Fast Radio Burst Progenitor Models

Transcription

1 Fast Radio Burst Progenitor Models Tony Piro Carnegie Observatories Fast Radio Bursts: New Probes of Fundamental Physics and Cosmology, February 13, 2017

2 What could FRBs be? Neutron stars collapsing to black holes, ejecting magnetic hair (Falcke & Rezzolla 14; Zhang 14) Merger of charged black holes (Zhang 16; Liu et al. 16; Liebling & Panenzuela 16) Magnetospheric activity during neutron star mergers (Totani 13) Unipolar inductor in neutron star mergers (Hansen & Lyutikov 01; Piro 12; Wang et al. 16) White dwarf mergers (Kashiyama et al. 13) Pulses from young neutron stars (Cordes & Wasserman 15; Connor et al. 15; Lyutikov et al. 16; Popov & Pshirkov 16; Kashiyama & Murase 17) Magnetars (Popov et al. 07; Kulkarni et al. 14; Lyubarsky 14; Katz 15; Pen & Connor 15) Sparks from cosmic strings (Vachaspati 08; Yu et al. 14) Evaporating primordial black holes (Rees 77; Keane et al. 12) White holes (Barrau et al. 14) Flaring stars (Loeb et al. 13; Maoz et al. 15) Axion stars (Tkachev 15; Iwazaki 15) Asteroids/comets falling onto neutron stars (Geng & Huang 15) Quark novae (Chand et al. 15) Dark matter-induced collapse of neutron stars (Fuller & Ott 15) Higgs portals to pulsar collapse (Bramante & Elahi 15) Planets interacting with a pulsar wind (Mottez & Zarka 15) Black hole superradiance (Conlon & Herdeiro 17) Extragalactic light sails (Lingam & Loeb 17) Schwinger instability in young magnetars (Lieu 17) Neutron star-white dwarf binaries (Gu et al. 16)

3 Repeating FRB Spitler et al. (2016) Proves in at least one case FRBs are not cataclysmic events

4 Non-Cataclysmic FRB Progenitors 1. Radio emission accompanying magnetar giant flares (Lyutikov 02; Popov & Postnov 10; Keane et al. 12; Pen & Connor 15; Kulkarni et al. 14; Lyubarsky 14; Katz 15) 2. Giant pulse analogues emitted by young pulsars (Cordes & Wasserman 16; Connor et al. 16; Lyutikov et al. 16; Popov & Pshirkov 16; Kashiyama & Murase 17) (Apologies if there are any missing references!)

5 Comparison to the SN rate Connor, Sievers, and Pen (2016)

6 Can DM be from the source? Nearly quadratic dispersion implies plasma cannot be too dense (Katz 2016) n e < m e! 2 4 e cm 3 Thus dispersing region must be sufficiently large R DM =DM/n e > cm Dispersing material must also be optically thin (Luan & Goldreich 2014; Katz 2016) n e < 10 4 (T/10 4 K) 3/2 (DM/10 3 pc cm 3 ) 1 cm 3 Potentially stricter, but depends on temperature Consistent with supernova remnant? (Connor et al. 16; Lyutikov et al. 16)

7 Localization of FRB (Chatterjee et al. 17; Tendulkar et al. 17)

8 Host of FRB : SFR (Tendulkar et al. 17; Metzger, Berger & Margalit 17; Perley et al. 16) uhf Star-formation rate (M O yr -1 ) ssfr = 10-8 yr yr yr yr -1 Type I/R Type II LVL (area ~ SFR) Stellar mass (M O )

9 Host of FRB : Metallicity (Tendulkar et al. 17; Metzger, Berger & Margalit 17; Perley et al. 16) uhf 12+log 10 [O/H] Type I/R Type II (pale if from M-Z) LVL (area ~ SFR) Stellar mass (M O )

10 Supernova remnant

11 Supernova Remnant Evolution Piro (2016)

12 Total DM including SNR Assuming we can subtract out the MW component, the remaining DM is DM total (t) =DM SNR (t)+dm Host +DM IGM DM SNR (t) = 3Mf = (vt) 2 M How do we eliminate these pesky unknown constants? M Use the change in the DM! f v 2 9 t2 yr pc cm 3 DM total ddm SNR dt t M M f tyr v 2 9 t3 yr pc cm 3

13 Comparing to FRB Over the ~4 years these bursts have repeated, the DM is the same within a few pc/cm 3 t & 60 M M 1/3 f So not crazy. Can we keep checking the DM? How accurately can DM be measured? We also know that the total DM < 225 pc/cm 3 (once MW and IGM is subtracted, Tendulkar et al. 17), which limits the mass to v 2 9 t yr 4 1/3 yrs M. 8 v2 9 f tyr 60 2 M

14 Is there sufficient rotational energy? Katz (2016) For a spinning down dipole, the spindown time and available energy (in ~1 ms) are t sd Ic 3 2(BR 3 ) B 2 12 P 2 msyrs E = (BR3 ) 2 4 c 3 t B 2 12P 4 ms erg If the neutron star spins down too fast, there won t be enough rotational energy when remnant becomes optically thin

