1. Tom Theuns Institute for Computational Cosmology, Durham, UK Department of Physics, Antwerp, Belgium Groningen 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 Neutral at z=1000 Ionized at z<6 COBE

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

4. Tom Theuns: IGM thermal history Reionisation by (“first”) stars. Reed et al. 2005

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

6. Tom Theuns: IGM thermal history

7. When the IGM is highly ionised, the (photo)-heating rate becomes small.

8. Tom Theuns: IGM thermal history

9. 2. Numerical simulations: c) photo-ionisation shocked gas unshocked, photo-ionised gas

10. Tom Theuns: IGM thermal history 2. Numerical simulations: c) photo-ionisation Photo-ionisation heating produces a well-defined  -T relation in the low-density IGM that produces the Ly  -forest. (Hui & Gnedin 1997)

11. Tom Theuns: IGM thermal history The IGM temperature affects the widths of the Lyman-  lines TT, Schaye & Haehnelt

12. 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

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

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

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

16. Tom Theuns: IGM thermal history Should we not see temperature fluctuations?

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

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

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

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

21. 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.