论文标题
Chandra在z> 5处检测三个X射线明亮的类星体
Chandra Detection of Three X-ray Bright Quasars at z>5
论文作者
论文摘要
我们报告了Chandra在$ z \ gtrsim5 $的Chandra检测到三个紫外线明亮的广播金星。我们已经收集了足够数量的光子来提取每个类星体的X射线光谱，以测量其基本X射线特性，例如X射线通量，Power Law Photon指数（$γ$）和光学到X射线光谱斜率（$α_ {\ rm ox} $）。 J074749+115352 at $ z = 5.26 $是X射线最亮的放射优惠Quiet Quasar，$ Z> 5 $。它可能具有短的时间尺度变化（在观察者框架中的$ \ sim3800 \ rm〜s $的时间表上，或者在其余框架中$ \ sim600 \ rm〜s $），但是，这在很大程度上嵌入了统计噪声中。我们提取该类星体的相位折叠光谱。有两个可区分的状态：一个“高柔软”状态，其平均X射线通量$ \ sim2.7 $的“低硬”状态和更陡峭的X射线频谱斜率（$γ= 2.40 _ { - 0.32}^{ - 0.32}^{+0.33} {+0.33} $ vs $ 1.78 _ _ { - 1.78 _ _ { - 0.24} = { - 0.24}^$ 0.25}我们还将本文中检测到的三个类星体与其他类星体样品进行了比较。我们发现J074749+115352，SMBH质量为$ M _ {\ rm smbh} \ oft1.8 \ times10^9 \ rm〜m_ \ odot $，$λ_ {\ rm edd} \ rm edd} \ oddd} \ rm edd} \ oddd} \ odot $ of 2.3 $它的平均$α_ {\ rm ox} = - 1.46 \ pm0.02 $，2-10 keV骨化校正系数为$ l _ {\ rm bol}/l _ {\ rm2-10kev} = 42.4 \ pm5.8 $，两者都与一些定义的缩放率相关。我们将这三个类星体的$γ$与不同的红移的其他样品进行了比较，并且基于$ z> 5 $ quasars的有限样本没有可靠测量X射线光谱属性的有限样本。
We report Chandra detection of three UV bright radio quiet quasars at $z\gtrsim5$. We have collected a sufficient number of photons to extract an X-ray spectrum of each quasar to measure their basic X-ray properties, such as the X-ray flux, power law photon index ($Γ$), and optical-to-X-ray spectral slope ($α_{\rm OX}$). J074749+115352 at $z=5.26$ is the X-ray brightest radio-quiet quasar at $z>5$. It may have a short timescale variation (on a timescale of $\sim3800\rm~s$ in the observer's frame, or $\sim600\rm~s$ in the rest frame) which is however largely embedded in the statistical noise. We extract phase folded spectra of this quasar. There are two distinguishable states: a "high soft" state with an average X-ray flux $\sim2.7$ times of the "low hard" state, and a significantly steeper X-ray spectral slope ($Γ=2.40_{-0.32}^{+0.33}$ vs $1.78_{-0.24}^{+0.25}$). We also compare the three quasars detected in this paper to other quasar samples. We find that J074749+115352, with a SMBH mass of $M_{\rm SMBH}\approx1.8\times10^9\rm~M_\odot$ and an Eddington ratio of $λ_{\rm Edd}\approx2.3$, is extraordinarily X-ray bright. It has an average $α_{\rm OX}=-1.46\pm0.02$ and a 2-10 keV bolometric correction factor of $L_{\rm bol}/L_{\rm2-10keV}=42.4\pm5.8$, both significantly depart from some well defined scaling relations. We compare $Γ$ of the three quasars to other samples at different redshifts, and do not find any significant redshift evolution based on the limited sample of $z>5$ quasars with reliable measurements of the X-ray spectral properties.
