FRBs as Probes of Fundamental Physics

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1 FRBs as Probes of Fundamental Physics Xue-Feng Wu Purple Mountain Observatory, Chinese Academy of Sciences

2 Outline Einstein s equivalence principle tests Constraints on the rest mass of photon Summary and prospect 2

3 Outline Einstein s equivalence principle tests Constraints on the rest mass of photon Summary and prospect 3

4 Einstein s Equivalence Principle 100 anniversary of Einstein s General Relativity ( ) 4

5 Einstein s Equivalence Principle Weak Equivalence Principle (WEP): inertial mass = gravitational mass (all the test particles have the same acceleration in the gravitational field, independent of their masses) An alternative statement of WEP is that the trajectory of a freely falling test body (one not acted upon by such forces as electromagnetism and too small to be affected by tidal gravitational forces) is independent of its internal structure and composition. Clifford M. Will, 2014, Living Reviews Relativity, 17, 4 (Strong)Equivalence Principle (EP): The result of a local non-gravitational experiment by a free-falling person in a gravitational field, is independent of the gravitational field 5

6 Einstein s Equivalence Principle Einstein s happiest idea Einstein s Equivalence Principle (EEP): 1 WEP valid; 2 Local Lorentz Invariance(LLI): The outcome of any local non-gravitational experiment is independent of the velocity of the freely-falling reference frame in which it is performed. 3 Local Position Invariance(LPI): The outcome of any local non-gravitational experiment is independent of where and when in the universe it is performed. Will, 2014, Living Reviews Relativity, 17, 4 6

7 Einstein s Equivalence Principle Parametrized Post Newtonian formalism (PPN): Will, 2014, Living Reviews Relativity, 17, 4 7

8 Einstein s Equivalence Principle PPN parameters: Will, 2014, Living Reviews Relativity, 17, 4 8

9 Einstein s Equivalence Principle PPN parameters: Will, 2014, Living Reviews Relativity, 17, 4 9

10 Tests of post-newtonian gravity in the Milky Way SN1987A: Milky Way version of

Where:LMC,distance ~ 50 kpc When: (1)neutrino burst:feb., 23.

443UT, 1987 ~ 3 hrs later than neutrino burst Masatoshi Koshiba Riccardo Giacconi

and Masatoshi Koshiba "for pioneering contributions to astrophysics, in particular

10 10 Tests of post-newtonian gravity in the Milky Way SN1987A: Milky Way version of the Pisa tower experiment Raymond Davis Jr. Where:LMC,distance ~ 50 kpc When: (1)neutrino burst:feb., UT, 1987 Kamioka IMB (2)optical: Feb., UT, 1987 ~ 3 hrs later than neutrino burst Masatoshi Koshiba Riccardo Giacconi The Nobel Prize in Physics 2002 was divided, one half jointly to Raymond Davis Jr. and Masatoshi Koshiba "for pioneering contributions to astrophysics, in particular for the detection of cosmic neutrinos" and the other half to Riccardo Giacconi "for pioneering contributions to astrophysics, which have led to the discovery of cosmic X- ray sources.

11 Tests of post-newtonian gravity in the Milky Way SN1987A: Milky Way version of the Pisa tower experiment (Courtesy by Longo, 1988, PRL) Shapiro delay: (1)d~50 kpc (2)b=12 kpc (3)MW s U(r)=-GM/r (mass of LMC is <5% of MW) Longo, 1988, PRL;Krauss & Tremaine 1988, PRL 11

12 Tests of post-newtonian gravity in the Milky Way SN1987A: Milky Way version of the Pisa tower experiment (Courtesy by Longo, 1988, PRL) (1)time delay between photons and neutrinos(<6 hours) (1)time delay between 2 neutrinos(7.5mev, 40MeV)<10 s Longo, 1988, PRL;Krauss & Tremaine 1988, PRL 12

13 Testing WEP with cosmic transients IceCube neutrinos GWB Blazar GRB b Gao, Wu, Meszaros, 2015, ApJ 13

Testing WEP with cosmic transients Testing WEP with GRB ev MeV GeV photons GRB 090510 GRB 080319B Racusin et al.

