1. ASTR 1040 Accel Astro: Stars & Galaxies
Structure
formation
model
Prof. Juri Toomre TAs: Ben Brown, Adam Jensen
Lecture 30 Thur 4 May 06
zeus.colorado.edu/astr1040-toomre

2. Ultimate Joys of Cosmology
Look at early “eras” involved with the big-bang beginning
Discuss development of large-scale structure in the universe
Final Exam Review tonight Thur 4 May by Ben Brown, 7-9pm – Review Set # 4 still available
Final Exam (comprehensive) here, Mon 8 May 1:30-4:00 pm

3. Evolution
of Universe
1 billion years
380,000 years
3 minutes

4. Models of universe – and its fates
SIZE
OPEN
CRITICAL
(FLAT)
CLOSED
NOW
TIME

5. How can universe be accelerating??
Conjecture: An unknown force at large scales begins to counteract pull of gravity
“Dark energy” – outweighs every other form of mass/energy
73%
Baryons: 4.4% Cold Dark Matter: 23% ,
with a FLAT universe and early inflation

6. With alarming new ideas like inflation and dark energy ….
No doubt Einstein would have been concerned – maybe even troubled!

7. D. A. The universe to vastly expand (‘inflation”)
Grand unified theories of physics predict that the very early universe (10-32 seconds after the start) may have had a phase transition, releasing energy and causing: D.
A. The universe to vastly expand (‘inflation”)
B. Tiny fluctuations predicted by quantum mechanics to expand large enough to contribute to the fluctuations we see in the cosmic background radiation now
C. Any curvature of space to be reduced
D. All of the above

8. Some say the world will end in fire Some say with ice
From what I’ve tasted of desire
I hold with those who favor fire
But if I had to perish twice
I think I know enough of hate
To say that for destruction ice
Is also great
And would suffice
-- Robert Frost
National Poet Laureat

9. Now turn to the VERY Beginning

10. Big bang
idea
COSMIC
FIREBALL
George
GAMOW
(1948)
Oops ! Pure
HELIUM

11. Making helium in first 3 minutes
JUST DO NOT MAKE EVERYTHING INTO HELIUM !

12. HOT
Big Bang
did the trick!

13. Matter and Anti-matter
Protons slightly outnumber anti-protons
At end of particle era, universe contains some matter!
Universe ratio today:
1 billion photons (light)
1 leftover proton
(matter)

14. H and He ratio after 3 minutes

15. During first 3 minutes Making the elements How much DEUTERIUM
made depends
on density of
ordinary matter
(baryons)

16. Sensitivity in making the light elements

17. After first
3 minutes
RADIATION
ERA
--> 380,000 yr
MATTER
ERA

18. Era of Atoms After “recombination”:
Finally cool enough for electrons to combine with nuclei to form atoms (380,000 yrs)
Photons now “decoupled” = free to become CMB of future
Universe becomes transparent to light

19. What is Olber’s paradox?
A. If the universe was infinite, any direction you looked you would eventually see a star
B. If the universe was infinitely old, the starlight would have time to get here
C. The sky should look bright at night–because all directions would have starlight
D. All of the above

20. Era of Atoms and Galaxies
About 1 billion years after Big Bang, first stars and galaxies start to form ( Z = 10 ?)

21. Forming first stars and galaxies
SIMULATIONS

22. Simulating large-scale structure
COLD DARK MATTER
GALAXY CLUSTERING

23. Forming filaments in cosmic fabric Kravtsov

24. Evolve and rotate viewing

25. Co-moving frame in overview

26. Simulation: Dark matter structure now
140 M ly across

27. Dark matter cosmic web

28. Forming galaxy clusters

29. Web of 3 million real galaxies in sky
~ 30 degress across

30. Galaxy clustering in ever deeper surveys

31. Galaxies are always moving: “Hubble flow” + respond to local clustering
Milky Way at center
is moving toward
Virgo cluster, then
Coma supercluster
600 M ly across

32. The Big Mysteries What will be the fate of the universe ?
What is the universe made of ?
What is the dark matter ?
Is the theory of inflation correct ?
What is the dark energy ?
Which of this, if any, should we believe?
Science is not about belief, it’s about exploration…