exotic physics in the dark ages katie mack institute of astronomy / kavli institute for cosmology,...
TRANSCRIPT
Exotic Physicsin the Dark Ages
Katie MackInstitute of Astronomy / Kavli Institute for
Cosmology, University of Cambridge
19 February 2010 Cosmological Reionization Katie Mack 2/35
Summary
Future high-redshift 21cm observations will be uniquely suitable for constraining exotic physics in the Dark Ages
19 February 2010 Cosmological Reionization Katie Mack 3/35
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]
19 February 2010 Cosmological Reionization Katie Mack 4/35
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
19 February 2010 Cosmological Reionization Katie Mack 5/35
19 February 2010 Cosmological Reionization Katie Mack 6/35
19 February 2010 Cosmological Reionization Katie Mack 7/35
Spin temperature and signal
Pri
tchard
& L
oeb 2
00
8
CMB temp
Gas kinetic
temp
Spin temp
What happens to this picture when energy is
injected during the Dark Ages?
19 February 2010 Cosmological Reionization Katie Mack 8/35
Exotic physics in the Dark Ages
Dark Ages
Astrophysically, the Dark Ages are simple: gas is cooling adiabatically and undergoing gravitational collapse
19 February 2010 Cosmological Reionization Katie Mack 9/35
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
19 February 2010 Cosmological Reionization Katie Mack 10/35
Primordial black holes
Pre-stellar black holes Formed in the early universe No stellar intermediary
19 February 2010 Cosmological Reionization Katie Mack 11/35
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)
19 February 2010 Cosmological Reionization Katie Mack 12/35
Hawking radiation
Spectrum is roughly (but not exactly) blackbody spectral distribution
• Temperature ~ M-1
• Power ~ M-2
• Lifetime ~ M3
19 February 2010 Cosmological Reionization Katie Mack 13/35
Hawking radiation
Spectrum is roughly (but not exactly) blackbody spectral distribution
• Temperature ~ M-1
• Power ~ M-2
• Lifetime ~ M3 Mass
Pow
er
z0300
19 February 2010 Cosmological Reionization Katie Mack 14/35
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 the 21cm signal
19 February 2010 Cosmological Reionization Katie Mack 15/35
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 the 21cm signal
19 February 2010 Cosmological Reionization Katie Mack 16/35
Results – ionization history
high-mass PBHs
19 February 2010 Cosmological Reionization Katie Mack 17/35
Results – ionization history
low-mass PBHs
19 February 2010 Cosmological Reionization Katie Mack 18/35
Results – brightness temperature
19 February 2010 Cosmological Reionization Katie Mack 19/35
Results – 21cm power spectrum
M = 5 x 1010 kgM =
10
11 k
g
M =
10
13 k
g
19 February 2010 Cosmological Reionization Katie Mack 20/35
1010 1011 1012 1013 1014
10-2
10-6
10-8
10-10
10-12
10-4
gamma-ray constraint
potential 21cm
constraint
PBH mass (kg)
19 February 2010 Cosmological Reionization Katie Mack 21/35
Implications
21cm observations can detect energy injection from PBHs in the Dark Ages
Limits from 21cm can improve upon existing limits
19 February 2010 Cosmological Reionization Katie Mack 22/35
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?
19 February 2010 Cosmological Reionization Katie Mack 23/35
Cosmology with 21cm
A few proposed uses of 21cm observations:
19 February 2010 Cosmological Reionization Katie Mack 24/35
Cosmology with 21cm
A few proposed uses of 21cm observations:
Exotic energy injection:
19 February 2010 Cosmological Reionization Katie Mack 25/35
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)
19 February 2010 Cosmological Reionization Katie Mack 26/35
Cosmology with 21cm
A few proposed uses of 21cm observations:
21cm structure mapping:
• Longer reach than galaxy surveys
• More information than CMB
Mao et al. 2008
19 February 2010 Cosmological Reionization Katie Mack 27/35
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)
19 February 2010 Cosmological Reionization Katie Mack 28/35
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
19 February 2010 Cosmological Reionization Katie Mack 29/35
21cm power spectrum
Bowman et al. 2007
Furlanetto et al. 2006
Finkbeiner et al. 2008
decayin
g d
ark
matt
er
“excit
ing
” d
ark
matt
er
cosmological parameters α, h, ns, Ωb
19 February 2010 Cosmological Reionization Katie Mack 30/35
Brightness temperature
Furlanetto et al. 2006
Finkbeiner et al. 2008
Valdes et al 2007
decayin
g d
ark
matt
er
“excit
ing
” d
ark
matt
er
decaying and annihilating DM
See next talk
by Marcos
Valdes
19 February 2010 Cosmological Reionization Katie Mack 31/35
Redshift space information
Pritchard & Loeb 2008
isotropic
μ4: sourced by velocity correlation
s
μ2
19 February 2010 Cosmological Reionization Katie Mack 32/35
Angular power spectrum and higher orders
Natarajan & Schwarz 2009
Cooray et al. 2008
Gordon & Pritchard 2009
annihilating DM
primordial isocurvature perturbations
primordial non-gaussianity
19 February 2010 Cosmological Reionization Katie Mack 33/35
Probing really small scales
Tegmark & Zaldarriaga 2009
Small scale measurements plus large volume equals lots of Fourier modes
distant future instrument
19 February 2010 Cosmological Reionization Katie Mack 34/35
Probing really small scales
Khatri & Wandelt 2008
Khatri & Wandelt 2009
varying fundamental “constants”
cosmic superstrings
Pla
nck
19 February 2010 Cosmological Reionization Katie Mack 35/35
Outlook Future 21cm
experiments can constrain cosmology and exotic physics
Foregrounds and instrumental challenges make it difficult, but worth trying
Cosmological parameter
Improvement in constraint with second-generation array
Dark energy density
1.7
Matter density 2.5
Baryon density 1.5
Neutrino mass 3.0
Spectral index ns 1.4
Running in spectral index α
2.7Barger et al. 2009
Furlanetto et al. 2009; McQuinn et al. 2006
19 February 2010 Cosmological Reionization Katie Mack 36/35