Cosmic Rays

Liz PuchnarewiczMullard Space Science LaboratoryUniversity College Londonwww.mssl.ucl.ac.uk

What are they?photons= light packets

atomicfragments

protonneutronelectron

ion

…moving very fast!!

atom

Stripping an atom

Stripping an atom

Stripping an atom

Stripping an atom

Stripping an atom

Stripping an atom

Stripping an atom

Stripping an atom

• ion = “stripped” nucleus

• massive (compared to protons, neutrons and electrons. And photons)

• positively charged

Energizing to CRs

photonsmass-less, v=speed of light

particlese -

p+

n Z+

light mediummediumheavy

… so need to accelerate particles to speedsclose to the speed of light

Accelerating particles

How are particles pushed to the speed of light?

Slung out by the

enormous gravitatio

nal potentials

of black holes

Thrown out by massive stellar explosions - supernovaeDragged out

by intense electric and

magnetic fields –

eg in pulsars

hydrogen

helium

Supernovae

siliconcarbonheliumiron

hydrogen

helium

Supernovae

carbonsiliconheliumiron

Supernovae

Supernovae

Supernovae

Crab NebulaHubble (red) and Chandra (blue) composite of the Crab Nebula. The progenitor star went supernova about 1000 years ago.

A cosmic blast wave

M. DeBord, R. Ramaty and B. Kozlovsky (GSFC), R. Lingenfelter (UCSD), NASA

Atoms are torn from the brownish bands of dust by shock waves (represented by orange rings). The shocks in the expanding blast wave then accelerate the atoms to near light speeds firing them into interstellar space like cosmic bullets.

Supermassive black holes

Black holes in quasars throw out particles at near-light speeds and produce high-E photons

Pulsars

Light cylinderOpenmagnetosphere

r=c/

BClosed magnetosphere

Neutron starmass = 1.4 solar massesradius = 10 kmB = 10 to 10 Tesla4 9

Pulsars – the movie

A bit of history

First discovered during high altitude balloon flights by Victor Hess

1912

Pierre Auger discovered extensive air showers

1938

Enrico Fermi proposed cosmic ray shock accelerators

1949

GZK cutoff proposed1966

Highest energy cosmic ray ever (3x1020eV) observed by the Fly’s Eye

1991

Air showers

0

e- e+

Cerenkov radiation

Whipple

Next generation is VERITAS = 7 Whipple array

10m -ray telescope – Cerenkov radiation detector

248 mirrors

Largest and most sensitive - so far

The cosmic ray legBelow the knee –Milky Way sources (supernovae, pulsars)

Knee to ankle –Galaxies and quasars

Ankle - ??

Fly’s Eye

EUSO

ESA mission - planned for launch 2009

Observes fluoresence in Earth’s atmosphere

OWL

Orbiting Wide-angle Light-collectors

Nightglow

Global warming by cosmic rays

not many cosmic rays

lots of cosmic rays

The End

For more information, visit:http://www.sciencedaily.com/releases/2002/07/020731080631.htm http://antwrp.gsfc.nasa.gov/apod/ap980618.htmlhttp://www.auger.org/