FRB 171019: An event of binary neutron star merger? Jinchen Jiang, Weiyang Wang, Rui Luo, Shuang Du, Xuelei Chen, Kejia Lee&Renxin Xu Peking University & National Astronomical Observatories of China jiangjinchen@pku.edu.cn October 12, 2019 Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 1 / 14
Overview 1 Observation 2 Model One-off burst Cooling of the proto-compact star Repeating bursts 3 Discussion Luminosity Detection time interval DM variation Event rate 4 Summary Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 2 / 14
Observation Kumar P., et al., 2019 (arXiv:1908.10026) TOA d Obs Freq Obs Time DM Fluence Burst Width No Telescope (pc / cm 3 ) (Jy · ms) (MHz) (h) (MJD) (ms) 1 ab 986 . 6 58045 . 56061371 461 ± 1 219 ± 5 5 . 4 ± 0 . 3 ASKAP 1129.5-1465.5 2 b 58319 . 356770492 456 . 1 ± 0 . 4 0 . 60 ± 0 . 04 4 . 0 ± 0 . 3 10 . 6 GBT 720-920 3 b 58643 . 321088777 457 ± 1 0 . 37 ± 0 . 05 5 . 2 ± 0 . 8 4 c 17 ± 3 58700 . 38968 460 . 4 ± 0 . 2 6 ± 2 CHIME 400-800 � 7 a Shannon, R. M., Macquart, J.-P., Bannister, K. W., et al. 2018, Nature, 562, 386 b Kumar P., et al., 2019 (arXiv:1908.10026) c CHIME/FRB Collaboration 2019, The Astronomer’s Telegram, 13013, 1 d Burst time of arrivals are referenced at different frequencies: 1464 MHz for ASKAP, 920 MHz for GBT, and 400 MHz for CHIME. Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 3 / 14
Luminosity ����������� Provided by Rui Luo Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 4 / 14
A complex model Bright FRB Neutrino/Photon cooling Faint FRBs Starquake NS-NS merger One-off burst: unipolar induction at the end of inspiral. Repeating bursts: Starquake and magnetic reconnection on the remnant compact star. Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 5 / 14
Model: One-off burst ( GM (1 + q ) /a 3 ) 0 . 5 Ω = a ( a Ω c ) 0 . 5 r cap ≃ Bright FRB B Ω r 2 cap Φ ≃ 2 c n e = M n GJ ˙ Φ πr 2 E cap n e ec ≃ 10 − 3 ˙ E ∼ 1 × 10 45 erg / s L ∼ NS-NS merger (Here L is the luminosity in 10 7 − 10 11 Hz.) Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 6 / 14
Cooling of the proto-compact star Neutron Star Neutrino/Photon cooling ∼ 10 1 − 10 2 years Chamel N., Haensel P., 2008, LRR, 11, 10 Strangeon Star E in = 7 . 8 × 10 6 E in , 52 R − 4 t solid = s ∼ 90d 6 4 πR 2 σT 4 p Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 7 / 14
Model: Repeating bursts Electric field generated by magnetic connection E � ≃ 2 πσ s v A B = 2 . 1 × 10 9 σ s, − 3 v A , 8 B 14 esu c Electric field generates plasma Faint FRBs E � 4 πeλ = 3 . 5 × 10 12 σ s, − 3 Ω osc , 3 B 14 cm − 3 n e ≃ Coherent radiation Starquake N e = µn e ( γ e c ν ) 3 = 9 . 4 × 10 22 µ − 1 η 1 σ s, − 3 Ω osc , 3 B 14 γ 3 e, 2 ν − 3 9 L iso = 8 . 3 × 10 40 N pat µ − 1 η 1 σ 2 s, − 3 Ω 2 osc , 3 B 2 14 γ 8 e, 2 ν − 4 erg s − 1 9 Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 8 / 14
