a life of an ultrahigh energy cosmic ray Kumiko Kotera , Institut - PowerPoint PPT Presentation

From the magnetized Universe to neutrinos: a life of an ultrahigh energy cosmic ray Kumiko Kotera , Institut d’Astrophysique de Paris UCL HEP - 05/10/12

The puzzle of ultrahigh energy cosmic rays Why do we care about cosmic-rays? Energies that cannot be reproduced on Earth! Universe thru different eyes The puzzle: What source(s)? What physical mechanism(s)? flux 30 orders of magnitude Why is it so difficult? - detection issues energy - Particle Physics issues 10 orders of LHC - astrophysical issues magnitude 2

Astrophysical issues Active Galactic UHECRs are charged particles and the Universe is magnetized Nuclei (AGN) clusters source?? Gamma-ray bursts (GRB) pulsars Physics of powerful astrophysical objects is not known in detail 3

Particle Physics issues angle plan de la gerbe longitudinal développement development of longitudinal shower de la gerbe capteurs fluorescence "oeils de mouche" telescopes point d'impact LHC Cerenkov tank cuves Cerenkov shower extension latérale extension de la gerbe ultrahigh energies that cannot be reproduced on Earth ( E ~ 2 x 10 20 eV ) shower development (hadronic interactions) still unknown 4

Detection issues low flux! 1 particle/km 2 /century necessity to build larger and larger observatories 5

Since 1990 in ultrahigh energy cosmic rays Auger SOUTH Cerenkov tanks: 3000 km 2 1.5 km separation fluorescence detector (FD) sites: 4 (180 o ) ~100 events E > 5.7x10 19 eV ~30 events E > 5.7x10 19 eV Telescope Array (TA) Northern hemisph. scintillators: 762 km 2 1.2 km separation FD sites - 3 (180 o ) K.K. & Olinto 11 6

What observational information do we have? energy spectrum arrival directions in the sky chemical composition n o t o r p other messengers: secondary gamma-rays, n o r i neutrinos 7

Crucial information from the energy spectrum UHECR energy budget [@E=10 19 eV]: ~ 0.5x10 44 erg Mpc -3 yr -1 (2010) Katz et al. 09 acceleration to E>10 20 eV necessary magnetic luminosity (L B ≡ ε B L outflow ): L B > 10 45.5 erg/s Γ 2 β -1 Lemoine & Waxman 09 22% systematics 8

E UHECR > 10 20 eV: first selection of sources black holes/jets/hot spots Active Galactic acceleration limited Nuclei (AGN) updated Hillas diagram neutron star by radiation losses K.K. & Olinto 11 e.g. Norman et al. 1995, proton 10 20 eV Rachen & Biermann 1995, Henri et al. 1999, Lemoine & Waxman 2009 steady Fe 10 20 eV sources white accretion shocks AGN dwarf clusters R ~ 1-10 Mpc, B downstr ~ 1 µ G --> E ~ 10 20 eV ? but maybe B upstream << 1 µ G AGN jets e.g. Kang et al. 1997, GRB Miniati et al., 2000, hot spots Murase et al. 2008 SNR Gamma-ray accelation ok, IGM shocks bursts (GRB) but tight energy budget because rare source e.g. Waxman 1995, Vietri 1995, Murase 2008 transient confinement of particle in source: � sources particle Larmor radius < size of source ecrit r L ≤ L et pulsars very promising for � � B fast-spinning magnetized � − 1 � E r L = 1 . 08 Mpc Z − 1 ones! 10 18 eV 1 nG Fang, K.K., Olinto, Fryer, in prep. confinement dans une source de taille s’´ ecrit ! caution when applied to relativistic outflows 9

Crucial information from the energy spectrum maximum acceleration energy? GZK cut-off? or UHECR energy budget [@E=10 19 eV]: ~ 0.5x10 44 erg Mpc -3 yr -1 (2010) Katz et al. 09 acceleration to E>10 20 eV necessary magnetic luminosity (L B ≡ ε B L outflow ): L B > 10 45.5 erg/s Γ 2 β -1 Lemoine & Waxman 09 22% systematics 10

Energy losses for UHECRs for proton cosmic rays: backgrounds: CMB IR/optical/UV photons E p � m π ( m π + 2 m p ) c 4 � − 1 ∼ 10 19 eV � ǫ 6 x 10 19 eV pion photoproduction p + γ − → N + n π , 10 − 3 eV 2 ǫ duction de paires ´ E p � m e m p electrons-positrons : � − 1 ∼ 5 × 10 18 eV � → p + e + + e − ǫ 10 19 eV p + γ − pair photoproduction 10 − 3 eV ǫ 10000 Mpc cosmological expansion 1000 pair production energy loss distance source distance scale < 100s Mpc 100 pion production 10 GZK cut-off > 6 x 10 19 eV 1 10 17 10 18 10 19 10 20 10 21 proton energy [eV] 11

