arXivDaily arXiv每日学术速递 周一至周五更新
arXiv周末暂无论文更新,休息一下吧,周末愉快~~
arXiv 1807.06015astro-ph.GA
收藏

ALMA的$^{3}P_{1}-^{3}P_{0}$观测:一种令人困惑的分子外流,以及外流在(U)LIRGs的全局$α_{\rm CO}$因子中的作用

ALMA [CI]$^{3}P_{1}-^{3}P_{0}$ observations of NGC6240: a puzzling molecular outflow, and the role of outflows in the global $α_{\rm CO}$ factor of (U)LIRGs

Claudia Cicone, Paola Severgnini, Padelis P. Papadopoulos, Roberto Maiolino, Chiara Feruglio, Ezequiel Treister, George C. Privon, Zhi-yu Zhang, Roberto Della C… 展开作者

Claudia Cicone, Paola Severgnini, Padelis P. Papadopoulos, Roberto Maiolino, Chiara Feruglio, Ezequiel Treister, George C. Privon, Zhi-yu Zhang, Roberto Della Ceca, Fabrizio Fiore, Kevin Schawinski, Jeff Wagg

摘要:

本文给出NGC 6240的ALMA和ACA [CI] $^{3}P_{1}-^{3}P_{0}$([CI](1-0))观测结果,并结合ALMA CO(2-1)和IRAM PdBI CO(1-0)数据研究了大质量分子(H $_2$)外流的物理性质。我们发现H $_2$外流的后退和接近两侧,东西对齐,总范围超过10千秒差距。高分辨率($0.24"$)[CI](1-0)线像令人惊讶地揭示出流出辐射峰值在两个活动星系核之间,而不是在两个活动星系核中的任何一个上,并且它主导着这个核区域的速度场。我们结合[CI](1-0)和CO(1-0)数据来限制流出物中CO到H的$_2$转换因子($α_{\rm CO}$),其平均值为$2.1\pm1.2~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$。我们估计NGC 6240的总H $_2$气藏的$60\pm20$ %被夹带在流出物中,从而产生质量损失率为$\dot{M}_{\rm out}=2500\pm1200~M_{\odot}~yr^{-1}$ $\equiv 50\pm30$ SFR。这种能量排除了一个纯粹的恒星形成驱动的风,但令人费解的形态挑战了经典的辐射模式活动星系核反馈的情况。对于静止气体,我们计算$\langleα_{\rm CO}\rangle = 3.2\pm1.8~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$,它至少是通常用于(U)LIRG的值的两倍。我们观察到一个试探性的趋势,增加$r_{21}\equiv L^{\prime}_{\rm CO(2-1)}/L^{\prime}_{\rm CO(1-0)}$比率与速度分散和测量$r_{21}>1$的流出,而$r_{21}\simeq1$在静止的气体。我们提出,分子流出是温暖的位置,强烈的非结合相,部分降低了(U)LIRGs中CO线的不透明度,从而降低了它们的全局$α_{\rm CO}$并增加了它们的$r_{21}$值。

英文摘要:

We present ALMA and ACA [CI]$^{3}P_{1}-^{3}P_{0}$ ([CI](1-0)) observations of NGC6240, which we combine with ALMA CO(2-1) and IRAM PdBI CO(1-0) data to study the physical properties of the massive molecular (H$_2$) outflow. We discover that the receding and approaching sides of the H$_2$ outflow, aligned east-west, exceed 10 kpc in their total extent. High resolution ($0.24"$) [CI](1-0) line images surprisingly reveal that the outflow emission peaks between the two AGNs, rather than on either of the two, and that it dominates the velocity field in this nuclear region. We combine the [CI](1-0) and CO(1-0) data to constrain the CO-to-H$_2$ conversion factor ($α_{\rm CO}$) in the outflow, which is on average $2.1\pm1.2~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$. We estimate that $60\pm20$ % of the total H$_2$ gas reservoir of NGC6240 is entrained in the outflow, for a resulting mass-loss rate of $\dot{M}_{\rm out}=2500\pm1200~M_{\odot}~yr^{-1}$ $\equiv 50\pm30$ SFR. This energetics rules out a solely star formation-driven wind, but the puzzling morphology challenges a classic radiative-mode AGN feedback scenario. For the quiescent gas we compute $\langleα_{\rm CO}\rangle = 3.2\pm1.8~\rm M_{\odot} (K~km~s^{-1}~pc^2)^{-1}$, which is at least twice the value commonly employed for (U)LIRGs. We observe a tentative trend of increasing $r_{21}\equiv L^{\prime}_{\rm CO(2-1)}/L^{\prime}_{\rm CO(1-0)}$ ratios with velocity dispersion and measure $r_{21}>1$ in the outflow, whereas $r_{21}\simeq1$ in the quiescent gas. We propose that molecular outflows are the location of the warmer, strongly unbound phase that partially reduces the opacity of the CO lines in (U)LIRGs, hence driving down their global $α_{\rm CO}$ and increasing their $r_{21}$ values.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