论文标题
用宽OVI和X射线探测热热的环境培养基
Probing the Warm-Hot Circumgalactic Medium with broad OVI and X-rays
论文作者
论文摘要
螺旋星系中的大多数重型质量(CGM)中的大部分肿块被认为是温暖的,温度约为$ 10^6 $ k。狭窄的OVI吸收线探测了$ \ log \ rm t(k)= 5.5 $的较凉的分量,但是宽OVI吸收剂有可能探测热CGM的热CGM。在这里,我们提出了376 ks chandra letg的观测值,对精心选择的星系进行了观测,其中宽OVI的存在以及LYA的非检测表明暖热气体。预计将以$ \ \ 10^6 $ k出现的最强行是ovii $λ21.602$。在红移波长处有一条吸收线的暗示,但是该线的意义未能更好。考虑到其他几条线的优势,一个物理模型提供了更好的约束。我们最佳拟合吸收器模型具有$ \ log \ rm t(k)= 6.3 \ pm 0.2 $和$ \ log \ rm n_ {h}(cm^{ - 2})= 20.7^{+0.3} _ { - 0.5} $。这些参数与基于紫外线观测的热热等离子体模型一致。其他凉气阶段的OVI模型的排除在$ 99 $%的信心中排除在外。因此,我们有暗示性的,但没有结论性的证据,证明了OVI吸收商从该试点计划的浅水观察中探测了热热气体。大约800K的XMM-Newton观测将明确检测OVII和OVIII的预期吸收系。 Xrism,Arcus和Athena等未来的任务将彻底改变CGM科学。
Most of the baryonic mass in the circumgalactic medium (CGM) of a spiral galaxy is believed to be warm-hot, with temperature around $10^6$K. The narrow OVI absorption lines probe a somewhat cooler component at $\log \rm T(K)= 5.5$, but broad OVI absorbers have the potential to probe the hotter CGM. Here we present 376 ks Chandra LETG observations of a carefully selected galaxy in which the presence of broad OVI together with the non-detection of Lya was indicative of warm-hot gas. The strongest line expected to be present at $\approx 10^6$K is OVII $λ21.602$. There is a hint of an absorption line at the redshifted wavelength, but the line is not detected with better than $2σ$ significance. A physical model, taking into account strengths of several other lines, provides better constraints. Our best-fit absorber model has $\log \rm T(K) =6.3\pm 0.2$ and $\log \rm N_{H} (cm^{-2})=20.7^{+0.3}_{-0.5}$. These parameters are consistent with the warm-hot plasma model based on UV observations; other OVI models of cooler gas phases are ruled out at better than $99$% confidence. Thus we have suggestive, but not conclusive evidence for the broad OVI absorber probing the warm-hot gas from the shallow observations of this pilot program. About 800ks of XMM-Newton observations will detect the expected absorption lines of OVII and OVIII unequivocally. Future missions like XRISM, Arcus and Athena will revolutionize the CGM science.