Transcript The Accelerating Universe

L. Perivolaropoulos
http://leandros.physics.uoi.gr
Department of Physics
University of Ioannina
l
Obs
Dist. Ind.
L
4 d L2
dL
l
L
4 a(t0 ) 2 x 2 ( z ) 1  z 
2
a ( t0 ) 1

 d L ( z )  x( z )(1  z )
l
L
4 a(t0 ) x ( z ) 1  z 
2
2
2
a ( t0 ) 1

 d L ( z )  x( z )(1  z )
cdt  a( z )dx( z )
1
2
a
1  d  dL ( z) 
2   z   H  z    

a
c  dz  1  z  
Know L
Measure l(z)

1
1
d
dz
L
 H ( z )
 d L ( z ) 
l ( z)
 dz
 L
m

M

2.5log
10 
Distance Modulus:

 l 
d L2



  t0  a  t 0 

1  z  
 t  a t 
~ t past
r 
1
H  z
cz
Accelerating Universe:
a
H t  
(rate of expansion) was smaller in the past.
a
Thus H-1(t) was larger in the past.
~ at 
Expand. Phot. Meth./SnII
Planetary Nebulae
Surf. Brightness Fluct.
Tully Fisher
Brightest Cluster Gal.
Glob. Cluster Lum. Fun.
Sunyaev-Zeldovich
Gravitational Lensing
Best Choice
for
Cosmology
M B  19
Degeneracy pressure
always fails at same
mass.
HST
closeby SnIa
m( z )  M 46
 5log  d L  z  / Mpc   25
Accelerating
44
Decelerating
?
42
~ t past
40
38
Gold Dataset (157 SNeIa):
Riess et. al. 2004
H t  
36
~ at 
34
0
0.25
0.5
0.75
z
1
1.25
1.5
1.75
a
a
 dL 

5 log empty
d
 L 
 dL 

5 log empty
d
 L 
Gold Dataset (157 SNeIa):
Riess et. al. 2004
 dL 

5 log empty
 dL 
 dL 

5 log empty
 dL 
Gold Dataset (157 SNeIa):
Riess et. al. 2004
dust produced from vacuum with time
SN Factory
Carnegie SN Project
ESSENCE
CFHT Legacy Survey
Higher-z SN Search
(GOODS)
SNAP
Expected:
Decelerated Expansion due to Gravity
Observed:
Accelerated Expansion
Q: What causes the Acceleration?
a
4 G
4 G

m      3 pX  

 i  3 pi   


a
3
3
i
w
Equation of State:
pX


a
4 G

m    1  3w 



a
3
Necessary condition for acceleration:
w 
1
3
 Negative
Pressure 
 ~ a
d

3
a
   pX d

p X  w 
2
H ( z)
 H 02
2

0 m 
a

a2
 =?

 a 

 
3




~ a
3

8 G
 a0 



0m 
  

3 
 a 
 0 m 1  z    X
3
0 m
 0.3
crit
 z 
31 w 


a


(from large scale structure observations)
SnIa d L z 
1  d  d L ( z) 
H  z    

c  dz  1  z  

dz
1 z  H  z 
0 
t0  
1
H0
z0
z0
q  z   1  z 

d ln H  z 
1
dz
aa
q0   2
a 0
H ( z )2  H 02 0 m 1  z    X  z 
2
d ln H
1 z 
1

pDE ( z )
3
dz
w z 

2
 DE ( z )
3
 H0 
1 
 0 m 1  z 
 H 
a
4 G

  m    1  3w  

a
3 
3
w z 

0 , X  z 
• Einstein (1915) G.R.:
Gmn = k Tmn
• Einstein (1917) G.R. + Static Universe + Matter only:
Gmn - L gmn = k Tmn
GM L r 2
V r   

r
6
The biggest blunder of my life
Since I introduced this term, I had always
a bad conscience....
I am unable to believe that such an ugly
thing is actually realized in nature
A. Einstein 1947 letter to Lemaitre
0m  L  1 (Flatness)
a
8 G
L
3
 a0 
2
H ( z)  2 
0 m     H 0 0 m 1  z    L
3
3
a
 a 

3
2
2

 L 
d L ( z )obs
2.5 log10 
  m( z )  M  25  5 log10
Mpc
 l ( z) 
z
d L ( z )th  c 1  z  
0
dz 
H  z ;  0 m

