1 / 49

THE DARK SIDE OF THE FORCE - Black Holes and Dark Matter

THE DARK SIDE OF THE FORCE - Black Holes and Dark Matter. Weldon J. Wilson Department of Physics & Engineering University of Central Oklahoma. Planets. Stars. Comets. Galaxies. Historically, astronomers have harvested light. Is there material that does not emit or absorb light?. Yes!.

aline-chapman
Télécharger la présentation

THE DARK SIDE OF THE FORCE - Black Holes and Dark Matter

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. THE DARK SIDE OF THE FORCE -Black Holes and Dark Matter Weldon J. Wilson Department of Physics & Engineering University of Central Oklahoma

  2. Planets Stars Comets Galaxies Historically, astronomers have harvested light Is there material that does not emit or absorb light? Yes!

  3. Particle Physics Astronomy Cosmology Dark Matter What is it made of? We don’t know How much is there? Most of the Universe!

  4. How do we know? “We see it as Columbus saw America from the shores of Spain. Its movements have been felt, trembling along the far-reaching line of our analysis, with a certainty hardly inferior to that of ocular demonstration” Sir John Herschel (referring to evidence for Neptune, 150 years ago)

  5. The stars in a typical galaxy comprise at most 10% of its mass! Rotation Curves of Spiral Galaxies Spiral galaxies like our own Milky Way are rotating. The rate of rotation can be measured, and used to determine the mass of the galaxy. NGC 253 (David Malin, AAO)

  6. Revised notion of a galaxy

  7. With our Dark Matter glasses on:

  8. Understanding the nature and distribution of Dark Matter is one of the most pressing open questions in the physical sciences today A cosmological Rosetta stone? Dark Matter • governs the majestic rotation of galaxies • seeds the evolution of cosmic structures • determines the fate of the Universe

  9. closed open The Mass Budget of the Universe “Critical” density Ordinary (“Baryonic”) Matter, at most 10% of critical density “Best Guess” Density of the Universe Stars, less than 1% of critical density

  10. Gas, Dust Ordinary Matter Exotic Particles New Physics! Stars MAssive Compact Halo Objects Jupiters? Black Holes? Brown Dwarfs? Massive Neutrinos ?? Weakly Interacting Massive Particles Axions What is the Galactic Dark Matter?

  11. DM + DM neutrinos Searching for Particle Physics Dark Matter • Direct Detection of WIMPs • Direct Detection of Axions • Fossil Record - tracks in mica • Neutrino experiments: 1) Do neutrinos have a non-zero mass? 2) Searches for annihilation decay products

  12. Searching for WIMPs Experimental Challenges: low rate background discrimination Thermal and ionization signature in laboratory apparatus Deep underground cryogenic experiment

  13. Is the mass of the neutrino exactly zero? A new generation of experiments will determine properties of neutrinos Sudbury Neutrino Observatory, Canada SuperKamiokande, Japan

  14. Scanning for Axions • Specific prediction relates the axion’s mass to its interaction rate • In a strong magnetic field, axions convert to light signal sensitive detector frequency superconducting magnet (LLNL/MIT/Florida)

  15. Telescope Star MACHO Searching for MACHOsHow do you look for something that can’t be seen? Use the one thing that is known about Dark Matter: - It Gravitates!

  16. Gravitational Lensing Within the solar system, deflection of light grazing past the sun provides a stringent test of General Relativity Over cosmological distances, lensing by intervening galaxies produces dramatic effects

  17. From a Black Hole Not even Light Escapes

  18. Gravitational Lensing By a Moving Mass

  19. The Signature of Gravitational Microlensing star Brightness

  20. MACHO speed mass duration depends on speed and mass of MACHO peak depends on how close it passes to line of sight The Signature of Gravitational Microlensing star Brightness

  21. you are here Gravitational Microlensing by MACHOs • Unlikely! • One star in a million is lensed at any given time • Distinctive signature is a brightening of a background star Requires a population of stars just outside the Galactic dark halo, but close enough to monitor individual stars

  22. towards Galactic Center towards Large Magellanic Cloud MACHO Project - lines of sight you are here (M65, David Malin, AAO)

  23. Single Image 77 Mbytes = 3 Seattle phone books Typical night 5,000 Mbytes = 200 phone books! Total to date 5,000 Gbytes = 200,000 phone books The Needle in the Haystack More repeated measurements of stars than the entire cumulative previous history of astronomy

  24. Image Analysis 77 Mbytes per frame Image Archive AlertSystem Database Time Series Analysis The MACHO Project - Data Analysis

  25. boom! Many stars are variable! Eclipsing Binary systems Periodic variable stars Exotic stars...

  26. Eclipsing Binary Star System

  27. Periodic Variable Stars

  28. Microlensing has been detected • The trick is distinguishing microlensing from intrinsic stellar variability • More than 200 events seen towards Galactic center • Valuable new tool for astrophysics

  29. Amplification days

  30. Gravitational Microlensing is Very Useful • Lensed stars are brighter! Can get detailed data • Better detail than Hubble Space Telescope • Mass tomography of the Galaxy • Search for distant planets around disk stars • Search for Dark Matter

  31. Looking for Planets with Microlensing • Take advantage of hundreds of events towards Galactic Center • Planetary companions to lensing stars in Galactic disk produce excursions in light curves • Sensitive to Earth-mass planets • Preliminary data look encouraging

  32. As for the search for MACHOs... After looking at more than twenty million stars for two years - a pair of observations: • No short events seen. • A handful of surprisingly long events detected...

  33. excluded 1 million times less massive than the sun one tenth as massive as the sun Lack of short events rules out a wide range of MACHOs being the Dark Matter Eliminating DM candidates is major progress!

  34. A detection of Dark Matter? But wait! Eight microlensing events were seen in a two-year period, after monitoring twenty million stars This significantly exceeds the single event expected from “known” stars in the Galaxy

  35. The Puzzle The detected events last roughly 80 days, corresponding to lenses with about 1/10th the mass of the sun What could these things be? If the preliminary results endure, this could be a turning point

  36. So, what is the matter? The least radical option: • MACHOs and/or massive neutrinos. More speculative: • exotic elementary particles never before seen

  37. We live in a special time in human history Some of the most fundamental questions in cosmology are being successfully addressed by experiments. The measurements are difficult, with results that sometimes appear contradictory. A much more complete understanding will take shape in the decade to come.

  38. Next-generation microlensing projects, along new lines of sight Neutrino Results Results from WIMP and Axion Searches Other observational cosmology projects The Future

More Related