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Year 1 Cosmology Results from the Dark Energy Survey

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Year 1 Cosmology Results from the Dark Energy Survey Year 1 Cosmology Results from the Dark Energy Survey Elisabeth Krause on behalf of the Dark Energy Survey collaboration TeVPA 2017, Columbus OH Our Simple Universe On large scales, the Universe can be modeled with remarkably few parameters age of the Universe geometry of space density of atoms density of matter amplitude of fluctuations scale dependence of fluctuations [of course, details often not quite as simple] Our Puzzling Universe Ordinary Matter “Dark Energy” accelerates the expansion 5% dominates the total energy density smoothly distributed 25% acceleration first measured by SN 1998 “Dark Matter” 70% Our Puzzling Universe Ordinary Matter “Dark Energy” accelerates the expansion 5% dominates the total energy density smoothly distributed 25% acceleration first measured by SN 1998 “Dark Matter” next frontier: understand cosmological constant Λ: w ≡P/ϱ=-1? 70% magnitude of Λ very surprising dynamic dark energy varying in time and space, w(a)? breakdown of GR? Theoretical Alternatives to Dark Energy Many new DE/modified gravity theories developed over last decades Most can be categorized based on how they break GR: The only local, second-order gravitational field equations that can be derived from a four-dimensional action that is constructed solely from the metric tensor, and admitting Bianchi identities, are GR + Λ. Lovelock’s theorem (1969) [subject to viability conditions] Theoretical Alternatives to Dark Energy Many new DE/modified gravity theories developed over last decades Most can be categorized based on how they break GR: The only local, second-order gravitational field equations that can be derived from a four-dimensional action that is constructed solely from the metric tensor, and admitting Bianchi identities, are GR + Λ. Lovelock’s theorem (1969) [subject to viability conditions] Theoretical Alternatives to Dark Energy Many new DE/modified gravity theories developed over last decades Most can be categorized based on how they break GR: The only local, second-order gravitational field equations that can be derived from a four-dimensional action that is constructed solely from the metric tensor, and admitting Bianchi identities, are GR + Λ. Lovelock’s theorem (1969) [subject to viability conditions] Need simple tests to confront classes of models with data Are data from Does the dark energy density Do measurements of cosmic change as space expands? early Universe distances and growth of and late Universe structure agree? “Equation of state” parameter fit by the same parameters? w=pressure/density M. Betoule et al.: Joint cosmological analysis of theType SNLS and Ia SDSS SN SNe state Ia of the art Testing 0.2dark energy 46 HST C 44 β − and gravity0.15 1 42 X ↵ SNLS + 40 ) coh 0.1 G ( SDSS 38 • Λ size difficult to explain M Planck Collaboration: Cosmological parameters − B 36 0.05 m Low-z = The CMB temperature data alone does not strongly constrain • Important to test GR over 34 µ [JLA, Betoule+ 2014] w, because of a strong geometrical degeneracy even for spatially- cosmological0 scales flat models. From Planck we find 0 0.5 1 04 +0.62 redshift CDM 0 2 = . , + , ⇤ w 1 54 (95% Planck TT lowP) (51) 00 0.50 µ − − • Expansion history − 0 2 Fig. 7. Values of σcoh determined for seven subsamples of the Hubble − µ 04 σ residuals: low-zz< 0.03 and z > 0.03 (blue), SDSS z < 0.2 and z > 0.2 − i.e., almost a 2 shift into the phantom domain. This is partly, 2 1 0 (green), SNLS z < 0.5 and z > 0.5 (orange), and HST (red). 10− 10− 10 but not entirely, a parameter volume e↵ect, with the average ef- z Planck Collaboration: Cosmologicalfective χ2 improving parameters by ∆χ2 2 compared to base ⇤CDM. BAO state of the art h i⇡ Table 9. Values of σcoh used in the cosmological fits. Fig. 8. Top: HubbleBAO diagram state of the combined of the sample. art The distance This is consistent with the preference for a higher lensing am- modulus redshift relation of the best-fit ⇤CDM cosmology for a fixed plitude discussed in Sect. 5.1.2, improving the fit in the w < 1 1 1 67.2 H01.10= 70 km s− Mpc− is shown as the black line. Bottom: residu- region, where the lensing smoothing amplitude becomes slightly− • Sample σcoh als from theSDSS best-fit MGS⇤CDM cosmology as a functionWiggleZ of redshift. The From supernovae, BAOs, 66.4 Testing Dark Energylow- z I 0.134 weighted1.6 average of the residuals in logarithmic redshift bins of width larger. However, the lower limit in Eq. (51) is largely determined − 1 1 CMB peaks positionSDSS-II 0.108 ∆z/z 0.24 are shown as black dots. by the (arbitrary) prior H0 < 100 km s− Mpc− , chosen for the Planck ⇠ 