52813 uw astr 323 sp13 eric agol 2013 10 in an

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Unformatted text preview: & source dA = % ( $α' !! •  Defined by: •  The former is used for supernovae; the laRer for megamaser distances •  In a flat€Universe, € 2 dL ( z) = ( )r0 (z) = ( ) d A ( z) •  r0(z) can be computed numerically •  Distance modulus for standard candle is: m − M = 5log10 r0 + 5log10 (1 + z) − 5 5/28/13 UW, ASTR 323, SP13, Eric Agol ©2013 9 Accelera8ng Universe •  For concordance model: 1 /2 #Ω & Ωm ,0 da 2 = H0 % r2,0 + + ΩΛ ,0a ( %a ( dt a $ ' •  Taking deriva8ve w.r.t. 8me: $Ω ' Ωm ,0 d 2a 2 r ,0 = H0 & − 3 − 2 + ΩΛ ,0a ) 2 &a ) dt 2a % ( •  Plugging in concordance values: " 0.315 % d 2a 2 = H0 $ − + 0.685' = 2 2 dt t # & 2 H0 0 •  Rate of expansion of Universe is ________! 5/28/13 UW, ASTR 323, SP13, Eric Agol ©2013 10 Δµ •  In an accelera8ng Universe, supernovae at high redshig are a _______ distance •  Thus they appear ______, having a _____ magnitude than a Universe with ΩΛ=0 Wood- Vasey 5/28/13 (ΩM, ΩΛ) = (0.27, 0.73) (ΩM, ΩΛ) = (0.3, 0.0) (ΩM, ΩΛ) = (1.0, 0.0) 42 µ Evidence for accelera8on 46 44 40 38 36 34 0.01 0.10 1.00 1.5 1.0 0.5 0.0 −0.5 −1.0 nearby ESSENCE −1.5 0.01 et al...
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