Yi Mao, MIT Collaborators: Max Tegmark, Alan Guth, Matias Zaldarriaga, Matt McQuinn, Oliver Zahn,...
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Transcript of Yi Mao, MIT Collaborators: Max Tegmark, Alan Guth, Matias Zaldarriaga, Matt McQuinn, Oliver Zahn,...
Yi Mao, MITCollaborators: Max Tegmark, Alan Guth,
Matias Zaldarriaga, Matt McQuinn, Oliver Zahn, Tom Faulkner, Ted Bunn, Serkan Cabi
Constraining cosmological and gravitational parameters with upcoming astrophysical data
But the best is yet
to comePrecision CMB (polarization, small scales), precision lensing ……
and 21cm tomography
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
Murchison Widefield Array (MWA)• Located in western Australia • 500 antennas; array diameters 1500m; • Measures z=6~12
Murchison Widefield Array (MWA)• Located in western Australia • 500 antennas; array diameters 1500m; • Measures z=6~12
Yi Mao
Fermilab seminarJanuary 23, 2008
Other arrays• Square Kilometre Array (SKA)• Low Frequency Array (LOFAR)• 21cm Array (21CMA)
• Square Kilometre Array (SKA)• Low Frequency Array (LOFAR)• 21cm Array (21CMA)
Yi Mao
Fermilab seminarJanuary 23, 2008
21cm Power spectrum21cm Power spectrum
• 21cm power spectrum is not isotropic because of redshift space distortion!
• 21cm power spectrum is not isotropic because of redshift space distortion!
How accurately can 21cm tomography
constrain cosmological parameters?
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
LOFAR MWA SKA
MID
OP
T
Size of compact core
Siz
e of
tot
al in
ner
core
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
Size of compact core
Siz
e of
tot
al in
ner
core
MWA in OPT model
YM, Tegmark, McQuinn, Zaldarriaga & Zahn (2008)
Yi MaoFermilab seminarJanuary 23, 2008
Generalize PPN
• A general geometry is determined by metric (g) and connection (), both independent of each other.
• Three quantities characterize the departure from Minkowski spacetime:
Yi MaoFermilab seminarJanuary 23, 2008
Yi Mao
Fermilab seminarJanuary 23, 2008
Solar system constraints on f(R) Chameleon
Faulkner, Tegmark, Bunn and YM (2007)
Yi Mao
Fermilab seminarJanuary 23, 2008
Constraints on cubic f(R) model
Faulkner, Tegmark, Bunn and YM (2007)
Yi Mao
Fermilab seminarJanuary 23, 2008
Outlook
• 3D HI mapping: direct view into the dark ages, precision constraints on cosmological parameters
• Better understanding of the Epoch of Reionization• New tests of Einstein gravity on scales from the solar
system to the cosmos• Common question for cosmology and gravitation: Dark energy = cosmological constant or modified gravity? Dark matter = new particles or TeVeS/MOND? Can GR (and standard cosmological model) be further
tested?
Yi Mao
Fermilab seminarJanuary 23, 2008
21cm line21cm line
•
• Spin temperature , where
• Emission if Ts > Tcmb; absorption if Ts < Tcmb• Saturated when Ts >> Tcmb; arbitrarily large when Ts << Tcmb• The last factor makes the anisotropy!
•
• Spin temperature , where
• Emission if Ts > Tcmb; absorption if Ts < Tcmb• Saturated when Ts >> Tcmb; arbitrarily large when Ts << Tcmb• The last factor makes the anisotropy!
Yi Mao
Fermilab seminarJanuary 23, 2008
Ts couplingsTs couplings
• Absorption of CMB photons and stimulated emission
• Collisions with H, e, p: Ts Tk
• Scattering of UV photons( the Wouthuysen-Field Effect): Ts TLya
• Absorption of CMB photons and stimulated emission
• Collisions with H, e, p: Ts Tk
• Scattering of UV photons( the Wouthuysen-Field Effect): Ts TLya
Furlanetto, Oh & Briggs 2006
Yi Mao
Fermilab seminarJanuary 23, 2008
• zdec~150: compton heating.
Tk = Tcmb before zdec; Tk~(1+z)2 after.
• Z1: Ts = Tk before z1; Ts Tcmb after.
• Zh: IGM Tk > Tcmb.
• Zc: Wouthuysen-Field Effect couples Ts = Tk again.
• Zr: reionization.
• zdec~150: compton heating.
Tk = Tcmb before zdec; Tk~(1+z)2 after.
• Z1: Ts = Tk before z1; Ts Tcmb after.
• Zh: IGM Tk > Tcmb.
• Zc: Wouthuysen-Field Effect couples Ts = Tk again.
• Zr: reionization.
Thermal histroy of IGMThermal histroy of IGM