14 Testing WEP with cosmic transients Testing WEP with GRB ev MeV GeV photons GRB GRB B Racusin et al., 2008, Nature Constraint on the PPN gamma with GRBs: (1) GRB (z=0.90): (2) GRB B (z=0.94): (3) Hipparcos (Froeschle et al. 1997): Abdo et al., 2009, Nature (1)-(3), ev MeV GeV, Gao, Wu, & Meszaros, P., 2015, ApJ, 810,

15 Testing WEP with cosmic transients Testing WEP with blazar kev TeV photons Mrk 421 Wei, Wang, Gao, Wu*, 2016, ApJL Constraint on the PPN gamma with blazars: (1) Mrk 421 (z=0.031): (2) Mrk 501 (z=0.034): (3) PKS (z=0.117) (4) GRB (Gao, Wu & Meszaros et al. 2015): ev MeV GeV, therefore,from (1)-(4), ev MeV GeV TeV, Furniss et al., 2015, ApJ 15

16 Testing WEP with cosmic transients Testing WEP with gravitational waves GW150914: first GW event 1. Merger phase t(150 Hz)- t(30 Hz) ~ 0.2 s 2. Ringdown phase t(100 Hz)- t(200 Hz) ~ ms Wu,Gao,Wei,Meszaros,Zhang,Dai, Zhang,Zhu,2016,PRD,94, Abbott et al. 2016, PRL, 116,

Discovery of Fast Radio Bursts 1. First FRB(Lorimer 2007) FRB 010724 Lorimer Burst 2. More FRBs (Keane et al. 2011; Thornton et al.

17 Discovery of Fast Radio Bursts 1. First FRB(Lorimer 2007) FRB Lorimer Burst 2. More FRBs (Keane et al. 2011; Thornton et al. 2013; Burke-Spolaor & Bannister 2014; Spitler et al. 2014; Ravi et al. 2015, etc.) 3. Event rate: ~several x 1,000 FRBs/sky/day Lorimer et al., 2007, Science 17

18 Advantages of FRBs in WEP tests Dispersion Measures (DM) smaller difference in arrival times!!! Thorton, et al., 2013, Science (1.2GHz-1.5GHz)< 1 s 18

2 sigma confidence level @ t=1076 s Deng & Zhang (2014) estimated the

19 Possible associations of FRBs with GRBs Bannister et al. 2012, ApJ: GRB A GRB A 6.6 sigma confidence t=524 s 6.2 sigma confidence t=1076 s Deng & Zhang (2014) estimated the redshift of the two GRBs with DM: z = (0.554, 0.687) for GRB A z = (0.130, 0.246) for GRB A 19

20 Possible associations of FRBs with GRBs FRB : gamma-ray counterpart? GRT position FRB+GRT position FRB position DeLaunay et al. (2016, ApJL): association probability: 3.2σ confidence 20

FRB 150418: first afterglow and redshift? radio afterglow & host galaxy z = 0.492? radio flares from host AGN? (Williams & Berger, 2016, etc.

21 FRB : first afterglow and redshift? radio afterglow & host galaxy z = 0.492? radio flares from host AGN? (Williams & Berger, 2016, etc.) coincidence of this FRB and radio flares is quite low (Li & Zhang, 2016) cosmic comb model (Zhang 2017) Keane et al., 2016, Nature, 530,

FRB 121102: first confirmed host galaxy and redshift FRB

22 FRB : first confirmed host galaxy and redshift FRB (repeating): z=0.193 at least some FRBs are at cosmological distances Gemini: Gillet (GMOS) Chatterjee et al., 2017, Nature, 541, 58; Tendulkar et al., 2017, ApJL 22

Testing WEP with FRBs FRBs vs. GRBs : 2 orders of magnitude better (Milky Way potential) Constraint on the PPN gamma with FRBs: (1) FRB 110220 (z~0.81): Red (from top to bottom): Δt(DM)=0.

