Astro105 Lecture19

Slide1: 

Astro 105: Our Place in the Universe Lecturers: J.P.Ostriker A.E.Shapley J.E. Gunn P. Steinhardt Lecture 19

Plan of Lectures 19: 

Plan of Lectures 19 Reading Review The Best Current Cosmological Model Some Problems and Some Coincidences

Reading: : 

Reading: A.Guth: Inflationary Universe V. Rubin: Dark Matter M. Rees: Just Six Numbers

In Dimensionless Form: 

In Dimensionless Form Everything is either mass or energy; together they determine the geometry of the universe.

WMAP CBR SKY: 

WMAP CBR SKY Page et al; 2003

WMAP Spectrum of Cosmic Perturbations: 

WMAP Spectrum of Cosmic Perturbations Spherical Harmonic Multi-pole => (Amplitude)2 (Aplitude)2

CBR:WMAP contributions: 

CBR:WMAP contributions |n-1|/n << 1 = 0.01+-0.04. -> scale invariant density fluctuation spectrum: P(k) ~ k1. b / | m- b| << 1 = 17.1%+-0.25%. ->dark matter dominance: d ~ 6 b tot = 1.02 +- 0.04. -> geometrically flat universe: tot = 1 4) | hopt –hcbr | << 1 = 5%+-10%; confirms time-scale |8cbr- 8clstr | / 8 << 1 = 0.29+-0.45; confirms amplitude Cosmological model and initial density fluctuations are fixed!

Slide9: 

Omega Dark Matter Dark Energy Ordinary Chemical Elements The Inventory of the Universe 0 1

The Model Passes Observational Tests at Various Epochs: eg: 

The Model Passes Observational Tests at Various Epochs: eg Z ~ 106 : Light Element Nucleosynthesis Z ~ 103 : Cosmic Background Radiation 6 > Z > 2 : Lyman alpha cloud absorptions 4 > Z > 0 : Galaxy Formation Rate Z ~ 0: Large Scale Structure of Galaxies

Slide11: 

Nagamine, Fukugita Cen and Ostriker (2001) Star Formation Cosmic History

Sloan Digital Sky Survey: 2003200,000 galaxies: 

Sloan Digital Sky Survey: 2003 200,000 galaxies

Cmbgg OmOl: 

Cmbgg OmOl CMB + LSS

Cmbgg OmOl: 

Cmbgg OmOl CMB + LSS How clumpy is the Universe?

Slide15: 

Where we are now…. 2005 100

In Detail: Best Current Cosmological Model (prior: LCDM): 

In Detail: Best Current Cosmological Model (prior: LCDM) total = 1 (assumption) baryon = 0.0486 ± 0.0019 cdm = 0.260 ± 0.037 baryon = 0.0486 ± 0.0019 lambda = 0.691 ± 0.036 radiation = 5.1 x 10-5 n = 0.966 ± 0.023 H0 = 68.3 ± 6.75 km/s/Mpc 8 = 0.894 ± 0.057 scat = 0.103 ± 0.054 Tegmark et al (2003): astro-ph 0310723

A Worry: Different forms of matter () have similar values now but were very different at other times. A coincidence or is this deep?: 

A Worry: Different forms of matter () have similar values now but were very different at other times. A coincidence or is this deep? 1) Better theory (string theory) will derive these results? 2) Divine providence? 3) It had to be this way for us to ask the question (“Anthropic Principle”)? 4) At other times it would also have been true! Leave this vexed question for now and come back..

A More Critical Look at the Low Red-Shift Tests: 

A More Critical Look at the Low Red-Shift Tests of model:

A Joker In The Deck ??? : 

A Joker In The Deck ??? Is the CDM paradigm wrong at small scales ? Too many small galaxies predicted? Central galaxy densities predicted too large? Too many satellite galaxies predicted? Too many galaxies in voids predicted? Too late ionization predicted? Etc…….. Or is it simply that it is too hard to compute correctly in the extreme non-linear domain?

Will the Problems Give Clues To The Nature Of The Dark Matter ?: 

Will the Problems Give Clues To The Nature Of The Dark Matter ? Standard: Weakly Interacting Cold Dark Matter (CCDM). Variant: Strongly Self-Interacting Dark Matter (SIDM). Variant: Warm Dark Matter (WDM). Variant: Decaying Dark Matter (DDM). Variant: Repulsive Dark Matter (RDM). Variant: Self-Annihilating Dark Matter (SADM). Variant: Fuzzy Dark Matter (FDM). Variant: Massive Black Holes as dark matter (BH). Etc, etc,…

Warm Dark Matter: 

Warm Dark Matter 20 megaparsec boxes at redshift z = 1 (0.35 keV particle) Bode, Ostriker and Turok(2000)

Warm Dark Matter (Closeup): 

Warm Dark Matter (Closeup) Standard Cold Dark Matter, 1.0 Megaparsec Warm Dark Matter (1.5keV), 1.0 Megaparsec

Conclusions: 

Conclusions Uniform, Isotropic, Hot Big-Bang Model is a Very Good Fit to Suite of Observables. Inflationary Origin for Perturbations Fits Large Scale Structure Observations. Cold Dark Matter Paradigm Works Well. Flat, K = 0, Model is Satisfactory. “New”, Repulsive Force, Cosmological Constant or Quintessence Seems Required.

Do We Understand the Cosmos?: 

Do We Understand the Cosmos? The general picture that we have works well. Apart from some (important) details, all predictions match our improving observations. But, we have said this before! Each time, some apparent detail has been a clue to a basic omission. Something ignored. My view: this will happen again. AND

The Nature of the DM is Unknown: All Tests are on Small Scales and are Problematic!: 

The Nature of the DM is Unknown: All Tests are on Small Scales and are Problematic! Shortage of Visible Satellite Galaxies: baryonic physics a plausible explanation. Number of Small Galaxies: understood from baryonic physics. Absence of Dwarf Galaxies in Voids: probably ok given baryonic physics. ====================================== Dark Matter in Dwarf Systems: incomprehensible at present. Shortage of DM Satellite Systems: a problem. Absence of DM Cusps in Galaxies: a serious problem.

Slide26: 

“The rest is silence” William Shakespeare