arXiv 1202.08822012-02-21astro-ph.COphysics.space-ph

Z=2.2时的超阻尼莱曼α QSO吸波材料

A Super-Damped Lyman-alpha QSO Absorber at z=2.2

Varsha P. Kulkarni, Joseph Meiring, Debopam Som, Celine Peroux, Donald G. York, Pushpa Khare, James T. Lauroesch

备注：: Accepted for publication in the Astrophysical Journal. Submitted Dec. 10, 2011; accepted Feb. 19, 2012

摘要：

我们报告了在斯隆数字巡天观测中发现的位于类星体Q1135-0010的$z_{abs}=2.2068$上的“超阻尼”莱曼α吸收体，以及后续的VLT UVES光谱。与DLA线拟合的Voigt曲线指示log $N_{\rm H I} = 22.05 \pm 0.1$。这是迄今为止发现的第二个具有如此高PDMATHAMO的类星体DLA。我们推导出元素丰度[Si/H] = $-1.10 \pm 0.10$，[Zn/H] = $-1.06 \pm 0.10$，[Cr/H] = $-1.55 \pm 0.10$，[Ni/H] = $-1.60 \pm 0.10$，[Fe/H] = $-1.76 \pm 0.10$，[Ti/H]= $-1.69 \pm 0.11$，[P/H] = $-0.93 \pm 0.23$，[Cu/H] = $-0.75 \pm 0.14$ .我们的数据表明，在DLA槽中检测到Ly- $α$发射，这意味着在没有尘埃衰减的情况下，$\sim$ 10 $M_{\odot}$/年$^{-1}$的恒星形成率。还检测到C II $^{*} \, λ1336$吸收，表明SFR表面密度$-2 < {\rm log} \, \dot{ψ_{*}} < 0$ $M_{\odot}$ yr $^{-1}$ kpc $^{-2}$。我们估算了C II $^{*}$ /C II的$3.5 \times 10^{-4}$至24.7 cm $^{-3}$范围内的电子密度，以及Si II $^{*}$ /Si II的$\sim$ 0.5-0.9 cm $^{-3}$范围内的电子密度。总的来说，这是一个强有力的恒星形成，适度富集的吸收体，但相对较低的尘埃消耗。拟合的SDSS光谱产生低红银河系，大麦哲伦星云，或SMC消光曲线。未检测到CO吸收，并且Cl吸收较弱。低尘埃和分子含量，让人想起一些SMC视线，可能是由于较低的金属量，和较强的辐射场（由于较高的SFR）。最后，我们比较了这种吸收体与其他类星体和伽玛暴的DLAs。

英文摘要：

We report the discovery of a "super-damped" Lyman-alpha absorber at $z_{abs}=2.2068$ toward QSO Q1135-0010 in the Sloan Digital Sky Survey, and follow-up VLT UVES spectroscopy. Voigt profile fit to the DLA line indicates log $N_{\rm H I} = 22.05 \pm 0.1$. This is the second QSO DLA discovered to date with such high $N_{\rm H I}$. We derive element abundances [Si/H] = $-1.10 \pm 0.10$, [Zn/H] = $-1.06 \pm 0.10$, [Cr/H] = $-1.55 \pm 0.10$, [Ni/H] = $-1.60 \pm 0.10$, [Fe/H] = $-1.76 \pm 0.10$, [Ti/H] = $-1.69 \pm 0.11$, [P/H] = $-0.93 \pm 0.23$, and [Cu/H] = $-0.75 \pm 0.14$. Our data indicate detection of Ly-$α$ emission in the DLA trough, implying a star formation rate of $\sim$10 $M_{\odot}$ yr$^{-1}$ in the absence of dust attenuation. C II$^{*} \, λ1336$ absorption is also detected, suggesting SFR surface density $-2 < {\rm log} \, \dot{ψ_{*}} < 0$ $M_{\odot}$ yr$^{-1}$ kpc$^{-2}$. We estimate electron density in the range $3.5 \times 10^{-4}$ to 24.7 cm$^{-3}$ from C II$^{*}$/C II, and $\sim$0.5-0.9 cm$^{-3}$ from Si II$^{*}$/Si II. Overall, this is a robustly star-forming, moderately enriched absorber, but with relatively low dust depletion. Fitting of the SDSS spectrum yields low reddening for Milky Way, LMC, or SMC extinction curves. No CO absorption is detected, and C I absorption is weak. The low dust and molecular content, reminiscent of some SMC sight-lines, may result from the lower metallicity, and a stronger radiation field (due to higher SFR). Finally, we compare this absorber with other QSO and GRB DLAs.

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英文摘要：

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