23 Testing WEP with FRBs FRBs vs. GRBs : 2 orders of magnitude better (Milky Way potential) Constraint on the PPN gamma with FRBs: (1) FRB (z~0.81): Red (from top to bottom): Δt(DM)=0.001Δt(obs) Δt(DM)=0.999Δt(obs) Blue(from top to bottom): d=1mpc, 0.5z, 2z, 3z (2) FRB/GRB A (z=0.246): (3) FRB/GRB A (z=0.166) Uncertainty of FRB distance will NOT affect the constraint too much: Wei, Gao, Wu, & Meszaros, P., 2015, PRL 23

24 Testing WEP with FRBs Tingay & Kaplan, 2016, ApJL, 820, 2, L31 FRB vs. FRB (Wei et al. 2015): ~ 1 order of magnitude better Considering the span of the energies, introducing the constraint on instead of, where is the ratio of high and low energies used in the limit. 24

25 Large-scale structure vs. Milky Way potential : ~ 4 orders of magnitude better Nusser, 2016, ApJL, 821, L2 Constraint on the PPN gamma by LSS: (1) FRB (z~0.81): Testing WEP with FRBs (2) FRB (z=0.492?): (3) GRB (z=0.903): (4) GRB B (z=0.937): see also Zhang, Shuang-Nan, arxiv:

26 Testing WEP with Crab pulsar giant pulse Hankins & Eilek, 2007, ApJ 26

27 Testing WEP with Crab pulsar giant pulse most stringent limit with MK Yang & Zhang, 2016, PRD (rapid communications), 94,

28 Outline Einstein s equivalence principle tests Constraints on the rest mass of photon Summary and prospect 28

29 Upper limits on the photon mass Maxwell s equations/einstein special relativity have a basic assumption: all electromagnetic radiation travels in vacuum at the constant speed c The photon mass should be strictly zero Otherwise, the Maxwell s equations changed to Proca equations Ultimate upper limit(uncertainty principle): Upper limit adopted by the Particle Data Group: Olive et al. (2014): Most stringent limit: Chibisov (1976) : analysis of the mechanical stability of the magnetized gas, however, depends on many assumptions. The most direct and model-independent method: Measuring the frequency dependence of the velocity of light 29

30 Photon mass limit by the stability of the magnetized gas Magnetic fields of Jupiter and Earth: (Davis-jr et al. 1975,PRL;Fischbach et al.1994,prl) Solar wind: adopted by Particle Data Group 30

31 Photon mass limit by the stability of the magnetized gas Magnetic fields of Jupiter and Earth: (Davis-jr et al. 1975,PRL;Fischbach et al.1994,prl) Solar wind: 31

32 Massive photons and fundamental physics Physical Review D, 93(8),id Massive photons have been evoked for (i.e., Retino et al., 2016, Astroparticle Physics,82, 49) (1) dark matter, (2) inflation, (3) charge conservation, (4) magnetic monopoles, (5) Higgs boson, etc., and in (a) applied physics, (b) superconductors, (c) light shining through walls experiments. 32

33 Velocity dispersion from the nonzero photon mass If the photon has a non-zero rest mass: Dispersion of the group speed of photons in vacuum: where, If A can be constrained by observations, then the mass of photon is: 33

difference lower frequency longer distance shorter arrival time redshift z

34 The time delay induced by the nonzero photon mass If the source is not at cosmological distance If the source is cosmological,the arrival time difference lower frequency longer distance shorter arrival time redshift z higher frequency photon lower frequency photon smaller A more stringent constraint observer z=0 34

35 Astronomical Constraints on the photon mass in History Tu, Luo, Gillies, 2005, Rep. Prog. Phys 35

36 Astronomical Constraints on the photon mass in History Measurement of the frequency dependence of the velocity of light dispersion in the arrival time of optical wavelengths of 0.35 and 0.55 μm (Warner & Nather,1969,Nature) arrival time of optical and radio emission (Lovell et al. 1964,Nature) time delay between radio and the gamma-ray emissions (Schaerfer. 1999, PRL) 36

