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
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 0 4 +0.62 redshift CDM 0 2 = . , + , ⇤ w 1 54 (95% Planck TT lowP) (51) 0 0 0.50 µ • Expansion history
0 2 Fig. 7. Values of coh determined for seven subsamples of the Hubble µ 0 4 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 2 improving parameters by 2 2 compared to base ⇤CDM. BAO state of the art h i⇡ Table 9. Values of coh 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 coh 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 0 00
r tom region is associated with extreme values for cosmological /
V 0 05 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 ( 0 10 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 ) 0 15 that break the geometrical degeneracy. Adding Planck lensing BOSS CMASS Expansion history of cosmological model (see the discussion in Sect. 5.5). drag 2 8 3 0 3 2 3 4 r BOSS3 4 LOWZ and BAO, JLA and H0 (“ext”) gives the 95 % constraints: • Not so much information on Fig. 27./ 0.95Samples from the distribution of the dark energy pa- V 6DFGS 3 2 +0.091 rametersD w0 and wa using Planck TT+lowP+BAO+JLA data,
= . + + ( 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 of3 0 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 . < < . 0 12 0 14 0 16 +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↵ 0.50 16 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 0 14 a cosmological constant (hereafter ⇤CDM), SNe Ia alone pro- -CMB: sound horizon in early Universe 0 12 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 art0 3 0 4 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- +lowP +lensing. The points with 1 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. (4), we fit a ⇤CDM SDSS 38 ↵ 1 2 z < showM eters the 68, %, M andand 95 %M confidencefrom Eq. (4). ranges The Hubble allowed diagram by Planck for tion⌦ch of, state showing at consistency1. In PCP13 of, the the addition data, but of also the SNLS that the SNe BAO • Λ size difficosmologycult to to explain supernovae measurements by minimizing the fol- B Planck Collaboration: Cosmological parameters excellent agreement with ΛCDM TT6.3.+lowP the Dark JLA+ energylensing. sample and the ⇤CDM fit are shown in Fig. 8. We find datameasurement pulled w into can⇠ the tighten phantom the domainPlanck atconstraints the 2 level, on reflecting the matter B lowing function: 36 a best fit value for ⌦m of 0.295 0.034. The fit parameters are 0.05 m thedensity. tension between the SNLS sample and the Planck 2013 base The physical explanationLow-z for the observed± accelerated expansion 2 1 0.8= given in the first row of Table 10. ⇤CDMThe CMB parameters. temperature As noted data in alone Sect. does5.3, thisnot strongly discrepancy constrain is no • Important to= (testµˆ µ⇤CDM GR(z; ⌦ overm))†C (µˆ µ⇤CDM(z; ⌦m)) (15) 34 limited information on dark energy/modified gravity of theTheµ UniverseFor changes consistency is to currently the checks, data not we points known. fit ourJLA, compared full Betoule+ In sample standard excludingto 2014 figure⇤CDM sys- 15 the of wlonger, because present, of a strong following geometrical improved degeneracy photometric even calibrations for spatially- of tematic uncertainties and we fit subsamples[JLA, Betoule+ labeled according2014]71.2 to cosmologicalwith0 C scalesthe covariance matrix of µˆ described in Sect. 5.5 andPCP13accelerationare as is follows. provided We by a have cosmological replaced constant the SDSS satisfying DR7 mea- an flatthewhich models. SNe just data From grazes in thePlanck JLA the BOSS sample.we find CMASS One consequence 68 % error of ellipse this is plotted the 0 0.5 1 surementsthe0 4 data of included:Percival SDSS et al./+⇢SNLS,(2010= lowz) with+SDSS the andrecent lowz analysis+SNLS. of -at most w0, wa µ⇤CDM(z; ⌦m) = 5 log10(dL(z; ⌦m)/10 pc) computed for a fixedequation of state w pDE DE 1. However, there are70.4 many ⇤ 13 1 1 ⌘ ⌦ ↵ tighteningin Fig. 15 of. Evidently, the errors+0.62 in the Eqs.Planck (52a)–(base52c⇤) aroundCDM parameters the CDM are
