All Figures

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig1.eps} \end{figure}$ Figure 1: Observed SED of all EROs in the optical and near-IR up to 10 $\mu$ m. The two most extreme objects, the sub-mm galaxy A1835-#2 and AC114-#1, are indicated in red and yellow respectively. A1835-#11, whose properties including the photometric redshift remain highly uncertain, is shown in blue.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig2.eps} \end{figure}$ Figure 2: $\chi ^2$ map as a function of redshift and extinction ( $\chi ^2(z,A_V)$ ) for A1835-#2, displaying in dark the most probable regions on a logarithmic scale. Solid lines enclose the 1 to 3 $\sigma$ contours (confidence levels of 68, 90 and 99% respectively). The (z, A_V) projection plane presented in this figure corresponds to the best $\chi ^2$ found through the model-age parameter space for templates from the BCCWW group. Note the degeneracy of the photometric redshift solutions in this plane. Formally the best fit is found at high redshift ( $z_{\rm fit}$ > 7). However, for various reasons, including the 24 $\mu$ m and sub-mm SED and the exceptional luminosity of this object if at high z, the most likely redshift of this galaxy is $\sim$ 3. See discussion in text.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig3.eps} \end{figure}$ Figure 3: A1835-#2: Comparison of best fit high-z solution (black, $z_{\rm fit}$ = 7.46) with model fits at $z\sim 3$ . Blue: Bruzual & Charlot model (SF history as ellipticals at age of 0.36 Gyr + 2.4 mag $A_{\rm v}$ extinction). Red: GRASIL template of NGC 6090 with $A_{\rm v}$ = 1.4. See discussion in text.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig4.eps} \end{figure}$ Figure 4: Observed SED of the ERO/sub-mm galaxy A1835-#2 including VLT, Spitzer (IRAC, MIPS), SCUBA observations. The model fits are the same as shown in Fig. 3. Note that the two fits with GRASIL models at $z \sim 2.8$ -2.9 reproduce well the MIPS 24 $\mu$ m flux and bracket the observed sub-mm points.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.6cm,clip]{7127fig5.eps} \end{figure}$ Figure 5: Same as Fig. 2 for A1835-#1.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{7127fig6.eps} \end{figure}$ Figure 6: A1835-#1: Comparison between fits with Bruzual and Charlot models at z=0.50 (black) and 1.35 (blue), and fits with dusty starburst models from GRASIL templates at z=1.75 (M 82, red) and 0.4 (green, M 82 plus additional extinction of $A_{\rm v}$ = 3.8.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig7.eps} \end{figure}$ Figure 7: Same as Fig. 2 for A1835-#4.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig8.eps} \end{figure}$ Figure 8: A1835-#4: Comparison between fits with BCCWW galaxy template at z=1.20, and fits with the M 82 template from GRASIL at z=1.24 (and no additional extinction).
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In the text

$\begin{figure} \par\includegraphics[angle=-90,width=8.5cm,clip]{7127fig9.eps} \end{figure}$ Figure 9: Same as Fig. 2 for A1835-#17.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig10.eps} \end{figure}$ Figure 10: A1835-#17: Comparison between fits with Maraston (2005) templates at z=0.81and $A_{\rm v}$ = 1, and fits with dusty starburst models from GRASIL templates at z=0.60 and 0.79 plus additional extinction of $A_{\rm v}$ $\sim$ 3.6. Note that the Maraston template does not include dust emission, which would be expected for such a high extinction.
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig11.eps} \end{figure}$ Figure 11: Same as Fig. 2 for AC114-#1.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig12.eps} \end{figure}$ Figure 12: AC114-#1: Best fit SEDs with Bruzual & Charlot templates (black line: burst of 4.5 Gyr age and A_V = 2.4 at z=1.3), S04gyr templates (red: 1.0 Gyr, A_V=2.8, z=1.6), and with GRASIL templates (blue: M 52 template + A_V=3.8, z=1.0). Note that by, construction, only the GRASIL templates include dust emission.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig13.eps} \end{figure}$ Figure 13: Model fits for A1835 #3 (black) and #10 (blue) using GRASIL templates showing predictions for the Herschel/sub-mm/ALMA spectral domain.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig14.eps} \end{figure}$ Figure 14: Comparison of photometric redshifts derived with or without IRAC photometry for selected objects. Left panels: $\chi ^2$ of the best fitting template versus redshift obtained from SED fits including all the photometry (black solid lines), or obtained from SED fits excluding the IRAC photometric measurements (red dashed lines). Right panels: best-fit SED including all photometry (black solid curve) and excluding IRAC photometry (red solid). The observations are shown by the blue symbols. From top to bottom the objects are: A1835-#2, #4, and #17. These objects illustrate three types of behaviour: 1) degenerate/ambiguous low- and high-z solutions even with IRAC photometry (#2, top panels), 2) degenerate/ambiguous low- and high-z solutions whose degeneracy is lifted thanks to IRAC photometry (#4, middle panel), and 3) unconstrained photometric z from ground-based photometry, which becomes well defined low-z solution with IRAC photometry (#17, bottom panel).
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In the text

