Astronomy & Astrophysics

All Figures

$\begin{figure} \par\includegraphics[angle=-90,width=8.9cm,clip]{0371_f1.ps}\includegraphics[angle=-90,width=8.9cm,clip]{0371_f2.ps}\end{figure}$ Figure 1: Left hand panel: image of Q2233+131 in the wavelength range 5200-5300 Å. This image shows the 16 $\times$ 16 spatial pixel ("spaxel'') field of view of PMAS corresponding to $8\hbox {$^{\prime \prime }$ }$ $\times$ $8\hbox {$^{\prime \prime }$ }$ . The QSO is centered in the field at (0, 0). Right hand panel: co added narrow band image of the Q2233+131, with a field of view of $8\hbox {$^{\prime \prime }$ }$ $\times$ $8\hbox {$^{\prime \prime }$ }$ , north is up and east is left. Selecting the wavelength range 5040-5055 Å an extended object of roughly $5\hbox {$^{\prime \prime }$ }$ $\times$ $3\hbox {$^{\prime \prime }$ }$ appears, which is the extended Ly $\alpha$ emission from the DLA galaxy. The selected wavelengths correspond to the DLA absorption trough in the QSO spectrum. The centroid of the QSO is at (0, 0) while the position of the DLA galaxy found from the broad band observations in D96 and in the space-based images is at (-0 $.\!\!^{\prime\prime}$ 9, -2 $.\!\!^{\prime\prime}$ 2). Apparently, the extended source overlaps with the position of theQSO, but this is caused by the fact that some QSO emission is present at the longest selected wavelengths ( $\lambda > 5050$ Å), as emission fromthe red wing of the DLA line has been included. Contours of 5-8 $\sigma$ levels above the background have been overplotted for guiding the eye. The contours correspond to the combined emission from the Ly $\alpha$ nebula and the QSO. The high signal at the left edge of the field at (3.5, 1) is caused by a bad fiber.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=14cm,clip]{0371_f3.ps}\end{figure}$ Figure 2: Spectrum of Q2233+131. All spaxels within a radial aperture of 2 $^{\prime \prime }$ have been coadded and then scaled to the total flux of the QSO, measured within a 3 $^{\prime \prime }$ radial aperture. The bright line at 5200 Å is Ly $\alpha$ emission from the QSO. This and other emission lines from the QSO are labeled under the spectrum. The DLA line at 5050 Å and the corresponding metal absorption lines belonging to this system are labeled above the spectrum. Redshifts of all lines are given in Table 1.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.8cm,clip]{0371_f4.ps}\end{figure}$ Figure 3: Spectrum of the extended emission associated with the DLA galaxy at z=3.15 in Q2233+131. The spectrum has been obtained by co-adding $\sim$ 35 spectra which appear to be associated with the DLA galaxy in the image in Fig. 1. The few spaxels which are overlapping the position of the QSO have not been coadded, since these are contaminated by flux from the wing of the QSO and not associated with the Ly $\alpha$ emission object. An emission line at 5050 Å corresponds to Ly $\alpha$ at the redshift of the DLA line in the QSO. The broad emission feature at $\sim$ 5200 Å is due to residual Ly $\alpha$ emission from the QSO at a radial distance of 2 $^{\prime \prime }$ from the centre of the QSO. For comparison we have plotted the total QSO spectrum in the middle panel with the same wavelength range. Note the scale on the y-axis differs by a factor of $\sim$ 30 between the two plots. In the lower panel we have plotted the DLA spectrum where a scaled QSO spectrum has been subtracted.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7cm,clip]{0371_f5.ps}\hspace*{1.2cm} \includegraphics[angle=-90,width=7cm,clip]{0371_f6.ps}\end{figure}$ Figure 4: The images show the lowest (5 $\sigma$ ) contour level taken from Fig. 1. The chosen division between a north and a south region is indicated in the left panel, and the division between an east and a west region to the right. In both cases the emission spatially coincident with the QSO has not been included.
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In the text

$\begin{figure} \par\includegraphics[angle=90,width=8.8cm]{0371_f7.ps}\end{figure}$ Figure 5: Spectra of the four different regions of the emission line object. The north, south, east, and west regions correspond to those listed in Table 2. All regions are seen to have the same double peaked profile of the Ly $\alpha$ line.
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In the text

$\begin{figure} \par\includegraphics[width=17cm,clip]{0371f6.eps}\par\end{figure}$ Figure 6: The left hand panel shows a section of the PMAS spectra consisting of spectra from 100 fibers around the region of the DLA. The spectra are oriented with a horizontal dispersion direction. Here are shown 6 groups of spectra where the emission from the extended nebula is visible within the small circles. Each group can be considered as representing a 0 $.\!\!^{\prime\prime}$ 5 wide two-dimensional long slit spectrum. In comparison we have in the upper right hand panel shown an artificial long-slit spectrum one would have obtained with a 1 $.\!\!^{\prime\prime}$ 0 slit placed in the north-south orientation as indicated in Fig. 7. The lower right hand panel shows the corresponding one-dimensional spectrum from extracting the Ly $\alpha$ emission spectrum. This is directly comparable to that in D96, in the sense that it exhibits the same red-winged profile, the same line flux, and the same line width. Note that the emission within the small circles do not overlap spatially with the QSO emission.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{0371_f11.ps}\end{figure}$ Figure 7: A negative 8 $^{\prime \prime }$ $\times$ 8 $^{\prime \prime }$ WFPC2 image of the Q2233+131. North is up and east is left. The identified absorbing galaxy is seen towards the south of the QSO and the contours of the object in Fig. 1 are overlaid. Note again, that the emission is a sum of the Ly $\alpha$ emission from the nebula and some emission from the QSO. The levels of the contours correspond to 5-8 $\sigma$ above the median background, with steps of 0.75 $\sigma$ . There is a peak in the Ly $\alpha$ emission close to the location of the DLA galaxy. The position of the artificial slit from which the spectrum in Fig. 6 was created is indicated by the vertical dashed lines.
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=7cm,clip]{0371_f5.ps}\hspace*{1.2cm} \includegraphics[angle=-90,width=7cm,clip]{0371_f6.ps}\end{figure}$	Figure 4: The images show the lowest (5 $\sigma$ ) contour level taken from Fig. 1. The chosen division between a north and a south region is indicated in the left panel, and the division between an east and a west region to the right. In both cases the emission spatially coincident with the QSO has not been included.
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$\begin{figure} \par\includegraphics[angle=90,width=8.8cm]{0371_f7.ps}\end{figure}$	Figure 5: Spectra of the four different regions of the emission line object. The north, south, east, and west regions correspond to those listed in Table 2. All regions are seen to have the same double peaked profile of the Ly $\alpha$ line.
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