21 cm Cosmology. Miguel F. Morales Boulder, October 5 th, 2010

Transcription

1 21 cm Cosmology Miguel F. Morales Boulder, October 5 th, 2010

2 See invited ARAA review Reionization and Cosmology with 21-cm Fluctuations Miguel F. Morales 1 and J. Stuart B. Wyithe 2 1 Department of Physics, University of Washington, Seattle, Washington 98195; mmorales@phys.washington.edu 2 School of Physics, University of Melbourne, Parkville, 3052 Victoria, Australia; swyithe@unimelb.edu.au

3 The cosmological HI signal

4 How did galaxies form?? EOR Big Bang CMB ~6 redshift 0 (now)

5 Short history of hydrogen Neutral Hydgrogen Ionized Hydgrogen EOR Big Bang CMB ~6 redshift 0 (now)

6 Dark energy with HI 10 0 <F HI > V, <F HI > M z Wyithe & Loeb (2007) <F H1 > V related to Lyman-α absorption, ~10-4 <F H1 > M related to H1 emission, ~10-2

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8 z Mpc/h HI during EoR Zahn Furlanetto, Sokasian, Hernquist (2004)

9 Statistical EoR detection iy v v f Image Cube FT Sky Coordinates f Visibilities FT Frequency h Fourier Representation ix u u

10 Spherical symmetry v h u Morales & Hewitt (2004)

11 EoR power spectrum 10 3 (k 3 P / 2π 2 ) 1/2 [Mpc -3/2 Jy Hz] k [Mpc -1 ] z = 8, 360 hours of integration Furlanetto, Zaldarriaga, Hernquist (2004a,b) Bowman, Morales & Hewitt (2005) Kaplinghat (2005)

12 Power spectrum dynamics McQuinn

13 HI power spectra evolution Lidz

14 Why is this hard? Foregrounds Galactic emission (polarized and Faraday rotated) Bright point sources Faint point sources Instrumental contamination Radio recombination lines RFI Mode mixing!

15 Foreground symmetry y z FT x

16 k-space measurement! +,01'23$1'&3 $ &9'((& 45&!)4 '65(78)5* " #$%&'%$()*+! +,-./!"#$%"&'()*'

17 Mode mixing Frontier of foreground subtraction is interactions between calibration and foregrounds Need measurement fidelity of Effectively a product of the calibration errors and foreground uncertainty

18 Examples Chromatic array beam (PSF) & residual source flux, residual frequency ripple Polarized foreground & polarization mis-calibration, flux leakage from Q & U I Antenna beam dependence & point sources, decorrelation of visibilities at different frequencies Frequency Position Mis-subtracted source Representative line of sight

19 k-space measurement! +,01'23$1'&3 $ &9'((& 45&!)4 '65(78)5* " #$%&'%$()*+! +,-./!"#$%"&'()*'

20 Bright source location error Datta et al. (2010)

21 Foreground subtraction Datta et al. (2010)

22 Confusion level sources!" " 6%&&'.50:5.(8/*&.8),&12.*3!*(4356$37.89 &! k [cm pc 1 ]!"!!! "!"!#!"!!!" " Bowman et al. (2008)

23 k-space measurement! +,01'23$1'&3 $ &9'((& 45&!)4 '65(78)5* " #$%&'%$()*+! +,-./!"#$%"&'()*'

24 MWA sensitivity

25 MWA power spectrum sensitivity 10 3 (k 3 P / 2π t2 ) 1/2 [Mpc -3/2 Jy Hz] k [Mpc -1 ] z = 8, 360 hours of Furlanetto, Zaldarriaga, Hernquist (2004a,b) Bowman, Morales & Hewitt (2005) Kaplinghat (2005)

26 k-space Fisher matrixes Tuning parameter sensitivity Visbal, in prep.

27 Opportunities for lunar 21 cm Low RFI No ionosphere Slow rotation rate Dark ages (redshift > 40) Very large arrays, novel hardware (e.g. MOFF?) Challenge of very fast ground-based development

28 See invited ARAA review Reionization and Cosmology with 21-cm Fluctuations Miguel F. Morales 1 and J. Stuart B. Wyithe 2 1 Department of Physics, University of Washington, Seattle, Washington 98195; mmorales@phys.washington.edu 2 School of Physics, University of Melbourne, Parkville, 3052 Victoria, Australia; swyithe@unimelb.edu.au