$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig15.eps} \end{figure}$ Figure 15: Same as Fig. 2 for HUDF-J2. Formally the best fit is found at high redshift ( $z_{\rm fit}$ $\sim$ 6.4-7.4). However, for various reasons, including the 24 $\mu$ m flux and the exceptional luminosity of this object if at high z, we consider it more likely that this galaxy is at $z \sim 2.4$ -2.6. See discussion in text.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig16.eps} \end{figure}$ Figure 16: $z \sim 1.8$ -2.6 SED fits to the observations of HUDF-J2 from Mobasher et al. (2005). Black line: fit with BCCWW templates at $z_{\rm fit}$ = 2.59. Red: GRASIL M 82 template and additional A_V=2.8 at $\mbox{$z_{\rm fit}$ }\sim 1.8$ . Blue: GRASIL HR10 template without additional extinction at $\mbox{$z_{\rm fit}$ }\sim 2.3$ .
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig17.eps} \end{figure}$ Figure 17: SED fits to the observations of HUDF-J2. The near-IR and IRAC/Spitzer photometry is taken from Mobasher et al. (2005); in the optical we adopt either ( (i) the $z_{\rm 850LP}$ non-detection from Mobasher et al. (2005) or ( (ii) the revisited photometry from Dunlop et al. (2006) yielding a B₄₃₅ non-detection plus detections in V₆₀₆, i₇₇₅ and $z_{\rm 850LP}$ . Fitting ( (i) with BCCWW templates yields a best fit at high-z ( $z \sim 7.4$ , black line). Fitting ( (i) with GRASIL templates, we obtain a best fit at $z \sim 1.8$ with the M 82 template and additional A_V=2.8 (red line) or at $z \sim 2.3$ with the HR10 template (and no additional extinction; shown in blue). Adopting (ii) the best fit with GRASIL templates is at $z \sim 2.3$ with the HR10 template (and no additional extinction; shown in green). Note that all "low-z'' solutions using GRASIL templates naturally reproduce the observed 24 $\mu$ m flux.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig1.eps} \end{figure}$	Figure 1: Observed SED of all EROs in the optical and near-IR up to 10 $\mu$ m. The two most extreme objects, the sub-mm galaxy A1835-#2 and AC114-#1, are indicated in red and yellow respectively. A1835-#11, whose properties including the photometric redshift remain highly uncertain, is shown in blue.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig3.eps} \end{figure}$	Figure 3: A1835-#2: Comparison of best fit high-z solution (black, $z_{\rm fit}$ = 7.46) with model fits at $z\sim 3$ . Blue: Bruzual & Charlot model (SF history as ellipticals at age of 0.36 Gyr + 2.4 mag $A_{\rm v}$ extinction). Red: GRASIL template of NGC 6090 with $A_{\rm v}$ = 1.4. See discussion in text.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig4.eps} \end{figure}$	Figure 4: Observed SED of the ERO/sub-mm galaxy A1835-#2 including VLT, Spitzer (IRAC, MIPS), SCUBA observations. The model fits are the same as shown in Fig. 3. Note that the two fits with GRASIL models at $z \sim 2.8$ -2.9 reproduce well the MIPS 24 $\mu$ m flux and bracket the observed sub-mm points.
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$\begin{figure} \par\includegraphics[angle=270,width=8.6cm,clip]{7127fig5.eps} \end{figure}$	Figure 5: Same as Fig. 2 for A1835-#1.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{7127fig6.eps} \end{figure}$	Figure 6: A1835-#1: Comparison between fits with Bruzual and Charlot models at z=0.50 (black) and 1.35 (blue), and fits with dusty starburst models from GRASIL templates at z=1.75 (M 82, red) and 0.4 (green, M 82 plus additional extinction of $A_{\rm v}$ = 3.8.
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$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig7.eps} \end{figure}$	Figure 7: Same as Fig. 2 for A1835-#4.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig8.eps} \end{figure}$	Figure 8: A1835-#4: Comparison between fits with BCCWW galaxy template at z=1.20, and fits with the M 82 template from GRASIL at z=1.24 (and no additional extinction).
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$\begin{figure} \par\includegraphics[angle=-90,width=8.5cm,clip]{7127fig9.eps} \end{figure}$	Figure 9: Same as Fig. 2 for A1835-#17.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig10.eps} \end{figure}$	Figure 10: A1835-#17: Comparison between fits with Maraston (2005) templates at z=0.81and $A_{\rm v}$ = 1, and fits with dusty starburst models from GRASIL templates at z=0.60 and 0.79 plus additional extinction of $A_{\rm v}$ $\sim$ 3.6. Note that the Maraston template does not include dust emission, which would be expected for such a high extinction.
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$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig11.eps} \end{figure}$	Figure 11: Same as Fig. 2 for AC114-#1.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig12.eps} \end{figure}$	Figure 12: AC114-#1: Best fit SEDs with Bruzual & Charlot templates (black line: burst of 4.5 Gyr age and A_V = 2.4 at z=1.3), S04gyr templates (red: 1.0 Gyr, A_V=2.8, z=1.6), and with GRASIL templates (blue: M 52 template + A_V=3.8, z=1.0). Note that by, construction, only the GRASIL templates include dust emission.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig13.eps} \end{figure}$	Figure 13: Model fits for A1835 #3 (black) and #10 (blue) using GRASIL templates showing predictions for the Herschel/sub-mm/ALMA spectral domain.
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$\begin{figure} \par\includegraphics[angle=270,width=8.5cm,clip]{7127fig15.eps} \end{figure}$	Figure 15: Same as Fig. 2 for HUDF-J2. Formally the best fit is found at high redshift ( $z_{\rm fit}$ $\sim$ 6.4-7.4). However, for various reasons, including the 24 $\mu$ m flux and the exceptional luminosity of this object if at high z, we consider it more likely that this galaxy is at $z \sim 2.4$ -2.6. See discussion in text.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{7127fig16.eps} \end{figure}$	Figure 16: $z \sim 1.8$ -2.6 SED fits to the observations of HUDF-J2 from Mobasher et al. (2005). Black line: fit with BCCWW templates at $z_{\rm fit}$ = 2.59. Red: GRASIL M 82 template and additional A_V=2.8 at $\mbox{$z_{\rm fit}$ }\sim 1.8$ . Blue: GRASIL HR10 template without additional extinction at $\mbox{$z_{\rm fit}$ }\sim 2.3$ .
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