Electromagnetic Counterparts to Neutron Star Binary Mergers Shota Kisaka (Aoyama Gakuin Univ.) Collaborators : Kunihito Ioka, Takashi Nakamura, Ehud Nakar, Takanori Sakamoto Merger of Neutron Star Binaries EM counterparts to GW sources are important to maximize scientific returns from the detection of GWs. Metzger & Berger 12 e.g., ・Localization ・Origin of short GRBs ・Equation of state ・r-process enrichment
NS NS BH
NS NS binary Merger Ejecta Hotokezaka+ 13 Bounded mass 1 Md 10 M Ejecta mass⇠ 4 2 NS-NS: Mej 10 10 M ⇠ 1 BH-NS: Mej . 10 M Ejecta velocity v 0.1 0.3c ej ⇠ Homologous expansion R v t ej ⇠ ej r-process nucleosynthesis Neutron-rich Ejecta ⇒ Tn capture MBH 1053 erg (a/MBH =0.5) ⇠ 3M ✓ ◆ ・Disk gravitational energy: 52 Md 10 1 erg ⇠ 10 M ✓ ◆ ・Ejecta kinetic energy: 2 51 Mej vej 10 2 erg ⇠ 10 M 0.3c ✓ ◆ ・Radioactivity: ⇣ ⌘ 49 ✏ Mej 10 3 2 erg ⇠ 10 10 M ⇣ ⌘ ✓ ◆ NS or BH ・Magnetic field: B 2 1048 erg ⇠ 1015G ✓ ◆ Metzger & Berger 12 EM Counterparts ・Gamma-ray Bursts t < 106 s Rotation/disk grav. energies ・Macronovae/Kilonovae t ~ 10 day Radioactivity (?) ・Remnants of Merger Ejecta t ~ yr Ejecta kinetic energy NS or BH Metzger & Berger 12 Gamma-Ray Bursts Light Curve Extended emission : L ~ 1048 erg/s, T ~ 102 s Plateau emission : L ~ 1045 erg/s, T ~ 104 s cf. Prompt emission L ~ 1050 - 1051 erg/s T ~ 0.1 – 1 s Total energy is comparable ~ 1050 - 1051 erg Prompt emission Prompt NS scenario (Gompertz+ 13) (Propeller → wind) BH scenario (SK & Ioka 15) Gompertz+ 13 (BZ jet + B-field evolution) Light Curves Model : SK & Ioka 15 1050 1050 50 48 10 48 10 10 48 46 10 10 1046 46 44 10 10 1044 44 42 10 10 GRB 050509B GRB 050724 42 GRB 051210 42 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 10-2 100 102 104 106 10-2 100 102 104 106 t [s] t [s] t [s] 50 1050 10 1050 48 48 10 10 1048 46 46 10 1046 10 1044 44 GRB 051221A 1044 GRB 051227 10 GRB 060313 42 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 100 102 104 106 10-2 100 102 104 106 10-2 100 102 104 106 t [s] t [s] t [s] 50 10 50 50 10 10 1048 1048 1048 46 1046 10 1046 44 10 1044 44 42 GRB 060614 GRB 060801 10 GRB 061006 10 1042 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 100 102 104 100 102 104 106 t [s] t [s] t [s] Light Curves Model : SK & Ioka 15 1050 1048 50 48 10 46 10 10 1048 46 1044 10 1046 42 44 10 10 44 GRB 061201 GRB 061210 10 GRB 070714A L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 100 102 104 106 100 102 104 106 t [s] t [s] t [s] 1050 1050 1050 48 1048 10 48 10 46 1046 10 46 10 44 1044 10 44 GRB 070714B GRB 070724A GRB 070809 10 42 42 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10 10-2 100 102 104 100 102 104 106 100 102 104 t [s] t [s] t [s] 1050 1050 48 1050 10 1048 48 46 10 10 46 10 46 44 10 10 44 GRB 071227 10 GRB 080123 44 GRB 080426 42 10 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 100 102 104 106 100 102 104 100 102 104 t [s] t [s] t [s] Light Curves Model : SK & Ioka 15 1052 1050 1048 1050 1048 1048 1046 1046 46 10 1044 1044 44 42 GRB 080702A 42 GRB 080905A 10 GRB 080503 10 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 10-2 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] 1050 52 1050 10 48 1048 10 1050 46 46 10 10 1048 44 10 1044 1046 42 GRB 090426 10 GRB 080919 GRB 081024A 44 1042 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 10-2 100 102 104 100 102 104 106 t [s] t [s] t [s] 1052 1050 48 1050 