Discussion Luminosity Observation L iso Model L iso 6 × 10 43 erg / s ∼ 10 43 erg / s ASKAP (merger) burst 6 × 10 40 erg / s GBT (starquake) bursts 10 41 − 10 42 erg / s > 2 × 10 42 erg / s CHIME (starquake) burst The luminosity difference between the ASKAP burst and the GBT bursts is consistent with the difference between the merger burst and starquake bursts in our model. The luminosity of the CHIME burst is larger than the GBT bursts. This can be explained by an increase of the patch number N p at in the starquake model. A repeating burst as luminous as the ASKAP burst would rule out our model. Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 9 / 14
Discussion: Detection time interval Kumar P., et al., 2019 (arXiv:1908.10026) Time interval limitation Telescope Obs Time (h) TOA (MJD) The 1st GBT burst is ∼ 9 ASKAP 986 . 6 58045 . 56061371 months after ASKAP burst. Parkes 12 . 4 – There could be undetected 58319 . 356770492 GBT 10 . 6 bursts in the 9 months. 58643 . 321088777 CHIME 17 ± 3 58700 . 38968 → t solid ∼ 3 months ≤ 9 months � Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 10 / 14
Discussion: DM variation Jet may change the DM? E jet Γ m p c 2 ∼ π ( rθ ) 2 ln e N e ∼ ( r ∼ c ∆ t ) � r + l E jet n e ( r ′ ) dr ′ ∼ DM = π Γ m p c 4 ∆ t 2 θ 2 r 7 . 8 × 10 − 3 E jet , 50 Γ − 1 2 θ − 2 − 1 ∆ t − 2 pc · cm − 3 . = 7 No significant change of DM. DM (pc / cm 3 ) Telescope MJD ASKAP 58045 . 6 461 ± 1 58319 . 4 456 . 1 ± 0 . 4 GBT 58643 . 3 457 ± 1 CHIME 58700 . 4 460 . 4 ± 0 . 2 Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 11 / 14
Discussion: Event rate The event rate of repeating sources should be smaller than the event rate of NS-NS merger. Neutrino/Photon cooling Faint FRBs Bright FRB Starquake Spin down NS-NS merger Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 12 / 14
Summary Observations show the first brighter burst of FRB 171019 followed by three weaker repeaters about one year later. We propose a unified frame 1 The first one-off FRB is generated at the moment before NS-NS or SS-SS merger through, e.g., unipolar inductor mechanism. 2 The nascent remnant SS takes ∼ 100 d to be solidified which accounts for the halcyon period between the one-off burst and the followed repeaters. 3 After the solidification, starquakes induced by the spin-down of the SS generate the subsequent three weaker repeating FRBs. If another bright burst just like the first one of FRB 171019 were to be detected, it would mean that our model should be ruled out. Thanks! Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 13 / 14
Appendix: One-off burst Ω = ( GM (1 + q ) /a 3 ) 0 . 5 ∼ 3 . 7 × 10 3 rad s − 1 � 1 � 1 r cap ≃ a ( a Ω � M 4 � 1 + q 3 4 c ) 0 . 5 = 1 . 8 × 10 6 a 6 . 5 cm 4 1 . 4M ⊙ 2 Φ ≃ B Ω r 2 � M � � 1 + q � cap = 6 . 2 × 10 19 B 12 V . 2 c 1 . 4M ⊙ 2 � 1 � 1 � M 2 � 1 + q − 3 2 n e = M n GJ = 4 . 1 × 10 16 M 3 6 . 5 B 12 cm − 3 a 2 1 . 4M ⊙ 2 � 3 � 3 � M 2 � 1 + q − 3 2 E ≃ Φ πr 2 ˙ cap n e ec = 1 . 3 × 10 48 M 3 B 2 6 . 5 erg s − 1 a 2 12 1 . 4M ⊙ 2 L ∼ 10 − 3 ˙ E ∼ 1 × 10 45 erg / s Jiang et al. (PKU&NAOC) FRB 171019 October 12, 2019 14 / 14
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