Probing highly obscured, self-absorbed galaxy nuclei with vibrationally excited HCN
Probing highly obscured, self-absorbed galaxy nuclei with vibrationally excited HCN
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DOI：
10.1051/0004-6361/201526410
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发表时间：
2015-04
影响因子：
6.5
通讯作者：
S. Aalto;S. Martin;F. Costagliola;E. González-Alfonso;S. Muller;K. Sakamoto;G. Fuller;S. Garcia-Burillo;P. Werf;R. Neri;M. Spaans;F. Combes;S. Viti;S. Muhle;L. Armus;A. Evans;E. Sturm;J. Cernicharo;Christian Henkel;T. Greve
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文献类型：
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作者：
S. Aalto;S. Martin;F. Costagliola;E. González-Alfonso;S. Muller;K. Sakamoto;G. Fuller;S. Garcia-Burillo;P. Werf;R. Neri;M. Spaans;F. Combes;S. Viti;S. Muhle;L. Armus;A. Evans;E. Sturm;J. Cernicharo;Christian Henkel;T. Greve
高分辨率（0。4）IRAM PdBI和阿尔马对（超）亮红外星系（（U）LIRGs）IRAS 17208-0014、Arp 220、IC 860和Zw 049.057的毫米和亚毫米观测揭示了振动激发（nu（2）= 1）J = 3-2和4-3 HCN的强谱线发射。发射是从埋藏的、紧凑的（r 5 x 10（13）L-圆点kpc（-2））中出现的。这些原子核可能是由超大质量黑洞（SMBH）和/或热（>200 K）极端恒星爆发提供动力的。HCN的振动（nu（2）= 1）谱线由14 μ m的中红外辐射激发，当H-2柱密度超过10（24）cm（-2）时，它是研究（U）LIRG核的动力学、质量和物理条件的极好探针。很明显，这些谱线开辟了一条新的有趣的途径，以获得最模糊的活动星系核和星暴。振动激发的HCN作为一个代理的吸收中红外发射从嵌入的核，这使得重建的内在的，更热的尘埃SED。与此相反，我们显示出强有力的证据表明，基态振动态（。= 0），J = 3-2和4-3转动谱线由于强的自吸收和连续吸收而不能探测到高度遮蔽的致密核区。HCN和HCO+线轮廓是双峰的，因为吸收和非圆形运动的证据，可能在形式的流入或流出。到目前为止，在外部星系中的振动激发HCN的检测仅限于ULIRGs和早期型螺旋LIRGs，我们讨论了可能的原因。我们初步认为，振动激发的HCN发射峰连接到一个快速的核生长阶段，强反馈阶段之前。
We present high resolution (0.'' 4) IRAM PdBI and ALMA mm and submm observations of the (ultra) luminous infrared galaxies ((U)LIRGs) IRAS 17208-0014, Arp220, IC 860 and Zw049.057 that reveal intense line emission from vibrationally excited (nu(2) = 1) J = 3-2 and 4-3 HCN. The emission is emerging from buried, compact (r 5 x 10(13) L-circle dot kpc(-2). These nuclei are likely powered by accreting supermassive black holes (SMBHs) and/or hot (>200 K) extreme starbursts. Vibrational, nu(2) = 1, lines of HCN are excited by intense 14 mu m mid-infrared emission and are excellent probes of the dynamics, masses, and physical conditions of (U)LIRG nuclei when H-2 column densities exceed 10(24) cm(-2). It is clear that these lines open up a new interesting avenue to gain access to the most obscured AGNs and starbursts. Vibrationally excited HCN acts as a proxy for the absorbed mid-infrared emission from the embedded nuclei, which allows for reconstruction of the intrinsic, hotter dust SED. In contrast, we show strong evidence that the ground vibrational state (. = 0), J = 3-2 and 4-3 rotational lines of HCN and HCO+ fail to probe the highly enshrouded, compact nuclear regions owing to strong self-and continuum absorption. The HCN and HCO+ line profiles are double-peaked because of the absorption and show evidence of non-circular motions-possibly in the form of in-or outflows. Detections of vibrationally excited HCN in external galaxies are so far limited to ULIRGs and early-type spiral LIRGs, and we discuss possible causes for this. We tentatively suggest that the peak of vibrationally excited HCN emission is connected to a rapid stage of nuclear growth, before the phase of strong feedback.