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黑洞基本面:用射电和X射线发射宽线活动星系核的较大样本重新研究

The black hole fundamental plane: revisit with a larger sample of radio and X-ray emitting broad-line AGNs

Zhao-Yu Li, Xue-Bing Wu, Ran Wang

摘要:

利用最近公布的SDSS X射线活动星系核目录,结合FIRST 20 cm射电巡天,研究了黑洞1.4GHz射电光度($L_r$)、0.1-2.4 keV X射线光度($L_X$)和黑洞质量($M$)之间的基本面关系,即$log L_r=ξ_{RX}log L_X+ξ_{RM}log M +const$ .为此,我们收集了725个宽线活动星系核的大样本,其中包括498个射电强源和227个射电静源。我们的结果与我们以前基于115个SDSS活动星系核的小样本工作基本一致。我们确认,无线电响亮的对象有一个陡峭的斜率($ξ_{RX}$)在无线电X射线的关系相对于无线电安静的对象,和黑洞基本平面上的黑洞质量($ξ_{RM}$)的依赖性是弱的。我们还发现射电强活动星系核和射电静活动星系核的软X射线亮度和宽发射线亮度之间存在着相似斜率的紧密相关关系,这意味着它们的软X射线发射是未知的,可能与吸积过程有关。利用目前较大的活动星系核样本,我们可以研究射电强子样本和射电静子样本的黑洞基平面关系的红移演化。我们发现,没有明确的证据表明,无线电安静的活动星系核的演化,而无线电大声的有一个微弱的趋势,即$ξ_{RM}$减少的红移增加。这可以部分地理解为由于观测到的作为红移函数的射电频谱指数的演变。最后讨论了相对论性聚束效应和其他与黑洞基平面有关的不确定性。

英文摘要:

We use a recently released SDSS catalog of X-ray emitting AGNs in conjunction with the FIRST 20cm radio survey to investigate the black hole fundamental plane relationship between the 1.4GHz radio luminosity ($L_r$), 0.1-2.4 keV X-ray luminosity ($L_X$), and the black hole mass ($M$), namely, $log L_r=ξ_{RX}log L_X+ξ_{RM}log M +const$. For this purpose, we have compiled a large sample of 725 broad-line AGNs, which consists of 498 radio-loud sources and 227 radio-quiet sources. Our results are generally consistent with those in our previous work based on a smaller sample of 115 SDSS AGNs. We confirm that radio-loud objects have a steeper slope ($ξ_{RX}$) in the radio-X-ray relationship with respect to radio-quiet objects, and the dependence of the black hole fundamental plane on the black hole mass ($ξ_{RM}$) is weak. We also find a tight correlation with a similar slope between the soft X-ray luminosity and broad emission line luminosity for both radio-loud and radio-quiet AGNs, which implies that their soft X-ray emission is unbeamed and probably related to the accretion process. With the current larger sample of AGNs, we are able to study the redshift evolution of the black hole fundamental plane relation for both radio-loud and radio-quiet subsamples. We find that there is no clear evidence of evolution for radio-quiet AGNs, while for radio-loud ones there is a weak trend where $ξ_{RM}$ decreases as the redshift increases. This may be understood in part as due to the observed evolution of the radio spectral index as a function of redshift. Finally, we discuss the relativistic beaming effect and some other uncertainties related to the black hole fundamental plane (Abridged).

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