1. Lyman- Emission from The Intergalactic Medium
Juna A. Kollmeier
Theorsts:
Zheng Zheng (IAS), David H. Weinberg (OSU),
Jordi Miralda-Escudé (ICREEA), Romeel Davé (Steward) Neal Katz (U.Mass)
Observers:
Kurt Adelberger (McKenzie), Joe Hennawi (UCB),
Jason Prochaska (UCSC), Chuck Steidel (Caltech)

2. Precision Cosmology Viel et al. 2006 WMAP team Hinshaw et al. 2003
Courtesy M. Tegmark

3. Precision Galaxy Formation?
Galaxy formation is far more complicated than cosmology!

4. The Formation of Structure
Courtesy of A. Kravtsov

5. The IGM: Absorption
Lyman-a forest powerful tool: traces mass and can be connected to cosmology!
Courtesy of W. Sargent

6. The IGM: Absorption
1d-Skewers
3d IGM

7. --> Galaxy/IGM connection!
Why Lyman-a emission?
Look at the universe in Lyman-a eyes:
FULL 3D INFORMATION!
Ionizations lead to recombinations:
--> emission of Lyman-a photon 2P 1S g
Cosmic web in emission
--> Galaxy/IGM connection!

8. DETECTIONS! Nilsson et al. 2007 Steidel et al. 2000
Weidinger et al. 2004
Reuland et al. 2003
Francis et al. 2006

9. Sources of Ly Emission
Fluorescence from uniform UVB
Fluorescence from local sources
(internal and external)
Cooling radiation
Stars and quasars
Predictions for these phenomena require Radiative Transfer!

10. Frequency Diffusion Flux Frequency Shift
Zheng & Miralda-Escude 2002, ApJ, 578

11. Monte Carlo Radiative Transfer of Resonant Line Radiation
From Simple Structures:
Structures predicted by CDM:
Zheng & Miralda-Escude 2002, ApJ, 578

12. Monte Carlo Radiative Transfer of Resonant Line Radiation
Select observation direction
Select photon’s initial position in gas according to emissivity
Scatter photon according to velocity, temperature, density field
At each scattering, accumulate image/spectrum
P(esc)
P(esc)
P(esc)
Observation Direction

13. A 2.5 Mpc region From z=2 SPH Simulation
GAS DENSITY
GAS TEMPERATURE

14. Predicted Image + 2D Spectra
From Kollmeier et al. in prep

15. Fluorescence by Local Sources
Optically thick patches of IGM can be near bright sources (stars, QSOs)
The density combined with the high photoionization rate increases recombination rate
Careful balance!

16. Effect of Quasar on X
1D distribution of neutral fraction in the plane of the QSO
y=0

17. Case I: Transverse
From Adelberger, Steidel, Kollmeier, Reddy, ApJ, 2006, 637, 745

18. Detection?
To Quasar
40’’
From Adelberger, Steidel, Kollmeier, Reddy, ApJ, 2006, 637, 745

19. Model Predictions

20. Match?
Simultaneous match of high surface brightness and large absorber size not successful
Improvements to model? Add heating from QSO does increase SB (but why would this not evaporate the cloud). Ly not from QSO (but why such good agreement with “mirror”)?
Something else?

21. Case II: Line of Sight

22. Detection?
From Hennawi, Prochaska, Kollmeier & Zheng in prep

23. Model Predictions QSO Behind DLA
Total Flux (predicted) = 5.33 x erg/s/cm2
Total Flux (observed) = 4.3 x erg/s/cm2

24. Once you have 1 Lyman Limit System you have many!
For the Future
Integral field units on big telescopes could produce
this:
Once you have 1 Lyman Limit System you have many!

25. Summary IGM is rife with information on structure formation!
Monte Carlo radiative transfer of Lya now included in cosmological simulations Many applications for studying galaxy formation at high and low redshift
fluorescence of Lyman limit systems by UVB
fluorescence of DLAs by local sources
cooling radiation from galaxy formation in action
Lya emitters
sources of reionization
Required to interpret programs underway
Helpful for designing future surveys