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Exotic Physics in the Dark Ages. Katie Mack Institute of Astronomy / Kavli Institute for Cosmology, University of Cambridge. Summary. Future high-redshift 21cm observations will be uniquely suitable for constraining exotic physics in the Dark Ages. Summary.

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exotic physics in the dark ages

Exotic Physicsin the Dark Ages

Katie Mack

Institute of Astronomy / Kavli Institute for Cosmology, University of Cambridge

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

Cosmological Reionization

summary1
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

summary2
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

slide6

Dark Ages

Cosmological Reionization

spin temperature and signal

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

exotic physics in the dark ages1
Exotic physics in the Dark Ages
  • Astrophysically, the Dark Ages are simple: gas is cooling adiabatically and undergoing gravitational collapse

Dark Ages

Cosmological Reionization

exotic physics in the dark ages2
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

primordial black holes
Primordial black holes
  • Pre-stellar black holes
    • Formed in the early universe
    • No stellar intermediary

Cosmological Reionization

primordial black holes1
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

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

Cosmological Reionization

hawking radiation1
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

pbh evaporation and igm ionization
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

pbh evaporation and igm ionization1
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

results ionization history
Results – ionization history

high-mass PBHs

Cosmological Reionization

results ionization history1
Results – ionization history

low-mass PBHs

Cosmological Reionization

results brightness temperature
Results – brightness temperature

Cosmological Reionization

results 21cm power spectrum
Results – 21cm power spectrum

M = 1011 kg

M = 1013 kg

M = 5 x 1010 kg

Cosmological Reionization

slide20

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

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

Cosmological Reionization

implications1
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

cosmology with 21cm
Cosmology with 21cm

A few proposed uses of 21cm observations:

Cosmological Reionization

cosmology with 21cm1
Cosmology with 21cm

A few proposed uses of 21cm observations:

Exotic energy injection:

Cosmological Reionization

cosmology with 21cm2
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

cosmology with 21cm3
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

cosmology with 21cm4
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

observations
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

21cm power spectrum
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

brightness temperature
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

redshift space information
Redshift space information

isotropic

μ2

μ4: sourced by velocity correlations

Pritchard & Loeb 2008

Cosmological Reionization

angular power spectrum and higher orders
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

probing really small scales
Probing really small scales

distant future instrument

Small scale measurements plus large volume equals lots of Fourier modes

Tegmark & Zaldarriaga 2009

Cosmological Reionization

probing really small scales1
Probing really small scales

cosmic superstrings

varying fundamental “constants”

Planck

Khatri & Wandelt 2009

Khatri & Wandelt 2008

Cosmological Reionization

outlook
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

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