BAO from the DR14 QSO sample

Transcription

1 BAO analysis from the DR14 QSO sample Héctor Gil-Marín (on behalf of the eboss QC WG) Laboratoire de Physique Nucleaire et de Hautes Energies (LPNHE) Institut Lagrange de Paris (ILP) Paris 28th Aug 2017

2 The eboss survey : the eboss survey Apache Point Observatory (APO) 2.5-m telescope. SDSS-III project BOSS: Baryon Oscillation Spectroscopic Survey SDSS-IV project eboss: extended Baryon Oscillation Spectroscopic Survey 3 galaxy clustering programs (ELG, LRG, quasars) + Ly-α new selection algorithms to identify redshift of galaxies BOSS had 99% success rate identifying redshifts of LRGs first eboss tests showed 70% of success rate on LRGs using same BOSS algorithms!

3 The eboss survey : the eboss survey eboss survey: ELG, LRG and QSO samples LRG 0.6 < z < 1.0; z eff = ELG 0.6 < z < 1.1; z eff = QSO 0.8 < z < 2.2; z eff = 1.5. Ly-α z eff = 2.33 [Credit : Anand Raichoor]

4 The eboss survey : the eboss survey

5 The eboss survey : the eboss survey assuming Planck ΛCDM cosmology eboss year 6 Planck ΛCDM f σ8(z) BOSS DR12 6dFGS SDSS MGS GAMA WiggleZ Vipers z

6 The eboss survey Low Density of Quasars! Shot noise dominated covariance matrices (traditional) Reconstruction algorithms do not provide much signal gain

7 The eboss survey : the eboss survey QSO DR14 area 2044 deg 2. quasar range: 0.8 < z < 2.2 (z eff 1.5) Number quasars: 147,000 Low density: [Mpc/h] 3 3 disconnected areas: 2 SGC & NGC.

8 The eboss survey : the eboss survey Alphabetical paper Ata et al submitted to the Journal arxiv: First in 0.8 z 2.2 D V = 3855 ± 170 r d /r d,fid Mpc at z=1.52 (4.4% precision) 2.5σ BAO significance DR14 Area: % precision DR16 Area: % precision eboss is working!

9 By assuming a wrong cosmological model (Ω m ) we change the line-of-sight clustering respect to the angular clustering, creating a measurable anisotropy: constrains H(z) and D A (z) (or a combination of both). d comov (z) = z 0 cdz H(z ; Ω m ) The BAO scale is determined by the comoving sound horizon at reconvination scale (standard ruler) r s = 1 H 0 Ω 1/2 m a 0 da c s (a + a eq ) 1/2

10 Baryonic Acoustic Oscillations k α k α = Hfid (z) H(z) k α k α = D A(z) D fid A (z) [Anderson et al. 2014, BOSS DR11] Surveys measure angles and redshifts, and these are affected by the assumed fiducial model. This changes the apparent/observed position of the BAO peak in the power spectrum differently in the radial and angular direction Isotropic Correlation Function / Power Spectrum sensitive to D V (z) = [ ] (1 + z) 2 DA 2 cz 1/3 (z) H(z)

11 We perform two complementary and independent analyses on the same dataset using the i) Power Spectrum and ii) Correlation Function. Both observables should contain the same amount of information, but in practice are affected differently by noise and systematic effects. We use mocks (1000 EZ mocks) and (400 QPM mocks) to estimate the covariance matrices and perform systematic tests. We model the broadband shape of the PS/CF phenomenologically and the BAO as linear+damping (Σ nl ) P(k, α) = P sm (k) {1 + [O lin (k/α) 1] e 1 2 Σ2 k2} nl smooth PS: P sm (k) B 2 P lin nw(k) + A 1 k + A 2 + A 3 /k

12 DR14 QSO isotropic Power spectrum and Correlation function SGC, χ 2 /dof =22.1/27 NGC, χ 2 /dof =33.2/ SGC, χ 2 /dof =28.3/24 NGC, χ 2 /dof =21.0/24 kp0(k) (h 2 Mpc 2 ) s 2 ξ0(s) (h 2 Mpc 2 ) k (hmpc 1 ) s (h 1 Mpc) Actual data + diagonal errors from EZ mocks. Dashed lines mean of the EZ-mocks

13 DR14 QSO isotropic Power spectrum and Correlation function 10(P Psmooth)/Psmooth k(hmpc 1 ) 10 3 (ξ[s] ξsmooth) s (h 1 Mpc) Actual data + diagonal errors from EZ mocks. Solid lines best-fit model

14 Tests on Mocks Power Spectrum α DR14 Mocks Power Spectrum σ(α) Correlation Function α Correlation Function σ(α) Correlation coefficient between PS and CF ρ = Data is a very typical case of mocks (both in measurement and error).

15 Tests on Mocks NL effects shift the BAO peak to higher α. 0.1% effect on measured α. Negligible on data!

16 Tests on data Both P(k) and ξ(s) measurements are very consistent! ξ(s) P (k) P (k) + ξ(s) χ σ σ 1σ α BAO

17 Cosmology Fully consistent with LCDM + Planck. Ly-α 2.5 measurement dominates at high z. Further analyses will focus on redshift weighting schemes. Distance/Distance(PlanckΛCDM) SDSS MGS WiggleZ BOSS DR12 6dFGS DR14 quasars BOSS Lyα Redshift

18 BAO Summary Summary, We have a robust BAO isotropic measurement at z 1.5. with 4.4% precision: D V (1.52) = 3855 ± 170 r d /r d,fid Mpc. Very consistent with mocks and between P and ξ observables. Fully consistent with LCDM+Planck

19 BAO Summary Summary, We have a robust BAO isotropic measurement at z 1.5. with 4.4% precision: D V (1.52) = 3855 ± 170 r d /r d,fid Mpc. Very consistent with mocks and between P and ξ observables. Fully consistent with LCDM+Planck First BAO science result from WG, but not last one. More complex BAO analyses will be done in the forthcoming months (weighting z evolution). Future quasar releases (DR16) will focus on the anisotropic quasar BAO Constrain D A and H. Further information on D V can be extracted from RSD analysis (several papers to be released this Fall)