> News < AMS-02 will be launched onboard the Shuttle Endeavour On May 2nd 2:33 P.M. from NASA Kennedy space center!

> News < Anti-matter, dark matter measurement By measuring the cosmic rays (Mainly electron, positron, proton, anti-proton and light nuclei) AMS-02 will be launched onboard the Shuttle Endeavour On May 2nd 2:33 P.M. from NASA Kennedy space center!

> News < Anti-matter, dark matter measurement By measuring the cosmic rays (Mainly electron, positron, proton, anti-proton and light nuclei) e + e - AMS-02 will be launched onboard the Shuttle Endeavour On May 2nd 2:33 P.M. from NASA Kennedy space center!

99 Years from Discovery : What is our current picture on Cosmic Rays? #5 How do Cosmic Rays gain their energy? Presented by Nahee Park

#4 Looking at the universe through different glasses I. Electromagnetic radiation II. Interactions of EM radiation III. Connection to Cosmic Rays

#4 Looking at the universe through different glasses I. Electromagnetic radiation - Covering wide energy range - more than 15 decades order!(radio, infra-red, visible light, ultra-violet, X-ray, gamma-ray) II. Interactions of EM radiation - Photoelectric effect - Compton scattering - Pair production III. Connection to Cosmic Rays - Full understanding of interactions of cosmic rays ( e.g. air shower) - EMR can provide information of cosmic rays origin ( EMR is not bending in magnetic field and we know what can create them by understanding the interactions!)

#5 How do Cosmic Rays gain their energy? I. Acceleration mechanism of CR II. Nature-made-accelerator in the universe & measurements

#5 How do Cosmic Rays gain their energy? I. Acceleration mechanism of CR II. Nature-made-accelerator in the universe & measurements Quite overlapping with 68th Compton Lecture s #5 (given by Brian Humensky)

LHC - Best of man-made accelerator LHC (The Large Hadronic Collider) (http://lhc-machine-outreach.web.cern.ch/lhc-machineoutreach/) 27 km long circular tunnel First collisions at an energy of 3.5 TeV per beam ( March 30th 2010) Designed to collide two counter rotating beams of protons and heavy ions. ( Foreseen Proton-proton collision of energy 7TeV per beam ) Beam is guided by magnetic field generated by superconductive magnet ( 8.4 Tesla = 8.4 10 4 Gauss) Beam line is maintained as vacuum state 10-10 Torr (~3 million molecules/cm 3 ) Annual power consumption: 800,000 MWh ( ~ $30 million per year for electricity)

How do Cosmic Ray gain their energy? Power source Power for accelerators to keep working Acceleration mechanism Mechanism which can accelerate particles to high energy

How do Cosmic Ray gain their energy? Power source Power for accelerators to keep working Acceleration mechanism Mechanism which can accelerate particles to high energy LHC physics

How do Cosmic Ray gain their energy? Power source Power for accelerators to keep working Acceleration mechanism Mechanism which can accelerate particles to high energy LHC beam energy (design goal) LHC physics

Additional points to fit in... Items need to be explained Should cover the wide range of cosmic rays fluxes Should explain stable fluxes of cosmic rays Should explain smooth curvature of fluxes of cosmic rays Should explain characteristics of cosmic rays Knee, Ankle Should explain proton dominant composition of cosmic rays

Acceleration Theory by Enrico Fermi Acceleration mechanism by Enrico Fermi (1949) Particle can gain small amount of energy in average when it is reflected by a cloud, which contains turbulent magnetic field (Elastic collision) The longer it stays, particle will gain higher energy [Movie] Strange case of the cosmic rays (1957) Magnetized cloud

Shock Acceleration Theory If there is a plane shock wave (with magnetic field) moving with high speed, then particle can gain energy by crossing the shock front downstream upstream Shock wave * Faster acceleration then magnetic cloud s case * Provide prediction of slope in cosmic rays fluxes

Conditions for Acceleration Site Should have Magnetic field strong enough to hold particles until it reaches high energy High speed shock wave There should be enough amount of acceleration sites in the galaxy with considerably stable supply

Acceleration Candidate Site Supernova Remnant [animation] A supernova remnant is the structure resulting from the explosion of a massive star the supernova. A supernova remnant is bound by an expanding shock wave ejected material expanding from the explosion the interstellar material it sweeps up and shocks along the way. Shock wave speed : 1,000 ~ 10,000 km/s Magnetic field strength : 10 μg ~ several mg? Maximum possible accelerating energy ~ Z 10 14 ev Tycho supernova remnant low energy x-ray (hot expanding debris) : red high energy x-ray (high energy electron) : blue

Is it really the accelerator? Hints Energy budget Assuming 1 SN per 50 years, 10~20% of their kinetic energy can explain cosmic rays power budget Check List Composition at Knee region?

