Strangelets from space. Jes Madsen University of Aarhus, Denmark

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1 Strangelets from space Jes Madsen University of Aarhus, Denmark

2 Strangelets from space What are strangelets? Why are they interesting as ultra-high energy cosmic rays? Could a significant cosmic strangelet flux exist and be measured? A strangelet search with the Alpha Magnetic Spectrometer (AMS-02) on the International Space Station.

3 Ordinary strangelets Witten; Farhi & Jaffe Madsen, PRD 50 (1994) 3328 B=(145 MeV) 4 m s =50,100, 300MeV Shell-model vs. liquid drop model Bulk A Surface tension A 2/3 CurvatureA 1/3

4 4 B = (145MeV) vs. (165MeV) 4

5 CFL-strangelets Madsen, PRL 87 (2001)

6 Strangelets have low Z/A Heiselberg, PRD 48 (1993) 1418 [Ordinary strangelets] Madsen, PRL 87 (2001) [CFL] 0.3A 2/3 8A 1/3 Nuclei 0.5A 0.1A

7 Strangelet charge Ordinary Z = 8 m A 1/3 (A>>1000) Z = 0.1 m A (A<<1000) Color-flavor locked Z = 0.3 m 150 A 2/3 Vacuum polarisation dominates at high A => lower Z [Madsen & Larsen, PRL 90 (2003) ]

8 Cronin, Gaisser & Swordy (1997)

9 Detection of UHECR s (Anchordoqui et al. Int.J.Mod.Phys.A18 (2003) 2229

10 Is there a GZK-cutoff? Abbasi et al. (High Resolution Fly s Eye Collaboration), PRL 92 (2004)

11 Plausible sources for UHECR s (Anchordoqui et al. Int.J.Mod.Phys.A18 (2003) 2229 Supernovae explosions [147, 148]. Large scale Galactic wind termination shocks [149]. Pulsars (neutron stars) [150]. Active galactic nuclei (AGNs) [151]. BL Lacertae (BL Lac) a sub-class of AGN [152, 153]. Spinning supermassive black holes associated with presently inactive quasar remnants[154, 155] Large scale motions and the related shock waves resulting from structure formation in the Universe [157] such as accretion flow onto galaxy clusters and cluster mergers [158, 159]. Relativistic jets and hot-spots produced by powerful radiogalaxies. [161, 162, 163]. The electrostatic polarization fields that arise in plasmoids produced in planetoid impacts onto neutron star magnetospheres [166]. Magnetars pulsars with dipole magnetic fields approaching 1015 G [167, 168, 169] appear also as serious candidates [170, 171]. Starburst galaxies [172, 173, 174]. MHD winds of newly formed strongly magnetized neutron stars [175]. Gamma ray burst (GRB) fireballs [176, 177, 178, 179]. Strangelets, stable lumps of quark matter, accelerated in astrophysical environments [180]. Hostile aliens with a big CR gun [181].

12 Why are strangelets interesting as ultra-high energy cosmic rays? Madsen & Larsen, PRL 90 (2003) Avoids the acceleration problem of ordinary UHECR candidates 2. Avoids the GZK cut-off from interaction with 2.7K cosmic microwave background

13 Why are strangelets interesting as ultra-high energy cosmic rays? Madsen & Larsen, PRL 90 (2003) Z STRANGELET >> Z NUCLEUS possible Better acceleration in known sources (E MAX = R MAX Z; R MAX magn.field x size) Rigidity R = p/z (= E/Z if relativistic)

14 Hillas-plot for E(max)=10 20 ev Stecker/Olinto (2000)

15 Hillas-plot for E(max)=10 20 ev Strangelet Z=10 4

16 Why are strangelets interesting as ultra-high energy cosmic rays? Madsen & Larsen, PRL 90 (2003) Less susceptible to GZK-cut-off from high-lorentz-factor interactions with 2.7K CMB-photons because of High A Low Z/A

17 Eliminating the GZK-cutoff a) Photo-pion production cut-off at E γ Amp eva photo-pion π b) Photo-disintegration at E γ Amp eva photo-dis dis c) Photo-pair-production above E γ Amp eva photo-pair pair γ dis 10MeV / 2 1 de / dt Z A small for low Z / γ γ π A mπ / E2. 7K E 2. 7K pair 2me / E2. 7K

18 Measuring strangelets at GeV Find low Z/A cosmic rays with high precision equipment in space => AMS-02

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21 Alpha Magnetic Spectrometer AMS-02 International Space Station (2012) PURPOSE Cosmic rays Antimatter (anti-he) Dark matter Strangelets

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25 Choutko (MIT)

26 Strangelets from strange star binary collisions 1 binary neutron star collision per years in our Galaxy Release of 10-6 solar masses per collision Basic assumptions: SQM absolutely stable! All mass released as strangelets with mass A (fluxes for mass A give lower limit of flux if mass spectrum of masses below A)

27 Strangelet propagation Acceleration in supernova shocks etc Source-flux powerlaw in rigidity Diffusion in galactic magnetic field Energy loss from ionization of interstellar medium and pion production Spallation from collision with nuclei Escape from galaxy Reacceleration from passing shocks

28 Cosmic strangelet flux Z=8, A=138 [CFL] Flux (per [year GV sqm sterad]) Source Interstellar Solar System Madsen (2004) PRELIMINARY Rigidity (GV)

29 Cosmic strangelet flux Z=8, A=138 [CFL] Flux above R (per [year sqm sterad]) Solar System Interstellar Source Madsen (2004) PRELIMINARY Rigidity (GV)

30 Total CFL-strangelet flux Total flux (per [year sqm sterad]) No geomagnetic cutoff Interstellar Solar System Madsen (2004) PRELIMINARY Z

31 Total CFL-strangelet flux Total flux (per [year sqm sterad]) No geomagnetic cutoff Interstellar Solar System Madsen (2004) PRELIMINARY A

32 Conclusions Strangelets have low Z/A CFL and non-cfl strangelets differ wrt. Z Experimental verification/falsification of Strangelet existence Realistic from AMS-02 [2007/8-2010] Possible from lunar soil search experiment [Sandweiss et al. (Yale); Fisher et al. (MIT); Madsen (Aarhus) 2004] (A,Z)-relation (CFL or ordinary) Optimistic, but not impossible from AMS-02 or perhaps lunar soil search