CDM Confidence0 2 contours for and the nuisance parameters , fiducial value of H = 70redshift km s Mpc , assuming an unper- m = . , + , 0 thepossible SDSS⇤ alternatives, Main Galaxy typically Sample described (MGS) either of Ross in et terms al. ( of2014 extra) at w 1 54 (95% Planck TT lowP) (51) 0.00 0 value w = 1 when we0.50 combine the JLA sample with Planck. µ and M are given in Fig. 9 for the JLA and the lowz+SNLS in good agreement with both the isotropized DV BAO measure- • Expansionturbed history Friedmann-Lematre-Robertson-Walker geometry, whichzdegrees= 0. of15, freedom and by associated the Anderson with scalar et al. fields(2014 or) analysis modifications69.6 of the e↵ 0 2 Fig. 7. Values of coh determined for seven subsamples of the Hubble sample fits. The correlation between ⌦m and any of the nuisance mentsIf w plotteddi↵ers from in Fig.1,14 it, is and likely with to the change anisotropic with time. constraints We is an acceptable approximation (Ben-Dayan et al. 2013). The µ 0 4 residuals: low-zz< 0.03 and z > 0.03 (blue), SDSS z < 0.2 and z > 0.2Baryonof general parameters Oscillation relativity is less Spectroscopic on than cosmological 10% for the Survey JLA scales sample. (BOSS) (for reviews ‘LOWZ’ see e.g., sam- i.e., almost a 2 shift into the phantom domain. This is partly, 2 1 0 considerplotted here in Fig. the15 case. of a Taylor expansion of w at first order in 10 10 1068.8 (green),13 SNLS z < 0.5 and z > 0.5 (orange), and HST (red). pleCopeland at zeThe↵ et=⇤ al.0CDM.200632. model Both; Tsujikawa is of already these2010 well analyses). constrained A detailed use peculiar studyby the of SNLS theseveloc-H but not entirely, a parameter volume e↵ect, with the average ef- This value is assumed purely for convenience and using another z Planck Collaboration: Cosmologicalthe scaleIn2 this factor, parameters paper, parameterized we use the2 by 6dFGS, SDSS-MGS and BOSS- value would not a↵ect the cosmological fit (beyond changing accord-itymodels fieldand and reconstructions low- thez data constraints thanks to their sharpenimposed large the redshiftby Planck BAO lever-arm. featureand other However, and data reduce is fective improving by 2 compared to base ⇤CDM. LOWZ BAO measurementsh i⇡ of DV/rdrag (Beutler et al. 2011; ingly the recovered value of M1 ). presentedFig.the 8. additionTop in: a Hubble separate of/ the diagram numerous paper, ofPlanck the and combined well-calibrated Collaboration sample. SDSS-IIThe XIV distance(2015 data ). This is consistent with the preference for a higher lensing am- Table 9. Values of coh used in theB cosmological fits. the errors on DV BAOrdrag. The state blue pointsof the in Fig.art14 show a re- Ross et al. 2014; Andersonw = w0 + et(1 al. 2014a)wa). and the CMASS-DR11(53) analysismodulusHere of we redshift the will WiggleZ relation limit of ourselves redshift the best-fit surveyto⇤CDM the most by cosmologyKazin basic for et extensions al. a fixed(2014) plitude discussed in Sect. 5.1.2, improving the fit in the w < 1 1 1 A22, page 15 of 32 anisotropic BAO measurements of Anderson et al. (2014). Since of H⇤0 CDM,= 70 km which s Mpc can is beshown phenomenologically as the black line. Bottom described: residu- in region,More complex where the models lensing of smoothing dynamical amplitude dark energy becomes are discussed slightly • From supernovae,Sample BAOs, coh applyingals from peculiar the best-fit velocity⇤CDM cosmology reconstructions. as a function The of reconstructions redshift. The the WiggleZ volume partially overlaps that of the BOSS- low-z 0.134 causestermsweighted of small the average shifts equation of in theD residuals ofV/ staterdrag incompared parameter logarithmic tow redshift thealone. unreconstructed bins Specifically of width larger.in Planck However, Collaboration the lower XIV limit(2015 in Eq.). ( Figure51) is largely27 shows determined the 2D CMASS sample, and the correlations1 have not1 been quantified, CMB peaks positionSDSS-II 0.108 WiggleZwe z will/z 0 use results.24 are the shown ofcambBlake