Probing dark matter and the physical state of the IGM with the Lyα forest

Transcription

1 Probing dark matter and the physical state of the IGM with the Lyα forest Martin Haehnelt in collaboration with: George Becker, James Bolton, Jonathan Chardin, Laura Keating, Ewald Puchwein, Debora Sijacki, Volker Springel, Matteo Viel (and quite a few more)

2 Dark Matter Gas Galaxies Neutral hydrogen Neutral hydrogen is an excellent tracer of the matter distribution.

3 Lyα absorption by neutral hydrogen λ obs = 1216 (1+z) Å Hydrogen in the IGM is photoionized: Recombination Photoionization α n HII n e = Γ n HI

4 A real spectrum A prominent forest of Lyα absorption lines at λ obs = 1216 (1+z) Å.

5 High resolution High S/N! x10 x10 A treasure trove of information!

6 matter power spectrum on small and intermediate scales thermal history of the IGM ionization state of the IGM reionization metal enrichment (high-redshift galaxies)

7 observed simulated Big telescopes and big computers!

8 How cold is cold dark matter?

9 CDM ΛCDM WDM 1.4keV Lovell et al. 2012

10 Free-streaming erases structure cold dark matter ΛCDM warm dark matter WDM 0.5 kev 30 comoving Mpc/h z=3

11 The effect of the free-streaming of (warm) dark matter on the small scale structure in the flux distribution.

12 Our latest WDM results Ø more and better data Ø more and better simulations Ø extensive scrutiny for systematic errors Ø improved and conservative analysis M wdm > 3.3 kev (2σ C.L) 2 kev WDM disfavoured at about 4σ! Viel, Becker, Bolton, Haehnelt 2013

13 DM is pretty cold fluctuation amplitude ΛCDM Bode et al There is little room left for the effect of warm DM on the DM halo mass function (or DM halo profiles). Our best bet to push this further is probably looking at neutral hydrogen before reionization with 21cm emission.

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15 Excellent data and accurate simulations are key!

16 The thermal state of the IGM

17 The effects of temperature and free streaming are not degenerate Viel, Becker, Bolton, Haehnelt 2013

18 T ρ (γ-1) Taking non-equilibrium effects during the reionization and helium affects the temperatures noticably.

19 Becker et al. (2010) γ=1.56 Rudie et al T ρ (γ-1) γ=1.56 Bolton et al 2014

20 The thermal history with Haardt& Madau 2012 Works remarkably well with non-equilibrium solver once corrected for HeIII volum filling factor Puchwein et al. 2014

21 The ionization state of the IGM

22 A much improved measurement of the effective optical depth Becker et al. 2013

23 The ionizing emissivity N ion Γ ion l mfp τ α ˆρ 2 Γ phot Bolton et al h 3 τ α ˆ ρ 2 Γ phot H T 0.7 Ω bar 0.5 Γ phot Ω mat Becker &Bolton 2013 corresponds to about 1-2 ionizing photons per hydrogen atom photon-starved reionization

24 τ eff with Haardt& Madau 2012 Puchwein et al. 2014

25 Robertson et al.

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27 Becker et al Spatial fluctuations of hydrogen ionising flux at z>6 are now well quantified.

28 Full radiative transfer simulations with ATON/RAMSES optically thin self-shielding included full-radiative transfer Chardin et al. in preparation Need sufficient resolution to reproduce Lyman-Limit-Systems to reproduce spatial ionising flux fluctuations.

29 Metals at high redshift

30 Keating & Haehnelt 2014.

31 Keating & Haehnelt 2014.

32 Keating & Haehnelt 2014.

33 The End

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