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arXiv 1601.07567astro-ph.GAastro-ph.CO
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z=1星系-类星体对对指向SDSSJ1422-0001的MUSE冷流盘的可能特征

Possible Signatures of a Cold-Flow Disk from MUSE using a z=1 galaxy--quasar pair towards SDSSJ1422-0001

N. Bouché, H. Finley, I. Schroetter, M. T. Murphy, P. Richter, R. Bacon, T. Contini, J. Richard, M. Wendt, S. Kammann, B. Epinat, S. Cantalupo, L. A. Straka, J.… 展开作者

N. Bouché, H. Finley, I. Schroetter, M. T. Murphy, P. Richter, R. Bacon, T. Contini, J. Richard, M. Wendt, S. Kammann, B. Epinat, S. Cantalupo, L. A. Straka, J. Schaye, C. L. Martin, C. Péroux, L. Wisotzki, K. Soto, S. Lilly, C. M. Carollo, J. Brinchmann, W. Kollatschny

摘要:

我们利用背景类星体探测了$z=0.91$低质量恒星形成星系周围环星系气体的存在。来自VLT上新的多单元光谱探测器(MUSE)的数据显示,主星系的尘埃校正恒星形成率(SFR)为4.7 $\pm$ 0.2 Msun/年,在240 kpc(30”)范围内没有伴星,低至0.22 Msun/年(5 $σ$)。使用高分辨率光谱(UVES)的背景类星体,这是偶然对齐的星系主轴(与方位角$α$只有$15^\circ$),我们发现,在气体运动学跟踪低电离线,明显的签名与预期的“冷流盘”延伸至少12千秒差距($3\times R_{1/2}$)一致。我们估计的质量吸积率$\dot M_{\rm in}$是至少两到三倍大于SFR,使用的几何约束的IFU数据和HI柱密度的$\log N_{\rm HI} \simeq 20.4$从{ \it HST}/COS NUV光谱。通过对低电离线(例如Zn II、Cr II、Ti II、Mn II、Si II)的详细分析,吸积物质似乎富集到约0.4 $Z_\odot$(尽管存在很大的不确定性:$\log Z/Z_\odot=-0.4~\pm~0.4$),这与星系金属丰度($12+\log \rm O/H=8.7\pm0.2$)相当,意味着过去流出物的回收率很大。蓝移的MgII和FeII的星系光谱从MUSE数据显示的外流的存在。MgII和FeII双峰比表明由于散射过程的发射填充,但MUSE数据没有显示任何荧光FeII* 发射的迹象。

英文摘要:

We use a background quasar to detect the presence of circum-galactic gas around a $z=0.91$ low-mass star forming galaxy. Data from the new Multi Unit Spectroscopic Explorer (MUSE) on the VLT show that the host galaxy has a dust-corrected star-formation rate (SFR) of 4.7$\pm$0.2 Msun/yr, with no companion down to 0.22 Msun/yr (5 $σ$) within 240 kpc (30"). Using a high-resolution spectrum (UVES) of the background quasar, which is fortuitously aligned with the galaxy major axis (with an azimuth angle $α$ of only $15^\circ$), we find, in the gas kinematics traced by low-ionization lines, distinct signatures consistent with those expected for a "cold flow disk" extending at least 12 kpc ($3\times R_{1/2}$). We estimate the mass accretion rate $\dot M_{\rm in}$ to be at least two to three times larger than the SFR, using the geometric constraints from the IFU data and the HI column density of $\log N_{\rm HI} \simeq 20.4$ obtained from a {\it HST}/COS NUV spectrum. From a detailed analysis of the low-ionization lines (e.g. ZnII, CrII, TiII, MnII, SiII), the accreting material appears to be enriched to about 0.4 $Z_\odot$ (albeit with large uncertainties: $\log Z/Z_\odot=-0.4~\pm~0.4$), which is comparable to the galaxy metallicity ($12+\log \rm O/H=8.7\pm0.2$), implying a large recycling fraction from past outflows. Blue-shifted MgII and FeII absorptions in the galaxy spectrum from the MUSE data reveal the presence of an outflow. The MgII and FeII doublet ratios indicate emission infilling due to scattering processes, but the MUSE data do not show any signs of fluorescent FeII* emission.

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