J. Goodman – May 2010 Physics Olympics Neutrinos, Dark Matter and the Cosmological Constant The Dark Side of the Universe

J. Goodman – May 2010 Physics Olympics Outline The Cosmological Question – the fate of the UniverseThe Cosmological Question – the fate of the Universe How do we know what the Universe is made of:How do we know what the Universe is made of: –From atoms to quarks and leptons Why do we think there is Dark MatterWhy do we think there is Dark Matter Data on the accelerating UniverseData on the accelerating Universe –Type Ia supernova –Cosmic Microwave Background Dark EnergyDark Energy Neutrino AstronomyNeutrino Astronomy

J. Goodman – May 2010 Physics Olympics The Big Question in Cosmology What is the ultimate fate of the Universe?What is the ultimate fate of the Universe? –Will the Universe continue to expand forever? –Or will it collapse back on itself? We were told:We were told: –The answer depends on the energy density in the Universe –   –     mass  and     is the critical density. –If  mass > 1 then the Universe is closed and it will collapse back –If  mass < 1 then the Universe is open and it will expand forever  stars = (1/2%)  stars = (1/2%) –Is this the answer? Theory says     > 1  < 1

J. Goodman – May 2010 Physics Olympics How do we know there really are atoms? Brownian Motion - Einstein

J. Goodman – May 2010 Physics Olympics Seeing Atoms in the 21 st Century

J. Goodman – May 2010 Physics Olympics Seeing Atoms - Iron on Copper

J. Goodman – May 2010 Physics Olympics Seeing into Atoms Atomic Spectra –We see spectral lines –The colors and the spacing of these lines tell us about the structure of the atoms E

J. Goodman – May 2010 Physics Olympics Hydrogen Spectra

J. Goodman – May 2010 Physics Olympics The structure of matter (cont.) All of this eventually gave a deeper understanding Eventually this led to Our current picture of the atom and nucleus

J. Goodman – May 2010 Physics Olympics What are fundamental particles? We keep finding smaller and smaller things

J. Goodman – May 2010 Physics Olympics How do we see particles? Most particles have electric charge –Moving charged particles knock electrons out of atoms –As other electrons fall in - the atom emits light The light from your TV is from electrons hitting the screen The light from your TV is from electrons hitting the screen In a sense we are “seeing” electrons In a sense we are “seeing” electrons

J. Goodman – May 2010 Physics Olympics The search for fundamental particles Proton and electronProton and electron –These were known to make up the atom The neutron was discoveredThe neutron was discovered Free neutrons were found to decayFree neutrons were found to decay –They decayed into protons and electrons –But it looked like something was missing In 1930 Pauli postulated a unseen neutral particleIn 1930 Pauli postulated a unseen neutral particle In 1933 Fermi named it the “neutrino” (little neutron)In 1933 Fermi named it the “neutrino” (little neutron)

J. Goodman – May 2010 Physics Olympics How do we know about things we can’t see? Three Body Decay Two Body Particle Decay neutrino

J. Goodman – May 2010 Physics Olympics Our current view of underlying structure of matter P is uud N is udd   is ud k  is us and so on… The Standard Model } Baryons } Mesons (nucleons)

J. Goodman – August 2009 Teachers as Scholars Omega Minus Discovery ParticleSymbolMakeup Rest mass MeV/c^2 BSLifetimeDecay Modes Omega sss x The omega-minus was produced by a K- p collision which produced the omega- minus and two kaons.

