The X-ray luminosity function of Active Galactic Nuclei in the redshift interval z=3-5
A. Georgakakis, J. Aird, J. Buchner, M. Salvato, M. -L. Menzel, W. N. Brandt, I. D. McGreer, T. Dwelly, G. Mountrichas, K. Koki, I. Georgantopoulos, L. -T. Hsu,… 展开作者
A. Georgakakis, J. Aird, J. Buchner, M. Salvato, M. -L. Menzel, W. N. Brandt, I. D. McGreer, T. Dwelly, G. Mountrichas, K. Koki, I. Georgantopoulos, L. -T. Hsu, A. Merloni, Z. Liu, K. Nandra, N. P. Ross
我们结合Chandra天文台的深X射线测量数据和宽域/浅域XMM-XXL场,估算了红移z=3-5范围内活动星系核X射线光度函数。该样品由近340个光源组成,其光度(212)或光谱(128)红移在上述范围内。深、浅测量场的组合提供了三个数量级的亮度基线,Lx(2- 10 keV)~ 1 e43 - 1 e46 erg/s(z>3)。我们遵循贝叶斯方法来确定分箱AGN空间密度,并探讨其演变的模型无关的方式。我们的方法占泊松误差的测定X射线通量和光度红移估计的不确定性。我们证明,后者是必不可少的空间密度的无偏测量。我们发现活动星系核X射线光度函数在红移区间z=3-4和z=4-5之间有强烈的演化。也有暗示性的证据表明,这种演变的幅度是光度依赖。Lx<1 e ~(45)erg/s的活动星系核的空间密度在上述红移区间内下降了5倍,而较亮的活动星系核的演化似乎较温和。将我们的X射线光度函数与类似红移的紫外/光学选择类星体的光度函数进行比较,在明亮的光度下,Lx> 1 e 45 erg/s,两者有很大的一致性。然而,UV/光学光度函数的暗端斜率比X射线选择活动星系核的暗端斜率更陡。这意味着在z>3时,I型活动星系核分数随着亮度的降低而增加,这与较低红移时建立的趋势相反。我们还评估了活动星系核在保持氢的高红移电离的意义。我们的X射线光度函数产生的电离光子速率密度不足以使宇宙在红移z>4时保持电离。计算中的一个不确定性来源是X射线选定活动星系核的紫外光子逃逸分数。
英文摘要:
We combine deep X-ray survey data from the Chandra observatory and the wide-area/shallow XMM-XXL field to estimate the AGN X-ray luminosity function in the redshift range z=3-5. The sample consists of nearly 340 sources with either photometric (212) or spectroscopic (128) redshift in the above range. The combination of deep and shallow survey fields provides a luminosity baseline of three orders of magnitude, Lx(2-10keV)~1e43-1e46erg/s at z>3. We follow a Bayesian approach to determine the binned AGN space density and explore their evolution in a model-independent way. Our methodology accounts for Poisson errors in the determination of X-ray fluxes and uncertainties in photometric redshift estimates. We demonstrate that the latter is essential for unbiased measurement of space densities. We find that the AGN X-ray luminosity function evolves strongly between the redshift intervals z=3-4 and z=4-5. There is also suggestive evidence that the amplitude of this evolution is luminosity dependent. The space density of AGN with Lx<1e45erg/s drops by a factor of 5 between the redshift intervals above, while the evolution of brighter AGN appears to be milder. Comparison of our X-ray luminosity function with that of UV/optical selected QSOs at similar redshifts shows broad agreement at bright luminosities, Lx>1e45erg/s. The faint-end slope of UV/optical luminosity functions however, is steeper than for X-ray selected AGN. This implies that the type-I AGN fraction increases with decreasing luminosity at z>3, opposite to trends established at lower redshift. We also assess the significance of AGN in keeping the hydrogen ionised at high redshift. Our X-ray luminosity function yields ionising photon rate densities that are insufficient to keep the Universe ionised at redshift z>4. A source of uncertainty in this calculation is the escape fraction of UV photons for X-ray selected AGN.
