Astronomy & Astrophysics

All Figures

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f1a,height=6.3cm,angle... ...lip=} & \psfig{file=MS3731.f1f,height=6.3cm,clip=}\\ \end{tabular} \end{figure}$ Figure 1: Sample of Chandra X-ray spectra and their corresponding IR SED fitting spectra. The left panels show X-ray spectra for three moderately absorbed $\rho$ Oph sources (GY135, VSSG11 and WL5). Their corresponding IR spectral energy distribution (SED) are in the right panels. Note the physical parameters ( ${N}{_{\rm H,X}}$ , $T_{\rm X}$ , $L_{\rm X}$ ) derived from the X-ray spectra, using the default solar ISM abundances in XSPEC (Sect. 2), and the corresponding (A_J, $T_{\rm bb}$ , $L_{\rm bol}$ ) derived from the IR SED fitting (Sect. 3). See Tables 3 and 4 for the errors.
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In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f2a,width=8.1cm,height... ...g{file=MS3731.f2b,width=8.2cm,height=6.1cm,clip=}\\ \end{tabular} \end{figure}$ Figure 2: JHK and JKL color-color diagrams for X-ray selected (>100 counts) Class III sources in $\rho$ Oph. The solid lines are the intrinsic colors of dwarfs and giants (Bessell & Brett 1988). The dashed lines extending from the extremity of the ZAMS/RGB are Rieke & Lebofsky (1985) reddening vectors representing A_J=5 mag ( $A_{V} \simeq 16$ mag). The typical error bar is shown in the upper left corner.
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In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f3a,width=7cm,height=5... ... \psfig{file=MS3731.f3h,width=6.8cm,height=5.1cm}\\ \end{tabular} \end{figure}$ Figure 3: JHK and JKL color-color diagrams for X-ray sources in Cha I, NGC 1333, IC 348 and Orion Nebula. The solid lines are the unreddened ZAMS and red giant branch. The dashed lines extending from the extremity of the ZAMS/RGB are Rieke & Lebofsky (1985) reddening vectors representing A_J=5 mag ( $A_{V} \simeq 16$ mag). The plus signs (+) are sources representing IR L band excess, open circles ( $\circ$ ) are faint X-ray sources (<100 counts) without IR excess and filled circles ( $\bullet$ ) are the bright bona-fide Class III X-ray sources with >100 counts used in this paper. The representative error bar is shown in the upper left corner.
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In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f4a,width=8.4cm,clip=} & \psfig{file=MS3731.f4b,width=8.4cm,clip=}\\ \end{tabular} \end{figure}$ Figure 4: Confidence contours of ${N}{_{\rm H,X}}$ versus temperature spectral fit of IRS 55 in the $\rho$ Oph cloud detected by both Chandra (left) and mutually XMM-Newton (right). The contours are 1 $\sigma$ , 2 $\sigma$ and 3 $\sigma$ levels respectively. The values of ${N}{_{\rm H,X}}$ from these two independent observations are consistent within 1 $\sigma$ confidence.
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In the text

$\begin{figure} \par\includegraphics[width=7.5cm,clip]{MS3731.f5} \end{figure}$ Figure 5: Comparison of the values of the dust extinction A_J derived from spectroscopy (Luhman & Rieke 1999) and those derived from the IR SED fitting (this work) for 10 Class III sources in $\rho$ Oph. The dashed line is the linear fitting line. The solid line is the equality line A_J (this ${\rm work}) = A_{J}$ (Luhman & Rieke 1999).
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In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f6a,width=7.8cm,height... ...file=MS3731.f6d,width=8cm,height=6.3cm,clip=}\\ [3mm] \end{tabular} \end{figure}$ Figure 6: X-ray absorption column density ${N}{_{\rm H,X}}$ versus visual extinction A_J for Class III sources in a) $\rho$ Oph, b) R CrA and Cha I, c) IC 348, d) Orion Nebula using the default standard solar ISM abundances in XSPEC. The error bars in X-ray column densities are represented by vertical bars at 90% confidence (1.6 $\sigma$ ). The dashed line in $\rho$ Oph is the fitting curve: $N_{\rm H}=5.57$ ( $\pm$ 0.35) $\times$ 10²¹ A_J (cm^-2). The shaded area is the range of published galactic gas/dust relationship (see Table 5). The symbol size is proportional to the number of photons detected in X-ray spectra in log (from 195 to 7378). Note that A_J is up to 14 mag ( $A_{V}\simeq 45$ mag) in the $\rho$ Oph region whereas A_J< 1.5 mag (A_V< 5 mag) in the other regions.
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In the text

