Astronomy & Astrophysics

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$\begin{figure} \par\includegraphics[width=7.4cm,clip]{Zw.ps}\hspace*{2.3cm} \includegraphics[width=7.4cm,clip]{Delta.ps}\end{figure}$ Figure 1: Left panel: The two- and three-point quasar-galaxy correlation functions, averaged within disks of radius $\theta$ , are plotted as a function of angular scale for a flat Universe with $\Omega _0=0.3$ . All the quasars are located at redshift 1.5, and the galaxies are distributed according to Eq. (31), with a peak at z=0.3. The dashed curve shows the two-point correlation function $\bar{w}(\theta)$ and the solid line the three-point function $\bar{z}(\theta)$ . As dotted lines are plotted the corresponding correlation functions for a linear evolution of the perturbation. Near one arcminute, the triple correlator $\bar{z}$ reaches the $\sim$ $2\%$ level, assuming a linear bias of unity. At larger angular scales, the amplitude drops steeply. Right panel: We plot the expected extra scatter of galaxies around quasars for a flat Universe with $\Omega _0=0.3$ (thick line) and considering a galaxy density of 1 per arcmin². We also show the different contributions to Eq. (18).
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{s3.ps}\end{figure}$ Figure 2: The skewness $S'_3(\theta )$ is shown as a function of angle $\theta$ for three different cosmological models. The solid line is the prediction based on the non-linear description of the power spectrum and the bispectrum. The dashed line shows the perturbation-theory calculation.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{plot_s3_variation_s8.ps}\hspace*{6mm} \includegraphics[width=7.5cm,clip]{plot_s3_variation_G.ps}\end{figure}$ Figure 3: The dependence of the skewness S₃' on $\sigma _8$ and $\Gamma$ is shown for two different cosmologies ( $\Omega _0=1$ and 0.3) and three different angular scales, 1', 5' and 10'. A value of $\Gamma =0.21$ is used when $\sigma _8$ varies and we fix $\sigma _8=0.9$ when $\Gamma$ varies. The dependence of S'₃ on $\sigma _8$ goes down to $10\%$ at small scales and is at the one percent level when $\Gamma$ changes.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{n_qso.ps}\end{figure}$ Figure 4: Number of quasars required for a 3- $\sigma$ detection of the excess scatter $\Delta$ of the galaxy counts near quasars, as a function of angular scale $\theta$ , and according to our simplified noise estimation. Three different values for the galaxy number density are assumed, namely 1, 2, and $3~{\rm arcmin}^{-2}$ . The vertical line indicates the mean angular separation of 20' between distant quasars in the SDSS.
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In the text

$\begin{figure} \par\includegraphics[width=8.3cm,clip]{s3.ps}\end{figure}$	Figure 2: The skewness $S'_3(\theta )$ is shown as a function of angle $\theta$ for three different cosmological models. The solid line is the prediction based on the non-linear description of the power spectrum and the bispectrum. The dashed line shows the perturbation-theory calculation.
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