J. Goodman – August 2009 Teachers as Scholars Quark Properties QuarkSymbolSpinCharge Baryon Number SCBT Mass* UpU1/2+2/31/ MeV DownD1/2-1/31/ MeV CharmC1/2+2/31/ MeV StrangeS1/2-1/31/ MeV TopT1/2+2/31/ GeV BottomB1/2-1/31/ GeV

J. Goodman – August 2009 Teachers as Scholars Baryons

J. Goodman – August 2009 Teachers as Scholars Baryons Mesons

Table of Baryons ParticleSymbolMakeup Rest mass MeV/c^2 SpinBS Lifetime (seconds> Decay Modes Proton p uud938.31/2+10Stable... Neutron n ddu939.61/ Lambda uds /2+12.6x Sigma uus /2+10.8x Sigma uds /2+16x Sigma dds /2+11.5x Delta uuu12323/ x Delta uud12323/ x Delta udd12323/ x Delta ddd12323/ x Xi Cascade uss13151/ x Xi Cascade dss13211/ x Omega sss16723/ x Lmabda udc22811/2+102x

J. Goodman – August 2009 Teachers as Scholars Lepton Properties ParticleSymbol Anti- particle Rest mass MeV/c 2 L(e)L(muon)L(tau) Lifetime (seconds) Electron Stable Neutrino (Electron) ~0(<7 x ) +100Stable Muon x10 -6 Neutrino (Muon) ~0(<0.27)0+10Stable Tau x Neutrino (Tau) ~0(<31)00+1Stable

J. Goodman – August 2009 Teachers as Scholars SuperSymmetry NameSpinSuperpartnerSpin Graviton2Gravitino3/2 Photon1Photino1/2 Gluon1Gluino1/2 W +,- 1Wino +,- 1/2 Z0Z0 1Zino1/2 Higgs0Higgsino1/2

J. Goodman – May 2010 Physics Olympics Measuring the Universe

J. Goodman – May 2010 Physics Olympics Why do we think there is dark matter? Isn’t obvious that most of the matter in the Universe is in Stars? Spiral Galaxy

J. Goodman – May 2010 Physics Olympics Measuring the Matter in Galaxies In a gravitationally bound system out past most of the mass V ~ 1/r 1/2In a gravitationally bound system out past most of the mass V ~ 1/r 1/2 We can look at the rotation curves of other galaxiesWe can look at the rotation curves of other galaxies –They should drop off This is evidence for invisible matter or “Dark Matter”

J. Goodman – May 2010 Physics Olympics Why do we think there is dark matter? There must be a large amount of unseen matter in the halo of galaxies –Maybe 20 times more than in the stars! –Our galaxy looks 30 kpc across but recent data shows that it looks like it’s 200 kpc across College Park

J. Goodman – May 2010 Physics Olympics Lensing

J. Goodman – May 2010 Physics Olympics Gravitational Lensing

J. Goodman – May 2010 Physics Olympics Gravitational Lensing

J. Goodman – May 2010 Physics Olympics Clusters produce distinctive tangential patterns

J. Goodman – May 2010 Physics Olympics Gravitational Lensing

J. Goodman – May 2010 Physics Olympics Measuring the energy in the Universe We can measure the mass of clusters of galaxies with gravitational lensingWe can measure the mass of clusters of galaxies with gravitational lensing These measurements give  mass ~0.3These measurements give  mass ~0.3 We also know (from the primordial deuterium abundance) that only a small fraction is nucleons  nucleons < ~0.04We also know (from the primordial deuterium abundance) that only a small fraction is nucleons  nucleons < ~0.04 Gravitational lensing

J. Goodman – May 2010 Physics Olympics Movies

J. Goodman – May 2010 Physics Olympics Dark Matter

J. Goodman – May 2010 Physics Olympics Dark Matter

J. Goodman – May 2010 Physics Olympics Why do we care about neutrinos? NeutrinosNeutrinos –They only interact weakly –If they have mass at all – it is very small They may be small, but there sure are a lot of them!They may be small, but there sure are a lot of them! –300 million per cubic meter left over from the Big Bang –with even a small mass they could be most of the mass in the Universe!

