Gontcho, SGA; Miralda-Escude, J; Font-Ribera, A; Blomqvist, M; Busca, NG; Rich, J; (2018) Quasar - CIV forest cross-correlation with SDSS DR12. Monthly Notices of the Royal Astronomical Society (MNRAS) , 480 (1) pp. 610-622. 10.1093/mnras/sty1817.

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Abstract

We present a new determination of the large-scale clustering of the CIV forest (i.e. the absorption due to all CIV absorbers) using its cross-correlation with quasars in the Sloan Digital Sky Survey Data Release 12. We fit a linear bias model to the measured cross-correlation. We find that the transmission bias of the CIV forest, bFc, at a mean redshift of z=2.3 , obeys (1+βc)bFc=−0.024±0.003 . Here, βc is the linear redshift space distortion parameter of the CIV absorption, which can only be poorly determined at βc = 1.1 ± 0.6 from our data. The most accurately determined combination marginalized over βc is (1+0.44βc)bFc=−0.0170±0.0014 . The transmission bias is related to the bias of CIV absorbers and their host haloes, bτc, through the effective mean optical depth of the CIV forest, which we estimate at τ¯c(z)≃0.01 from previous studies of the CIV equivalent width distribution. We then find 1 < bτc < 1.7, with the large error arising from uncertainties in βc and τ¯c . This CIV bias is lower than the DLA bias bDLA ≃ 2 measured previously from the cross-correlation of DLAs and the Ly α forest, indicating that most CIV absorbers are hosted by haloes of lower mass than DLAs. More accurate determinations of τ¯c(z) and βc are necessary to check this conclusion.

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