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

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)


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


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


Increased CPU power has made the simulations more realistic

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


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


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


Other flux statistics fit well as too.

Flux PDF Flux PS


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


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


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



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



The IGM temperature affects the widths of the Lyman- lines

TT, Schaye & Haehnelt


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


IGM temperature as function of redshift.

Schaye et al.


Photo-heating rate is less than adiabatic cooling rate


If no other heat sources, HI reionization late?

Theuns et al.


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


Tom Abel

Ciardi et al.


Wavelets are also sensitive to line-widths

Theuns & Zaroubi


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

Theuns et al.Zaldarriaga.


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


Sloan DA too noisy to see anything?

Bernardi et al.


To do list:

better constrain T evolution better constrain fluctuations

other heating sources? (cosmic rays? X-rays? dust?)

Thank you.

Documents

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