J. Goodman – May 2010 Physics Olympics Facts about Neutrinos Neutrinos are only weakly interactingNeutrinos are only weakly interacting 40 billion neutrinos continuously hit every cm 2 on earth from the Sun (24hrs/day)40 billion neutrinos continuously hit every cm 2 on earth from the Sun (24hrs/day) Interaction length is ~1 light-year of steelInteraction length is ~1 light-year of steel 1 out of 100 billion interact going through the Earth1 out of 100 billion interact going through the Earth

J. Goodman – May 2010 Physics Olympics What about neutrino mass? Could it be neutrinos?Could it be neutrinos? How much neutrino mass would it take?How much neutrino mass would it take? –Proton mass is 938 MeV –Electron mass is 511 KeV –Neutrino mass of 2eV would solve the galaxy rotation problem – 20eV would close the Universe Theories say it can’t be all neutrinosTheories say it can’t be all neutrinos –They have difficulty forming the kinds of structure observed. The structures they create are too large and form too late in the history of the universe

J. Goodman – May 2010 Physics Olympics Does the neutrino have mass?

J. Goodman – May 2010 Physics Olympics Detecting Neutrino Mass If neutrinos of one type transform to another type they must have mass: The rate at which they oscillate will tell us the mass difference between the neutrinos and their mixingThe rate at which they oscillate will tell us the mass difference between the neutrinos and their mixing

J. Goodman – May 2010 Physics Olympics Neutrino Oscillations 1 2 = Electron Electron 1 2 = Muon Muon

J. Goodman – May 2010 Physics Olympics Super-Kamiokande

J. Goodman – May 2010 Physics Olympics Super-Kamiokande

J. Goodman – May 2010 Physics Olympics Super-K Huge tank of water shielded by a mountain in western JapanHuge tank of water shielded by a mountain in western Japan –50,000 tons of ultra clean water –11,200 20in diameter PMTs –Under 1.5km of rock to reduce downward cosmic rays (rate of muons drops from ~100k/sec to ~2/sec)(rate of muons drops from ~100k/sec to ~2/sec) 100 scientists from US and Japan100 scientists from US and Japan Data taking began in 1996Data taking began in 1996

J. Goodman – May 2010 Physics Olympics Super-K site

J. Goodman – May 2010 Physics Olympics Super-K site Mozumi

J. Goodman – May 2010 Physics Olympics How do we see neutrinos? muon   electron e e-

J. Goodman – May 2010 Physics Olympics Cherenkov Radiation Boat moves through water faster than wave speed. Bow wave (wake)

J. Goodman – May 2010 Physics Olympics Cherenkov Radiation Aircraft moves through air faster than speed of sound. Sonic boom

J. Goodman – May 2010 Physics Olympics Cherenkov Radiation Aircraft moves through air faster than speed of sound. Sonic boom

J. Goodman – Univ. of Maryland Cherenkov Radiation

J. Goodman – May 2010 Physics Olympics Cherenkov Radiation When a charged particle moves through transparent media faster than speed of light in that media. Cherenkov radiation Cone of light

J. Goodman – May 2010 Physics Olympics Cherenkov Radiation

J. Goodman – May 2010 Physics Olympics Detecting neutrinos Electron or muon track Cherenkov ring on the wall The pattern tells us the energy and type of particle We can easily tell muons from electrons

J. Goodman – May 2010 Physics Olympics A muon going through the detector

J. Goodman – May 2010 Physics Olympics A muon going through the detector

J. Goodman – May 2010 Physics Olympics A muon going through the detector

J. Goodman – May 2010 Physics Olympics A muon going through the detector

J. Goodman – May 2010 Physics Olympics A muon going through the detector

J. Goodman – May 2010 Physics Olympics A muon going through the detector

J. Goodman – May 2010 Physics Olympics Stopping Muon

J. Goodman – May 2010 Physics Olympics Stopping Muon – Decay Electron

J. Goodman – May 2010 Physics Olympics Neutrino Production Ratio predicted to ~ 5% Absolute Flux Predicted to ~20% :

J. Goodman – May 2010 Physics Olympics Atmospheric Oscillations about 13,000 km about 15 km Neutrinos produced in the atmosphere We look for transformations by looking at s with different distances from production SK