Is it really the accelerator? Hints Energy budget Assuming 1 SN per 50 years, 10~20% of their kinetic energy can explain cosmic rays power budget Check List Composition at Knee region? Galactic

Is it really the accelerator? Hints Energy budget Assuming 1 SN per 50 years, 10~20% of their kinetic energy can explain cosmic rays power budget Check List Composition at Knee region? Galactic Extragalactic

Using Gamma-ray as indicator Cosmic rays cannot point to the acceleration site But, due to environmental conditions, cosmic rays will lose their energy can create gamma rays can travel without bending inside the magnetic field Proton electron Nuclear interaction π 0 decay gamma-ray Bremsstrahlung Matter gamma-ray Magnetic field

Using Gamma-ray as indicator Cosmic rays cannot point to the acceleration site But, due to environmental conditions, cosmic rays will lose their energy can create gamma rays can travel without bending inside the magnetic field electron Proton Nuclear interaction π 0 decay gamma-ray Bremsstrahlung gamma-ray Matter electron Synchrotron radiation Magnetic field gamma-ray

Gamma-ray at SNR Gamma-ray detection at SNR Tycho IC443 SN1006

Easier to confirm for electron Proton electron Acceleration of electron in SNR (or other astronomical object) is easier to detect compared to proton Bremsstrahlung Matter Nuclear interaction π 0 decay gamma-ray gamma-ray electron Synchrotron radiation Magnetic field gamma-ray electron Inverse Compton scattering Photon field gamma-ray Bfield : 30μG Top: Modelling was done by using an electron spectrum in the form of a power law with an index of 2.1, an exponential cutoff Bfield : 120μG at 10 TeV and a total energy of We = 3.3 10 47 erg. The magnetic Electron vs. Proton ratio : 1:10,000 field amounts to 30 µg. Centre: Modelling using a proton spectrum in the form of a power law with an index of 2.0, an exponential cutoff at 80 TeV and a total proton energy of Wp = 3.0 10 50 erg (using a lower energy cut off of 1 GeV). The electron/proton ratio above 1 GeV was Kep = 1 10 4 with an electron spectral index of 2.1 and cutoff energy at 5 TeV. The magnetic field amounts to 120 µg and the average medium density is 0.085 cm 3.consistency, the VHE -ray energy distribution was determined from the sum of the two previously defined regions. In this phe-nomenological model the current distribution of particles (electrons and/or protons) is prescribed with a given spectral shape corresponding to a power law with an exponential cutoff, from which emission due to synchrotron radiation, bremsstrahlung and IC scattering on the Cosmic Microwave Background (CMB) photons is computed. The π0 production through interactions of

Gamma ray from other galaxy Gamma-ray detection at other galaxy M82 (The Cigar Galaxy) * Starburst galaxy * 12 Million L.Y away * 10 times faster star formation rate * supernovae rate is 0.1 to 0.3 per year * high mean gas density of about 150 particles per cm 3

Will it be enough to explain all? Galactic Cosmic Rays Extragalactic Cosmic Rays If there is a powerful enough accelerator which can create higher energy than supernova remnant, there should be very strong activity detectable by other messengers Kink happens possibly, Limit of accelerator (or acceleration mechanism) Limit of source It will be very hard to confine ultra high energy cosmic rays within the galaxy

Ultra High Energy Cosmic Ray Ultra High Energy Cosmic Ray (UHCR) Hunting for the highest cosmic rays continued throughout 1960s Air showers from higher than 10 20 ev has been reported Greisen-Zatsepin-Kuzmin cutoff (1966) 10 20 ev cosmic rays cannot travel further than ~ 13 Mpc due to interactions with cosmic microwave background (CMB) 2010

Possible Mechanism Bottom-up scenario Basically extend the principle of galactic accelerator, and put more powerful object 10 20 ev 10 21 ev 10 20 ev Top-bottom scenario Very high energy, unknown particle loses it s energy by decaying into known, highest energy cosmic rays

UHCR The most highest energy cosmic rays may be able to give us directional information... Pierre Auger Observatory, 2009 - Arrival direction of 69 CR with E 55 EeV ( 5.5 10 19 ev)

Next Lecture How cosmic rays travel to Earth? Astrophysics with Electromagnetic Radiation Astrophysics with galactic Cosmic Rays Source something happened here (scattering, energy loss, spallation, escape, re-acceleration...)

Next Lecture How cosmic rays travel to Earth? Astrophysics with Electromagnetic Radiation Direction of thinking Astrophysics with galactic Cosmic Rays Source something happened here (scattering, energy loss, spallation, escape, re-acceleration...)