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A Precise Measurement of H 0 from DES, BAO, and BBN Eduardo Rozo, University of Arizona On behalf of the Dark Energy Survey Collaboration Statistical challenges for large scale structure in the era of LS LSST What I Wont Be Talking About

  1. A Precise Measurement of H 0 from DES, BAO, and BBN Eduardo Rozo, University of Arizona On behalf of the Dark Energy Survey Collaboration Statistical challenges for large scale structure in the era of LS LSST

  2. What I Won’t Be Talking About Mass calibration of the DES redMaPPer cluster catalogue. WL This Work RM+CMB (Baxter et al. 2017) WL (Melchior et al. 2017) WL (Simet et al. 2017) 10 15 SZ (Saro et al. 2015) Mass [M � ] Tamas Varga Tom McClintock 10 14 S17 pivot S15 pivot B17 4% systematic uncertainty M17 10 100 Richness λ McClintock et al, on arxiv in ~2 weeks.

  3. What I Won’t Be Talking About Mass calibration of the DES redMaPPer cluster catalogue. Matteo Costanzi log 10 h M | λ = 40 , z = 0 . 35 i This work Melchior et al. (2017) Baxter et al. (2018) Simet et al. (2017) Murata et al. 2017 Baxter et al. (2016) Farahi et al. (2016) Saro et al. (2015) Mantz et al. (2016) 14 . 3 14 . 4 14 . 5 14 . 6 14 . 7 14 . 8 Bl Blinded cosmology

  4. A Precise Measurement of H 0 from DES, BAO, and BBN

  5. The Hubble Constant Problem Freedman 2017.

  6. Why It Matters “The single most important complement to the CMB for measuring the dark energy equation of state at z ∼ 0.5 is a determination of the Hubble constant to better than a few percent.”

  7. Basic idea: • In flat LCDM, CMB already constrains all cosmological parameters. • CMB accurately predicts both the expansion history and growth of large scale structure. • Deviations in any of these observables can provide evidence of dark energy. • H 0 is the cosmological parameter that varies the most as we vary dark energy while holding the CMB fixed. H 0 constraints are especially powerful probes of dark energy!

  8. An Under-appreciated Fact In a flat LCDM model, BAO+BBN + (any probe of ! m ) = Hubble constant measurement DES+BAO+BBN results in a very clean measurement of H! Though see Aubourg et al. 2015.

  9. A Precise Measurement of H 0 from DES+BAO+BBN

  10. The BAO Story I Usually Hear BAO = Baryon Acoustic Oscillations • The CMB measures the sound horizon r s of the photon- baryon fluid in the early Universe. • This sound horizon is imprinted into the galaxy density today: BAO is a standard ruler calibrated by the CMB. • With r s calibrated, we can use BAO to measure H(z) and D A using BAO observables.

  11. The BAO Story I Usually Hear BAO = Baryon Acoustic Oscillations • The CMB measures the sound horizon r s of the photon- baryon fluid in the early Universe. • This sound horizon is imprinted into the galaxy density today: BAO is a standard ruler calibrated by the CMB. • With r s calibrated, we can use BAO to measure H(z) and D A using BAO observables. True but incomplete.

  12. Th The B BAO S Sto tory ry Over/under-densities launch density waves.

  13. After decoupling, pressure goes to zero, and so the waves stall. Gravitational accretion preserves the density peak from the stalled waves in the dark matter.

  14. What Does BAO Measure? The sound horizon scale is imprinted into the galaxy density distribution. What is r s ? c s = sound speed = r s = c s t '(/'! t = time to recombination P depends T CMB ! depends on T CMB and Ω # ℎ % t depends on T CMB , Ω & ℎ % . :: assumes no early DE.

  15. What Does BAO Measure? The sound horizon scale is imprinted into the galaxy density distribution. What is r s ? c s = sound speed = r s = c s t !"/!$ t = time to recombination P depends T CMB $ depends on T CMB and Ω & ℎ ( t depends on T CMB , Ω ) ℎ ( . :: assumes no early DE. Parameters: Ω & ℎ ( , Ω ) ℎ (

  16. BAO Observables We don’t measure distances. We measure: • angles: ! s = r s /D A • redshift intervals: Δ z = H(z)r s /c. H(z) depends on: H 0 ( ℎ) , Ω ' ℎ % . D A is an integral over H(z). Parameters: Ω # ℎ % , Ω ' ℎ % , ℎ

  17. Bottom Line A single BAO measurements is degenerate in Ω " ℎ $ , Ω % , ℎ. Ω " ℎ $ : BBN measures this number Ω % : DES measures this number DES+BAO+BBN can measure h !

