Exotic Physics in the Dark Ages

1. Exotic Physicsin the Dark Ages Katie Mack Institute of Astronomy / Kavli Institute for Cosmology, University of Cambridge

2. Summary • Future high-redshift 21cm observations will be uniquely suitable for constraining exotic physics in the Dark Ages Cosmological Reionization

3. Summary • Future high-redshift 21cm observations will be uniquely suitable for constraining exotic physics in the Dark Ages • My work: the evaporation of primordial black holes can produce interesting signatures in the all-sky 21cm brightness temperature and the power spectrum [arXiv:0805.1531] Cosmological Reionization

4. Summary • Future high-redshift 21cm observations will be uniquely suitable for constraining exotic physics in the Dark Ages • My work: the evaporation of primordial black holes can produce interesting signatures in the all-sky 21cm brightness temperature and the power spectrum [arXiv:0805.1531] • Other approaches and focused searches in 21cm can improve our understanding of cosmology and fundamental physics Cosmological Reionization

5. Cosmological Reionization

6. Dark Ages Cosmological Reionization

7. What happens to this picture when energy is injected during the Dark Ages? Spin temperature and signal Spin temp Gas kinetic temp CMB temp Pritchard & Loeb 2008 Cosmological Reionization

8. Exotic physics in the Dark Ages • Astrophysically, the Dark Ages are simple: gas is cooling adiabatically and undergoing gravitational collapse Dark Ages Cosmological Reionization

9. Exotic physics in the Dark Ages • Astrophysically, the Dark Ages are simple: gas is cooling adiabatically and undergoing gravitational collapse • If any process injects energy into the IGM before z~30, it interrupts the cooling and alters the 21cm brightness temperature Dark Ages PBHs? Decaying DM? Annihilating DM? Cosmic strings? Cosmological Reionization

10. Primordial black holes • Pre-stellar black holes • Formed in the early universe • No stellar intermediary Cosmological Reionization

11. Primordial black holes • Pre-stellar black holes • Formed in the early universe • No stellar intermediary • Two radiation regimes: • evaporation: energy injection into IGM through Hawking radiation • accretion: X-ray radiation from accretion disks (see Ricotti, Ostriker & KJM 2008, ApJ 680, 829) Cosmological Reionization

12. Hawking radiation • Spectrum is roughly (but not exactly) blackbody spectral distribution • Temperature ~ M-1 • Power ~ M-2 • Lifetime ~ M3 Cosmological Reionization

13. Hawking radiation • Spectrum is roughly (but not exactly) blackbody spectral distribution • Temperature ~ M-1 • Power ~ M-2 • Lifetime ~ M3 Power Mass 300 0 z Cosmological Reionization

14. PBH evaporation and IGM ionization • Currently strongest constraints on PBH evaporation come from the gamma-ray background • Alteration of ionization/temperature history during Dark Ages may be seen in the21cm signal Cosmological Reionization

15. PBH evaporation and IGM ionization • Currently strongest constraints on PBH evaporation come from the gamma-ray background • Alteration of ionization/temperature history during Dark Ages may be seen in the21cm signal Cosmological Reionization

16. Results – ionization history high-mass PBHs Cosmological Reionization

17. Results – ionization history low-mass PBHs Cosmological Reionization

18. Results – brightness temperature Cosmological Reionization

19. Results – 21cm power spectrum M = 1011 kg M = 1013 kg M = 5 x 1010 kg Cosmological Reionization

20. 10-2 10-4 gamma-ray constraint 10-6 10-8 10-10 potential 21cm constraint 10-12 1010 1011 1012 1013 1014 PBH mass (kg) Cosmological Reionization

21. Implications • 21cm observations can detect energy injection from PBHs in the Dark Ages • Limits from 21cm can improve upon existing limits Cosmological Reionization

22. Implications • 21cm observations can detect energy injection from PBHs in the Dark Ages • Limits from 21cm can improve upon existing limits • What about other kinds of exotic physics? Cosmological Reionization

23. Cosmology with 21cm A few proposed uses of 21cm observations: Cosmological Reionization

24. Cosmology with 21cm A few proposed uses of 21cm observations: Exotic energy injection: Cosmological Reionization

25. Cosmology with 21cm A few proposed uses of 21cm observations: • Dark matter decay and annihilation(Furlanetto et al. 2006, Valdes et al. 2007, Finkbeiner et al. 2008, Myers & Nusser 2008, Natarajan & Schwarz 2009) Cosmological Reionization

26. Cosmology with 21cm A few proposed uses of 21cm observations: • Longer reach than galaxy surveys • More information than CMB 21cm structure mapping: CMB SDSS 21 cm Mao et al. 2008 Cosmological Reionization

27. Cosmology with 21cm A few proposed uses of 21cm observations: • Dark matter decay and annihilation(Furlanetto et al. 2006, Valdes et al. 2007, Finkbeiner et al. 2008, Myers & Nusser 2008, Natarajan & Schwarz 2009) • Cosmological parameter estimation(McQuinn et al. 2006, Bowman et al. 2007, Mao et al. 2008) • Primordial non-gaussianity(Cooray et al. 2008) • Varying fundamental “constants”(Katri & Wandelt 2007 & 2009) • Primordial gravitational waves(Bharadwaj & Sarkar 2009) • Inflationary parameters(Barger et al. 2009) • Neutrino masses(Pritchard & Pierpaoli 2008) • Cosmic superstrings(Khatri & Wandelt 2008) • Primordial isocurvature perturbations(Gordon & Pritchard 2009) Cosmological Reionization

28. Observations • 21cm brightness temperature • Exotic physics affects the 21cm all-sky brightness temperature signal • 21cm power spectrum • 21cm power spectrum depends on matter power spectrum as well as gas physics – can be used to distinguish structure formation models • Redshift space distortions • If the 3D 21cm power spectrum can be measured accurately enough, the underlying matter power spectrum can be extracted, which can be tested against cosmological models Cosmological Reionization

29. 21cm power spectrum cosmological parameters α, h, ns, Ωb decaying dark matter Furlanetto et al. 2006 “exciting” dark matter Bowman et al. 2007 Finkbeiner et al. 2008 Cosmological Reionization

30. Brightness temperature decaying dark matter decaying and annihilating DM See next talk by Marcos Valdes Furlanetto et al. 2006 Valdes et al 2007 “exciting” dark matter Finkbeiner et al. 2008 Cosmological Reionization

31. Redshift space information isotropic μ2 μ4: sourced by velocity correlations Pritchard & Loeb 2008 Cosmological Reionization

32. Angular power spectrum and higher orders primordial isocurvature perturbations annihilating DM Gordon & Pritchard 2009 primordial non-gaussianity Natarajan & Schwarz 2009 Cooray et al. 2008 Cosmological Reionization

33. Probing really small scales distant future instrument Small scale measurements plus large volume equals lots of Fourier modes Tegmark & Zaldarriaga 2009 Cosmological Reionization

34. Probing really small scales cosmic superstrings varying fundamental “constants” Planck Khatri & Wandelt 2009 Khatri & Wandelt 2008 Cosmological Reionization

35. Outlook • Future 21cm experiments can constrain cosmology and exotic physics • Foregrounds and instrumental challenges make it difficult, but worth trying Barger et al. 2009 Furlanetto et al. 2009; McQuinn et al. 2006 Cosmological Reionization

36. Cosmological Reionization