things big & small dhiman chakraborty ([email protected])

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THINGS BIG & THINGS BIG & SMALL SMALL Dhiman Chakraborty ([email protected])

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  • THINGS BIG & SMALLDhiman Chakraborty ([email protected])

    THINGS BIG AND SMALL

  • Outline: Part 2 Up to the grandest: the Universe at largeBig Bang Cosmology: a brief overviewThe three tests of BB cosmologyCosmic Microwave Background (CMB) Flat UniverseLarge Scale Structure (LSS) Dark matterExpansion of the Universe: Supernova 1a (SN1a) Dark E Recent/current/proposed experimental programs using ground- and space-based telescopes:CMB: COBE, WMAP, PlanckLSS: HST, SDSS, LSST, Chandra, XMM-Newton, SN1a: HZSNT, SCP, SNAPSummary of planned HEP & cosmology projectsOutlook

    THINGS BIG AND SMALL

  • Up to the grandest

    THINGS BIG AND SMALL

  • Big Bang cosmology t=0: the beginning of time & space represents an essential singularity with infinite matter-energy density (r) and temperature (T).An expansion ensues, governed primarily by GTR.T & r fall as the universe expands.

    THINGS BIG AND SMALL

  • Epochs & dominant components? :
  • Evolution of the Universe

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  • Evolution of the Universe

    Time Since the Big BangThe state of the UniverseHuman Equivalent379,000 yearsThis is a time when the pattern of the Cosmic Microwave Background light was set. The Universe was just cool enough for atoms to form for the first time. At this stage, the Universe is the equivalent of a baby just 19 hours old. 200 million yearsThe matter in the Universe condensed by gravity until the first stars ignited. WMAP has detected this event at about 200 million years after the Big Bang. (WMAP does not see the light of the first stars directly, but has detected a polarized signal that is the tell-tale signature of the energy released by the first stars.) The Universe is the equivalent of a baby of 13 months, just old enough to begin taking its first steps. 1 billion yearsThe first galaxies began to form at about this time. Unlike a human child, the Universe has reached the end of its formative years at this young age. There are no further notable cosmic events past this stage. At this age, the Universe is equivalent to a child just under six years old. 13.7 billion yearsThe present day Universe with its billions upon billions of stars and galaxies is found to be 13.7 billion years old, an age with a margin of error of close to 1 percent. An adult person at 80.

    THINGS BIG AND SMALL

  • Pillars of the Big Bang theoryCosmic microwave backgroundAbundance of the light elementsEvidence of cosmic expansionObservationally, these measurements are completely independent of each other. They must provide even support for the theory to hold water.

    THINGS BIG AND SMALL

  • Hubbles law Based on experimental observation (1929):On average, all galaxies are moving away from each other with speed proportional to distance. Corollary: on large scales, the universe is homogeneous and isotropic- it looks the same in all directions and in all parts theres no center nor edge.Metric for a homogeneous & isotropic universe:

    R(t): scale factor (dimensionless)

    THINGS BIG AND SMALL

  • The Friedman equation governs the expansion of a uniform gas-filled universe r = Energy density (matter+radiation+vacuum) z t (large z small t, present R = R0 z=0 ). H0 60 km/s/Megaparsec (1 Mpc 3.26 light-year) where ,: Red shift (Doppler effect): critical density ( k=0, flat universe)

    THINGS BIG AND SMALL

  • The density components : density parameter (i=normal matter, neutrino, dark matter, dark energy, )In general, In a flat universe dominated by:: equation of state parameter

    THINGS BIG AND SMALL

  • Geometry of the UniverseCurrent data = 1

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  • Structure formation Jeans instability in self-gravitating systems cause formation of structures.Needs initial seed density fluctuations.Density fluctuations grow little in a radiation- or vacuum-dominated universe.Density fluctuations grow linearly in a matter -dominated universe.Baryonic matter alone falls far short of explaining the level of structure seen today.

    THINGS BIG AND SMALL

  • Theoretical arguments for dark matter Spiral galaxies made of bulge+disk: unstable as a self-gravitating system need a (nearly) spherical halo.With only baryons as matter, structure forma-tion starts too late for us to exist at this timeMatter-radiation equality achieved too late,Baryon density fluct. cant grow until decoupling,Need larger electrically neutral component.

    THINGS BIG AND SMALL

  • Size-evolution of the universe

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  • Observational verification A Standard Model of cosmology emerges from extensive surveys of:Anisotropy in cosmic microwave background (earliest structures visible, z 3000): CMBLarge-scale structures (e.g. Galaxies, clusters, grav. lensing, z 5, dark matter,): LSSType 1a supernova brightness & redshift (std. candles, z 0.5, dark energy): SN1aEach gives a linear equation in M, any two of these determine M, ; the 3rd serves as a cross-check.

    THINGS BIG AND SMALL

  • CMB: Peeking into the universes infancy with the Wilkinson Microwave Anisotropy Probe

    THINGS BIG AND SMALL

  • WMAP talk about thermal resolution!

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  • WMAP talk about spatial resolution!

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  • LSS: Surveying galaxies & clusters with normal (HST, SDSS) & x-ray (Chandra, XMM-Newton) visionThe XMM-Newton x-ray observatory

    THINGS BIG AND SMALL

  • LSS: Dark matter in galaxy clusters Galaxies form clusters bound in a gravitational well.Hydrogen gas in the well gets heated, emits x-ray.Allows us to determine the baryon fraction of the cluster.