as blackimplementation et dots. al. (2011) ofand the lead “parameterized to reductions bymarginalized the (arbitrary) posterior prior H distribution0 < 100 km for s w0Mpcand w,a chosenfor the for com- the ⇠ we do not use the WiggleZ results in this paper. It is clear from SNLS 0.080 post-Friedmann” (PPF) framework of Hu & Sawicki (=2007. ) and Hubblebination parameter.Planck+BAO Much+JLA. of the The posterior JLA SNe volume data are in again the phan- cru- in the errors[Planck on the 2015 distance XIII] measurements(Planck+BAO+SN) at ze↵ 0 44 and Fig. 14 that the combined BAO likelihood is dominated by the HST 0.100 Fang= et0 00 al.. (2008) to test whether there is any evidence that= .w tomcial region in breaking is associated the geometrical with extreme degeneracy values at for low cosmological redshift and ze↵ 0 73. The point labelled BOSS CMASS at ze↵ 0 57 two BOSS measurements. varies0 with 05 time. This framework aims to recover the behaviour with these data we find no evidence for a departure from the M / parameters,which are excluded by other astrophysical data. The • AgreementNotes. Those values with correspond LCDM to the weighted mean per survey of theshows DV rdrag from the analysis of Anderson et al. (2014), up- ⇤ In the base CDM model, the Planck data constrain the values shown in Fig. 7, except for HST sample for which we use thedatingof canonical0 the 10 BOSS-DR9 (i.e., those analysis with a standard of Anderson kinetic et term) al. (2012 scalar) used field in mildbase tension⇤CDM with cosmology. base ⇤CDM The points disappears in Fig. as we27 show add more samples data Hubble constant H0 and matter density ⌦m to high precision: average value of all samples. They do not depend on a specific choicePCP13cosmologies0. 15 minimally coupled to gravity when w 1, and thatfrom break these the chains geometrical colour-coded degeneracy. by the value Adding of HPlanck0. Fromlensing these of cosmological model (see the discussion in Sect. 5.5). 1 1 accurately2 8 approximates3 0 3 2 3 4 them for values w 1. In these mod- andMCMC BAO, chains, JLA and weH find0 (“ext”)H0 = (681 gives.2 the11.1) 95 km% constraints: s Mpc . Much • In fact, the Anderson3 4 et al. (2014) analysis⇡ solves jointly for H = (67.3 1.0) km s Mpc± Not so much information on Fig.els 27. theSamples speed of from sound the is equal distribution to the speed of the of dark light energy so that pa- the higher0 values of H0 would favour the phantom regime, w < 1. the positions of the BAO3 2 feature in both the line-of-sight and + . ± Planck TT+lowP. (27) rameters w0 and wa using Planck TT+lowP+BAO+JLA data, ⌦ = . 0 091 . clustering of the dark energy inside the horizon is strongly sup- w =Asm1 pointed.0230 3150.096 out in0Planck013 Sects.TT5.5.2+lowPand+5.6extthe ; CFHTLenS weak(52a) DE/Gravity:6. ⇤CDM constraints at most from w SNe0, Iaw alonea transverse directions (the3 0 distortion in the transverse direction ± ) colour-codedpressed. The by advantage the value of of the using Hubble the PPF parameter formalismH0. is Contours that it is lensing data+ are0.085 in tension with the Planck base ⇤CDM parame- caused by the background cosmology is sometimes called the w = 1.006 0.091 Planck TT+lowP+lensing+ext ; (52b) The SN Ia sample presented in this paper covers the redshiftshowpossible the corresponding to[Planck study the 2015 “phantom 682 XIII %8 and] domain”, 95 % limits.w < Dashed1, including grey lines tran- ters.With Examples the addition of this of tension the BAO can measurements, be seen in investigations these constraints of Alcock-Paczynski e↵ect, Alcock0 12 0 &14 Paczynski0 16 1979), leading to +0.075 range 0.01 < z < 1.2. This lever-arm is su cient to provideintersectsitions at across the point the “phantom in parameter barrier”, spacew corresponding= 1, which is to not a cos- pos- wdarkare= strengthened energy1.019 and. modified significantlyPlanck TT gravity,, TE to , EE since+lowP some+lensing of these+ext mod-. joint constraints on the angular diameter↵ 0 16 distance D (z ) and 0 080 a stringent constraint