Mapping the Universe spectroscopic surveys for BAO measurements Meeting on fundamental cosmology, june 2016, Barcelona, Spain Johan Comparat 1
Baryonic acoustic oscillations The acoustic length scale is the comoving distance sound waves travelled from Big Bang until recombination r s = z=1100 dz c s(z) H(z) = 144 Mpc = 0.59672 0.00038 degrees on the CMB at a precision of 0.1% with Planck! Imprint measureable on the 2-pt correlation function / power spectrum of the complete matter field δ m. We measure the 2PCF of galaxies δ obs = b(1 + βμ 2 )δ m. Eisenstein & Hu (1998), Planck collaboration (2015) 2
Baryonic acoustic oscillations This measurement of the BAO scale is nearly free of systematics <0.3% (see Padmanabhan et al. 2012, Ross et al. 2012, Angulo et al. 2014, Prada et al. 2014) Future cosmology experiments aim measuring the BAO feature in galaxy clustering for redshift z<4 down to the 0.3% level. 3
SDSS-III/BOSS observations At higher z 1 year : photometry, 4 years : spectroscopy Alam et al. 2015 ApJ. 1501.00963 4
With galaxies; V=7 Gpc 3 /h 3 SDSS-III/BOSS results SEE TALKS THIS AFTERNOON BY Hector Gil-Marín Andreu Font-Ribera With Ly-alpha quasars; V=50 Gpc 3 /h 3 Delubac et al. (2014). 1404.1801; Gil-Marin et al. (2015). 1509.06386, Aubourg et al. (2014) 5
Next steps charting the unknown Where to explore now? With what spectrograph? Dawson et al. 2015 Low redshift : TAIPAN (Australia) and LoRCA (Spain) 1m Higher redshift : <2020 : eboss 2.5m >2020 : DESI (US) and 4MOST (Chile) 4m 6
SDSS-IV eboss, a pathfinder Mapping accurately the redshift range 0.6 < z < 3.5 7
Aims of the eboss survey RSD 4% BAO 2% Dawson et al. 2015 8
BAO measurement process Selection function n(z, RA,DEC) vs. photometry quality, stellar density, galactic dust galaxy population and its evolution redshift measurement completeness simulations High resolution mock catalog, HOD, SHAM, SAMS Approximate method to produce covariance mocks LRG : extension of BOSS knowledge. ELG & QSO : new challenges! 9
First results this summer with 2yr data Target selection, QSO & Ly alpha QSO Using SDSS + WISE with XDQSOz to select (0.9<z<2.2) quasars, 70 per sq. deg. Mag limit: g<22 or r<22 Median redshift 1.5 Redshift efficiency 70% Area 7500 sq. deg +PTF variability, eboss adds 6.6 new Ly alpha QSO per sq. deg. Myers et al. 2015 1508.04472, Palanque-Delabrouille et al. 2015 10
A tracer to cover the transition between DM and DE around redshift 0.8 Target selection test for ELGs DV at 2% needs : Area 1000-1500 deg2 Density 135 / deg2 in 0.7<z<1.1 Bias = 1.4 strong emission lines to identify quickly and accurately redshifts Test : Use DECaLS g,r,z optical bands (legacysurvey.org) select g<22.8 and Comparat et al. 2015, 1509.06400 11
Observations start in September for 2 yr Target selection, test results Bias around 1.7 (>1.4) Median redshift 0.86, 76% have a reliable redshift in 0.7<z<1.1 Density 180 /deg2 * eff > 150 DECaLS Photometry available on an area 1000-1500 deg2 Observations start in September 2016! Comparat et al. 2015, 1509.06400 12
ELG redshift completeness Redshift accuracy depends on the strength of the emission lines Redshift window : completeness vs. redshift End-2-end sims needed! Comparat et al. 2015, 1509.06400 Comparat et al. 2016 13
E2E: Emission line Luminosity Function ELGs are sampling the emission line LF and the mass function in an incomplete manner We have measured anew the [OII], Hbeta, [OIII] LFs to contruct completeness models Nbody + GALFORM (Gonzalez-Perez + 2014) reproduces the luminosity functions and observed mag & color distributions Comparat et al. 2016, 1605.02875 14
In preparation E2E: ELG stellar population Create a library of truthful ELG templates for the E2E simulation. Measure the stellar population (mass, metallicity, sfr) on stacks of ELG spectra following the LF with Firefly (Wilkinson, Maraston et al. 2015) Add spectra to the simulation Inform the completeness function and high fidelity mocks Comparat, Maraston et al. In prep. 15
BAO measurement process Selection function n(z, RA,DEC) vs. photometry quality, stellar density, galactic dust the galaxy population in terms of galaxy evolution Redshift measurement a completeness criterion simulations High resolution mock catalog, HOD, SHAM, SAMS Approximate method to produce covariance mocks LRG : extension of BOSS knowledge. ELG & QSO : new challenges! 16
Mocks and simulations for ELGs Use photometry from CFHT-LS and LenS + spectroscopy from SDSS-III, VIPERS and DEEP2 data. Combine monopole and angular clustering with the g g lensing Compare to high resolution N body lightcones from MultiDark, we find a good model. Favole, Comparat et al. 2015 17
Halos & ELGs Favole, Comparat et al. 2015 18
Timeline for the results and data release First clustering results expected this summer using LRG, QSO and Ly alpha QSO along a data release of 1/3 of eboss. ELG obs start in September! Zhao et al. 2015 19
Outlook. Emission line galaxies and quasars, pixels for the most precise far-universe map with DESI, 4MOST, EUCLID 2 multi fiber spectrographs are being built : At Kitt Peak (USA), DESI (desi.lbl.gov) At Paranal (chile), 4MOST (4most.eu) In total by 2024, we will have an exhaustive map of 40 000 000 galaxies and quasars covering 0.6 < z < 3.5 EUCLID satellite to cover H alpha ELG in the infrared to redshift 2 20
Thank you for your attention Questions? Zhu, Comparat et al. 2015. 1507.07979 21