COSMIC RAYS DAY WINDWARD COMMUNITY COLLEGE - SEPTEMBER 26, 2015 VERONICA BINDI - UNIVERSITY OH HAWAII INTRODUCTION TO COSMIC RAYS
MAJOR QUESTIONS: Are there forms of matter in the Universe that do not exist on Earth? Does antimatter exist in space? Like anti-stars or anti-galaxies. What is dark matter made of?
HOW DO WE ANSWER ALL THESE QUESTIONS?
IT TAKES LONG TIME TO ESCAPE FROM THE SOLAR SYSTEM Voyager 1: launched in 1977 is Earth's Farthest Spacecraft has recently left the Solar System New Horizons: launched in 2006 reached Pluto in 2015
SOLAR SYSTEM LOCATION IN OUR GALAXY
STUDYING COSMIC MESSENGERS:
DISCOVERY OF COSMIC RAYS: 1912 Victor Hess flew in a balloon during a solar eclipse and found that radiation increased with altitude. He discovered that this radiation was coming from space: cosmic radiation. Won the Nobel Prize in 1936.
WHAT ARE COSMIC RAYS?
WHAT ARE COSMIC RAYS?
WHAT ARE COSMIC RAYS? CR are charged particles composed of the same subatomic particles that make up all matter on Earth (H, He, ions). About 79% of all CRs are nuclei of hydrogen atoms (protons), almost 14% are nuclei of Helium and 7% are heavier nuclei. The rest consist of electrons and and extremely energetic light rays known as gamma rays.
WHAT ARE COSMIC RAYS?
WHAT ARE COSMIC RAYS? Cosmic rays are tiny particles from outer space. These particles, invisible to naked eye, have enormous amount of energy. Cosmic rays travel almost at the speed of light. A cosmic ray could zip around the Earth more than 7 times in one second!
ARE COSMIC RAYS DANGEROUS AT EARTH? The Earth is constantly bombarded by Cosmic Rays.
CAN WE SEE COSMIC RAYS AT EARTH? The Earth is constantly bombarded by Cosmic Rays. Some of the effects of CR can be seen with the naked eye. Aurora borealis and aurora australis appear in the night when CR from the Sun enter our atmosphere.
COSMIC RAY AIR SHOWERS Our atmosphere acts as a 'radiation shield. Most of the particles get absorbed by the atmosphere. The only particles that reach the ground are either relatively stable or very energetic.
MUON One such particle is the high energy muon (e-lab)
WHERE DO COSMIC RAYS COME FROM?
THE UNIVERSE IS THE MOST POWERFUL ACCELERATOR Cosmic Ray flux is divided in three main regions. There are many more low energy CR than High Energy CR! LHC Flux number of arriving particles per (unit area x unit time) ev (very small) unit of energy!one volt times the charge of a single electron!1 ev = 1.609 x 10-19 joules
COSMIC RAYS FROM THE SUN: SOLAR ENERGETIC PARTICLES
COSMIC RAYS FROM THE SUN As a byproduct of the nuclear fusion that causes it to shine, the Sun constantly produces CRs. These CRs propagate to Earth in solar wind, rivers of particle that carry into space one million tons of matter every second. During Solar flares and Coronal Mass Ejection CR are emitted by the Sun.
WHERE DO GALACTIC COSMIC RAYS COME FROM?
COSMIC RAYS FROM SUPERNOVAE EXPLOSION A red supergiant (8-10 solar mass) ends its life with a big explosion called supernova. Shockwave from the supernova hits gas surrounding the explosion, accelerating CRs up to 10 15 ev.
EXTRA-GALACTIC ORIGIN OF UHECR WHERE DO THEY COME FROM? We do not know any astrophysical object in our Galaxy that is able to accelerate CRs to such energies. Are there extragalactic objects that generate UHECR? If yes, what are they?
POSSIBLE SOURCES: AGN Active Galactic Nuclei (AGN) are compact regions at the centre of a galaxy, composed of an accretion disk around a central super-massive black hole and are sometimes associated with jets terminating in hot spots that can be detected in radio.
POSSIBLE SOURCES: GAMMA RAY BURSTS Gamma Ray Burst (GRB) is a very short and intense burst caused by the collapse of a black hole or neutron star followed by a longer lived after glow.
POSSIBLE SOURCES: GALAXY COLLISION, ULTRA FAST SPINNING PULSAR Large-scale shocks due to merging galaxies or clusters of galaxies UHECRs (with E > 10 18 ev) travel straight and their direction should point towards their origin.
LOOK FOR SOURCES OF UHECR Are the extremely energetic UHECRs from all over the place? Or are they from one specific direction? Possibly from the same direction of a known AGN? The UHECRs that have been detected so far (red dots) together with the nearby AGNs (blue dots) are shown in the picture.
GROUND BASED OBSERVATORIES Can detect either particles or light from the atmospheric shower.
GROUND BASED OBSERVATORIES Particle detector - Yangbajing International Cosmic Ray in Tibet
PA R T I C L E S & F L U O R E S C E N C E D E T E C T O R Twice the area of Oahu!!!
PA R T I C L E S & F L U O R E S C E N C E D E T E C T O R
HOW WE DETECT HIGH ENERGY COSMIC RAYS To detect high energy cosmic rays, observatories are built on the ground. Good: experiment can be really big! AS BIG AS WE WANT! Bad: they have to measure atmospheric showers and it takes some work to figure out the original primary CR. But it can be done to some extent!
HOW WE DETECT COSMIC RAYS To detect CRs observatories are launched into space: Good: we study the original cosmic ray before it interacts with the atmosphere PRIMARY COSMIC RAY. Bad: they are expensive detectors and usually too small to catch a lot of CRs especially at high energy.
COSMIC RAY EXPERIMENT IN SPACE ISS (AMS-02, ISS CREAM, CALET, DAMPE) Satellite (PAMELA, ACE, Voyager 1&2, FERMI, SOHO ) Balloon (BESS, TIGER, TRACER, HEAT, CREAM, ) Antartica PAMELA
DIRECT MEASUREMENT OF CR AMS-02 experiment (the experiment I m working on here at UH Manoa) SuperTiger
ME AND MY COLLABORATORS FROM UNIVERSITY OF HAWAII
DIRECT MEASUREMENT OF COSMIC RAYS AMS-02 experiment
A M S - 0 2 I N S PA C E C O L L E C T E D ALREADY 60 BILLION EVENTS AMS POCC
AMS-02 GOALS AMS-02
AMS-02 GOALS Look for dark matter in space New forms of matter Studies galactic cosmic rays emitted by Super Novae Cosmic rays from the Sun Influence of the solar activity on the cosmic rays.
C R A R E N O T H A R M F U L AT E A R T H B U T In space without the protection of our atmosphere astronauts need some other type of shielding from the radiation (spacesuits and walls on spacecrafts).
JOURNEY TO MARS 2 days 390 km Communications (near real-time) 1-3 years 228,000,000 km Communications (up to 42 minutes) It is part of our job at UH to work with NASA to improve shielding for astronauts during human missions to Mars.
MORE INFO http://www.phys.hawaii.edu/ams02/ http://ed.ted.com/lessons/how-cosmic-rays-help-usunderstand-the-universe-veronica-bindi
CONCLUSION Understanding CR requires sophisticated detectors in space and big telescopes on Earth.