The “Big Question” of Cosmology Cosmology and Religion in Art 1 The Dark Night Sky The Hubble Ultradeep Field 2 Darkness at Night: Olbers’ Paradox The Large Forest Analogy 3 Edgar Allen Poe 4 The Cosmic Distance Ladder The Cosmic Distance Ladder 1 Distance Measurements via Parallax Hipparcos Satellite Before Launch 2 GAIA – A Planned Future Mission Estimating the Distance to a Stop Light 3 Cepheid Variable Stars The Period-Luminosity Relation for Cepheid Variable Stars Henrietta Leavitt 4 HST Observations of Cepheid Variable Stars in M100 at ~ 20 Mpc HST key project measured Cepheid distances to ~ 25 galaxies within 25 Mpc. An Example Globular Cluster 5 Distances from Type 1a Supernovae Origin of Type 1a Supernovae 6 Mass Discovery of Type 1a Supernovae Light Curves of Type 1a Supernovae Peak luminosity and subsequent fading are related. 7 SNAP – A Planned Mission to Measure Distances to Type 1a Supernovae Radioactive Decay 8 Oldest Rocks on Earth Oldest Rocks on Earth 9 Oldest Rocks from the Moon 4.6 Billion Year Old Meteorite 10 The Oldest Star Clusters The Oldest White Dwarfs 11 The Andromeda Galaxy Some of the Most Distant Galaxies 12 Optical Spectrum of a Galaxy Recession velocity = 14387 km / s Hα z = 0.0479 Flux Hβ [O III] Vesto Slipher 1 Redshifted Spectra Redshifted Spectra 2 Edwin Hubble The Original Hubble Law 3 Modern-Day Hubble Law Today our best value for the Hubble constant is 70 +/- 5 km / s / Mpc. Measurements of the Hubble Constant 4 Recent Measurements of the Hubble Constant Raisin-Bread Analogy 5 Balloon Analogy Einstein’s General Theory of Relativity - 1915 6 Willem De Sitter Einstein with Hubble 7 TheThe LocalLocal GroupGroup Members of the IC 342 / Maffei Group IC 342 1 The IC 342 / Maffei Group Hickson Compact Groups 2 Hot X-ray Emitting Gas in a Group of Galaxies NGC 2300 Group of Galaxies The Virgo Cluster of Galaxies 3 M87: The Giant Galaxy in the Core of the Virgo Cluster The Coma Cluster of Galaxies 4 The Hercules Cluster of Galaxies Abell 3528 – A Cluster Merger 5 300 of the Brightest X-ray Clusters in the Sky Gravitational Lensing in Abell 2218 6 Nearby Clusters of Galaxies Nearby Superclusters 7 Sloan Digital Sky Survey: Example of Galaxy Survey Methods Distribution of Galaxies in the Universe from the 2dF Survey 8 Distribution of Galaxies in the Universe from the Sloan Digital Sky Survey Comparison of Redshift Surveys 9 Redshift Clustering in the Hubble Deep Field-North Superclustering Seen in X-rays About 6 Mpc across 10 Simulations of Galaxy and Structure Formation Largest Simulation to Date 11 “Power Spectrum” of Density Variations on Different Scales “Power Spectrum” of Density Variations on Different Scales 12 Uniformity on the Very Largest Scales - Radio Galaxies Sky Distribution of Radio Sources from the NRAO VLA Sky Survey Uniformity on the Very Largest Scales - Quasars 13 Uniformity on the Very Largest Scales - The Cosmic Microwave Background 14 Sun - Eight Minutes Ago Nearest Stars - Few Years Ago 1 Andromeda Galaxy - 2.5 Million Years Ago Distant Galaxies - Billions of Years Ago 2 Redshifts in the Hubble Deep Field-North Effect of Distance on Observations of Galaxies and the Need for High Angular Resolution 3 Comparison of Ground-Based versus Space-Based Imaging James Webb Space Telescope (JWST) 4 Simulated JWST Deep Field Studying Distant Galaxies with Gravitational Lensing 5 Some of the Most Distant Known Galaxies: “Pieces” of Present-Day Galaxies Galaxies at Intermediate Distances: Merging of the “Pieces” 6 Simulations of Forming Galaxies The Earth Simulator Supercomputer The Cosmic History of Star Formation in Galaxies 7 Merger-Induced Star Formation in the “Antennae” Other Merging Systems - The “Mice” and the “Tadpole” 8 Star Formation Triggered by a Close Interaction and a Galactic Wind “Super Star Clusters” in M82 9 “Super Star Clusters” in M101 Dust-Obscured Star Formation Markarian 231 10 Submillimeter Galaxies: Dust-Obscured Star Formation in the Distant Universe Evolution of the Quasar Population 11 Supermassive Black Holes in Nearby Galaxies: Relics of the Quasars Relations Between Galaxy Bulges and Their Central Black Holes Milky Way Sombrero Galaxy 12 Active Galaxy Winds as an Agent of Black Hole vs. Galaxy Feedback 13 Modern-Day Hubble Law Main Evidence for the Big Bang The Hubble Law The existence and properties of the cosmic microwave background Primordial nucleosynthesis and the observed light element abundances 1 How Far Can We Look Back in Time? The Plasma-to-Gas Transition of Our Universe - “Recombination” Plasma - Nuclei and Electrons Gas - Atoms 2 BlackbodyBlackbody RadiationRadiation “Cooling” of the Cosmic Microwave Background 3 MicrowavesMicrowaves Arno Penzias and Robert Wilson 4 Robert Dicke and Jim Peebles George Gamow, Ralph Alpher, Robert