THINGS BIG

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THINGS BIG SMALL

• Dhiman Chakraborty
• (dhiman_at_fnal.gov)

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Outline Part 2

• Up to the grandest the Universe at large
• Big Bang Cosmology a brief overview
• The three tests of BB cosmology
• Cosmic Microwave Background (CMB) ? Flat Universe
• Large Scale Structure (LSS) ? Dark matter
• Expansion of the Universe Supernova 1a (SN1a) ?
  Dark E
• Recent/current/proposed experimental programs
  using ground- and space-based telescopes
• CMB COBE, WMAP, Planck
• LSS HST, SDSS, LSST, Chandra, XMM-Newton,
• SN1a HZSNT, SCP, SNAP
• Summary of planned HEP cosmology projects
• Outlook

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Up to the grandest
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Big Bang cosmology

• t0 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.

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Epochs dominant components

• ? lt10-43 s string (?)
• Inflation 10-38 s vacuum (inflaton driven?)
• Quantum fluctuations imprinted on metric, to be
  seen later as anisotropies in cosmic microwave
  background.
• Baryogenesis 10-36 s radiation/matter(?)
• WIMP decoupling
• Big Bang Nucleosynthesis (BBN) 1 s radiation
• neutrino decoupling. Best tested part, nB/ng
  only parameter.
• Cosmic Microwave Background (CMB) 1012 s matter
• photon decoupling ? transition to
  matter-dominated era.
• Present 5?1017 s vacuum
• Dark energy drives the universe into
  accelerated expansion.

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Evolution of the Universe
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Evolution of the Universe
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Pillars of the Big Bang theory

• Cosmic microwave background
• Abundance of the light elements
• Evidence of cosmic expansion
• Observationally, these measurements are
  completely independent of each other. They must
  provide even support for the theory to hold water.

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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)

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The Friedman equation
where ,

• governs the expansion of a uniform gas-filled
  universe
• r Energy density (matterradiationvacuum)
• z ? t (large z ? small t, present ? R R0 ?
  z0 ).
• H0 ? 60 km/s/Megaparsec (1 Mpc ? 3.26
  light-year)

critical density (? k0, flat universe)
Red shift (Doppler effect)
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The density components
In general,
equation of state parameter
In a flat universe dominated by

• density parameter (inormal matter, neutrino,
  dark matter, dark energy, )

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Geometry of the Universe
Current 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.

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Theoretical arguments for dark matter

• Spiral galaxies made of bulgedisk 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 time
• Matter-radiation equality achieved too late,
• Baryon density fluct. cant grow until
  decoupling,
• Need larger electrically neutral component.

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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) CMB
• Large-scale structures (e.g. Galaxies, clusters,
  grav. lensing, z ? 5, ? dark matter,) LSS
• Type 1a supernova brightness redshift (std.
  candles, z ? 0.5, ? dark energy) SN1a
• Each gives a linear equation in ?M, ?? ? any two
  of these determine ?M, ?? the 3rd serves as a
  cross-check.

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CMB Peeking into the universes infancy
with the Wilkinson Microwave Anisotropy Probe
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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) vision

• The XMM-Newton x-ray observatory

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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.

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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.
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LSS Chandra discovers "Rivers Of Gravity" that
define the cosmic landscape
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LSS Surveying galaxies clusters with normal
(HST, SDSS) x-ray (Chandra, XMM-Newton) vision

• The sky is not so dark in x-ray HST (L), Chandra
  (R)

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Sloan Digital Sky Survey (SDSS)
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LSS
The M78 nebula, a nursery of stars, as seen by
SDSS

• It 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.

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LSS CMB surveys agree
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SN1a measuring the rate of cosmic expansion
using high-z supernovae 1a as standard candles

• Nuclear chain reaction in stars with M?2Msun
  (more complex - binaries etc.)
• As bright as host galaxy
• Brightness not const, but related to fall-off
  rate.
• Apparent brightness gives distance.
• Red shift (z) gives relative radial velocity.

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SN1a Clear evidence of accelerated expansion

• By SCPHZSNT using HST ground-based telescopes.
• The cosmological constant fits the bill.
• Can in principle be something else with ve p.
• Generally called Dark Energy.

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Expansion history of the universe
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SN1a Next step the Joint Dark Energy Mission
The proposed Supernova/ Acceleration Probe (SNAP)
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The cosmic concordance

• CMB ? ?1? flat universe.
• LSS ?M ? 0.3
• SN1a ?L-2?M ? 0.1

• Remarkable agreement
• Dark Matter 23 4
• Dark Energy 73 4
• (Baryons 4 0.4, Neutrinos 0.5)
• Remarkable precision (10)
• Remarkable results

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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.

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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?

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Particle dark matter

• Suppose an elementary particle constitutes DM
• WIMP (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).

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Neutralino dark matter
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The enigma of dark energy

• A naïve estimate of the cosmological constant in
  quantum field theory ? rL ? MPlanck4?10120 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) !!!

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Particle physics at the energy frontier
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The many connections
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Conclusions

• Theres 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 using
• Collider experiments (LHC, ILC)
• Direct searches (CDMS-II)
• Indirect searches (ICECUBE)
• Dark energy best investigated by JDEM (SNAP?).

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The larger US efforts
From the report of the Quantum Universe
subcommittee commissioned by HEPAP (DOE/NSF)
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The smaller US efforts
From the report of the Quantum Universe
subcommittee commissioned by HEPAP (DOE/NSF)
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HEPAP recommendation to DOE/NSF
(by subpanel on Long Range Planning for U.S. HEP)
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Outlook

• A 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.

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THANK YOU!

• Feel free to contact the speaker
• for more information
• dhiman_at_fnal.gov