10 1048 48 10 1046 46 1046 10 44 44 10 10 GRB 090510 GRB 090515 1044 GRB 090621B 42 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10-2 100 102 104 10-2 100 102 104 10-2 100 102 104 106 t [s] t [s] t [s] Light Curves Model : SK & Ioka 15 50 1050 10 50 10 48 48 10 10 48 10 46 46 10 10 1046 1044 1044 44 GRB 091109B 10 GRB 100117A 42 GRB 100625A 42 42 10 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 10-2 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] 50 1050 1050 10 48 48 10 10 1048 1046 1046 46 1044 10 44 42 GRB 100702A 10 GRB 100724A 44 GRB 101219A 10 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 10-2 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] 1050 50 1050 10 48 48 10 1048 10 46 1046 10 1046 44 10 44 1044 GRB 110112A 10 GRB 111020A GRB 111117A 1042 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] Light Curves Model : SK & Ioka 15 50 50 10 10 1050 48 48 10 1048 10 46 1046 10 1046 44 44 44 GRB 111121A 10 GRB 120305A 10 10 GRB 120521A L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 10-2 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] 50 10 1050 1050 48 1048 48 10 10 46 46 10 46 10 10 1044 44 44 GRB 120804A 42 10 10 GRB 121226A 10 GRB 130603B L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 100 102 104 106 10-2 100 102 104 106 t [s] t [s] t [s] 1052 1050 1050 1050 48 48 10 10 1048 46 46 10 10 46 44 10 1044 GRB 130912A 10 GRB 131004A GRB 140129B L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 10-2 100 102 104 100 102 104 t [s] t [s] t [s] Light Curves Model : SK & Ioka 15 50 50 10 1050 10 48 48 48 10 10 10 46 46 1046 10 10 44 44 1044 10 10 GRB 140903A GRB 140930B GRB 150120A 42 42 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10 10-2 100 102 104 106 10-2 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] 50 10 50 1050 10 48 48 1048 10 10 46 46 10 1046 10 44 1044 10 1044 1042 GRB 150301A GRB 150423A 1042 GRB 150424A L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 10-2 100 102 104 106 10-2 100 102 104 106 t [s] t [s] t [s] 50 50 10 10 50 48 10 1048 10 1048 46 46 10 10 46 44 10 10 44 GRB 150831A 10 GRB 151127A 44 GRB 151229A 42 10 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 10-2 100 102 104 10-2 100 102 104 t [s] t [s] t [s] Light Curves Model : SK & Ioka 15 1050 50 10 50 48 10 10 48 10 48 46 10 10 46 10 46 44 10 10 44 GRB 160303A 10 GRB 160408A 1044 GRB 160410A 42 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 106 10-2 100 102 104 10-2 100 102 104 106 t [s] t [s] t [s] 50 50 10 10 1050 48 1048 10 1048 46 46 10 1046 10 44 44 10 1044 10 GRB 160411A GRB 160525B GRB 160601A 42 42 42 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] 10 10-2 100 102 104 10-2 100 102 104 106 10-2 100 102 104 t [s] t [s] t [s] 1050 1050 1050 48 48 10 10 1048 46 46 10 10 46 44 10 44 10 10 44 GRB 160624A 42 GRB 160821B 10 GRB 160927A 42 10 L (0.3-10 keV)[erg/s] 10 L (0.3-10 keV)[erg/s] L (0.3-10 keV)[erg/s] 10-2 100 102 104 10-2 100 102 104 106 10-2 100 102 104 106 t [s] t [s] t [s] Luminosity and Duration Extended emission : L ~ 1047-1050 erg/s, T ~ 102 – 103 s Plateau emission : L ~ 1043-1047 erg/s, T ~ 104 – 105 s 1050 1049 1048 1047 10 52 10 48 erg erg 1046 Extended 1045 Emission Luminosity [erg/s] 1044 Plateau 1043 Emission 101 102 103 104 105 106 Duration [s] Scattering ・ Emission region locates inside the ejecta, re < r. ・ Optical depth τ >> 1. Emission