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Fundamental physics from astronomical observations
Raul Jimenez
ICREA
ICC University of Barcelona
icc.ub.edu/~jimenez
Courtesy of Planck and SKA teams
Ultimate Experiments
In cosmology one can actually perform ultimate experiments, i.e. those which contain ALL information available for measurement in the sky. The first one of its kind is be Planck (in Temperature) and in this decade we will also have such experiments mapping the galaxy field. Question is: how much can we learn about fundamental physics, if any, from such experiments?
There are many examples: 1. Dark Energy 2. Inflation 3. Neutrino masses 4. Nature of initial conditions 3. Beyond the Standard Model Physics
State of the art of data then… (~1992)
(DMR)COBE
CMB
380000 yr (a posteriori information)
~14 Gyr
Extremely successful model
Avalanche of data
And it still holds!
Vacuum energy (also known as dark energy or cosmological constant)
1917 vacuum
V1
V2
E1= ρv V1
E2>E1
Negative pressure!
E2= ρv V2
Λ
Supernovae
Standard candles
FLDL π4
=
Function of geometry and Content of Universe
Dark Energy(The basics)
Action describing the dynamics of the universe is:
}matterp SqVqqgRm
gxdtdS +−∂∂
+−−= ∫ )(216
23
νµ
µν
π
Consider quintessence a perfect fluid:
)(21
)(21
2
2
qVqp
qVq
Q
Q
−=
+=
ρ
Which has conservation law:
0)(3 =++ qqq pH ρρ
All left now is use Einstein eq: ( )qmpma
aH ρρπ
+=
= 2
22
38
Simon, Verde, RJ PRD (2005)
All left now is use Einstein eq: ( )qmpma
aH ρρπ
+=
= 2
22
38
And Klein-Gordon equation: 0'3 =++ VqHq
What I want to know is shape of potential V
1
1221 ;
εε
εεHH
H =−=
∑ −−−−−=i
ffiip
pwmHzV )(
21)1(
21)3()(
2
1 ρρε
But what I really need is V(q)
)(21)(
2
1 TTp
pmHqK +−= ρε
We can “measure” dark energy because of its effects on the expansion history of the universe: a(t) SN: measure dL CMB: A and ISW a(t) LSS or LENSING: g(z) or r(z) a(t) AGES: H(z) a(t)
''
)'1()1(0
dzdzdtzzd
zL ∫ ++=
dtdz
zzH
tata
)1(1)(
)()(
+−==
θ
)]0(/)([022 ρρ zHH =
QQ zwzH ρρ ))(1)((3 +−=
∫ +Ω+Ω+−=−
z
QQm wz
dzzdtdzH
0
2/12/510 ]}
)'1('3exp[)0()0({)1(
Reconstruct w(z): use dz/dt
z
Non-parametric!
(from Jimenez & Loeb 2002)
''
)'1()1(0
dzdzdtzzd
zL ∫ ++=Note:
dtdz
zzH
)1(1)(+
−=
w(z) in here
)()1(23
)(23
25)1(
4
12
2
2
zwz
zwzdtdz
dtzd
m +Ω−
++
= −
dtdz
zzH
)1(1)(+
−=
Relative aging of galaxies
Moresco, RJ, Cimatti, Pozzetti JCAP (2010)
The edge for z<0.2
The value of H0
Reconstruct w(z): CAN IT work?
At z=0 dz/dt gives Ho and we have SDSS galaxies:
dtdz
zzH
)1(1)(+
−=
A good test, to determine H(z=0)
Moresco, RJ, Cimatti, Pozzetti JCAP (2010) H(0) = 72.3 ± 2.8
The data at z>0 Stern, RJ et al. JCAP 2011 Moresco et al. 2011
However, one can go one step further and build an effective theory… …of expansion.
The simplest theory of expansion involves, besides gravity, a single canonically normalized expansion field described by the leading Lagrangian density
I can copy Weinberg for QCD, BUT here I cannot do scattering… so how to do the power counting?
mass gap
RJ, Talavera & Verde 2011 (arXiv:1107.2542)
If I obtain the modifications to gravity from growth of structure and/or GW, then I can obtain the lambdas from the expansion rate…
1
1221 ;
εε
εεHH
H =−=
Multiple uses of H(z)
A factor 5 improvement on universe transparency (Avgoustidis, Verde, RJ JCAP(2009))
Detection of aceleration/deceleration (Avgoustidis, Verde, RJ JCAP
(2009))
Multiple uses of H(z)
Constraints on the mass and number of relativistic particles (de Bernardis et al. JCAP0803:020,2008 Figueroa, Verde, RJ JCAP0810:038,2008) and on
the curvature (Stern et al. 2009)
Summary
• Vast quantity of high quality cosmo data fast approaching: CMB, BAOs, Gravitational waves, 21cm,…
• Fruitful interplay between HEP/cosmo theory and cosmological observation: constraints on axions, neutrino masses, neutrino hierarchy, nature of the initial conditions…
• First determinations of the expansion history of the Universe, H(z), already available at ~ 10% level. They already provide constraints on alternatives to the LCDM model.