Hermann 5 You Can “See” the CMB Cyanogen - Effects from the CMB Were Noticed Before Its Discovery 6 Directly Observing the Cooling of the CMB Cosmic Background Explorer (COBE) 7 Spectrum of the Cosmic Microwave Background Uniformity of the CMB 8 Anisotropy of the Cosmic Microwave Background Seeing the “Seeds” of Galaxies 9 Limitations of the COBE Maps Examples of Balloon and Ground- Based CMB Experiments Boomerang Cosmic Background Imager 10 Wilkinson Microwave Anisotropy Probe Current All-Sky Maps of the Cosmic Microwave Background WMAP 11 The Power Spectrum of the CMB Current Measurements of the CMB Power Spectrum 12 Cosmological Parameters from the CMB Power Spectrum Polarization of the CMB 13 Planck: An Upcoming CMB Mission 14 Thermal History of the Universe TooToo MuchMuch HeliumHelium Our Sun is about 28% helium by mass. 1 George Gamow and Ralph Alpher Nuclear Reactions in the Early Universe 2 Some More Details of the Nuclear Reactions in the Early Universe One Reason Why Physicists Are Good at Calculating Nuclear Reactions 3 Primordial Nucleosynthesis Measuring Cosmic Deuterium 4 The Life of Our Universe Before One Second At Very Early Times Our Universe Was Filled With a Plasma of Quarks, Anti-Quarks, and Gluons 5 Attempts to Make Quark-Gluon Plasmas on Long Island The Very Early Universe Contained Both Matter and Antimatter, in Nearly Equal Amounts Carl Anderson 6 Baryogenesis: Somehow the Matter Slightly “Won” Over the Antimatter Andrei Sakharov’s Conditions for Baryogenesis 7 Components of the Milky Way Examples of Rotation Curves 1 Expected Versus Observed Rotation Curves for Our Galaxy 21 cm Radiation as Tracer of Gas Clouds 21 cm map of our Galaxy 2 The Correct Way to Think about Our Galaxy Possible Dark-Matter Candidates 3 Evidence Against Red Dwarfs as the Dark Matter Gravitational Microlensing 4 Microlensing Targets Large Magellanic Cloud Small Magellanic Cloud Microlensing Light Curves 5 Microlensing Light Curves Microlensing by a Binary System 6 Neutrinos as Nonbaryonic Dark Matter About 100 neutrinos per cubic cm, throughout space. Mass is about 0.05 eV = 1 / 10,000,000 mass of Superkamiokande, an Example electron, although some uncertainty. of a Neutrino Observatory Neutrinos in the Universe have nearly as much mass as all of the stars! Other Types of Nonbaryonic Dark Matter XENON Dark Matter Detector 7 Large Hadron Collider at CERN The LHC will search for supersymmetric and other new subatomic particles. Dark Matter in M31 – Flat Rotation Curve 8 Dark Matter in Other Spiral Galaxies – Flat Rotation Curves NGC 3198 Dark Matter in Elliptical Galaxies – Evidence from X-ray Gas NGC 4697 optical NGC 4697 Chandra 9 Dark Matter in Clusters of Galaxies The Coma Cluster Fritz Zwicky Galaxy Motions in a Cluster of Galaxies The Coma Cluster 10 X-ray Evidence for Dark Matter in Clusters of Galaxies Need enough gravity to keep the X-ray gas from “boiling off” into intergalactic space. Gravitational Lensing Evidence for Dark Matter in Clusters of Galaxies 11 Gravitational Lensing in Abell 2218 Gravitational Lensing in 0024+1654 12 Gravitational Lensing in Abell 1689 Gravitational Lensing in Abell 1689 13 Masses of Some Galaxy Clusters The Acceleration of the Universe Examples of type 1a supernovae Thermonuclear detonation of white dwarf High-redshift supernovae are systematically fainter than expected based on extrapolation of low-redshift sources. Must be further away than expected. So need an effect to overcome the tendency of gravity to slow down the expansion. 14 Dark Energy in the Universe Cosmic acceleration suggests presence of “dark energy” that drives space apart. This “dark energy” dominates the mass-energy density of the Universe! Supporting evidence comes from studies of the cosmic microwave background, clusters of galaxies, and large-scale structure. What is this “dark energy”? Why is there the observed amount, not much more or much less? Schematic of Cosmic History 15 Dark-Energy Candidates The Future of the Universe We cannot predict the fate of the Universe until we understand dark energy. 16 Schematic of Cosmic History From “Seeds” to Galaxies 1 Dark Matter Halos in the Early Universe Star Formation in the Orion Nebula 2 Supercomputer Simulations of the Formation of the First Stars The Sun Compared to the First Stars 3 Recipe for Forming the First Stars The Deaths of the First Stars in Supernova Explosions 4 Future Prospects for Detecting the First Supernovae James Webb Space Telescope Thirty Meter Telescope Gamma-Ray Bursts from the First Stars? 5 A Gamma-Ray Burst at a Redshift of 6.29 Redshift Versus Time for Galaxies, Quasars, and Gamma-Ray Bursts 6 Environments of the First Quasars Optical Spectra and X-ray Images of Some of the First Quasars 7 Uncertainty About the Very Early Universe