1	Astr 5460 Fri., Jan. 31, 2003 Today: Textbook Ordering Astro-ph (xxx.lanl.gov) WIRO: not this weekend Assignment for Friday check Email feedback please Longair, Ch. 2 (Large Scale Struct.) Unless noted, all figs and eqs from Longair. Note: This class will meet W&F, 5440 will be M&W
2	Preliminaries Astro-ph preprints for the week: http://xxx.lanl.gov/astro-ph Keep looking – we’ll do this every week. Discuss homework assignment My solution and ancillary source files will be posted on the webpage (e.g., LaTex, sm, etc.)
3	Big Bang Essentials Hubble Expansion Black Body Background Radiation Light Element Abundances Age of oldest stars consistent with Ho age
4	Very Early Universe Isotropy – the universe looks the same in all directions, again strictly true on large scales Small Baryon/Anti-baryon asymmetry Close to critical (Omega = 1) (will be HW) Initial fluctuations to seed structure growth
5	Longair Chapter 2 Large scale distribution of radiation and matter in the Universe as determined through observational work. Cosmic Microwave Background Radiation Large-scale Distribution of Galaxies Hubble’s Law
6	Cosmic Microwave Background Observations First detected by Wilson and Penzias in 1960’s Serendipitous detection – thought is was noise in their radio telescope but couldn’t find cause. Only later heard of theoretical predictions Best spectrum observed by COBE satellite Red curve is theoretical prediction 43 Observed data points plotted there error bars so small they are covered by curve. it is covered by curve. Isotropy also measured by COBE T varies by less than 0.01 K across sky Small “dipole” anisotropy seen Blue = 2.721 Red = 2.729 Caused by motion of Milky Way falling towards the Virgo supercluster.
7	Research Notes Some Hubble studies performed using the CMBR as the reference-frame for galaxy velocities. Heliocentric velocities are relative to the sun, and there is still the motion of the sun around the Milky Way (about 225 km/s) and the motion of the Milky Way. Who will volunteer to do a short presentation on the MAP and PLANCK missions next week?
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9	Background Temp. Fluctuations Zeldovich and Sunyaev in late 1960s: Injection of energy at z > 1000, then leads to an equilibrium Bose-Einstein spectrum which depends on a dimensionless chemical potential μ:
10	Background Temp. Fluctuations Zeldovich and Sunyaev in late 1960s: Compton scattering by hot electrons in the IGM leads to a distortion of the background spectrum:
11	CMBR: How Isotropic?
12	Homework Assignment Verify by next Friday that if you redshift a blackbody spectrum that the spectrum remains a blackbody and that the blackbody temperature changes by a factor of 1+z. You need not turn this assignment in, but I may ask someone to demonstrate this on the blackboard.
13	Large-scale Distribution of Galaxies
14	Large-scale Distribution of Galaxies On small scales, the universe is very inhomogeneous (stars, galaxies). What about larger scales? Angular two-point correlation function w(θ):
15	Large-scale Distribution of Galaxies This function w(θ) describes apparent clustering on the sky down to some magnitude limit. More physically meaningful is the spatial two-point correlation function ξ(r) which describes clustering in 3-D about a galaxy:
16	Large-scale Distribution of Galaxies w(θ) isn’t so hard to measure from various surveys – just need positions. ξ(r) is harder – must have redshifts to do properly. Can make some assumptions however.
17	Large-scale Distribution of Galaxies
18	Large-scale Distribution of Galaxies
19	Large-scale Distribution of Galaxies
20	Large-scale Distribution of Galaxies
21	Large-scale Distribution of Galaxies
22	Large-scale Distribution of Galaxies
23	Hubble’s Law and Expansion
24	Hubble’s Law and Expansion
25	Hubble’s Law and Expansion
26	Hubble’s Law and Expansion
27	Hubble’s Law and Expansion
28	Hubble’s Law and Expansion
29	Hubble’s Law and Expansion
30	Conclusions On the largest scales it is appropriate to impose the conditions of isotropy and homogeneity, plus uniform expansion. These simplifications plus GR provide relatively simple “world models” that provide a framework for cosmology and the origin of galaxies and other large scale structures.
31	Hubble’s Law and Expansion