on a single parameter driving the evolu-mologicalsible for constant. canonical scalar fields. A e↵ els can modify the growth rate of fluctuations from the base the Hubble parameter H(z ↵). These constraints, using the tabu- 1 1 (52c) e ↵ 4 tion of the expansion rate. In particular, in a flat universe with 0 14 H0 = (67.6 0.6) km s Mpc a cosmological constant (hereafter ⇤CDM), SNe Ia alone pro-lated likelihood included in the CosmoMC module16, are plotted ± Planck TT+lowP+BAO. 0 12 The⌦ additionm = 0.310 of Planck0.008 lensing, or using the full Planck tem- vide an accurate measurement of the reduced matter density ⌦m.in Fig. 15. Samples from the Planck TT+lowP+lensing chains ± ) 39 2 0 2 0 3 0 4 perature+polarization likelihood together with the BAO, JLA,(28) However, SNe alone can only measure ratios of distances, whichare plotted coloured by the value of ⌦ch for comparison. The Fig. 14. Acoustic-scale distance ratio DV(z)/rdrag ⌦inm the base andTheseH data numbers does arenot consistentsubstantially with improve the Planck the constraint+lensing of con- are independent of the value of the Hubble constant today (H0This=length constraint of the degeneracy is unchanged line at is the set by quoted the allowed precision variation if we add in H 0 1 1 ⇤CDM model divided by the mean distance ratio from Planck0 Fig. 15. 68 % and 95 % constraints on the angular diameter dis- 100 h km s Mpc ). In this section we discuss ⇤CDM param-the JLA supernovae68% and 95% data2 confidence and the contoursH prior for of the Eq.⇤CDM (30). fit parame- Eq.straints (52a). All of Eq. of these (21). data Section set combinations5.4 discusses are the compatible consistency with of (orFig. equivalently 9. ⌦mh ). In the Planck0 TT+lowP+lensing ⇤CDM = . = . eter constraints from SNe Ia alone. We also detail the relativeTT in- +lowPters. Filled+lensing. gray contours The points result from with the fit 1 of theerrors full JLA are sample; as follows: red thetancethese baseD estimates⇤ACDM(z value0 of57)H of andwithw Hubble= direct1. In measurements. parameterPCP13, weH conservatively(z 0 57) from analysisFigure the26 lineillustrates is defined these approximately results in the by⌦m–⌦⇤ plane. We 0 fluence of each incremental change relative to the C11 analysis.greendashed star (6dFGS, contours fromBeutler the fit of et a al. subsample2011); excluding square (SDSSSDSS-II data MGS, the Anderson= . et al.+0.24(2014) analysis of the BOSS CMASS-DR11 adopt Eq. (50) as our most reliable constraint on spatial curva- quotedAlthoughw 1 low13 0 redshift.25, based BAO on combiningmeasurementsPlanck are inwith good BAO, agree- (lowz+SNLS). 1.7 sample. The fiducial sound horizon adopted by Anderson et al. Rossture. et OurD al.A Universe(02014.57));/r reddrag appears triangleH(0 to.57) be andrdrag spatially large/c circle flat to (BOSS an accuracy “LOWZ” of asment our most with reliablePlanck limitfor the on w base. The⇤ errorsCDM in cosmology, Eqs. (52a)–( this52c may) are not = 1 0.0004, (26) (2014) is rfid = 149.28 Mpc. Samples from the Planck 6.1. ⇤CDM fit of the Hubble diagram and0.5%. CMASS9 surveys,.384 Anderson0.4582 et al. 2014); and± small blue cir- substantiallybe true at high smaller,drag redshifts. mainly Recently, because BAO of the features addition have of the been JLA mea- cles (WiggleZ,free parameters as analysed in the fit by areKazin⌦ and et! the al. 2014 four nuisance). The grey param- bands SNeTTsured+ data,lowP in which the+lensing flux-correlation o↵er chains a sensitive are function plotted probe of of coloured the the dark Ly↵ by energyforest their of equa- value BOSS of Using the distance estimator given in Eq. (4), we fit a ⇤CDM m show16eters thehttp://www.sdss3.org/science/boss_publications.php 68↵, %, M and1 and 95 % confidencefrom Eq. (4). ranges The Hubble allowed diagram by Planck for tion⌦quasarsh of2, state showing (Delubac at z < consistency1. et In al.PCP132014 of), and the the in addition data, the cross-correlation but of also the SNLS that the SNe of BAO the cosmology to supernovae measurements