Cosmic Rays Liz Puchnarewicz Mullard Space Science Laboratory

Cosmic Rays Liz Puchnarewicz Mullard Space Science Laboratory University College London www. mssl. ucl. ac. uk

What are they? photons = light packets atomic fragmen ts proton neutro electro n n ion …moving very fast!!

Stripping an atom

Stripping an atom • ion = “stripped” nucleus • massive (compared to protons, neutrons and electrons. And photons) • positively charged

Energizing to CRs photons particles mass-less, v=speed of light elight p+ medium n Z+ medium heavy … so need to accelerate particles to speeds close to the speed of light

Accelerating particles How are particles pushed to the speed of lig Thrown Slung out by by the massive enormous stellar gravitationa explosions l potentials of black supernova holes Dragged e out by intense electric and magnetic fields – eg in pulsars

Supernovae hydrogen silicon helium carbon iron

Supernovae

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

A cosmic blast wave M. De. Bord, 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 nearlight speeds and produce high-E photons

Pulsars Open magnetosphere B r=c/w Light cylinder Closed magnetosphere Neutron star mass = 1. 4 solar masses radius = 10 km B = 10 4 to 109 Tesla

Pulsars – the movie

A bit of history 1912 First discovered during high altitude balloon flights by Victor Hess 1938 Pierre Auger discovered extensive air showers 1949 Enrico Fermi proposed cosmic ray shock accelerators 1966 GZK cutoff proposed 1991 Highest energy cosmic ray ever (3 x 1020 e. V) observed by the Fly’s Eye

Air showers p 0 g eg e+ g

Cerenkov radiation

Whipple 10 m g-ray telescope – Cerenkov radiation detector 248 mirrors Largest and most sensitive - so far Next generation is VERITAS = 7 Whipple array

The cosmic ray leg Below 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 atmospher e

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/2002/0 7/020731080631. htm http: //antwrp. gsfc. nasa. gov/apod/ap 980618. ht ml http: //www. auger. org/