The redshifted 21 cm background The redshifted 21 cm background and particle decays and particle decays Evgenii O. Vasiliev & Yuri A. Shchekinov Tartu Observatory, Estonia South Federal University, Russia Tõravere '07: Astrophysics and particle physics
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The redshifted 21 cm background and particle decays
Evgenii O. Vasiliev & Yuri A. Shchekinov Tartu Observatory, Estonia South Federal University, Russia. The redshifted 21 cm background and particle decays. T õravere '07: Astrophysics and particle physics. 21 cm line of neutal hydrogen. 21 cm line: van de Hulst (1945) - PowerPoint PPT Presentation
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The redshifted 21 cm background The redshifted 21 cm background and particle decaysand particle decays
Evgenii O. Vasiliev & Yuri A. Shchekinov
Tartu Observatory, Estonia
South Federal University, Russia
Tõravere '07: Astrophysics and particle physics
Tõravere '07: Astrophysics and particle physics
21 cm and “dark ages”
Hogan & Rees 1979, Madau et al 1997
“dark ages”
epoch of interest
21 cm line of neutal hydrogen
21 cm line: van de Hulst (1945)
possibility: Shklovsky (1949)
observations: e.g. Muller & Oort (1951)
exitation in the neutral IGM:
Wouthuysen (1952), Field (1958,1959)
Reionization and unstable particles (Sciama 1982, 1990)
LSS and unstable particles (Doroshkevich & Khlopov 1984 – )
Nucleosynthesis and unstable particles (Scherer 1984)
WMAP 1 year, large optical depth – strong requirements to UV photon production from first stellar and QSO objects
complementary sources of reionization
decaying dark matter
ultra high energy cosmic rays (UHECRs)
Doroshkevich et al 2003Hansen & Haiman 2004 Chen & Kamionkowski 2004 Kasuya et al 2004 Kasuya & Kawasaki 2004 Pierpaoli 2004Mapelli et al 2006 Biermann & Kusenko 2006Ripamonti et al 2006
…
possible solution: partial ionization due to extra sources
Tõravere '07: Astrophysics and particle physics
Extra ionization sourcesExtra ionization sources
decaying dark matter cold and warm DM, e.g. axino, neutralino, sterile neutrino
(Dolgov 2002, Hansen & Haiman 2004, Chen & Kamionkowski 2004, Mapelli et al 2006, Ripamonti et al 2006)
– decay rate
long lifetime – Hubble time > short lifetime – Hubble time <
UHECRsorigin from Super Heavy Dark Matter particles (>1012 GeV)
(Berezinsky et al 1997, Kuzmin & Rubakov 1998, Birkel & Sarkar 1998)
– production rate Peebles et al 2000Doroshkevich & Naselsky 2002
Tõravere '07: Astrophysics and particle physics
The modelThe modelIonization and temperature evolution (similar to Chen & Kamionkowski 2004):
UHECRs
Decaying particles
Heating rate
Peebles et al 2000Doroshkevich & Naselsky 2002
Modified version of the code RECFAST (Seager et al 1999)
“Smooth” or global signal evolution
Chen & Kamionkowski 2004
Chen & Kamionkowski 2004
Tõravere '07: Astrophysics and particle physics
Basics of 21 cm physicsBasics of 21 cm physics
Tõravere '07: Astrophysics and particle physics
spin temperature:
absorption of CMB photons
collisions with hydrogen atoms, protons, free electrons
scattering of Ly - Lyc photons (Wouthuysen-Field effect)
brightness temperature (or specific inrensity)
spin temperature (or exitation temperature)
Observable parameters: global signal & fluctuations
T* = 0.068 K – energy splitting
TS>>T
* in astrophysical applications
~3 of 4 atoms in the exited state
Ionization, spin and kinetic temperaturesIonization, spin and kinetic temperatures
CMB temperatureBlack – standard recombinationRed – UHECRsGreen – long living particlesBlue – short living
heating vs spin temperature
Tõravere '07: Astrophysics and particle physics
UHE cosmic raysUHE cosmic rays
standard recombination
✔weak extra ionization
✔negligible heating
Ly-alpha and Ly-c photons
Wouthuysen-Field effect ε= 0 ε= 0.3 ε= 1 ε= 3
Tõravere '07: Astrophysics and particle physics
long living particles (heating rate) short living particles (decay rate, density)
Decaying dark matter particlesDecaying dark matter particles
6x10-27 s-1
3x10-25 s-1
6x10-26 s-1
3x10-26 s-1
10-14 s-1 , 0.5
5x10-15 s-1 , 1
10-15 s-1 , 1
10-15 s-1 , 5
Tõravere '07: Astrophysics and particle physics
density in units 10-8 d at z
eq
Major impact: collisions or photons?Major impact: collisions or photons?
long living particles short living particles UHECRs
solid – collisions
dash – photons
Major impact: collisions or photons?Major impact: collisions or photons?
Power spectrum of 21 cm fluctuationsPower spectrum of 21 cm fluctuations
Tõravere '07: Astrophysics and particle physics
Barkana & Loeb (2005), Hirata & Sigurdson (2006)
– power spectrum
– baryon density fluctuations
– density-velocity cross spectrum
– velocity fluctuations
– cos(angle between line of sight and wavevector)
– brightness temperature fluctuations
Tõravere '07: Astrophysics and particle physics
standard recombination UHECRs
Tõravere '07: Astrophysics and particle physics
long living particles short living particles
standard recombination UHECRs
TTbb – – 21 cm brightness temperature fluctuations 21 cm brightness temperature fluctuations (in (in
mK)mK)
Discrimination between sources & Discrimination between sources & observationsobservationsobservations at three redshift – three wave-band observations
2 – “central” redshift
open – emissionfilled – absorption half-filled – emission/absorption
– standard recombination
– UHECRs
– long living particles
– short living particles
z1 z2 z3
1 20 40
Tõravere '07: Astrophysics and particle physics
Discrimination between sources & Discrimination between sources & observationsobservationsobservations at three redshift – three wave-band observations
2 – “central” redshift
open – emissionfilled – absorption half-filled – emission/absorption
– standard recombination
– UHECRs
– long living particles
– short living particles
z1 z2 z3
1 20 4010 30 50
Tõravere '07: Astrophysics and particle physics
Discrimination between sources & Discrimination between sources & observationsobservationsobservations at three redshift – three wave-band observations
2 – “central” redshift
open – emissionfilled – absorption half-filled – emission/absorption
– standard recombination
– UHECRs
– long living particles
– short living particles
standard recombination
z1 z2 z3
1 20 4010 30 5020 40 50
Tõravere '07: Astrophysics and particle physics
Minimum background flux
10 weeks – integration time
~10 mJy z = 20-40 LOFAR
~1-3 mJy z = 20-40 SKA/LWA
Black – standard recombinationGreen – UHECRsRed – long living particlesBlue – short living
z1 zc z3 δz = 0.. δzm
δz δz
m mm
m
Tõravere '07: Astrophysics and particle physics
✔ long living and short living unstable dark matter particles and UHECRs produce distinguishable dependences of brightness temperature on redshift
✔ future radio telescopes (such as LOFAR, LWA and SKA) seem to have sufficient flux sensitivity for detection the signal in 21 cm influenced by decaying particles and UHECRs (three wave-band observations)