The cold molecular gas regulates the activity of active galactic nuclei in massive galaxies
Qujing Normal University(曲靖师范学院);Nanjing University(南京大学);Peking University(北京大学);Fudan University(复旦大学);Guangxi Minzu University(广西民族大学);Yunnan Observatories, Chinese Academy of Sciences(中国科学院云南天文台);Anqing Normal University(安庆师范大学);Kunming University(昆明学院)
Hadronic origin of multi-TeV gamma rays and neutrinos from low-luminosity active galactic nuclei: implications of past activities of the Galactic center
低光度活动星系核(LLAGNs)中的辐射低效吸积流(RIAFs)被认为是宇宙射线和中微子源,可能对观测到的漫射中微子强度有很大贡献。我们表明,这种情况下自然预测强子多TeV的伽马射线过剩银河系中心周围。在人马座A $^*$(Sgr A $^*$)的RIAF中加速的质子逃逸并与Sgr A $^*$周围的致密分子气体相互作用,这被称为中心分子区(CMZ),并产生伽马射线和中微子。基于与IceCube数据兼容的理论模型,我们计算了CMZ的伽马射线谱,发现如果Sgr A $^*$在过去比现在更活跃,那么高能立体系统可能已经探测到了具有$\gtrsim 1$ TeV的伽马射线。我们的模型预测中微子应该来自CMZ,其光谱与伽马射线光谱相似。我们还表明,这样的伽马射线过剩,预计一些附近的星系托管LLAGN。
Variability-selected low-luminosity active galactic nuclei candidates in the 7 Ms Chandra Deep Field-South
在深X射线巡天中,已经发现了光度范围很广的活动星系核。然而,宇宙学上遥远的低光度活动星系核(LLAGN,$L_{\mathrm{X}} \lesssim 10^{42}$ erg s $^{-1}$)的识别仍然是一个挑战,由于来自宿主星系的显着污染。基于7 Ms Chandra Deep Field-South(CDF-S)调查,迄今为止最长的时间尺度($\sim 17$ years)的深X射线调查,我们利用X射线可变性选择技术来搜索在CDF-S X射线源中仍然未被识别的LLAGN。我们发现13个变量源从110个未分类的CDF-S X射线源。除了一个可能是超亮X射线源外,其余12个源的变化很可能是由于吸积超大质量黑洞造成的。这12个活动星系核候选者具有较低的本征X射线光度,中值为$7 \times10^{40}$ erg s $^{-1}$。它们通常不会被严重遮蔽,平均有效幂律光子指数为1.8。可变活动星系核在CDF-S中的比例与X射线光度无关,仅受观测到的净计数总数的限制,证实了以前的研究结果,即X射线可变性是活动星系核在很宽的光度范围内几乎无处不在的特性。对于高光度活动星系核,X射线光度与变率振幅之间存在反相关,但当光度下降到$\lesssim 10^{42}$ erg s $^{-1}$时,变率振幅不再依赖于光度。整个观测到的亮度变化趋势可以大致再现的经验AGN可变性模型的基…
Radio Core Size of Low-luminosity Active Galactic Nuclei under the MAD-jet model
Shanghai Astronomical Observatory, Chinese Academy of Sciences(中国科学院上海天文台);School of Astronomy and Space Sciences, University of Chinese Academy of Sciences(中国科学院大学天文与空间科学学院)
Millimeter Radio Continuum Emissions as the Activity of Super Massive Black Holes in Nearby Early-Type Galaxies and Low-Luminosity Active Galactic Nuclei
Relationship Between the Kinetic Power and Bolometric Luminosity of Jets: limitation from black hole X-ray binaries, active galactic nuclei, and gamma-ray bursts
The luminosity-dependent contribution from the broad line region to the wavelength-dependent lags in Mrk 110
我们在2019年2月和9月的两次密集监测活动中测量了高吸积率($L/L_{\rm Edd}\approx40\%$)活动星系核Mrk 110中X射线,紫外和光学波段之间的波长依赖性滞后。我们将观测结果分成三个不同X射线光度的区间。第一个间隔已经发表在Vincentelli et al.(2021)中,具有最低的X射线光度,并且没有表现出U带过剩的正滞后,也没有在大多数活动星系核中看到的X射线过剩的负滞后。然而,这些多余的滞后在随后的两个更高的X射线光度的间隔中被看到。虽然数据有限,但多余的滞后似乎与X射线光度成比例。我们的模型表明,预期从X射线再处理的吸积盘的滞后几乎没有变化,在所有增加光度。因此,由于U带过剩几乎肯定会产生从宽线区(BLR)的巴尔末连续发射,我们将这些滞后的变化归因于从BLR的贡献变化。这种变化很容易用BLR的内半径随电离光度的增加而增加来解释。