15 Is there sufficient rotational energy? Piro (2016) Favors quickly spinning (<2 ms) neutron stars with moderate B-field (<5x10 11 G)

16 What about FRBs &140514? Very different DMs: FRB , DM = pc/cm 3 FRB , DM = pc/cm 3 Similar positions within 9 arcmin: FRB , RA=22 h 34 m 38 s, DEC= FRB , RA=22 h 34 m 06 s, DEC= Could these be the same source? Maoz et al. (2016) conclude with 99% confidence that this is from the same repeating source based on location, FRB rate, and sky coverage

17 Assuming FRB & are the same source Over the 3.2 years, DM has changed by pc/cm 3 t 12 DM SNR (t+3.2) 2 DM SNR M M +DM stu 1/3 f v 2 9 1/3 yrs But we can even get a more model independent constraint! = t +DM 2 stu =0.596 t 2 (t +3.2) 2 < t<10.8yrs M<1.2(v 2 9/f)M

18 Stripped Envelope SN Light Curves Lyman et al. (2016) Absolute magnitude J 1994I 1996cb 1998bw 1999dn 1999ex 2002ap 2003bg 2003jd 2004aw 2004dk 2004dn 2004fe 2004ff 2004gq 2005az 2005bf 2005hg 2005kz 2005mf 2006T 2006aj 2006el 2006ep 2007C 2007Y 2007gr 2007ru 2007uy 2008D 2008ax 2009bb 2009jf 2010bh 2011bm 2011dh 2011hs iptf13bvn t p (applem/vc) 1/ log 10 Luminosity [erg/s] v (2E/M) 1/ Phase from peak [days]

19 Stripped Envelope SN Ejecta Masses IIb (9) Ib (13) Ic (8) Ic-BL (8) Pejcha 10 & Prieto (2015) Type IIP SNe Lyman et al. (2016) M<1.1(E 51 /f) 1/2 M f =0.1 Mej [M ] E K [10 51 ergs]

20 Neutron Stars (Hakobyan et al. 08) December 4, 2001 FRBs were 39 arcmin away :(

21 Persistent radio source! Chatterjee et al. (2017)

22 Young Magnetar FRB Model Metzger, Berger & Margalit 17 Synchrotron from either SN shock or pulsar nebula Argues for long term monitoring of persistent radio source.

23 Don t forget cataclysmic scenarios! Neutron stars collapsing to black holes, ejecting magnetic hair (Falcke & Rezzolla 13; Zhang 14) Merger of charged black holes (Zhang 16; Liu et al. 16; Liebling & Panenzuela 16) Magnetospheric activity during neutron star mergers (Totani 13) Unipolar inductor in neutron star mergers (Piro 12; Wang et al. 16) White dwarf mergers (Kashiyama et al. 13) Probably cannot produce the majority of FRBs, but we should keep them in mind

24 Blitzar NS collapsing to BH Falcke & Rezzolla (2014); Zhang (2014) NS accretes and spun up above usual maximum mass When spun down (magnetic braking?) NS collapses to BH, expelling B-field, producing FRB Lots of potential scenarios (NS mergers, fast spinning SNe, HMXBs, AIC) Many potential E&M and GW counterparts, but how will we uniquely know it s a blitzar?

25 Unipolar inductor during NS mergers Goldreich & Lynden-Bell 69; Hansen & Lyutikov 01; Lai 12; Wang et al. 16 Piro (2012)

26 Unipolar inductor emission Take ~1% of dissipation and put into radio as curvature radiation (Mingarelli, Levan, & Lazio 15) Large currents expected to repeatedly break circuit (Lai 12) Treating as an LR circuit (Piro, unpublished) flaring timescale is 1 Rtot t LR a c 4 /c Is the pair plasma surrounding the merger too dense for radio propagation? (Metzger & Zivancev 2016)

27 E&M counterparts to NS mergers Metzger & Berger (2012) GRB and afterglow Shattering of the NS crusts (Tsang et al. 12) Kilonova (~10 41 erg/s infrared to optical transient) Pulsar wind nebulae in radio (Piro & Kulkarni 13) Radio from ejecta-ism shock (Nakar & Piran 11) Relative timing of counterparts to FRB also important

28 Summary and Conclusion Repeating FRB argues for non-cataclysmic scenario unless strong evidence for multiple FRB progenitors Young neutron stars are attractive for producing rate and DM Rotational powering requires modest B-fields (<10 12 G) short P Host galaxy, DM constraints, suggest connection with stripped envelope supernovae Are FRBs and the same source? A 3 rd burst from this location would provide amazing constraints Cataclysmic scenarios are likely to have E&M and/or GW counterparts but probably cannot produce all FRBs

29 Questions How well can DMs be measured to look for changes? What are the limiting factors? How long do we have to stare at the location of FRBs and to rule out repeated bursts? What is the best strategy (cadence, targets, etc) for finding repeating bursts? When looking for E&M counterparts, are we searching parameter space to actually rule out models? Many of the counterparts (E&M, GW, etc) require nearby FRBs to be seen. Are we able to recover low DM FRBs?