1 / 21

Meaning of deceleration parameter

Meaning of deceleration parameter. q 0 tells you if the Universe is accelerating in its global expansion rate, or decelerating. Flat, matter dominated q0=1/2 Empty Universe q0=0 Flat, radiation dominated q0=1 Flat, Cosmological Constant dominated q0=-1. flat model.

ritarogers
Download Presentation

Meaning of deceleration parameter

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. Meaning of deceleration parameter q0 tells you if the Universe is accelerating in its global expansion rate, or decelerating. Flat, matter dominated q0=1/2 Empty Universe q0=0 Flat, radiation dominated q0=1 Flat, Cosmological Constant dominated q0=-1 • flat model

  2. Equation of State Revisited

  3. Distance as a function of redshift

  4. Exact Distance Solutions for open/closed & mixed models

  5. f(x1) f(x1+x) f(x) x1 x2 x1 x1+x Integrating functions • Use trapezoid rule Area  x(f(x1+x)+ f(x1))/2

  6. Trial numerical integration

  7. Angular Size Distance How big does an object look as a function of redshift Proper Motion Distance Apparent Angular velocity as a function of redshift Luminosity Distance How bright does an object appear as a function of redshift

  8. Cosmic Chronology • How old is an object as a function of redshift • Volume Test • How does the Volume per dz change as a function of z • Structure Test • How does structure evolve relative to a model • Density Test • Measure local density of Matter

  9. Luminosity Distance – GR + Homogenous Isotropic Universe for a monochromatic source (defined as inverse-square law) the flux an observer sees of an object at redshift z Brightness of object depends exclusively on what is in the Universe How much and its equation of state.

  10. The Deceleration Parameter Valid for all models Mattig (1958) provides exact solution for matter only Universes

  11. Distance Modulus Fractional distance change  ½(mag change) e.g. 0.1mag difference is 5% distance difference

  12. Angular Size Distance

  13. Attempts to fit/understand models: 1920-1995 • Number counts of Galaxies – Hubble,Yoshii/Peterson • Angular Size Distances - distant radio cores Kellerman • Loitering Universes with z=2 Quasars • Luminosity Distance with Brightest Cluster Galaxies

  14. Volume Effects At low z, N z3, for any non-diverging luminosity function, Hubble observed this to be true, demonstrating that Galaxies uniformly fill the local Universe. He and Humason were unable to reach conclusions on Geometry.

  15. Angular Size Distance with Compact Radio Sources Kellerman (1993)

  16. Stepanas & Saha 1995 Result not that constraining

  17. Excess z~2 QSOs: Loitering Universe Petrosian, V., Saltpeter, E.E. & Szekeres, P. 1967

  18. Brightest Cluster Galaxies Sandage, Humason & Mayhall 1956 Baum 1957 Peach 1970 Deceleration q0>1 But Tinsley 1976 showed Evolution dominates Cosmology

  19. Methods for Measuring Extra-Galactic Distances • Brightest Cluster Galaxies • Cepheids • Fundamental Plane (Dn-/Faber Jackson) • Lensing Delay • Planetary Nebulae • Tully-Fisher • Sunyaev-Zeldovich • Surface Brightness Fluctuations • Supernovae Ia • Supernovae II

More Related