    THINGS BIG AND SMALL

  • LSS: Chandra discovers "Rivers Of Gravity" that define the cosmic landscape Four independent teams of scientists have detected intergalactic gas with temperatures in the range 300,000 to 5 million degrees Celsius by observing quasars with the Chandra X-ray Observatory. An artist's rendering illustrates how X-rays from a distant quasar dim as they pass through a cloud of the intergalactic gas. By measuring the amount of dimming due to oxygen and other elements in the cloud - see the spectrum of the quasar PKS 2155-304 in the inset - astronomers were able to estimate the temperature, density and mass of the absorbing gas cloud.

    THINGS BIG AND SMALL

  • LSS: Chandra discovers "Rivers Of Gravity" that define the cosmic landscape

    THINGS BIG AND SMALL

  • LSS: Surveying galaxies & clusters with normal (HST, SDSS) & x-ray (Chandra, XMM-Newton) visionThe sky is not so dark in x-ray: HST (L), Chandra (R)

    THINGS BIG AND SMALL

  • Sloan Digital Sky Survey (SDSS)

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  • LSSIt is extremely important to know how the mass and energy, most of it dark, is distributed throughout the universe. A particle theory that contradicts cosmological observations will not be viable. The M78 nebula, a nursery of stars, as seen by SDSS

    THINGS BIG AND SMALL

  • LSS & CMB surveys agree

    THINGS BIG AND SMALL

  • SN1a: measuring the rate of cosmic expansion using high-z supernovae 1a as standard candlesNuclear chain reaction in stars with M2Msun (more complex - binaries etc.)As bright as host galaxyBrightness not const, but related to fall-off rate.Apparent brightness gives distance.Red shift (z) gives relative radial velocity.

    THINGS BIG AND SMALL

  • SN1a: Clear evidence of accelerated expansionBy SCP+HZSNT using HST & ground-based telescopes.The cosmological constant fits the bill.Can in principle be something else with ve p.Generally called Dark Energy.

    THINGS BIG AND SMALL

  • Expansion history of the universe

    THINGS BIG AND SMALL

  • SN1a: Next step: the Joint Dark Energy MissionThe proposed Supernova/ Acceleration Probe (SNAP)

    THINGS BIG AND SMALL

  • The cosmic concordanceCMB: 1 flat universe.LSS: M 0.3SN1a: L-2M 0.1 Remarkable agreement Dark Matter: 23% 4% Dark Energy: 73% 4% (Baryons: 4% 0.4%, Neutrinos: ~0.5%)

    Remarkable precision (~10%)

    Remarkable results

    THINGS BIG AND SMALL

  • Cosmology summary:The current state of knowledge:The Universe is geometrically flat,It is expanding with increasing speed,Dark energy dominates matter,Dark matter dominates baryonic matter,Baryonic matter dominates baryonic antimatter.

    THINGS BIG AND SMALL

  • Outstanding questions:Dark Matter: What is it? How is it distributed?

    Dark Energy: What is it? Why not WL ~ 10120? Why not WL = 0? Does it evolve?

    Baryons: Why not WB 0?

    Ultra-High-Energy Cosmic Rays: What are they? Where do they come from?

    What tools do we need to address these?

    THINGS BIG AND SMALL

  • Particle dark matterSuppose an elementary particle constitutes DMWIMP (Weakly Interacting Massive Particle).Heavy but stable, neutral, produced in early Universe.Left over from near-complete annihilation.No such candidate in the SM, must be new physics! TeV is the right energy scale.SUSY: the lightest supersymmetric particle (LSP) is a superpartner of a gauge boson in most models: the bino is a perfect candidate for a WIMP.There are other possibilities (axino, gravitino, axion, technibaryons, axion, Kaluza-Klein particles, )In any case, we should be able to produce such WIMPs at colliders of the next generation (LHC, ILC).

    THINGS BIG AND SMALL

  • Neutralino dark matter

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  • The enigma of dark energyA nave estimate of the cosmological constant in quantum field theory rL MPlanck410120 times the onserved value.The worst prediction in theoretical physics!People had argued that there must be some mechanism to set it to zero. But now it seems finite!!!Quintessence?A scalar field slowly rolling down the potential hill.Will set L to 0 when it reaches the minimum?Must be extremely light: O(10-42 GeV) !!!

    THINGS BIG AND SMALL

  • Particle physics at the energy frontier

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  • The many connections

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  • ConclusionsTheres mounting evidence for non-baryonic dark matter and dark energy.These immediately imply physics beyond the SM.Dark matter is likely to be at TeV scale. Search for dark matter usingCollider experiments (LHC, ILC)Direct searches (CDMS-II)Indirect searches (ICECUBE)Dark energy best investigated by JDEM (SNAP?).

    THINGS BIG AND SMALL

  • The larger US effortsFrom the report of the Quantum Universe subcommittee commissioned by HEPAP (DOE/NSF)

    THINGS BIG AND SMALL

  • The smaller US effortsFrom the report of the Quantum Universe subcommittee commissioned by HEPAP (DOE/NSF)

    THINGS BIG AND SMALL

  • HEPAP recommendation to DOE/NSF(by subpanel on Long Range Planning for U.S. HEP)

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  • OutlookA large number of particle physics, astrophysics, and cosmology projects both theoretical and experimental are underway. They complement each other toward a common goal to solve the most fundamental mysteries of nature.It is a truly INTERNATIONAL effort.We are living through a revolution in our understanding of the Universe on both the smallest and the largest scales.The next decade or two will usher us into a new era of observation and comprehension.

    THINGS BIG AND SMALL

  • THANK YOU!Feel free to contact the speaker for more information

    [email protected]

    THINGS BIG AND SMALL