Hélion du Mas des Bourboux

Baryon acoustic oscillations from the complete SDSS-III Ly α -quasar cross-correlation function at z = 2.4

We present a measurement of baryon acoustic oscillations (BAO) in the cross-correlation of quasars with the Lyα-forest flux transmission at a mean redshift of z = 2.40. The measurement uses the complete Sloan Digital Sky Survey (SDSS-III) data sample: 168 889 forests and 234 367 quasars from the SDSS data release DR12. In addition to the statistical improvement on our previous study using DR11, we have implemented numerous improvements at the analysis level enabling a more accurate measurement of this cross-correlation. We have also developed the first simulations of the cross-correlation that allow us to test different aspects of our data analysis and to search for potential systematic errors in the determination of the BAO peak position. We measure the two ratios DH(z = 2.40) /rd = 9.01 ± 0.36 and DM(z = 2.40) /rd = 35.7 ± 1.7, where the errors include marginalization over the non-linear velocity of quasars and the cross-correlation of metals and quasars, among other effects. These results are within 1.8σ of the prediction of the flat-ΛCDM model describing the observed cosmic microwave background anisotropies. We combine this study with the Lyα-forest auto-correlation function, yielding DH(z = 2.40) /rd = 8.94 ± 0.22 and DM(z = 2.40) /rd = 36.6 ± 1.2, within 2.3σ of the same flat-ΛCDM model. Key words: cosmological parameters / dark energy / large-scale structure of Universe

Measurement of BAO correlations at

Author(s): Bautista, JE; Busca, NG; Guy, J; Rich, J; Blomqvist, M; Du Mas Des Bourboux, H; Pieri, MM; Font-Ribera, A; Bailey, S; Delubac, T; Kirkby, D; Le Goff, JM; Margala, D; Slosar, A; Vazquez, JA; Brownstein, JR; Dawson, KS; Eisenstein, DJ; Miralda-Escude, J; Noterdaeme, P; Palanque-Delabrouille, N; Pâris, I; Petitjean, P; Ross, NP; Schneider, DP; Weinberg, DH; Yeche, C | Abstract:

z=2.3

We study the first year of the eBOSS quasar sample in the redshift range 0.9 < z < 2.2 which includes 68,772 homogeneously selected quasars. We show that the main source of systematics in the evaluation of the correlation function arises from inhomogeneities in the quasar target selection, particularly related to the extinction and depth of the imaging data used for targeting. We propose a weighting scheme that mitigates these systematics. We measure the quasar correlation function and provide the most accurate measurement to date of the quasar bias in this redshift range, b(Q) = 2.45 +/- 0.05 at (z) over bar = 1.55, together with its evolution with redshift. We use this information to determine the minimum mass of the halo hosting the quasars and the characteristic halo mass, which we find to be both independent of redshift within statistical error. Using a recently-measured quasar-luminosity-function we also determine the quasar duty cycle. The size of this first year sample is insufficient to detect any luminosity dependence to quasar clustering and this issue should be further studied with the final similar to 500,000 eBOSS quasar sample.

with SDSS DR12 \lya-Forests

Author(s): Bautista, JE; Busca, NG; Guy, J; Rich, J; Blomqvist, M; Du Mas Des Bourboux, H; Pieri, MM; Font-Ribera, A; Bailey, S; Delubac, T; Kirkby, D; Le Goff, JM; Margala, D; Slosar, A; Vazquez, JA; Brownstein, JR; Dawson, KS; Eisenstein, DJ; Miralda-Escude, J; Noterdaeme, P; Palanque-Delabrouille, N; Pâris, I; Petitjean, P; Ross, NP; Schneider, DP; Weinberg, DH; Yeche, C | Abstract:

Clustering of quasars in SDSS-IV eBOSS : study of potential systematics and bias determination

We present measurements of the cross-correlation of the triply-ionized carbon (CIV) forest with quasars using Sloan Digital Sky Survey Data Release 14. The study exploits a large sample of new quasars from the first two years of observations by the Extended Baryon Oscillation Spectroscopic Survey (eBOSS). The CIV forest is a weaker tracer of large-scale structure than the Ly

Measurement of baryon acoustic oscillation correlations at

\alpha

z=2.3

forest, but benefits from being accessible at redshifts

with SDSS DR12 Ly

z<2

\alpha

where the quasar number density from eBOSS is high. Our data sample consists of 287,651 CIV forest quasars in the redshift range

-Forests

1.4<z<3.5