用Gemini NIFS探测的NGC 4151中的进食与反馈。I.激发
Feeding versus Feedback in NGC 4151 probed with Gemini NIFS. I. Excitation
摘要：
我们利用Gemini近红外积分场摄谱仪（NIFS）在Z、J、H和K波段对Seyfert星系NGC 4151的窄线区（NLR）的发射线强度分布和比值进行了测绘，分辨率约为5000，空间分辨率为8 pc，覆盖了星系内部200 pc × 300 pc。给出了14条发射谱线的强度分布I（r）。(1)对于电离气体，I（r）从原子核沿位置延伸到~ 100 pc。角度PA=60/240 deg-NE-SW），与已知的双锥流出的起源一致;而对于复合线I（r）~ r^-1，对于禁戒线I（r）是平坦的（r^0）。(2)H_2发射谱线的强度分布避开了双锥区，延伸到r ~ 60 pc，垂直于双锥轴，支持了H_2发射气体在星系平面内的起源。(3)日冕线显示出陡峭的强度分布，用r^-2表示。利用[Fe Ⅱ]1.644/1.257的线比图和Pa_b/Br_g，我们得到沿NLR的E（B-V）~0.5的红化和在核处E（B-V）>1。我们的线比图[Fe II] 1.257/[P II] 1.189是第一张这样的河外源图。与[Fe II]/Pa_b图一起，这些线比与射电强度分布相关，映射了射电喷流产生的冲击效应，它可能释放了锁定在颗粒中的Fe，并产生了在离核约1角秒处观测到的[Fe II]发射的增强。在这些区域，我们得到了[Fe II]发射气体的密度N_e ~4000 cm^-3和温度T_e ~ 15000 K。对于H_2发射气体，我们得到T ~ 2100 K。电离气体和分子气体的不同强度分布、物理性质和位置表明，H_2发射气体跟踪活动星系核的馈电，而电离气体跟踪反馈。
英文摘要：
We have used the Gemini Near-infrared Integral Field Spectrograph (NIFS) to map the emission-line intensity distributions and ratios in the Narrow-Line Region (NLR) of the Seyfert galaxy NGC 4151 in the Z, J, H and K bands at a resolving power ~ 5000, covering the inner 200 pc x 300 pc of the galaxy at a spatial resolution of 8 pc. We present intensity distributions I(r) in 14 emission lines. (1) For the ionized gas, I(r) is extended to ~ 100 pc from the nucleus along pos. angle PA=60/240 deg-- NE--SW), consistent with an origin in the known biconical outflow; while for the recombination lines I(r) ~ r^-1, for the forbidden lines I(r) is flat (r^0). (2) The H_2 emission lines intensity distributions avoid the region of the bicone, extending to r ~ 60 pc, perpendicular to the bicone axis, supporting an origin for the H_2-emitting gas in the galaxy plane. (3) The coronal lines show a steep intensity profile, described by r^-2. Using the line-ratio maps [Fe II]1.644/1.257 and Pa_b/Br_g we obtain a reddening of E(B-V)~0.5 along the NLR and E(B-V)>1 at the nucleus. Our line-ratio map [Fe II] 1.257/[P II] 1.189 is the first such map of an extragalactic source. Together with the [Fe II]/Pa_b map, these line ratios correlate with the radio intensity distribution, mapping the effects of shocks produced by the radio jet, which probably release the Fe locked in grains and produce the enhancement of the [Fe II] emission observed at ~ 1 arcsec from the nucleus. At these regions, we obtain densities N_e ~4000 cm^-3 and temperatures T_e ~ 15000K for the [Fe II]-emitting gas. For the H_2-emitting gas we obtain T ~ 2100K. The distinct intensity distributions, physical properties and locations of the ionized and molecular gas suggest that the H_2-emitting gas traces the AGN feeding, while the ionized gas traces its feedback.
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