THINGS BIG SMALL Dhiman Chakraborty dhimanfnal gov Dhiman

THINGS BIG & SMALL Dhiman Chakraborty (dhiman@fnal. gov) Dhiman Chakraborty THINGS BIG AND SMALL

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 1 a (SN 1 a) Dark E – Recent/current/proposed experimental programs using ground- and space-based telescopes: • CMB: COBE, WMAP, Planck • LSS: HST, SDSS, LSST, Chandra, XMM-Newton, … • SN 1 a: HZSNT, SCP, SNAP • Summary of planned HEP & cosmology projects • Outlook Dhiman Chakraborty THINGS BIG AND SMALL 2

Up to the grandest… Dhiman Chakraborty THINGS BIG AND SMALL 3

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. Dhiman Chakraborty THINGS BIG AND SMALL 4

Epochs & dominant components • ? : <10 -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, n. B/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. Dhiman Chakraborty THINGS BIG AND SMALL 5

Evolution of the Universe Dhiman Chakraborty THINGS BIG AND SMALL 6

Evolution of the Universe Time Since The state of the Universe the Big Bang Human Equivalent 379, 000 years This 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 years The 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 years The 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 years The 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. Dhiman Chakraborty THINGS BIG AND SMALL 7

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 theory to hold water. Dhiman Chakraborty THINGS BIG AND SMALL 8

Hubble’s 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 – there’s no “center” nor “edge”. Metric for a homogeneous & isotropic universe: R(t): scale factor (dimensionless) Dhiman Chakraborty THINGS BIG AND SMALL 9

The Friedman equation where , - governs the expansion of a uniform gas-filled universe - r = Energy density (matter+radiation+vacuum) - z t (large z small t, “present” R = R 0 z=0 ). - H 0 60 km/s/Megaparsec (1 Mpc 3. 26 light-year) : critical density ( k=0, “flat” universe) : Red shift (Doppler effect) Dhiman Chakraborty THINGS BIG AND SMALL 10

The density components In general, : equation of state parameter In a flat universe dominated by: • Matter: w=0 • Radiation: w=1/3 • Vacuum: w=-1 : density parameter (i=normal matter, neutrino, dark matter, dark energy, …) Dhiman Chakraborty THINGS BIG AND SMALL 11

Geometry of the Universe Current data = 1 Dhiman Chakraborty THINGS BIG AND SMALL 12

Structure formation • Jeans instability in self-gravitating systems cause formation of structures. • Needs initial seed density fluctuations. • Density fluctuations grow little in a radiationor 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. Dhiman Chakraborty THINGS BIG AND SMALL 13

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 formation starts too late for us to exist at this time – Matter-radiation equality achieved too late, – Baryon density fluct. can’t grow until decoupling, – Need larger electrically neutral component. Dhiman Chakraborty THINGS BIG AND SMALL 14

Size-evolution of the universe Dhiman Chakraborty THINGS BIG AND SMALL 15

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 1 a supernova brightness & redshift (std. candles, z 0. 5, dark energy): SN 1 a Each gives a linear equation in M, any two of these determine M, ; the 3 rd serves as a cross-check. Dhiman Chakraborty THINGS BIG AND SMALL 16

CMB: Peeking into the universe’s infancy with the Wilkinson Microwave Anisotropy Probe Dhiman Chakraborty THINGS BIG AND SMALL 17

WMAP talk about thermal resolution! Dhiman Chakraborty THINGS BIG AND SMALL 18

WMAP talk about spatial resolution! Dhiman Chakraborty THINGS BIG AND SMALL 19

LSS: Surveying galaxies & clusters with normal (HST, SDSS) & x-ray (Chandra, XMM-Newton) vision Dhiman Chakraborty THINGS BIG AND SMALL The XMM-Newton x-ray observatory 20

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. Dhiman Chakraborty THINGS BIG AND SMALL 21

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. Dhiman Chakraborty THINGS BIG AND SMALL 22

LSS: Chandra discovers "Rivers Of Gravity" that define the cosmic landscape Dhiman Chakraborty THINGS BIG AND SMALL 23

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) Dhiman Chakraborty THINGS BIG AND SMALL 24

Sloan Digital Sky Survey (SDSS) Dhiman Chakraborty THINGS BIG AND SMALL 25

LSS 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. Dhiman Chakraborty The M 78 nebula, a nursery of stars, as seen by SDSS THINGS BIG AND SMALL 26

LSS & CMB surveys agree Dhiman Chakraborty THINGS BIG AND SMALL 27

SN 1 a: measuring the rate of cosmic expansion using high-z supernovae 1 a as standard candles • Nuclear chain reaction in stars with M 2 Msun (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. Dhiman Chakraborty THINGS BIG AND SMALL 28

SN 1 a: Clear evidence of accelerated expansion • By 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. Dhiman Chakraborty THINGS BIG AND SMALL 29

Expansion history of the universe Dhiman Chakraborty THINGS BIG AND SMALL 30

SN 1 a: Next step: the Joint Dark Energy Mission The proposed Supernova/ Acceleration Probe (SNAP) Dhiman Chakraborty THINGS BIG AND SMALL 31

The cosmic concordance • CMB: 1 flat universe. • LSS: M 0. 3 • SN 1 a: -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 Dhiman Chakraborty THINGS BIG AND SMALL 32

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. Dhiman Chakraborty THINGS BIG AND SMALL 33

Outstanding questions: • Dark Matter: What is it? How is it distributed? • Dark Energy: What is it? Why not L ~ 10120? Why not L = 0? Does it evolve? • Baryons: Why not B ≈ 0? • Ultra-High-Energy Cosmic Rays: What are they? Where do they come from? … What tools do we need to address these? Dhiman Chakraborty THINGS BIG AND SMALL 34

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! Te. V 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). Dhiman Chakraborty THINGS BIG AND SMALL 35

Neutralino dark matter Dhiman Chakraborty THINGS BIG AND SMALL 36

The enigma of dark energy • A naïve estimate of the cosmological constant in quantum field theory r. L MPlanck 4 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 Ge. V) !!! Dhiman Chakraborty THINGS BIG AND SMALL 37

Particle physics at the energy frontier Dhiman Chakraborty THINGS BIG AND SMALL 38

The many connections Dhiman Chakraborty THINGS BIG AND SMALL 39

Conclusions • There’s mounting evidence for non-baryonic dark matter and dark energy. • These immediately imply physics beyond the SM. • Dark matter is likely to be at Te. V scale. • Search for dark matter using – Collider experiments (LHC, ILC) – Direct searches (CDMS-II) – Indirect searches (ICECUBE) • Dark energy best investigated by JDEM (SNAP? ). Dhiman Chakraborty THINGS BIG AND SMALL 40

The larger US efforts From the report of the Quantum Universe subcommittee commissioned by HEPAP (DOE/NSF) Dhiman Chakraborty THINGS BIG AND SMALL 41

The smaller US efforts From the report of the Quantum Universe subcommittee commissioned by HEPAP (DOE/NSF) Dhiman Chakraborty THINGS BIG AND SMALL 42

HEPAP recommendation to DOE/NSF (by subpanel on Long Range Planning for U. S. HEP) Dhiman Chakraborty THINGS BIG AND SMALL 43

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. Dhiman Chakraborty THINGS BIG AND SMALL 44

THANK YOU! Feel free to contact the speaker for more information dhiman@fnal. gov Dhiman Chakraborty THINGS BIG AND SMALL 45