region SK, Ioka & Nakamura 15 2 re c t ⇠ 2 t 3 1012 cm ⇠ ⇥ 10 1s Ejecta ✓ ◆ ✓ ◆ r vt ⇠ v t 3 1013 cm ⇠ ⇥ 0.1c 104s ⇣ ⌘ ✓ ◆ Optical depth 2 ¯ 1 2 2 t A Mej v ⌧ 10 4 2 2 ⇠ 10 s 10 10 M 0.1c ✓ ◆ ✓ ◆ ✓ ◆ ⇣ ⌘ Detectability -4 10 Extended Emission 100Mpc Plateau Emission CALET HXM 10-6 INTEGRAL SPI-ACS ] Fermi GBM 2 -8 10 Swift BAT MAXI GSC iWF-MAXI -10 10 ISS-Lobster WFI Einstein Probe WXT Flux [erg/s/cm Swift XRT -12 10 3 ✏ = 10 eROSITA -14 10 Scattered Plateau 1 2 3 4 5 6 10 10 10 10 10 10 Lscatter ✏Lpl Duration [s] ⇠ 3 2 Isotropically scattered case : ✏ 5 10 (✓ /0.1) ⇠ ⇥ j 5 4 cf. ✏ 3 10 3 10 (Eichler & Levinson 99) ⇠ ⇥ ⇥ Macronovae Macronova Candidate Tanvir+ 13 Berger+ 13 Opt. NIR Metzger & Berger 12 t ~ 7 day 41 LNIR ~ 10 erg/s T < 4000 K (mr-mj ≥ 2.5) r-process Heating Model Nuclear heating rate 1.3 Jet 10 t 1 1 Q˙ 10 erg g s ⇠ 1day ✓ ◆ Central engine Torus Nuclear (or Disk) decay Hotokezaka+ 16 41 1 Mej L 10 erg s ⇠ 0.05M ✓ ◆ r-process Heating Model 2 1 Opacity 10cm g ⇠ Jet Central engine Kasen+ 13 Torus Nuclear Tanaka & Hotokezaka 13 (or Disk) decay M 1/2 t 7day ej peak ⇠ 0.05M ✓ ◆1/2 1/2 vej 2 1 ⇥ 10cm g 0.1c ✓ ◆ ⇣ ⌘ r-process Heating Model GRB 130603B Barnes+ 16 GRB 060614 Jin+ 15 GRB 050709 Jin+ 16 Light curve fitting Mej/M◉ GRB 050709 : ~ 0.1 Jin+ 16 GRB 060614 : ~ 0.25 Jin+ 15, Yang+ 15 GRB 130603B : ~ 0.05 - 0.1 Hotokezaka+ 16, Barnes+ 16 Simulation NS-NS : ~ 10-4 – 10-2 Hotokezaka+ 13 BH-NS : < 10-1 Kyutoku+ 15 X-ray-powered Macronova ? Fluxes of the X-ray and IR A single excesses are comparable. energy source? X-ray -12 GRB 130603B 10 r-band IR H-band ] X-ray ejecta photon -2 10-13 photon cm -1 ∝ t -2 -14 [erg s 10 ν F ν FIR/FX -15 10 GRB 050709 ~ 1 GRB 060614 ~ 0.1 SK, Ioka & Nakar 16 105 106 GRB 130603B ~ 0.4 Time after Burst [sec] Jin+ 16 X-ray-powered Macronova The merger ejecta heated by the irradiation of X-ray emit thermal infrared radiation. Physical setups ・Isotropic X-rays are generated near the central source. ・The ejecta cover a fraction of solid angle. ・The line-of-sight to the source is clean for the observers. SK, Ioka & Nakar 16 X-ray-powered Macronova The merger ejecta heated by the irradiation of X-ray emit thermal infrared radiation. Required conditions ・Absorption of X-ray photons τX > 1 ・Thermalization τIR > 1 ・Escaping thermal photons tdiff < t ・Temperature T < T SK, Ioka & Nakar 16 max Results Broad ranges of the allowed parameter regions SK, Ioka & Nakar 16 2 1 IR = 10 cm g 100 100 Excluded by radio Iron ejecta r-process ejecta obs. (Horesh+ 16) >1 -3 -1 X 10 < Mej/Msun < 10 r-process /c -1 /c -1 >1 model ej 10 ej 10 v v IR T<4000K T<4000K E E kin Metzger & Berger 12 Cassam-Chenai+ 08 Free expansion → Sedov-Taylor phase 1/3 1/3 3Mej 18 Mej Rdec = 7 10 2 cm 4⇡nmp ⇠ ⇥ 10 M ✓ ◆ ✓ ◆ 1/3 1 Rdec Mej ej tdec = 7 2 yr ej ⇠ 10 M 0.9 2 3 ✓ ◆ ✓ ◆ n = 10 cm High Energy Radiation Takami+ 14 Maximally allowed bolometric flux 2/3 3 2 ✏eEkin 12 Mej ej d 1 2 Fmax = 2 2 10 2 erg s cm 4⇡d tdec ⇠ ⇥ 10 M 0.9 100Mpc ✓ ◆ ✓ ◆ ✓ ◆ IC energy not affected by KN effect 1/15 1/5 M 11 ej ej ✏e =0.1 EIC . 2 10 2 eV ⇥ 10 M 0.9 n = 10 2cm 3 ✓ ◆ ✓ ◆ GRB 130603B @100Mpc CTA could give constraints on ejecta parameters. r-process ejecta Excluded by radio obs. (Horesh+ 16) 100 CTA r-process ejecta detectable region 0 10 X-ray powered 12 1 2 Fmax & 10 erg s cm model r-process model /c -1 >1 ej 10 v IR T<4000K /c -1 >1 ej 10 E v IR