J. Goodman – May 2010 Physics Olympics Atmospheric Neutrino Interactions Reaction Thresholds Electron: ~1.5 MeV Muon: ~110 MeV Tau: ~3500 MeV Charged Current Neutral Current e  e n p W +

J. Goodman – May 2010 Physics Olympics Telling particles apart MuonElectron

J. Goodman – May 2010 Physics Olympics Atmospheric Oscillations about 13,000 km about 15 km Neutrinos produced in the atmosphere We look for transformations by looking at s with different distances from production SK

J. Goodman – May 2010 Physics Olympics Moderate Energy Sample

J. Goodman – May 2010 Physics Olympics Neutrinos have mass Oscillations imply neutrinos have mass!Oscillations imply neutrinos have mass! We can estimate that neutrino mass is probably <0.2 eV – (we measure  M 2 )We can estimate that neutrino mass is probably <0.2 eV – (we measure  M 2 ) Neutrinos can’t make up much of the dark matter –Neutrinos can’t make up much of the dark matter – But they can be as massive as all the visible matter in the Universe! ~ ½ % of the closure density

J. Goodman – May 2010 Physics Olympics Hubble Law

J. Goodman – May 2010 Physics Olympics The expanding Universe

J. Goodman – May 2010 Physics Olympics The expanding Universe The Universe is expandingThe Universe is expanding Everything is moving away from everythingEverything is moving away from everything Hubble’s law says the faster things are moving away the further they are awayHubble’s law says the faster things are moving away the further they are away

J. Goodman – May 2010 Physics Olympics Supernova

J. Goodman – May 2010 Physics Olympics Actually Ia’s are “standardizable” candles

J. Goodman – May 2010 Physics Olympics Supernova Cosmology Project Set out to directly measure the deceleration of the UniverseSet out to directly measure the deceleration of the Universe Measure distance vs brightness of a standard candle (type Ia Supernova)Measure distance vs brightness of a standard candle (type Ia Supernova) The Universe seems to be accelerating!The Universe seems to be accelerating! Doesn’t fit Hubble Law (at 99% c.l.)Doesn’t fit Hubble Law (at 99% c.l.)

J. Goodman – May 2010 Physics Olympics The Cosmological Constant

J. Goodman – May 2010 Physics Olympics Energy Density in the Universe    may be made up of 2 parts a mass term and a “dark energy”  term (Cosmological Constant)    mass  energy Einstein invented  to keep the Universe staticEinstein invented  to keep the Universe static He later rejected it when he found out about Hubble expansionHe later rejected it when he found out about Hubble expansion He called it his “biggest blunder”He called it his “biggest blunder”  m   

J. Goodman – May 2010 Physics Olympics The expanding Universe

J. Goodman – May 2010 Physics Olympics What is the “Shape” of Space? Closed Universe   >1Closed Universe   >1 – C < 2  R Open Universe   <1Open Universe   <1 –Circumference (C) of a circle of radius R is C > 2  R Flat Universe   =1Flat Universe   =1 – C = 2  R – Euclidean space

J. Goodman – May 2010 Physics Olympics What is the “Shape” of Space? Open Universe   <1 –Circumference (C) of a circle of radius R is C > 2  R Flat Universe   =1 – C = 2  R – Euclidean space Closed Universe   >1 – C < 2  R

J. Goodman – May 2010 Physics Olympics Results of SN Cosmology Project The Universe is acceleratingThe Universe is accelerating The data require a positive value of  “Cosmological Constant”The data require a positive value of  “Cosmological Constant” If    =1 then they find    ~ 0.7 ± 0.1If    =1 then they find    ~ 0.7 ± 0.1