65.6 ) 1.05 SNLS 0.080 [Planck 2015 XIII] (Planck+BAO+SN) Hubble parameter. Much of the posterior volume in the phan- HST 0.100 drag 000 r tom region is associated with extreme values for cosmological / V 005 1.2 1.0 0.8 0.6 M parameters,which are excluded by other astrophysical data. The • AgreementNotes. Those values with correspond LCDM to the weighted mean per survey of the − D 1.00 − − − − ∆ values shown in Fig. 7, except for HST sample for which we use the ( 010 mild tension with base ⇤CDM disappears as we add more data / − w0 average value of all samples. They do not depend on a specific choice ) 015 that break the geometrical degeneracy. Adding Planck lensing − BOSS CMASS Expansion history of cosmological model (see the discussion in Sect. 5.5). drag 28 30 32 34 r BOSS34 LOWZ and BAO, JLA and H0 (“ext”) gives the 95 % constraints: • Not so much information on Fig. 27./ 0.95Samples fromβ the distribution of the dark energy pa- V 6DFGS 32 +0.091 rametersD w0 and wa using Planck TT+lowP+BAO+JLA data, β = . + + ( w 1 023 Planck TT lowP ext ; (52a) DE/Gravity:6. ⇤CDM constraints at most from w SNe0, Iaw alonea 0.096 comparison of distance and redshift colour-coded by the value of30 the Hubble parameter H0. Contours − − = . +0.085 + + + 0.90 Planck XIII, 2015 w 1 006 0.091 Planck TT lowP lensing ext ; (52b) The SN Ia sample presented in this paper covers the redshiftshow the corresponding[Planck 2015 682 XIII %8 and] 95 % limits. Dashed grey lines − − . < < . ffi 012 014 016 +0.075 range 0 01 z 1 2. This lever-arm is su cient to provideintersect at the point in parameter space corresponding to a cos- w = 1.019 0.080 Planck TT, TE, EE+lowP+lensing+ext . 0.1 0.2 0.3 0.4↵ 0.5016 0.6 0.7 0.8 − − standard rulers: angle subtendeda stringent by known constraint on scale a single parameter driving the evolu-mological constant. (52c) z ↵ 4 tion of the expansion rate. In particular, in a flat universe with 014 a cosmological constant (hereafter ⇤CDM), SNe Ia alone pro- -CMB: sound horizon in early Universe 012 The addition of Planck lensing, or using the full Planck tem- vide an accurate measurementM. Betoule of the reduced et al.: Joint matter cosmological density ⌦ analysism. of the SNLS and SDSS SNe Ia However, SNe alone can only measure ratios of distances, which TypeType Ia IA SN SN state state of of the the0 2art art03 04 perature+polarization likelihood together with the BAO, JLA, -BAO: same scale imprinted in late Universe Fig. 14.46 Acoustic-scale distance ratio DV(z)/rdrag ⌦inm the base and H data does not substantially improve the constraint of Testing are0.2dark independent energy of the value of the Hubble constant today (H0This= constraint is unchanged at the quoted precision if we add 0 1 1 ⇤CDM model divided by the mean distance ratio from Planck Fig. 15. 68 % and 95 % constraints on the angular diameter dis- 100 h km s− Mpc− ). In this section we discuss ⇤CDM param-the JLAFig. 9. supernovae68% and 95% data confidence and the contoursH0 prior for of the Eq.⇤CDM (30HST). fit parame- Eq. (52a). All of these data set combinations are compatible with C 44 tance D (z = 0.57) and Hubble parameter H(z = 0.57) from eter constraints from SNe Ia alone. We also detail the relativeTT in- +lowPβ +lensing. The points with 1 σ errors are as follows: the base ⇤ACDM value of w = 1. In PCP13, we conservatively Figureters. Filled26 grayillustrates contours these result from results the fit in of the the⌦ fullm– JLA⌦⇤ sample;plane. red We standard candle: brightness offluence source of each with incremental known change luminosity relative to the C11 analysis.green− dashed star (6dFGS, contours fromBeutler the fit of et a al. subsample2011); excluding square (SDSSSDSS-II data MGS, quotedthe Andersonw = 1. et13 al.+0.24(2014, based) analysis on− combining of the BOSSPlanck CMASS-DR11with BAO, and gravity0.15 1 adopt42 Eq. (50) as our most reliable constraint on spatial curva- 0.25 RossX (lowz et al.+SNLS).2014); red triangle and large circle (BOSS “LOWZ” assample. our most The reliable− fiducial− limit sound on w. horizon The errors adopted in Eqs. by (52aAnderson)–(52c) are et al. ture.↵ Our Universe appears to be spatially flat to anSNLS accuracy of fid supernovae + = . - 6.1. ⇤CDM fit of the Hubble diagram and CMASS40 surveys, Anderson et al. 2014); and small blue cir- substantially(2014) is r smaller,drag mainly149 28 because Mpc. of Samples the addition from of the the JLAPlanck 0.5%.) coh 0.1 cles (WiggleZ,G as analysed by Kazin et al. 2014). The grey bands SNeTT+ data,lowP which+lensing o↵er chains a sensitive are plotted probe of coloured the dark by energy their equa- value of ( free parameters in the fit are ⌦m and the four nuisance param- Using the distance estimator given in Eq.
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