Title: Dust and Cold Gas Properties of Starburst HyLIRG-Quasars at $z \sim 2.5$ Show Chinese title

Title: 尘埃和冷气体性质的星暴HyLIRG-类星体$z \sim 2.5$

Abstract: Some high-z active galactic nuclei (AGNs) are found to reside in extreme star-forming galaxies, such as hyper-luminous infrared galaxies (HyLIRGs), with AGN-removed $L_{\rm{IR}}$ of $>10^{13} L_{\rm{\odot}}$. In this paper, we report NOEMA observations of six apparent starburst HyLIRGs associated with optical quasars at $z\sim2-3$ in the Stripe 82 field, to study their dust and molecular CO properties. Five out of the six candidates are detected with CO(4-3) or CO(5-4) emission, and four in 2mm dust continuum. Based on the linewidth-$L'_{\rm{CO(1-0)}}$ diagnostics, we find that four galaxies are likely unlensed or weakly lensed sources. The molecular gas mass is in the range of $\mu M_{\rm{H_2}} \sim0.8-9.7\times10^{10} M_{\odot}$ (with $\alpha = 0.8 M_{\odot} (\rm{K km s^{-1} pc^2})^{-1}$ and $\mu$ is the unknown possible gravitational magnification factor). We fit their SEDs, after including the observed 2mm fluxes and upper limits, and estimate their apparent (uncorrected for possible lensing effect) star formation rates ($\mu$SFRs) to be $\sim400-2500$ $M_{\rm{\odot}} \rm{yr^{-1}}$ with depletion time of $\sim20-110$ Myr. We notice interesting offsets, of $\sim10-40$ kpc spatially or $\sim1000-2000$ km s$^{-1}$ spectroscopically, between the optical quasar and the mm continuum or CO emissions. The observed velocity shift is likely related to the blueshifted broad-emission-line region of quasars, though mergers or recoiling black holes are also possible causes, which can explain the spatial offset and the high intrinsic SFRs in the HyLIRG-quasar systems. Show Chinese abstract

Abstract: Some high-z active galactic nuclei (AGNs) are found to reside in extreme star-forming galaxies, such as hyper-luminous infrared galaxies (HyLIRGs), with AGN-removed $L_{\rm{IR}}$ of $>10^{13} L_{\rm{\odot}}$. In this paper, we report NOEMA observations of six apparent starburst HyLIRGs associated with optical quasars at $z\sim2-3$ in the Stripe 82 field, to study their dust and molecular CO properties. Five out of the six candidates are detected with CO(4-3) or CO(5-4) emission, and four in 2mm dust continuum. Based on the linewidth-$L'_{\rm{CO(1-0)}}$ diagnostics, we find that four galaxies are likely unlensed or weakly lensed sources. The molecular gas mass is in the range of $\mu M_{\rm{H_2}} \sim0.8-9.7\times10^{10} M_{\odot}$ (with $\alpha = 0.8 M_{\odot} (\rm{K km s^{-1} pc^2})^{-1}$ and $\mu$ is the unknown possible gravitational magnification factor). 我们拟合了它们的 SED（星系谱能量分布），在纳入观测到的 2 毫米流量和上限后，估计它们未校正（未修正可能的透镜效应）的恒星形成率（$\mu$SFRs）为 $\sim400-2500$ $M_{\rm{\odot}} \rm{yr^{-1}}$ ，耗尽时间为 $\sim20-110$ 百万年。 我们注意到有趣的空间偏移量，为 $\sim10-40$ 千秒差距，以及光谱偏移量，为 $\sim1000-2000$ 公里每秒$^{-1}$ ，存在于光学类星体与毫米波连续谱或 CO 辐射之间。 观测到的速度偏移很可能与类星体蓝移的大发射线区有关，尽管合并或喷射黑洞也可能是可能的原因，这些可以解释空间偏移和 HyLIRG-类星体系统中的高固有恒星形成率。