Tom Theuns Institute for Computational Cosmology, Durham, UK Department of Physics, Antwerp, Belgium...

Tom TheunsInstitute for Computational Cosmology, Durham, UKDepartment of Physics, Antwerp, Belgium

Munich 2005

ReionizationReionizationAnd the thermal history of the IGMAnd the thermal history of the IGM

Tom TheunsInstitute for Computational Cosmology, Durham, UKDepartment of Physics, Antwerp, Belgium

Tom Theuns: IGM thermal history

The intergalactic medium can be observed in absorption towards distant bright sources (QSOs, GRBs)

Tom Theuns: IGM thermal history

UVES+VLT and HiRes+Keck have revolutionised these data in terms of S/N and resolution

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 ‘94Gas density contours in a cosmological box of size 4Mpc

Hubble volume simulation

Tom Theuns: IGM thermal history

Increased CPU power has made the simulations more realistic

Simulated versus observed high-resolution spectrum.Which is which?

Tom Theuns: IGM thermal history

Voigt profile fits can be used to characterise the statistics of lines

Tom Theuns: IGM thermal history

The evolution of the column-density fits well with observations for an ionising background dominated by QSOs

Tom Theuns: IGM thermal history

Other flux statistics fit well as too.

Flux PDF Flux PS

Tom Theuns: IGM thermal history

Simulations with feedback produce metal lines not unlike the observed ones, without drastically altering the HI lines

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

Tom Theuns: IGM thermal history

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

Tom Theuns: IGM thermal history

Tom Theuns: IGM thermal history

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

Tom Theuns: IGM thermal history

Tom Theuns: IGM thermal history

The IGM temperature affects the widths of the Lyman- lines

TT, Schaye & Haehnelt

Tom Theuns: IGM thermal history

Line-width (b) and temperature are relatedColumn-density (NH) and density are relatedHence can determine -T relation

Schaye et al, Ricotti et al, McDonald et al

Tom Theuns: IGM thermal history

IGM temperature as function of redshift.

Schaye et al.

Tom Theuns: IGM thermal history

Photo-heating rate is less than adiabatic cooling rate

Tom Theuns: IGM thermal history

If no other heat sources, HI reionization late?

Theuns et al.

Tom Theuns: IGM thermal history

(Perceived?) Tension: zreion=17 (WMAP) or zreion around 6 (quasars)?

Tom Theuns: IGM thermal history

Tom Abel

Ciardi et al.

Tom Theuns: IGM thermal history

Wavelets are also sensitive to line-widths

Theuns & Zaroubi

Tom Theuns: IGM thermal history

Observed QSO looks similar to simulation with HeII reionisation, but without evidence for T fluctuations.

Theuns et al.Zaldarriaga.

Tom Theuns: IGM thermal history

IGM temperature also affects optical depth (because recombination rate depends on T)

Tom Theuns: IGM thermal history

Sloan DA too noisy to see anything?

Bernardi et al.

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.