Mej = 0.01 Msun

1m 4m 8m

MT 2016

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GW150914: EM follow-up

LVC and EM follow-up groups, 2016, ApJ, 826, L13

see talks by Nissanke and Tominaga for more details

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Pan-STARRS and PESSTO (i ~20 mag) Smar: et al. 2016 (see also Kasliwal et al. 2016; Soares-Santos et al. 2016; Morokuma et al. 2016) 10 deg

50 deg2 survey w/ 25 mag depth >~ 1000 supernovae and 1 GW source! Efficient selec:on is essen:al

Lessons from EM follow-up

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Selec:on of GW sources (from larger number of SNe)

20 21 22 23 24 25 26

  • 1

1 2 3 i i - z Type Ia SN NS-NS BH-NS Wind

z=0.3 z=0.5 z=0.7

1 5 1 5 10 1 5

16 18 20 22 24 26 28 5 10 15 20

  • 20
  • 18
  • 16
  • 14
  • 12
  • 10

Observed magnitude (200 Mpc) Absolute magnitude Days after the merger i-band Type Ia SN NS-NS BH-NS Wind

MT 2016

  • 0. Associa@on w/ nearby galaxies

Smoking gun

Extremely broad line spectrum <= higher velocity

  • 1. Short @mescale <= lower mass
  • 2. Faintness <= lower energy budget
  • 3. Red colors <= higher opacity
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Summary

  • NS merger: possible origin of r-process elements
  • Kilonova/macronova emission
  • Powered by radioac:ve decay of r-process nuclei
  • Short :mescale, faint emission
  • Peaks at red op:cal or near infrared
  • Constrains from short GRBs: consistent with models
  • Uncertainty in disk wind (mass and composi:on)
  • Prospects for GW-EM observa:ons
  • Selec:on by :mescale, faintness, and color
  • Smoking gun: the extremely broad-line spectra

GW+EM+Theory => Origin of r-process elements