Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H4385F1.ps} \end{figure}$ Figure 1: Transmission curves of the two narrow-band and the broad-band Bessel B and R filters used in this study.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{H4385F2.ps}\hspace*{3mm} \includegraphics[width=8cm,clip]{H4385F3.ps} \end{figure}$ Figure 2: The 400 $\times$ 400 arcsec² fields surrounding the QSOs BRI 1346-0322 (left panel) and Q 2138-4427 (right panel) as observed in the narrow-band filters. Both QSOs are identified by an " $\times$ '' at the field centre and the positions of selected LEGO candidates (see Sect. 2.1.1) are shown with boxes.
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In the text

$\begin{figure} \par\mbox{\includegraphics[width=5cm,clip]{H4385F4.ps}\includegra... ...cm,clip]{H4385F8.ps}\includegraphics[width=5cm,clip]{H4385F9.ps} }\end{figure}$ Figure 3: The top three panels concern the BRI 1346-0322 field and the lower three panels the Q 2138-4427 field. Left panels: simulated colour-colour diagram based on Bruzual & Charlot galaxy SEDs. The filled squares are 0<z<1.5 galaxies with ages from a few to 15 Gyr and the open triangles are 1.5<z<3.0 galaxies with ages from a few Myr to 1 Gyr. The dotted box encloses the simulated galaxy colours. The dashed line indicates colours of objects with a particular broad-band colour and with an SED in the narrow-band filter ranging from an absorption line in the upper right part to an strong emission line in the lower left part of the diagram. Middle panels: colour-colour diagrams for all objects detected at S/N>5 in either the narrow band or the B band. As expected, most objects have colours consistent with being in the dotted box. Due to the damped Ly $\alpha$ line Q 2138-4427 has a large positive $n{\rm (AB)}{-}B\rm (AB)$ colour. BRI 1346-0322 has a lower $n{\rm (AB)}{-}B\rm (AB)$ colour due to Ly $\alpha$ blanketing affecting the observed B-band flux. In the lower left part of the diagram there is a large number of objects with excess emission in the narrow filter. Candidate LEGOs are those objects with a 1 $\sigma$ upper limit on $n{\rm (AB)}{-}B\rm (AB)$ below the 98% percentile. Right panel: the colours of the QSOs and of the LEGO candidates. Candidates confirmed to be emission line objects based on our spectroscopic observations described in Sect. 3 are shown with filled symbols. Un-confirmed candidates are shown with open circles and un-observed candidates are shown with open triangles. The solid line indicates the median $n{\rm (AB)}{-}B\rm (AB)$ colour as a function of $n{\rm (AB)}{-}R\rm (AB)$ and the dotted lines indicate the 2% and 98% percentiles in the $n{\rm (AB)}{-}B\rm (AB)$ colour.
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In the text

$\begin{figure} \par\includegraphics[width=8.5cm,clip]{H4385F10.ps}\hspace*{3mm} \includegraphics[width=8.5cm,clip]{H4385F11.ps} \end{figure}$ Figure 4: Our selection criterion is illustrated by plotting the line equivalent width against the Ly $\alpha$ flux in the isophotal aperture for the LEGO candidates in the two fields. The continuous line shows our $n{\rm (AB)}{-}B\rm (AB$ ) colour selection criterion converted into equivalent width. Filled symbols indicate objects subsequently confirmed by spectroscopy to be emission-line sources. Open circles indicate objects that were observed, but not confirmed, and open triangles candidates not yet observed. The nature of the four foreground emission-line sources is also indicated.
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In the text

$\begin{figure} \par\epsfig{file=H4385F14.ps, width=5.3cm}\epsfig{file=H4385F15.p... ...width=5.3cm}\epsfig{file=H4385F31.ps, width=5.3cm}\vskip 0.2cm\par\end{figure}$ Figure 5: $16\times 16$ arcsec² images and 1-D spectra of 18 confirmed LEGOs in the field of BRI 1346-0322. For each candidate, we show images from the narrow-, B- and R-band filters (from left to right). The units on the ordinate of the spectra are counts in 1800 s (as in Fynbo et al. 2001). The region around the sky line at 5199 Å is covered due to large sky-subtraction residuals. The name, redshift and coordinates (Epoch 2000) are provided for each object.
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In the text

$\begin{figure} \par\epsfig{file=H4385F32.ps, width=5.3cm}\epsfig{file=H4385F33.p... ...5F48.ps, width=5.3cm}\epsfig{file=H4385F49.ps, width=5.3cm}\\\par\end{figure}$ Figure 6: $16\times 16$ arcsec² images and 1-D spectra of 23 confirmed LEGOs in the field of Q 2138-4427. For each candidate, we show images from the narrow-, B- and R-band filters (from left to right). The units on the ordinate of the spectra are counts in 1800 s (as in Fynbo et al. 2001). The name, redshift and coordinates (Epoch 2000) are provided for each object.
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In the text

