南京大学物理学院：暗能量扰动（PPT讲稿）Dark Energy Perturbations

i=610(0+p)=ik670bp=-1/367 6=-(1+n)/a-34)-31(pa=lao P h(1-3a)a ceo+ k Paleo + 1+ 1+ 3升 =-4Gp6+2(1+) All matter including DE +p=∑(a+p contribute to the metric perturbation ∑

All matter including DE contribute to the metric perturbation

Pa=sapa+3H(1+w)pa 2 2 ao/a ca Wa-w/37(1+wa) Adiabatic sound speed Cso>0: sound speed in the comoving frame Single fluid Cs Quintessence, phantom SO K-essence C<=Pxlpx=px/(px +2Xpxx)

: sound speed in the comoving frame Adiabatic sound speed Single fluid Quintessence, phantom  0 K-essence / /( 2 ) 2 s pX X pX pX XpX X c  =  = +