AMS-02 will be launched onboard the Shuttle Endeavour...

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AMS-02 will be launched onboard the Shuttle Endeavour On May 2nd 2:33 P.M.

from NASA Kennedy space center!

Anti-matter, dark matter measurementBy measuring the cosmic rays (Mainly

electron, positron, proton, anti-proton and light nuclei)

Saturday, May 14, 2011

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99 Years from Discovery : What is our current picture on

Cosmic Rays?

Presented by Nahee Park

#5 How do Cosmic Rays gain their energy?


#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

II. Interactions of EM radiation

III. Connection to Cosmic Rays

- Covering wide energy range - more than 15 decades order!(radio, infra-red, visible light, ultra-violet, X-ray, gamma-ray)

- Photoelectric effect- Compton scattering- Pair production

- 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!)



I. Acceleration mechanism of CRII. Nature-made-accelerator in the

universe & measurements



I. Acceleration mechanism of CRII. Nature-made-accelerator in the

universe & measurements

Quite overlapping with 68th Compton Lecture’s #5

(given by Brian Humensky)


LHC - Best of man-made acceleratorLHC (The Large Hadronic Collider)(http://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/)

✦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 × 104 Gauss)

✦Beam line is maintained as vacuum state 10-10 Torr (~3 million molecules/cm3)

✦Annual power consumption: 800,000 MWh ( ~ $30 million per year for electricity)


http://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/




Power sourcePower for accelerators to keep working

Acceleration mechanismMechanism which can accelerate particles to high energy

How do Cosmic Ray gain their energy?





LHC physics





LHC physics

LHC beam energy(design goal)





This should really exist in our galaxy - not just ideas !

LHC physics

LHC beam energy(design goal)


Additional points to !t in...

Should cover the wide range of cosmic rays fluxesShould explain stable fluxes of cosmic raysShould explain smooth curvature of fluxes of cosmic raysShould explain characteristics of cosmic rays

Knee, Ankle

Should explain proton dominant composition of cosmic rays

Items need to be explained


Acceleration Theory by Enrico FermiAcceleration mechanism by Enrico Fermi (1949)

Particle can gain small amount of energy in average when it is reflected by a cloud, which contains turbulentmagnetic field (Elastic collision)The longer it stays, particle will gainhigher energy [Movie] Strange case of the cosmic rays (1957)

Magnetizedcloud


Shock Acceleration TheoryIf there is a plane shock wave (with magnetic field) moving with high speed, then particle can gain energy by crossing the shock front

Shock wave

upstreamdownstream

* Faster acceleration then magnetic cloud’s case

* Provide prediction of slope in cosmic rays fluxes


Conditions for Acceleration SiteShould have

Magnetic field strong enough to hold particles until it reaches high energyHigh speed shock wave

There should be enough amount of acceleration sites in the galaxy with considerably stable supply


Acceleration Candidate SiteSupernova 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/sMagnetic field strength : 10 μG ~ several mG? Maximum possible accelerating energy

~ Z × 1014 eV

low energy x-ray (hot expanding debris) : redhigh energy x-ray (high energy electron) : blue

Tycho supernova remnant


http://www.youtube.com/watch?v=OyntBsxoEkA&feature=related

http://www.youtube.com/watch?v=OyntBsxoEkA&feature=related

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 ListComposition at Knee region?





Galactic





GalacticExtragalactic


Using Gamma-ray as indicatorCosmic 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

Matter

Magnetic field




Matter

electron

Bremsstrahlung

gamma-ray

Nuclear interaction

Proton

π0 decay

gamma-ray

Magnetic field




Matter

electron

Bremsstrahlung

gamma-ray

Nuclear interaction

Proton

π0 decay

gamma-ray

Magnetic field

electron

gamma-ray

Synchrotronradiation


Gamma-ray at SNR

Gamma-ray detection at SNR

Tycho

SN1006

IC443


Easier to con!rm for electronAcceleration of electron in SNR (or other astronomical object) is easier to detect compared to proton

Matter

electron

Bremsstrahlung

gamma-ray

Nuclear interaction

Proton

π0 decaygamma-ray

Magnetic field

electron

gamma-ray

Synchrotronradiation

Photon field

electron

gamma-ray

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 at 10 TeV and a total energy of We = 3.3 × 10 47 erg. The magnetic 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 γ-ray energy distribution was determined from the sum of the two previously defined regions. In this phe-nomenological model the current distribution of particles (elec- trons 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

Bfield : 30μG Bfield : 120μGElectron vs. Proton ratio : 1:10,000

Inverse Comptonscattering


Gamma ray from other galaxyGamma-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 cm3


Gamma ray from other galaxyGamma-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 cm3

cosmic ray density of ~ 250 eV cm-3 in the starburst core of M 82.

2009 Science


Will it be enough to explain all?

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

GalacticCosmic Rays

ExtragalacticCosmic Rays


Ultra High Energy Cosmic RayUltra High Energy Cosmic Ray (UHCR)

Hunting for the highest cosmic rays continued throughout 1960s

Air showers from higher than 1020eV has been reported

Greisen-Zatsepin-Kuzmin cutoff (1966)1020eV 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

1020eV

1021eV

1020eV

“Top-bottom” scenarioVery high energy, unknown particle loses it’s energy by decaying into known, highest energy cosmic rays


UHCRThe 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 ×1019 eV)


Next LectureHow cosmic rays travel to Earth?

Astrophysics with Electromagnetic Radiation

Astrophysics with galactic Cosmic Rays

Sourcesomething happened here

(scattering, energy loss, spallation, escape, re-acceleration...)







Direction of thinking


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