$\begin{figure} \par\epsfig{file=H4385F50.ps, width=5.3cm}\epsfig{file=H4385F51.p... ...dth=5.3cm}\epsfig{file=H4385F54.ps, width=5.3cm}\hspace*{3cm}}\par\end{figure}$ Figure 6: continued.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H4385F12.ps} \end{figure}$ Figure 7: Histogram of R(AB) magnitudes of 45 confirmed emission-line sources. Objects detected at less than 5 $\sigma$ in the R band are located in the last bin, corresponding to R=27, and the 4 foreground emission-line sources (three [O II] emitters and one C IV emitter) are indicated with the double-hatched pattern at the bright end. 85% of the LEGOs are fainter than the spectroscopic limit of R(AB) = 25.5 for LBGs.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H4385F13.ps} \end{figure}$ Figure 8: Redshift distributions of LEGOs in the two fields relative to the filter response curves. The redshifts of LEGOs in the field of BRI 1346-0322 fill out the volume probed by the filter, whereas LEGOs in the field of Q 2138-4427 have a very narrow redshift distribution.
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In the text

$\begin{figure} \par\epsfig{file=H4385F55.ps, width=5.3cm}\epsfig{file=H4385F56.p... ...pace*{5.5cm}\epsfig{file=H4385F58.ps, width=5.3cm}\hspace*{5.5cm}}\end{figure}$ Figure 9: Shown are $16\times 16$ arcsec² images and 1D spectra of the four candidates that turned out to be foreground objects with other lines than Ly $\alpha$ observed in the narrow-band filters (three [O II] emitters and an AGN with its C IV emission line). The spectra are not flux calibrated.
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In the text

$\begin{figure} \par\epsfig{file=H4385F59.ps, width=5.3cm}\epsfig{file=H4385F60.p... ...ile=H4385F66.ps, width=5.3cm}\epsfig{file=H4385F67.ps, width=5.3cm} \end{figure}$ Figure 10: Shown are $16\times 16$ arcsec² images and 1D spectra of serendipitously detected, probable LEGOs. The spectra are ordered by redshifts that range from z=1.98 to z=3.47. Note that the object LEGO1346_2b located at z=3.1251 is a neighbour to the z=3.1301 LEGO1346_2 seen in the lower left corner of the same image.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{H4385F1.ps} \end{figure}$	Figure 1: Transmission curves of the two narrow-band and the broad-band Bessel B and R filters used in this study.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{H4385F2.ps}\hspace*{3mm} \includegraphics[width=8cm,clip]{H4385F3.ps} \end{figure}$	Figure 2: The 400 $\times$ 400 arcsec² fields surrounding the QSOs BRI 1346-0322 (left panel) and Q 2138-4427 (right panel) as observed in the narrow-band filters. Both QSOs are identified by an " $\times$ '' at the field centre and the positions of selected LEGO candidates (see Sect. 2.1.1) are shown with boxes.
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$\begin{figure} \par\epsfig{file=H4385F32.ps, width=5.3cm}\epsfig{file=H4385F33.p... ...5F48.ps, width=5.3cm}\epsfig{file=H4385F49.ps, width=5.3cm}\\\par\end{figure}$	Figure 6: $16\times 16$ arcsec² images and 1-D spectra of 23 confirmed LEGOs in the field of Q 2138-4427. For each candidate, we show images from the narrow-, B- and R-band filters (from left to right). The units on the ordinate of the spectra are counts in 1800 s (as in Fynbo et al. 2001). The name, redshift and coordinates (Epoch 2000) are provided for each object.
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$\begin{figure} \par\epsfig{file=H4385F50.ps, width=5.3cm}\epsfig{file=H4385F51.p... ...dth=5.3cm}\epsfig{file=H4385F54.ps, width=5.3cm}\hspace*{3cm}}\par\end{figure}$	Figure 6: continued.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{H4385F13.ps} \end{figure}$	Figure 8: Redshift distributions of LEGOs in the two fields relative to the filter response curves. The redshifts of LEGOs in the field of BRI 1346-0322 fill out the volume probed by the filter, whereas LEGOs in the field of Q 2138-4427 have a very narrow redshift distribution.
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$\begin{figure} \par\epsfig{file=H4385F55.ps, width=5.3cm}\epsfig{file=H4385F56.p... ...pace{5.5cm}\epsfig{file=H4385F58.ps, width=5.3cm}\hspace{5.5cm}}\end{figure}$	Figure 9: Shown are $16\times 16$ arcsec² images and 1D spectra of the four candidates that turned out to be foreground objects with other lines than Ly $\alpha$ observed in the narrow-band filters (three [O II] emitters and an AGN with its C IV emission line). The spectra are not flux calibrated.
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$\begin{figure} \par\epsfig{file=H4385F59.ps, width=5.3cm}\epsfig{file=H4385F60.p... ...ile=H4385F66.ps, width=5.3cm}\epsfig{file=H4385F67.ps, width=5.3cm} \end{figure}$	Figure 10: Shown are $16\times 16$ arcsec² images and 1D spectra of serendipitously detected, probable LEGOs. The spectra are ordered by redshifts that range from z=1.98 to z=3.47. Note that the object LEGO1346_2b located at z=3.1251 is a neighbour to the z=3.1301 LEGO1346_2 seen in the lower left corner of the same image.
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