by minimizing the fol- B M c 6.3.the Dark JLA energy sample and the ⇤CDM fit are shown in Fig. 8. We find ⇠ lowing function: TT+lowP+lensing. datameasurement pulled w into can the tighten phantom the domainPlanck atconstraints the 2 level, on reflecting the matter a best fit value for ⌦ of 0.295 0.034. The fit parameters are m ± thedensity. tension between the SNLS sample and the Planck 2013 base 2 1 The physicalgiven in the explanation first row of for Table the10 observed. accelerated expansion 25 = (µˆ µ⇤CDM(z; ⌦m))†C (µˆ µ⇤CDM(z; ⌦m)) (15) ⇤CDM parameters. As noted in Sect. 5.3, this discrepancy is no of theThe UniverseFor changes consistency is to currently the checks, data not we points known. fit our compared full In sample standard excludingto figure⇤CDM sys- 15 the of longer present, following improved photometric calibrations of with C the covariance matrix of µˆ described in Sect. 5.5 andPCP13accelerationtematicare as uncertainties is follows. provided We and by a we have cosmological fit subsamples replaced constant the labeled SDSS according satisfying DR7 mea- to an thewhich SNe just data grazes in the JLA the BOSS sample. CMASS One consequence 68 % error of ellipse this is plotted the surementsequationthe data of of state included:Percivalw SDSSp et al./+⇢SNLS,(2010= lowz)1. with However,+SDSS the andrecent there lowz analysis+ areSNLS. many of µ⇤CDM(z; ⌦m) = 5 log10(dL(z; ⌦m)/10 pc) computed for a fixed DE DE tighteningin Fig. 15 of. Evidently, the errors in the Eqs.Planck (52a)–(base52c⇤) aroundCDM parameters the ⇤CDM are 13 1 1 Confidence contours⌘ for ⌦m and the nuisance parameters ↵, fiducial value of H0 = 70 km s Mpc , assuming an unper-thepossible SDSS alternatives, Main Galaxy typically Sample described (MGS) either of Ross in et terms al. ( of2014 extra) at + valuein goodw = agreement1 when we with combine both the the isotropized JLA sampleD withV BAOPlanck measure-. turbed Friedmann-Lematre-Robertson-Walker geometry, whichzdegrees=and0. of15,M freedomare and given by associated the in Fig.Anderson9 withfor the scalar et JLAal. fields(2014 and the or) analysis modifications lowz SNLS of the e↵ sample fits. The correlation between ⌦ and any of the nuisance mentsIf w plotteddi↵ers from in Fig.1,14 it, is and likely with to the change anisotropic with time. constraints We is an acceptable approximation (Ben-Dayan et al. 2013). The m Baryonof generalparameters Oscillation relativity is less Spectroscopic on than cosmological 10% for the Survey JLA scales sample. (BOSS) (for reviews ‘LOWZ’ see e.g., sam- considerplotted here in Fig. the15 case. of a Taylor expansion of w at first order in 13 Copeland et= al..2006; Tsujikawa 2010). A detailed study of these This value is assumed purely for convenience and using anotherple at zeThe↵ ⇤0CDM32. model Both is of already these well analyses constrained use peculiar by the SNLS veloc- the scaleIn this factor, paper, parameterized we use the by 6dFGS, SDSS-MGS and BOSS- models and the constraints imposed by Planck and other data is value would not a↵ect the cosmological fit (beyond changing accord-ity fieldand reconstructions low-z data thanks to their sharpen large the redshift BAO lever-arm. feature However, and reduce LOWZ BAO measurements of D /r (Beutler et al. 2011; ingly the recovered value of M1 ). presentedthe addition in a separate of/ the numerous paper, Planck and well-calibrated Collaboration SDSS-II XIV (2015 data ). V drag B the errors on DV rdrag. The blue points in Fig. 14 show a re- Ross et al. 2014; Andersonw = w0 + et(1 al. 2014a)wa). and the CMASS-DR11(53) analysisHere of we the will WiggleZ limit ourselves redshift surveyto the most by Kazin basic et extensions al. (2014) A22, page 15 of 32 anisotropic BAO measurements of Anderson et al. (2014). Since of ⇤CDM, which can be phenomenologically described in More complex models of dynamical dark energy are discussed applying peculiar velocity reconstructions. The reconstructions the WiggleZ volume partially overlaps that of the BOSS- causesterms of small