J. Goodman – May 2010 Physics Olympics Accelerating Universe

J. Goodman – May 2010 Physics Olympics Accelerating Universe

J. Goodman – May 2010 Physics Olympics Cosmic Microwave Background

J. Goodman – May 2010 Physics Olympics Measuring the energy in the Universe Studying the Cosmic Microwave radiation looks back at the radiation from 400,000 years after the “Big Bang”. This gives a measure of  0

J. Goodman – May 2010 Physics Olympics 2002 Results  0 =1  nucleon

J. Goodman – May 2010 Physics Olympics WMAP -2003

J. Goodman – May 2010 Physics Olympics WMAP Results

J. Goodman – May 2010 Physics Olympics WMAP

J. Goodman – May 2010 Physics Olympics

J. Goodman – May 2010 Physics Olympics Sloan Digital Sky Survey

J. Goodman – May 2010 Physics Olympics Summary of WMAP & SDSS

J. Goodman – May 2010 Physics Olympics WMAP and SDSS Varying  Total

J. Goodman – May 2010 Physics Olympics WMAP and SDSS Varying  Varying  b

J. Goodman – May 2010 Physics Olympics WMAP/SDSS and Neutrinos Varying Neutrinos  h 2 < (95%) Neutrino mass (degenerate) m<0.23 eV (95%) CMB Galaxy clustering m~0 eV m~0.3 eV m~1 eV (Spergel et al 2003)

J. Goodman – May 2010 Physics Olympics Density Fluctuations to Galaxies

J. Goodman – May 2010 Physics Olympics What does all the data say? Three pieces of data come together in one region    ~ 0.73  m ~ 0.27 (uncertainty  ~0.04) Universe is expanding & won’t collapse Only ~1/6 of the dark matter is ordinary matter (atoms) A previously unknown and unseen “dark energy” pervades all of space and is causing it to expand and accelerate

J. Goodman – May 2010 Physics Olympics Expansion History of the Universe

J. Goodman – May 2010 Physics Olympics Concordance model, aka  CDM

Combining the Data 2010 J. Goodman – May 2010 Physics Olympics

J. Goodman – May 2010 Physics Olympics Combining All Results Universe is 13.7 billion years old with a margin of error of close to 1%Universe is 13.7 billion years old with a margin of error of close to 1% Expansion rate (Hubble constant) value: H o = 71 km/sec/Mpc (with a margin of error of about 2%)Expansion rate (Hubble constant) value: H o = 71 km/sec/Mpc (with a margin of error of about 2%) Neutrinos only contribute as much matter as starsNeutrinos only contribute as much matter as stars Content of the Universe: 4% Atoms, 23% Cold Dark Matter, 72% Dark energy.Content of the Universe: 4% Atoms, 23% Cold Dark Matter, 72% Dark energy.

J. Goodman – May 2010 Physics Olympics Puzzles We are here

J. Goodman – May 2010 Physics Olympics What About Dark Matter? ~85% of the matter in the Universe is Dark Matter –At most a few % of the matter is baryons –Most people believe that the lightest SUSY particle is a stable neutralino and is probably the dark matter –These are weakly interacting and heavy –LHC should be the answer…

IceCube

J. Goodman – May 2010 Physics Olympics

J. Goodman – May 2010 Physics Olympics χ atm  cosmic-ray μ’s   χ Sun cosmic-ray

J. Goodman – May 2010 Physics Olympics What’s Next SNAP - JDEMSNAP - JDEM –Look at 1000’s of Ia Supernovae –Look back further in time – Z~1.7 –2m Mirror with a Gigapixel CCD

J. Goodman – May 2010 Physics Olympics Conclusion  tota l = ± –The Universe is flat! The Universe is : ~1/2% Stars ~1/2% Neutrinos ~27% Dark Matter (only 4% is ordinary baryonic matter) ~72% Dark Energy We can see ~1/2% We can measure ~1/2% We can see the effect of ~27% (but don’t know what most of it is) And we are pretty much clueless about the other 3/4 of the Universe There is still a lot of Physics to learn!

J. Goodman – May 2010 Physics Olympics