  18. BAO Measurement 30 6dFGS MGS SDSS − II WiggleZ LOWZ √ z CMASS 20 distance /r d Ly α auto Ly α cross √ z D M ( z ) /r d 10 √ z D V ( z ) /r d √ z zD H ( z ) /r d 0 . 1 0 . 2 0 . 5 1 . 0 2 . 0 z Aubourg et al. 2015

  19. Baryon Density from D/H Measurements Big Bang Nucleosynthesis • D burns to produce He. • More baryons faster burn. • D decreases w/ Ω " ℎ $ . But how to measure? 4 Burles et al. 2001 Cooke et al. (2001) Burles et al. (2001)

  20. Primordial D/H Measurement Use quasar absorption spectra • simultaneously model D and H absorption • Look for low-metallicity lines of sight • Ensures pristine primordial abundances • Look for damped Ly- ! systems. • Lots and lots of D and H means high S/N • Can model several absorption lines • simultaneously! Cook et al. 2016

  21. HIRES data HIRES data 1 . 0 1 . 0 Ly ↵ Ly8 1 . 0 1 . 0 0 . 5 0 . 5 0 . 0 0 . 0 Ly � Ly9 1 . 0 1 . 0 0 . 8 0 . 8 0 . 5 0 . 5 0 . 0 0 . 0 Ly � Ly10 1 . 0 1 . 0 0 . 5 0 . 5 0 . 6 0 . 6 0 . 0 0 . 0 Normalized Flux Normalized Flux Ly � Ly11 1 . 0 1 . 0 0 . 5 0 . 5 0 . 0 0 . 0 0 . 4 Ly ✏ 0 . 4 Ly12 1 . 0 1 . 0 0 . 5 0 . 5 0 . 0 0 . 0 Ly6 Ly13 1 . 0 1 . 0 0 . 2 0 . 5 0 . 2 0 . 5 0 . 0 0 . 0 Ly7 Ly15 Ly14 1 . 0 1 . 0 0 . 5 0 . 5 0 . 0 0 . 0 Cook et al. 2016 0 . 0 0 . 0 0 . 0 0 . 2 0 . 4 − 150 − 100 − 50 0 +50 +100 +150 0 . 0 − 150 − 100 − 50 0 . 2 0 +50 +100 +150 0 . 4 Velocity Relative to z

  22. Ly6 1 . 0 0 . 2 0 . 5 0 . 0 Ly7 1 . 0 0 . 5 0 . 0 0 . 0 − 150 − 100 − 50 0 +50 +100 +150 0 . 0 0 . 2 0 . 4 Cook et al. 2016

  23. BBN Constraints • Ω " ℎ $ = ( 2.208 ± 0.052 ) x 10 -2 • Dominant error: - uncertainty in the d(p, % ) 3 He rate. - ongoing experimental efforts to better constrain this rate. • BBN uncertainty is easily sub-dominant for our analysis.

  24. Dark Energy Survey Credit: Bjoern Soergel

  25. Funded by: ~4 ~400 sc scientist sts; s; US su suppor ort fr from om DOE E & NS NSF Collaborating institutions:

  26. DES Y1 Results 5:00h 4:00h 3:00h 2:00h 1:00h 0:00h 23:00h 2.00 –25 � –30 � 1.75 –35 � n gal [arcmin –2 ] –40 � 1.50 –45 � SPT 1.25 region –50 � 1.00 Y1 3x2pt analysis: gg-clustering + gg-lensing + cosmic shear

  27. S 8 = ! 8 ( " /0.3) 1/2 DES Year 1 results : 1708.01530

  28. Analysis Flat ! CDM • Minimal neutrino mass: ∑ m " = 0.06 eV • BBN from Cooke et al. • BAO from BOSS, SDSS main, 2dF, 6dF • DES Y1 combined probes •

  29. +1.2 H 0 = 67.2 km/s/Mpc − 1.0 Dark Energy Survey Year 1 Results: 1711.00403

  30. Comparison to External Data Sets Four independent data sets that reach percent level precision: • Planck: TT+low- l polarization • SPTpol: High- l polarization • SH0ES: Distance Ladder (cepheids + SN) • H0LiCOW Strong lensing o Da Data sets are statistically independent of each other: o no no covari rianc nce! e! o No No s shared o d obs bservational s systematics!

  31. Consistency Ω # , Ω $ , h, & 8 , n s Planck: Ω # , Ω $ , h, & 8 , n s SPTpol: Ω # , Ω $ , h, & 8 DES+BAO+BBN: h SH0ES: h H0LiCOW: Significance: 2.1 & ! 2 /DOF = 20.7/11 Al All data is con onsistent wi with flat LCD CDM mod odel.

  32. +1.2 DES+BAO+BBN: H 0 = 67.2 km/s/Mpc − 1.0 +0.4 Everything: H 0 = 69.1 km/s/Mpc − 0.6

  33. +1.2 DES+BAO+BBN: H 0 = 67.2 km/s/Mpc − 1.0 What’s going on here? +0.4 Everything: H 0 = 69.1 km/s/Mpc − 0.6

  34. Intersection of Planck w/ DES+BAO+BBN is at high h

  35. The Impact of Neutrino Masses

  36. Summary DES+BAO+BBN measures H 0 with the same precision as • Planck, yet is co comp mpletely y deco coupled from m the CMB . +1.2 H 0 = 67.2 km/s/Mpc • − 1.0 There are now 5 measurements of H 0 that are: • Statistically independent • Share no common observational systematics • The entire set has an acceptable ! 2 • No evidence for dynamical dark energy/MG •

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