37 Upper limits on the photon mass with more GRBs radio gamma-ray time delay, same as Schaefer (1999);GRB A different afterglow peak times between two radio frequency: peak times fitted by models:grb peak times observed:grb C peak time difference excluding the astrophysical intrinsic delay:δt is reduced but model (jet+synchrotron) dependent, e.g., GRB Zhang, Chai, Zou, & Wu, 2016, JHEAp, 11, 20 37

Dispersion by plasma effect t DM = 3 DM ( cm 2.

38 Dispersion by plasma effect t DM = 3 DM ( cm pc) 2 ν ν -2 degeneracy with the effect by the nonzero photon mass 38

39 Upper limits on the photon mass with FRB Keane, et al., 2016, Nature, 530, 453 (Warner & Nather,1969,Nature) (Lovell et al. 1964,Nature) (Schaerfer. 1999, PRL) (Wu, Zhang, Gao, Wei, Zou, Lei, Zhang, Dai, Meszaros, 2016, ApJL) (1) difference in arrival times between Cosmological origin: 1.5 GHz and 1.2 GHz: Δt < 0.8 s; (2) Host galaxy redshift z=0.492 (?) Extragalactic origin: FRB with host galaxy (d = 1 Mpc) and z=0.193 measured (Tendulkar et al. 2017) 39

Upper limits on the photon mass with FRB 150418

40 Upper limits on the photon mass with FRB Bonetti, et al., 2016, PLB (arxiv: ) 40

Upper limits on the photon mass with FRB 121102 FRB 121102: first well localized FRB (Chatterjee et al. 2017, Nature) with redshift measurement of z=0.

41 Upper limits on the photon mass with FRB FRB : first well localized FRB (Chatterjee et al. 2017, Nature) with redshift measurement of z=0.192 (Tendulkar et al. 2017, ApJL) total DM Milky Way DM extragalactic DM IGM DM host galaxy+circumburst DM 1.77x10^(-47) g Bonetti, et al., arxiv:

42 Radio Pulsars in the Magellanic Clouds The LMC and SMC are the only galaxies other than our own that have detectable pulsars: lower frequency longer distance shorter arrival time more stringent constraint on the photon mass LMC (~50 kpc): 21 radio pulsars SMC (~60 kpc): 5 radio pulsars (McCulloch et al. 1983; McConnell et al. 1991; Crawford et al. 2001; Manchester et al. 2006; and Ridley et al. 2013) Compared to the Crab pulsar (~2 kpc), radio pulsars in the LMC and SMC have two advantages: 1. Radio emission 2. Longer distance 42

43 Photon Mass Limits from Radio Pulsars minimizing C1 = DM / DIST 43

44 Photon Mass Limits from Radio Pulsars (1) LMC : PSR J L=49.7 kpc, DM=45 pc/cm^2 (2) SMC: PSR J L=59.7 kpc, DM=70 pc/cm^2 Wei, Zhang, Zhang & Wu, 2017,RAA, in press, arxiv: Manchester et al. 2006, ApJ, 649,

45 Photon Mass Limits from GRBs/FRBs/pulsars (Warner & Nather,1969,Nature) (Lovell et al. 1964,Nature) (Schaefer. 1999, PRL) (Wei et al.,2017, RAA) extragalactic origin(d=1 Mpc) (Wu, Zhang, Gao, Wei, Zou, Lei, Zhang, Dai & Meszaros, 2016, ApJL,) cosmological origin ( z=0.5 ) 45

46 Outline Einstein s equivalence principle tests Constraints on the rest mass of photon Summary and prospect 46

47 Summary: WEP tests Testing EEP with GRB photons ev MeV GeV, Δγ<10^(-3) Testing EEP with FRB photons GHz, Δγ<10^(-7) Testing EEP with Crab giant pulse photons GHz, Δγ<10^(-15) Testing EEP with TeV blazar photons kev TeV, Δγ<10^(-3) subtev TeV, Δγ<10^(-6) Testing EEP with GW events Hz gravitons, Δγ<10^(-9) The constraint will be improved by 2-4 orders of magnitude with large-scale structure fluctuation /Laniakea supercluster of galaxies potential 47

