1. Tom Theuns Institute for Computational Cosmology, Durham, UK Department of Physics, Antwerp, Belgium Munich 2005 Reionization And the thermal history of the IGM Tom Theuns Institute for Computational Cosmology, Durham, UK Department of Physics, Antwerp, Belgium

2. Tom Theuns: IGM thermal history The intergalactic medium can be observed in absorption towards distant bright sources (QSOs, GRBs)

3. Tom Theuns: IGM thermal history UVES+VLT and HiRes+Keck have revolutionised these data in terms of S/N and resolution

4. Tom Theuns: IGM thermal history The filamentary pattern of the cosmic web produces absorption lines very similar to those seen in QSO spectra. Cen & Ostriker ‘94 Gas density contours in a cosmological box of size 4Mpc Hubble volume simulation

5. Tom Theuns: IGM thermal history Increased CPU power has made the simulations more realistic Simulated versus observed high-resolution spectrum. Which is which?

6. Tom Theuns: IGM thermal history Voigt profile fits can be used to characterise the statistics of lines

7. Tom Theuns: IGM thermal history The evolution of the column-density fits well with observations for an ionising background dominated by QSOs

8. Tom Theuns: IGM thermal history Other flux statistics fit well as too. Flux PDFFlux PS

9. Tom Theuns: IGM thermal history Simulations with feedback produce metal lines not unlike the observed ones, without drastically altering the HI lines

10. Tom Theuns: IGM thermal history shocked gas unshocked, photo-ionised gas Most of the volume is filled with warm photo-ionised gas, with shocks occupying a small volume around haloes and large filaments

11. Tom Theuns: IGM thermal history When the IGM is highly ionised, the (photo)-heating rate becomes small.

12. Tom Theuns: IGM thermal history

13. Photo-ionisation heating produces a well-defined  -T relation in the low-density IGM that produces the Ly  -forest. (Hui & Gnedin 1997) Temperature of the IGM

14. Tom Theuns: IGM thermal history

15. The IGM temperature affects the widths of the Lyman-  lines TT, Schaye & Haehnelt

16. Tom Theuns: IGM thermal history Line-width (b) and temperature are related Column-density (NH) and density are related Hence can determine  -T relation Schaye et al, Ricotti et al, McDonald et al

17. Tom Theuns: IGM thermal history IGM temperature as function of redshift. Schaye et al.

18. Tom Theuns: IGM thermal history Photo-heating rate is less than adiabatic cooling rate

19. Tom Theuns: IGM thermal history If no other heat sources, HI reionization late? Theuns et al.

20. Tom Theuns: IGM thermal history (Perceived?) Tension: z reion =17 (WMAP) or z reion around 6 (quasars)?

21. Tom Theuns: IGM thermal history Tom Abel Ciardi et al.

22. Tom Theuns: IGM thermal history Wavelets are also sensitive to line-widths Theuns & Zaroubi

23. Tom Theuns: IGM thermal history Observed QSO looks similar to simulation with HeII reionisation, but without evidence for T fluctuations. Theuns et al. Zaldarriaga.

24. Tom Theuns: IGM thermal history IGM temperature also affects optical depth (because recombination rate depends on T)

25. Tom Theuns: IGM thermal history Sloan D A too noisy to see anything? Bernardi et al.

26. Tom Theuns: IGM thermal history To do list: better constrain T evolution better constrain fluctuations other heating sources? (cosmic rays? X-rays? dust?) Thank you.