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The Accelerating Universe (PowerPoint download)

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The Accelerating Universe (PowerPoint download) Powered By Docstoc
					   L. Perivolaropoulos
http://leandros.physics.uoi.gr
   Department of Physics
   University of Ioannina
                                                 L
                                            l
                 Dist. Ind.           Obs      4 d L
                                                    2



                              dL




                   L                       a ( t0 ) 1
l                                                    
                                           d L ( z )  x( z )(1  z )
     4 a(t0 ) 2 x 2 ( z ) 1  z 
                                      2
                   L                       a ( t0 ) 1
l                                                    
                                           d L ( z )  x( z )(1  z ) 1
     4 a(t0 ) 2 x 2 ( z ) 1  z 
                                      2




                                 cdt  a( z)dx( z)          2
                                                                 1
              a               1  d  d L ( z) 
     1     2   z  H  z       1  z   
                                                
              a               c  dz 
                                               
                                                                d
  Know L                           L                
                                        d L ( z )  H ( z )
                                                                dz

 Measure l(z)                    l ( z)               dz

                                     L
 Distance Modulus: m  M  2.5 log10                                 2
                                                                      dL
                                      l 



                                              t0  a  t 0 
                                 1  z           
~ t past
                                             t  a t 
                                           1
                                 r             cz
                                        H  z
             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          Best Choice
                                for
Surf. Brightness Fluct.
                            Cosmology
    Tully Fisher
Brightest Cluster Gal.
Glob. Cluster Lum. Fun.
 Sunyaev-Zeldovich
 Gravitational Lensing
M B  19




            Degeneracy pressure
            always fails at same
                   mass.
HST
closeby SnIa
m( z )  M 46 5log d L  z  / Mpc   25
                                  

                               Accelerating                                Decelerating
           44


           42                                               ?
                                                                ~ t past

           40


           38           Gold Dataset (157 SNeIa):                                                        a
                                                                                              H t  
                            Riess et. al. 2004                                                           a

           36
                                                                                            ~ at 
           34


                0       0.25      0.5        0.75       1           1.25    1.5      1.75
                                                    z
              dL 
        5 log empty 
             d      
              L 




      dL 
5 log empty 
     d      
      L 




                         Gold Dataset (157 SNeIa):
                             Riess et. al. 2004
                  dL 
            5 log empty 
                 d      
                  L 




      dL 
5 log empty 
     d      
      L 




                                                           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
  a
    
        3
                  i  3 pi    3  m      3 pX  
                i
                                                           
                           pX       a    4 G
                      w                     m    1  3w  
Equation of State:                a     3                        

 Necessary condition for acceleration:
         1
w           Negative     Pressure 
         3
                                            ~ a          
                                                                          =?


d       a3    pX d                a   
                                            3
                                                                        31 w 
                                                                 ~ a
p X  w                                        
                                                 


                a   2
                          8 G       a 
                                            3
                                                                       
H ( z)   2
                              0 m  0                       a 
                a2         3         a                             
                                                                       
 H0
   2
              0 m 1  z    X
                                  3
                                                 z 
              0 m
    0m              0.3
               crit         (from large scale structure observations)
     SnIa d L z 
                                                                                          
                                                                                                 dz
                                                                                    t0  
                                                                                          0 
                                                                                             1 z  H  z 
                                       1
        1  d  d L ( z) 
H  z       1  z   
        c  dz 
          
                          
                          
                                                                        H0
                                                                                                aa
                                                                                          q0   2
                                                z 0                                            a 0
                                                                        d ln H  z 
                                                   q  z   1  z                 1
                                       z 0                                 dz


                                                     2
                                                            
                                       H ( z ) 2  H 0 0 m 1  z    X  z 
                                                                               3
                                                                                                    0 , X  z 
                                2          d ln H
                                  1  z         1

                                                                w z 
                 pDE ( z )
         w z                3            dz
                  DE ( z )       H0 
                                        2

                              1        0 m 1  z 
                                                        3

                                  H 




      a    4 G
                m    1  3w  
      a     3                        
• Einstein (1915) G.R.:   Gmn = k Tmn

• Einstein (1917) G.R. + Static Universe + Matter only:
               Gmn - L gmn = k Tmn          V r   
                                                       GM L r 2
                                                        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
                                                                            0 m   L  1 (Flatness)
             8 G
                                                                                                  
                                                    3
        a    2
                        a0  L
H ( z)  2       0 m     H 0 0 m 1  z    L
     2                           2              3

        a     3         a   3


             L 
  2.5 log10 
             l ( z) 
                                                   d ( z )obs
                       m( z )  M  25  5 log10 L         Mpc                  
                                            z        dz 
     d L ( z )th  c 1  z  
                                            0   H  z ; 0 m       


                            d L ( z )obs    d L ( z; 0 m )th 
                                                                 2
                    N
      2  0 m                                                       min
                    i 1                           i
                                                     2
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

                                               L  0
        7 SnIa 0.35  z  0.65
                                                  L  1




   2. Observational Evidence from Supernovae for an Accelerating
               Universe and a Cosmological Constant
               S. Perlmutter et al., Nature 391 (1998) 51
                                   L  0.4
8 SnIa 0.35  z  0.83
                                   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

                                       L  0.7
16 SnIa 0.16  z  0.62                                            Ω Μ  1,  L  0
                                       for Flat Universe
                                                                   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
                                                    L  0.7
          11 new SnIa observed from HST
                                                    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                      for Flat Universe
 7 of them with z>1.25                      Decelerating Expansion starts
                                                       at z=0.46
                     min   0 m  0.3   177.1
                      2


                     SCDM   0 m  1  324.7
                      2




                                   2 ( m )
                              
Pr obability P  m   N e           2
                                                         z

                                                          dz
Physical Model  H  z; a1 , a2 ,..., an        ansatz 
                                                         0
                                                             
   z

  dz
 d L  z; a1 , a2 ,..., an  
                                 Data: d L  zi 
                                         obs
 0
      th
                                    2  2
                                                  
                                           min


                              H  z; a1 , a2 ,..., an 
                             
                             d L  z; a1 , a2 ,..., an 
  a1 , a2 ,..., an   
 Data: d L  zi 
         obs
                  
                              w  z; a1 , a2 ,..., an 
    2   min
           2



                               min  a1 , a2 ,..., an 
                                 2
                             
                                                                    
H z   H 0m 1 z   a2 1 z   a1 1 z   1 a2  a1  0m 
  2        2
           0
                        3           2




      a2  4.16  2.53
                                           2
                                                    174 .2
      a1  1.67  1.03                      m in
                                                    1
                                     min LCDM  177.1
                                      2
 min  171.7
  2
      What theory produces the features of best
                 parametrizations?
                          dwDE   z    0
wDE   z    0   1,                        0,
                                 dz
wDE   z    0.4   1


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
                     L     V  
                                      +: Quintessence
                          2           -: Phantom

                             1 2           Quint   1
                              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

     pX     a    4 G
w                   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,

				
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