the shifts equation in D ofV/ staterdrag compared parameter tow thealone. unreconstructed Specifically in Planck Collaboration XIV (2015). Figure 27 shows the 2D we will use the camb implementation of the “parameterized marginalizedCMASS sample, posterior and distribution the correlations for w haveand notw beenfor the quantified, com- WiggleZ results of Blake et al. (2011) and lead to reductions we do not use the WiggleZ results in this0 paper.a It is clear from post-Friedmann” (PPF) framework of Hu & Sawicki (=2007. ) and bination Planck+BAO+JLA. The JLA SNe data are again cru- in the errors on the distance measurements at ze↵ 0 44 and Fig. 14 that the combined BAO likelihood is dominated by the zFange↵ = et0 al..73.(2008 The) point to test labelled whether BOSS there CMASS is any evidence at ze↵ that= 0.w57 cial in breaking the geometrical degeneracy at low redshift and withtwo these BOSS data measurements. we find no evidence for a departure from the showsvariesD withV/r time.drag from This the framework analysis aims of Anderson to recover et the al. ( behaviour2014), up- of canonical (i.e., those with a standard kinetic term) scalar field base In⇤CDM the base cosmology.⇤CDM The model, points the inPlanck Fig. 27datashow constrain samples the dating the BOSS-DR9 analysis of Anderson et al. (2012) used in Hubble constant H and matter density ⌦ to high precision: PCP13cosmologies. minimally coupled to gravity when w 1, and from these chains colour-coded0 by the valuem of H0. From these = . . 1 1 accuratelyIn fact, approximates the Anderson them et al. for(2014 values) analysisw 1. solves In these jointly mod- for MCMC chains, we find H0 (681 2 11 1) km s Mpc . Much ⇡ H0 = (67.3 1.0) km s Mpc± theels positions the speed of of soundthe BAO is equal feature to the in both speed the of line-of-sight light so that the and higher values of H±0 would favour the phantomPlanck regime,TT+lowP.w < 1. (27) ⌦ = . . transverseclustering of directions the dark (the energy distortion inside the in horizon the transverse is strongly direction sup- Asm pointed0 315 out in0 013 Sects. 5.5.2 and 5.6 the CFHTLenS weak ± ) ⇤ causedpressed. by The the advantage background of using cosmology the PPF is formalism sometimes is called that it the is lensing data are in tension with the Planck base CDM parame- < With the addition of the BAO measurements, these constraints Alcock-Paczynskipossible to study the e↵ “phantomect, Alcock domain”, & Paczynskiw 1,1979 including), leading tran- to ters. Examples of this tension can be seen in investigations of sitions across the “phantom barrier”, w = 1, which is not pos- darkare strengthened energy and modified significantly gravity, to since some of these mod- joint constraints on the angular diameter distance D (z ) and sible for canonical scalar fields. A e↵ els can modify the growth rate of fluctuations from the base the Hubble parameter H(z ). These constraints, using the tabu- 1 1 e↵ H0 = (67.6 0.6) km s Mpc lated likelihood included in the CosmoMC module16, are plotted ± Planck TT+lowP+BAO. ⌦m = 0.310 0.008 in Fig. 15. Samples from the Planck TT+lowP+lensing chains ± ) 39 are plotted coloured by the value of ⌦ h2 for comparison. The (28) c These numbers are consistent with the Planck+lensing con- length of the degeneracy line is set by the allowed variation in H0 (or equivalently ⌦ h2). In the Planck TT+lowP+lensing ⇤CDM straints of Eq. (21). Section 5.4 discusses the consistency of m H analysis the line is defined approximately by these estimates of 0 with direct measurements. Although low redshift BAO measurements are in good agree- 1.7 DA(0.57)/rdrag H(0.57)rdrag/c ment with Planck for the base ⇤CDM cosmology, this may not = 1 0.0004, (26) 9.384 0.4582 ± be true at high redshifts. Recently, BAO features have been mea- ! sured in the flux-correlation function of the Ly↵ forest of BOSS 16http://www.sdss3.org/science/boss_publications.php quasars (Delubac et al. 2014) and in the cross-correlation of the
25 Testing Dark Energy
redshift cosmic shear space galaxy clusters distortions