$\begin{figure} \par\includegraphics[width=12cm]{MS3731.f7} \end{figure}$ Figure 7: Spatial distribution of our sample of Class III sources in $\rho$ Oph. Background: DSS R optical image. Foreground: ISOCAM $7+15~\mu$ m image (Abergel et al. 1996). This combination background map is taken from Grosso et al. (2000). The DCO⁺ map of Loren et al. (1990) is shown by contours and the dense cores are labeled. The circles ( $\circ$ ) are sources with $N_{\rm H,X}/A_{J}$ normalized by the regression line ( $5.57 \times 10^{21}$ cm^-2 mag^-1) with a correlation $\pm$ 10%. The triangles up ( $\bigtriangleup$ ) are sources with normalized values of $N_{\rm H,X}/A_{J}$ higher than 1.1 and the triangles down ( $\bigtriangledown$ ) are lower than 0.9. The dashed lines are Chandra and XMM field-of-views (squares and circles, respectively).
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In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f8a,width=8.4cm,angle=... ...psfig{file=MS3731.f8b,width=8.4cm,angle=-90,clip=}\\ \end{tabular} \end{figure}$ Figure 8: Chandra (left) and XMM-Newton (right) spectra of WL19 ( $N_{\rm H,X}=7{-}14 \times 10^{22}$ cm^-2, $T_{\rm X}=1.5{-}3$ keV, $L_{\rm X} = 0.4{-}1.5 \times 10^{30}$ erg s^-1, using the default standard solar ISM abundances in XSPEC).
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In the text

$\begin{figure} \par\psfig{file=MS3731.f9,width=8.8cm,clip=} \end{figure}$ Figure 9: DSS I band image and spatial distribution of our sample Class III sources in IC 348 with IRAS 60 $\mu$ m contours overlaid. The circles ( $\circ$ ) represent sources with $N_{\rm H,X}/A_{J}$ normalized by the galactic value of $N_{\rm H}/A_{J}$ with a correlation $\pm$ 10%. The triangles up ( $\bigtriangleup$ ) are sources with normalized values of $N_{\rm H,X}/A_{J}$ higher than 1.1 and the triangles down ( $\bigtriangledown$ ) are lower than 0.9.
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In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f10a,width=7.3cm,heig... ...fig{file=MS3731.f10d,width=7.3cm,height=5cm,clip=}\\ \end{tabular} \end{figure}$ Figure 10: Comparison between the derived ${N}{_{\rm H,X}}$ using "new'' solar abundances (Holweger 2001; Allende Prieto et al. 2001,2002) and a) those using "old'' solar abondances, b) those using photospheric F & G star abundances (Sofia & Meyer 2001; Reddy et al. 2003), c) those using diffuse ISM abundances (Wilms et al. 2000) and d) those using diffuse ISM B-star abundances (Sofia & Meyer 2001). The solid line is the equality line.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{MS3731.f11}\end{figure}$ Figure 11: Metallicity Z as a function of R_V for $\rho$ Oph using the "old'' solar and "local'' abundances. The shaded area represents the uncertainties. The dashed line is the extension of the empirical relation of Cardelli et al. (1989) valid for $2.6 \leq R_{V} \leq 5.6$ . The dotted and dashed-dotted lines indicate the metallicity for R_V= 3.1 and 4 (Vrba et al. 1993) using the "local'' and "old'' solar abundances.
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In the text

$\begin{figure} \par\psfig{file=MS3731.f12,width=8.8cm,clip=} \end{figure}$ Figure A.1: a) R_V, b) gas-to-dust extinction ratio $N_{\rm H}/A_{J}$ , and c) the mean grain size as a function of $a_{\rm min}$ . The dashed line and the shaded area in b) are the mean value $\pm$ $1\sigma$ of the observed ${N}{_{\rm H,X}}$ /A_J in $\rho$ Oph. The dotted lines represent the interval of $a_{\rm min}$ for R_V between 4 and 6.

In the text

$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f4a,width=8.4cm,clip=} & \psfig{file=MS3731.f4b,width=8.4cm,clip=}\\ \end{tabular} \end{figure}$	Figure 4: Confidence contours of ${N}{_{\rm H,X}}$ versus temperature spectral fit of IRS 55 in the $\rho$ Oph cloud detected by both Chandra (left) and mutually XMM-Newton (right). The contours are 1 $\sigma$ , 2 $\sigma$ and 3 $\sigma$ levels respectively. The values of ${N}{_{\rm H,X}}$ from these two independent observations are consistent within 1 $\sigma$ confidence.
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$\begin{figure} \par\includegraphics[width=7.5cm,clip]{MS3731.f5} \end{figure}$	Figure 5: Comparison of the values of the dust extinction A_J derived from spectroscopy (Luhman & Rieke 1999) and those derived from the IR SED fitting (this work) for 10 Class III sources in $\rho$ Oph. The dashed line is the linear fitting line. The solid line is the equality line A_J (this ${\rm work}) = A_{J}$ (Luhman & Rieke 1999).
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$\begin{figure} \par\begin{tabular}{cc} \psfig{file=MS3731.f8a,width=8.4cm,angle=... ...psfig{file=MS3731.f8b,width=8.4cm,angle=-90,clip=}\\ \end{tabular} \end{figure}$	Figure 8: Chandra (left) and XMM-Newton (right) spectra of WL19 ( $N_{\rm H,X}=7{-}14 \times 10^{22}$ cm^-2, $T_{\rm X}=1.5{-}3$ keV, $L_{\rm X} = 0.4{-}1.5 \times 10^{30}$ erg s^-1, using the default standard solar ISM abundances in XSPEC).
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