Title: Gas reservoir of a hyper-luminous QSO at z=2.6 Show Chinese title

Title: 红移 z = 2.6 的超亮 QSO 的气体储库

Abstract: Understanding the relationship between the formation and evolution of galaxies and their central super massive black holes (SMBH) is one of the main topics in extragalactic astrophysics. Links and feedback may reciprocally affect both black hole and galaxy growth. Observations of the CO line at redshifts of 2-4 are crucial to investigate the gas mass, star formation activity and accretion onto SMBHs, as well as the effect of AGN feedback. Potential correlations between AGN and host galaxy properties can be highlighted by observing extreme objects. Despite their luminosity, hyper-luminous QSOs at z=2-4 are still little studied at mm wavelengths. We targeted CO(3-2) in ULAS J1539+0557, an hyper-luminos QSO (Lbol> 10^48 erg/s) at z=2.658, selected through its unusual red colors in the UKIDSS Large Area Survey (ULAS). We find a molecular gas mass of 4.1+-0.8 10^10 Msun, and a gas fraction of 0.4-0.1, depending mostly on the assumed source inclination. We also find a robust lower limit to the star-formation rate (SFR=250-1600 Msun/yr) and star-formation efficiency (SFE=25-350 Lsun/(K km s-1 pc2) by comparing the observed optical-near-infrared spectral energy distribution with AGN and galaxy templates. The black hole gas consumption timescale, M(H_2)/dM(accretion)/dt, is ~160 Myr, similar or higher than the gas consumption timescale. The gas content and the star formation efficiency are similar to those of other high-luminosity, highly obscured QSOs, and at the lower end of the star-formation efficiency of unobscured QSOs, in line with predictions from AGN-galaxy co-evolutionary scenarios. Further measurements of the (sub)-mm continuum in this and similar sources are mandatory to obtain a robust observational picture of the AGN evolutionary sequence. Show Chinese abstract

Abstract: 理解星系及其中心超大质量黑洞（SMBH）的形成与演化之间的关系是河外天体物理学的主要课题之一。 黑洞和星系的增长可能相互影响。 在红移为2到4时观测CO谱线对于研究气体质量、恒星形成活动以及对SMBHs的吸积和活动星系核（AGN）反馈效应至关重要。 通过观测极端物体可以突出AGN和宿主星系属性之间的潜在相关性。 尽管它们亮度很高，但在毫米波段下，z=2-4的超亮QSOs仍鲜有研究。 我们选择了ULAS J1539+0557，一个位于z=2.658的超亮QSO（Lbol> 10^48 erg/s），它是在UKIDSS大面积巡天（ULAS）中通过异常红色选择的。 我们发现分子气体质量为4.1±0.8×10^10 Msun，气体分数为0.4-0.1，这主要取决于假设的源倾角。 我们还通过比较观测的光学-近红外光谱能量分布与AGN和星系模板，找到了恒星形成率（SFR=250-1600 Msun/yr）和恒星形成效率（SFE=25-350 Lsun/(K km s-1 pc2)的稳健下限。 黑洞气体消耗时间尺度，M(H_2)/dM(accretion)/dt，约为160百万年，与气体消耗时间尺度相似或更高。 气体含量和恒星形成效率与其他高亮度、高度遮蔽的QSOs相似，并且处于未遮蔽QSOs恒星形成效率的低端，符合AGN-星系共同演化情景的预测。 为了获得AGN演化序列的稳健观测图景，必须进一步测量此类源和类似源的（亚）毫米连续波。