“late-time structure” Q: Do all these measurements agree with predictions in the same, CMB fiducial ΛCDM model? BAO ✓ supernovae sensitivity to growth of structure of growth sensitivityto “expansion history”
sensitivity to expansion Testing Dark Energy with Galaxies
need redshift, understand galaxy bias
BAOs
lin. growth
clusters (over densities), non-lin. voids (under densities) structure two-point correlations three-point correlations,... LSS Probes of Dark Energy
Anderson et al. ’12 (BOSS)
Galaxy Clustering measure BAOs + shape of correlation function → growth of structure, expansion history key systematic: galaxy bias LSS Probes of Dark Energy
Weak Gravitational Lensing
credit: ESA LSS Probes of Dark Energy
Weak Gravitational Lensing light deflected by tidal field of LSS coherent distortion of galaxy shapes “shear” shear related to projected matter distribution key systematics shape measurements assume random intrinsic orientation, average over many galaxies credit: IAP measure shear correlation function/power spectrum probes total matter power spectrum (w/ broad projection kernel) measure average (tangential) shear around galaxies probes halo mass Testing Dark Energy II fiducial
Structure Growth growth rate growth
redshift space distortions ✓ Planck XIII galaxy clusters ✓ APS DPF Meeting, Aug 3 2017 ( ) redshift counts as functions of mass and redshift Mantz+2015 Testing Dark Energy II
Structure Growth
lensing { redshift space distortions ✓ CMB { galaxy clusters (✓) counts as functions of mass and redshift
weak lensing recent studies have claimed 2-3� tension with Planck • a fluke/non-issue? • a crack in LCDM? • a systematic error? Photometric Dark Energy Surveys Photometric Dark Energy Surveys
DES Y1 The Dark Energy Survey
● 5000 sq. deg. survey in grizY from Blanco @ CTIO ● 10 exposures, 5 years, >400 scientists ● Primary goal: dark energy equation of state ● Probes: Galaxy Clustering, Supernovae, Cluster counts, Gravitational lensing ● Status: − SV (150 sq. deg, full depth): most science done, catalogs public − Y1 (1500 sq. deg, 40% depth): data processed, results on cosmology last week − Y3 (5000 sq. deg, 50% depth): data processed, vetting catalogs − Y4: data taking finished (70% depth) The Dark Energy Survey Collaboration
Fermilab, UIUC/NCSA, University of Chicago, ~400 scientists; LBNL, NOAO, University of Michigan, University US support from of Pennsylvania, Argonne National Lab, Ohio State University, Santa-Cruz/SLAC/Stanford, Texas DOE & NSF A&M UK Consortium: UCL, Cambridge, Edinburgh, Nottingham, Portsmouth, Sussex ETH Zurich LMU Ludwig-Maximilians Universität Spain Consortium: CIEMAT, IEEC, IFAE
Brazil Consortium OzDES Consortium
CTIO
Dark Energy Survey @ OSU
Huff, Blazek, Ross, MacCrann, Troxel, Rozo, Honscheid Choi, Eifler DES Year 1 Galaxy Samples
• 26 million source galaxies • 4 redshift bins • Sources for cosmic shear & galaxy-galaxy lensing
• 660,000 redMaGiC galaxies with excellent photo-z’sSPT SV area previously • region Measure angularanalyzed clustering in 5 redshift bins • Use as lenses for galaxy-galaxy lensing
First Year of Data: ~1800 sq. deg. Analyzed 1321 s.d. after cuts With great statistical power comes great systematic responsibility
Unprecedented size and depth Two independent shape & photo-z of photometric data catalogs and calibrations
Drlica-Wagner, Rykoff, Sevilla+ 2017 Zuntz, Sheldon+; Samuroff+; Hoyle, Gruen+ 2017; Davis+, Gatti, Vielzeuf+, Cawthon+ in prep.
Full, validated treatment of covariance Theory and simulation tested, blind, and nuisance parameters (including ν) analysis with two independent codes, CosmoLike and CosmoSIS
Krause, Eifler+2017; MacCrann, DeRose+ in prep DES Y1 Shear Catalogs (Zuntz+17)
Metacalibration (Huff+17, Sheldon+17) : ● New method measuring estimator shear response internally by deconvolving, shearing, deconvolving. ● It uses g, r, i bands. ● 35 M galaxies (26 M for cosmology). im3shape: ● Best-fit bulge & disc models, calibrated with simulations. ● Only r-band. ● 22 M galaxies (18 M for cosmology).