N
 d L ( z )obs  d L ( z; 0 m )th 
i 1

 2  0 m   
2
2
i
 min


1. Measurements of the Cosmological Parameters Omega and Lambda
from the First 7 Supernovae at z >= 0.35
S. Perlmutter et al., Astrophys.J. 483 (1997) 565
7 SnIa 0.35  z  0.65
L  0
   L  1
2. Observational Evidence from Supernovae for an Accelerating
Universe and a Cosmological Constant
S. Perlmutter et al., Nature 391 (1998) 51
8 SnIa 0.35  z  0.83
 L  0.4
for Flat Universe
3. Discovery of Supernova Explosion at Half the Age of the Universe
A.G. Riess et al., Astron.J. 116 (1998) 1009-1038
16 SnIa 0.16  z  0.62
 L  0.7
for Flat Universe
Ω Μ  1, L  0
ruled out at 95%
4. Cosmological results from high-z supernovae
Tonry et al. The Astrophysical Journal, 594:1-24, 2003 September 1
193 SnIa 0.3  z  1.2
 L  0.7
for Flat Universe
5. New Constraints on ΩM, ΩΛ, and w from an Independent Set of 11
High-Redshift Supernovae Observed with the Hubble Space Telescope
R.A. Knop et al., The Astrophysical Journal, Volume 598, Issue 1, pp. 102-137
11 new SnIa observed from HST
 L  0.7
for Flat Universe
6. Type Ia Supernova Discoveries at z > 1 From the Hubble Space
Telescope: Evidence for Past Deceleration and Constraints on Dark
Energy Evolution
A. Riess et al. The Astrophysical 607:665-687,2004
157 SnIa 0.3  z  1.7 (Gold Sample)  L  0.71
16 new SnIa observed from HST
7 of them with z>1.25
for Flat Universe
Decelerating Expansion starts
at z=0.46
2
 min
 0m  0.3  177.1
2
 SCDM
 0m  1  324.7
Pr obability P   m   N e

 2 ( m )
2
z
Physical Model  H  z; a1 , a2 ,..., an 
 dz
0
ansatz 


z
 dz
Data: d Lobs  zi 
th
0

 d L  z; a1 , a2 ,..., an  

 2  2
min
 H  z; a1 , a2 ,..., an 

d L  z; a1 , a2 ,..., an 
Data: d Lobs  zi 

  a1 , a2 ,..., an   
2
 2   min
 w  z; a1 , a2 ,..., an 
2
  min
 a1 , a2 ,..., an 



H z   H 0m 1 z   a2 1 z   a1 1 z   1 a2  a1  0m 
2
2
0
3
a2  4.16  2.53
a1  1.67  1.03
2

2
min
 174.2
 1
2
min
 177.1
LCDM
2
min
 171.7
What theory produces the features of best
parametrizations?
wDE
z
 0   1,
wDE
z
 0.4   1
dwDE
z
dz
 0
 0,
What is the Fate of the Universe? (extrapolating
w(z) to z<0 (w(z)<-1))
• Quintessence: tracking scalar fields (Ratra & Peebles, Wetterich 1988, Coble et al. 1997,
Ferreira & Joyce 1998, Liddle & Scherrer 1999, Steinhardt et al. 1999, Perrotta &
Baccigalupi 1999, Brax & Martin 2000, Masiero et al. 2001, Doran et al. 2001, Corasaniti &
Copeland 2003,Perivolaropoulos 2005,Tsujikawa 2005)
• Extended Quintessence: non-minimal coupling to Gravity (Chiba, Uzan 1999, Perrotta et
al. 2000, Baccigalupi et al. 2000, Faraoni 2000, Bartolo & Pietroni 2000, Esposito-Farese &
Polarski 2001, Perrotta & Baccigalupi 2002, Perivolaropoulos 2005,Tsujikawa 2005)
• Coupled Quintessence: coupling with dark matter (Carroll 1998, Amendola 2000,
Matarrese et al. 2003)
• k-essence: modified kinetic scalar field energy (Aramendariz-Picon et al. 2001, Caldwell
2002, Malquarti et al. 2003)
•
•
•
•
•
•
•
Quantum Fluctuations of Scalar Field: (Onemli and Woodard 2004)
Spacetime microstructure: self-adjusting spacetime capable to absorb vacuum energy
(Padmanabhan, 2002)
Matter-Energy Transition: dark matter undergoes a phase transition to dark energy at
low redshifts (Basset et al. 2003)
Brane worlds: brane tension (Shani & Sthanov 2002, Sami & Dadhich 2004, Brown,
Maartens Papantonopoulos, & Zamarias 2005); cyclic-ekpyrotic cosmic vacuum
(Steinhardt &Tutok 2001)
Exotic particle physics: photons oscillating in something else at cosmological distances
(Csaki et al. 2002)
Chaplygin gas: dark matter and energy described by a single gas having variable
equation of state (Den et al. 2003, Carturan & Finelli 2003)
Scale-dependent Gravity: Gravity weaker on large scales (Dvali et al. 2003)
1 2
+: Quintessence
L     V  
2
-: Phantom
 Quint   1
1 2
   V  
p
 0
w  2

1
  1  2  V   Phant  < 1
 
2
To cross the w=-1 line the kinetic energy term
must change sign
(impossible for single phantom or quintessence field)
L.P., astro-ph/0504582
s0
(LCDM )
Radial Geodesics:
S. Nesseris, L. P., Phys.Rev.D70:123529,2004
w
pX

a
4 G


m    1  3w 



a
3
 ~ a31 w
S. Nesseris, L. Perivolaropoulos, Phys.Rev.D70:123529,2004
•2m Telescope
•~1 billion pixels, 144 CCDs
•350-1700 nm wavelength coverage
•Finds and follows 2500 SnIa each
year, out to z = 1.7
•Place good limits on both w and its
time evolution
•Dark Energy with Negative Pressure can explain
SnIa cosmological data indicating
accelerating expansion of the Universe.
•The existence of a cosmological constant is
consistent with SnIa data but other evolving
forms of dark energy crossing the w=-1 line
provide better fits to the data.
•New observational projects are underway and
are expected to lead to significant
progress in the understanding of the
properties of dark energy.
We measure shadows, and we search among ghostly errors of
measurement for landmarks that are scarcely more
substantial. The search will continue.
E. Hubble in The Realm of the Nebulae,