Crucial information from the energy spectrum maximum acceleration energy? GZK cut-off? or UHECR energy budget [@E=10 19 eV]: ~ 0.5x10 44 erg Mpc -3 yr -1 (2010) Katz et al. 09 ankle acceleration to E>10 20 eV necessary magnetic luminosity (L B ≡ ε B L outflow ): L B > 10 45.5 erg/s Γ 2 β -1 Lemoine & Waxman 09 extragalactic? Galactic? for particles with E > E GZK (~6x10 19 eV) sources within ~ few 100 Mpc ankle @ E~10 18.5 eV: Galactic/extragalactic transition? 22% systematics 12

What observational information do we have? energy spectrum arrival directions in the sky chemical composition n o t o r p other messengers: secondary gamma-rays, n o r i neutrinos 13

Puzzling composition measurements n o t o r p simulations n o r i n o t o r p n o r i T.A. Auger oct. 2011 ICRC 2011 Jui et al. 11 X max = parameter of the airshower sensitive to the composition HiRes, TA --> protons? all results compatible within systematics ??? what composition is that ??? 14

Puzzling composition measurements heavy nuclei? AGN Auger ICRC 2011 clusters ??? what composition is that ??? e.g., Lemoine 02, Pruet et al. 02, Wang et al. 08, GRB Murase et al. 08 T.A. ICRC 2011 pulsars at the sources: e.g., Ruderman & heavy nuclei if metal-rich or nucleosynthesis Sutherland 75, Arons & Scharlemann 79, escape difficult due to photo-disintegration in source? metal-rich surface, Blasi et al. 00, iron could escape Fang et al. in prep. 15

What observational information do we have? energy spectrum arrival directions in the sky chemical composition n o t o r p other messengers: secondary gamma-rays, n o r i neutrinos

Arrival directions in the sky & magnetic fields deflection : spatial decorrelation time delay : temporal decorrelation if transient source Extragalactic magnetic fields? poorly known (no observation) source?? upper limits: B l coh1/2 < 1-10 nG Mpc 1/2 simulations --> complex and contradictory Beck 08, Vallée 04, Dolag et al. 05, Sigl et al. 05, Ryu et al. 98, Donnert et al. 09... Auger Propagation of UHECR @ Earth in extragalactic magnetic fields? complicated because B not known e.g., Dolag et al. 05, Sigl et al. 05, Ryu et al. 98, Takami & Sato 08, KK & Lemoine 08 + Galactic magnetic fields... 17

Arrival directions in the sky seen by Auger density map of Swift-BAT hint of no powerful correlation source in arrival with LSS directions GRB AGN pulsars clusters OR steady sources? transient source? source already extinguished when UHECR arrives - particularly strong extragalactic magnetic field correlation with LSS with no visible counterpart - UHECR = heavy nuclei no correlation with secondary neutrinos, photons, grav. waves >165 events ( >4 years with Auger South) Will better statistics help? to reach a 5 σ significance 18

Separate source populations with anisotropy YES time delay effects (deflections in magnetic fields) -> distribution of UHECRs for transient sources different from LSS separation possible for 10 3 events deflection effects for above 60 EeV transient sources LSS isotropic Kalli, Lemoine, K.K., 2011 measurement of correlation btw observed and predicted event distributions 19

A clear necessity: increasing the statistics... JEM-EUSO E th > 10 20 eV duty cycle 20% Auger S x (~30) Adams et al. 2012, arXiv:1203.3451 20

... and look at other messengers Auger Coll. 2008 astrophysical sources acceleration no powerful sources UHECR as counterparts! Extragalactic magnetic fields? interactions on baryonic and photonic backgrounds at the source cosmogenic secondary astroparticles neutrinos γ rays observable? what information ? 21

What cosmogenic neutrinos could tell us K.K., Allard & Olinto, 2010 see also Decerprit & Allard 2011 cosmogenic neutrino fluxes and instrument sensivities FRII galaxies and other sources with strong emissivity evolution excluded by Fermi (diffuse gamma ray flux) Ahlers et al., 2010; Berezinsky et al., 2010 by Auger and soon by IceCube proton dominated dip model “reasonable” proton dominated ankle model proton dom., no source evolution pure iron, no source evolution iron rich, no source evolution 1) FRII galaxies excluded 2) reasonable models within reach? 3) there is a bottom 22

What if the IceCube PeV neutrino detection were true? S. Yoshida for the IceCube Coll., 2.46- σ measurement of 2 events at PeV energies seminar at APC (Paris), April 2012 - does not look atmospheric - FRII source evolution already ruled out - probably not cosmogenic neutrinos - neutrinos produced at sources --> evidence of UHECRs ~ 10 17 eV - either Galactic source --> check arrival direction, correlate with Galactic source catalogues - or extragalactic source if nothing in the Galaxy. If source is not transient, possible correlation with extragalactic source.