49 DESY1 Measurements: Cosmic Shear
Elliptical galaxy(Elvine-Poole spectrum +17) 4 metacalibration im3shape 10 (Troxel+17)
+ 6
⇠ 10
8 10
5 10 ⇠
7 10 101 102 101 102 ✓ (arcmin) ✓ (arcmin)
44 DESY1 Measurements: Galaxy Clustering
Elliptical galaxy(Elvine-Poole spectrum +17)
44 DESY1 Measurements: Galaxy-Galaxy Lensing
METACALIBRATION 2 10 (Elvine-Poole+17) redMaGiC HiDens redMaGiC HiDensElliptical galaxyredMaGiC spectrum HiDens 0.15 ✓ 4 ( 10 t 5 10 6 10 redMaGiC10 HiLum100 redMaGiC10 HigherLum100 10 100 0.✓60[arcmin] 0.20 ✓ 4 0.43 0.63 0.90 6 10 10 100 10 100 ✓ [arcmin] ✓ [arcmin] (Prat, Sanchez+17) IM3SHAPE 2 10 44 redMaGiC HiDens redMaGiC HiDens redMaGiC HiDens 0.15 ✓ 4 ( 10 t 5 10 6 10 redMaGiC10 HiLum100 redMaGiC10 HigherLum100 10 100 0.✓60[arcmin] ✓ 4 ( 10 t 5 10 6 10 10 100 10 100 ✓ [arcmin] ✓ [arcmin] Multi-Probe Methodology (Krause, Eifler+17) from data vector D to parameters p ● model data vector, incl. relevant systematics ○ implementation details should not contribute to error budget ○ are the systematics parameterizations sufficient for DES-Y1? ● covariance for ~450 data points ● sampler - don’t get the last step wrong... methods paper: validate model + implementation, covariance, sampling Multi-Probe Blinding (DES Collaboration 17) Goal: minimize confirmation bias Implementation: two-staged blinding process ● shear catalogs scaled by unknown factor, until catalogs fixed ● cosmo params shifted by unknown vector, until full analysis fixed ● (do not overplot measurement + theory) ● (clearly state any post-unblinding changes in paper) Multi-Probe Blinding (DES Collaboration 17) Goal: minimize confirmation bias Implementation: two-staged blinding process ● shear catalogs scaled by unknown factor, until catalogs fixed ● cosmo params shifted by unknown vector, until full analysis fixed ● (do not overplot measurement + theory) ● (clearly state any post-unblinding changes in paper) Lessons ● clearly define scope of blinding ○ e.g., parameter measurements vs. model testing ● make sure blinding scheme allows null tests ○ for parameter measurements, this may include consistency between probe ● someone not knowing what they’re doing, shouldn’t be able to unblind intentionally; someone knowing what they’re doing, shouldn’t be able to unblind unintentionally Multi-Probe Constraints: LCDM ● DES-Y1 weak lensing: factor ~2 increase in constraining power ● marginalized 4 cosmology parameters, 10 clustering nuisance parameters, and 10 lensing nuisance parameters ● consistent (Bayes Factor R = 2.8) cosmology constraints from weak lensing and clustering in (DES Collaboration 17) configuration space Key Result: Consistency of late Universe with Planck in ΛCDM ● DES and Planck constrain matter density and S8 with equal strength ● Difference in central values 1-2σ in the same direction as earlier lensing results ● Bayes Factor 4.2 – no evidence for inconsistency ● Still consistent (R=9.0) for joint low-z results + Planck, which is why we combine... Ωm Key Result: Combined Constraints in wCDM ● consistent constraints from geometric probes (R=244) (DES Collaboration 17) ● most precise parameter constraints from DES+Planck +BAO (BOSS) +SN (JLA) ● no evidence for w ≠-1 Steps forward: more precise tests of broader range of models ● DESY1++ is a precise test of currentCurrent geometrical geometric probes probes + DES Y5 (all probes) ΛCDM. Any potential + DESY5 discrepancies are smaller than its uncertainty. ● It does not explain ΛCDM. ● It is not very sensitive to models with time-varying forecast Dark Energy equation of changewwithof time state (among others) Forecast: Eifler++ ● Future joint analyses will be! Conclusions • DES Y1 Cosmology results from galaxy clustering, galaxy-galaxy lensing, and cosmic shear (3x2) are now out: 10 papers, with more to follow. • In context of ΛCDM, these measurements from galaxy surveys now rival precison of Planck CMB results for certain parameters: can compare low- and high-z Universe. • Precision will increase with larger data sets (Y1->Y3->Y5) and by bringing in more probes (clusters, SN, cross-correlations…), enabling tests of more complex models (w0waCDM, modified gravity,…) • DES Y1 results consistent with Planck CMB in context of ΛCDM. • DES Y1 results in combination with Planck, BAO, JLA SN provide stringent constraints on ΛCDM parameters.