48 Summary: photon mass constraints Constraints by the dispersion (time of flight) method: photon mass limit by GRBs/radio pulsars mγ< ~10^(-45) g photon mass limit by FRBs mγ < ~10^(-47) g one of most direct and conservative constraints. 48

49 Prospect: FRB observations Radio facilities: Parkes, Arecibo, GBT, etc. CHIME, FAST, Tianma, SKA (ASKAP), etc. The CHIME (Canadian Hydrogen Intensity Mapping Experiment) radio telescope: four fixed 20- by 100-m semi cylinders MHz FoV: 200 square degrees Operate in the latter half of 2017 could detect dozens of FRBs per day! Kaspi, V. M., 2016, Science

50 Prospect: FRB observations More diverse FRB features are expected to be discovered: pulse duration: shorter (sub millisecond) or longer? repetition: double-peaked? triple-peaked? etc. counterparts: EM signals and afterglows? associations: GRBs, GWs, neutrinos, pulsar giant pulses? Looking at the history of the GRB field, nature (the Universe) is more unexpected than we thought

51 Prospect: WEP tests with FRBs Multi-messenger Astronomy WEP tests can use different species of particle (different internal structure and composition) Δγ =γ(gw)-γ(photon) EM: from radio to gamma-ray GW: several Hz Neutrinos: MeV - TeV FRBs-GRBs-GWs (macronovae) triple events? FRBs with neutrinos, pulsar giant pulses? Wu,Gao,Wei,Meszaros,Zhang,Dai, Zhang,Zhu,2016,PRD,94,

52 Prospect: photon mass limit The upper limit on the photon mass could be improved if a sample of FRBs with redshift measured time delay by plasma effect due to IGM/host can be extracted lower frequency FRBs are discovered photon mass upper limit is proportional to frequency Thank you

53 Back up

54 Tests of post-newtonian gravity in the Solar system Tests of γ:i. The deflection of light GR effect Will, 2014, Living Reviews Relativity, 17, 4 54

55 Tests of post-newtonian gravity in the Solar system Tests of γ:ii. The (Shapiro) time delay of light A radar signal from Earth to the Source, then back to Earth The time delay by the Sun s gravity: a planet or satellite) Will, 2014, Living Reviews Relativity, 17, 4 55

56 Tests of post-newtonian gravity in the Solar system Tests of γ:results VLBI: quasars, 3C279 Hipparcos: optical starlight Viking: Mars lander Cassini: Saturn Will, 2014, Living Reviews Relativity, 17, 4 56

57 光子静止质量已有限制广义相对论 / 电磁理论基本假设若不为零, 麦克斯韦方程 ->Proca 方程光子质量限定方法 : 实验室检验 ( 安培定律库伦定律 ): Tu et al.2006: 天体物理检验 : 等离子体波动 (Ryutov 2007,PlasPhysControlFusion): 多波段光子时间延迟 (Schaefer 1999,PRL): 引力透镜 (Accioly & Pazszko 2004,PRD): 气体稳定性 (Chibisov 1976,SovPhysUsp): 国际粒子数据组 PDG 采用的上限 : = 1.783x10^-51 g 终极下限 ( 测不准原理, 时间不确定取宇宙时标 ): 57

arxiv: v1 [astro-ph.he] 24 Dec 2015

arxiv: v1 [astro-ph.he] 24 Dec 2015 Testing Einstein s Equivalence Principle with Fast Radio Bursts arxiv:1512.07670v1 [astro-ph.he] 24 Dec 2015 Jun-Jie Wei 1, He Gao 2, Xue-Feng Wu 1,3, and Peter Mészáros 4,5,6 1 Purple Mountain Observatory,