2, Dynamical dark energy 1, quintessence Peccei sola, Wetterich, 1987 letterich. 1988 Peebles. Ratra. 1988 Zlatev, Wang, Steinhardt, 1998 L=12(V中)2-V(p l/202-V W 22-1,1/202<<V,w→-1 1/22+1 l, phantom Caldwell 1999 L=-1/2(V)2-V() 1/202-V W 1 1/22+
2, Dynamical dark energy I, quintessence Peccei, Sola, Wetterich, 1987 Wetterich, 1988 Peebles, Ratra, 1988 Zlatev, Wang, Steinhardt, 1998 1/ 2( ) ( ) 2 L = −V 1/ 2( ) ( ) 2 L = − −V 1, 1/ 2 , 1 1/ 2 1/ 2 2 2 2 − → − + − = V w V V w II, phantom Caldwell, 1999 1 1/ 2 1/ 2 2 2 − − + − − = V V w
ll k-essence Amend ariz-Picon Mukhanov Steinhardt. 2000 L=K(0,X)x=1/2(V p=K,卩=-P+2x Quintessence, phantom are special cases of k-essence Cannot cross -1 Mv, quintom w crosses-1 L=1/2(vp)-1/2(vp)2-V(,%2)Feng, Wang, Zhang, 2004 L=1/2(V)2+x2(V2d)2-V() M ML, Feng, Zhang, 2005 L=(如+a(V)2+mv2 Cai, ML, Lu, Piao, Qiu, Zhang, 2007
2 L = K(, X) X =1/2() III, k-essence Amendariz-Picon, Mukhanov, Steinhardt, 2000 p K p 2XpX = , = − + Quintessence, phantom are special cases of k-essence W cannot cross -1 IV, quintom w crosses -1 1/ 2( ) 1/ 2( ) ( , ) 1 2 2 1 2 L = 1 − −V Feng, Wang, Zhang, 2004 1/ 2( ) ( ) ( ) 2 2 2 2 V M c L = + − ML, Feng, Zhang, 2005 2 2 L =V( ) 1+ ( ) + Cai, ML, Lu, Piao, Qiu, Zhang, 2007
Using observational data to search for DE models W acrucial parameter to distinguish different models Data fitting, model independent, parameterization Ce(a)=o0+a(1-a) DE perturbation, only vanished when W=-1(cosmological constant) Naively switch off DE perturbation is not consistent
W a crucial parameter to distinguish different models Data fitting, model independent, parameterization DE perturbation, only vanished when w=-1 (cosmological constant) Naively switch off DE perturbation is not consistent Using observational data to search for DE models
7000 ITImI 7000 6000 6000 5000 5000 4000 卡4000 3000 3000 s2000 2000 1000 1000 100 1000 10 100 1000 Without DE perturbation With de perturbation Weller. levies, 2003 Constant w and sound speed
Without DE perturbation With DE perturbation Weller, Lewies, 2003 Constant w and sound speed
Dark energy perturbations FRW background ds=a(nan-yi, dx'dr' Metric perturbation 32=a2(m){(1+2A)dn2-2B;dxd-[(1-2v)6+2 E, iild.r'dae'} Conformal Newtonian gauge ds2=a(n)2[(1+24bn2-(1-24)63fdr2dy Equations of perturbations 6G…=-8mG7 成v VO/=0
( )( ) 2 2 2 i j ds = a d − i jdx dx G = −8GT FRW background Metric perturbation Equations of perturbations = 0 T Conformal Newtonian Gauge Dark Energy Perturbations