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Diffuse galaxy cluster emission at 168 MHz within the Murchison Widefield Array Epoch of Reionization 0-h field
Publications of the Astronomical Society of Australia ( IF 4.5 ) Pub Date : 2021-03-18 , DOI: 10.1017/pasa.2021.7
S. W. Duchesne , M. Johnston-Hollitt , A. R. Offringa , G. W. Pratt , Q. Zheng , S. Dehghan

We detect and characterise extended, diffuse radio emission from galaxy clusters at 168 MHz within the Epoch of Reionization 0-h field: a $45^{\circ} \times 45^{\circ}$ region of the southern sky centred on R. A. ${}= 0^{\circ}$ , decl. ${}=-27^{\circ}$ . We detect 29 sources of interest; a newly detected halo in Abell 0141; a newly detected relic in Abell 2751; 4 new halo candidates and a further 4 new relic candidates; and a new phoenix candidate in Abell 2556. Additionally, we find nine clusters with unclassifiable, diffuse steep-spectrum emission as well as a candidate double relic system associated with RXC J2351.0-1934. We present measured source properties such as their integrated flux densities, spectral indices ( $\alpha$ , where $S_\nu \propto \nu^\alpha$ ), and sizes where possible. We find several of the diffuse sources to have ultra-steep spectra including the halo in Abell 0141, if confirmed, showing $\alpha \leq -2.1 \pm 0.1$ with the present data making it one of the steepest-spectrum haloes known. Finally, we compare our sample of haloes with previously detected haloes and revisit established scaling relations of the radio halo power ( $P_{1.4}$ ) with the cluster X-ray luminosity ( $L_{\textrm{X}}$ ) and mass ( $M_{500}$ ). We find that the newly detected haloes and candidate haloes are consistent with the $P_{1.4}$ $L_{\textrm{X}}$ and $P_{1.4}$ $M_{500}$ relations and see an increase in scatter in the previously found relations with increasing sample size likely caused by inhomogeneous determination of $P_{1.4}$ across the full halo sample. We show that the MWA is capable of detecting haloes and relics within most of the galaxy clusters within the Planck catalogue of Sunyaev–Zel’dovich sources depending on exact halo or relic properties.

中文翻译:

再电离 0-h 场的 Murchison 宽场阵列时期内 168 MHz 的漫射星系团发射

我们在再电离时代 0-h 场内检测并表征来自星系团的 168 MHz 扩展的漫射无线电发射:a $45^{\circ} \times 45^{\circ}$ 以RA为中心的南部天空区域 ${}= 0^{\circ}$ , 声明 ${}=-27^{\circ}$ . 我们检测到 29 个感兴趣的来源;在 Abell 0141 中新发现的光晕;在 Abell 2751 新发现的遗迹;4 个新光环候选者和另外 4 个新遗物候选者;和 Abell 2556 中的新凤凰候选者。此外,我们发现了九个具有不可分类的漫射陡光谱发射的星团,以及与 RXC J2351.0-1934 相关的候选双遗物系统。我们展示了测量的源属性,例如它们的积分通量密度、光谱指数( $\阿尔法$ , 在哪里 $S_\nu \propto \nu^\alpha$ ),以及可能的尺寸。我们发现几个漫射源具有超陡光谱,包括 Abell 0141 中的光晕,如果得到证实,则显示 $\alpha \leq -2.1 \pm 0.1$ 目前的数据使它成为已知的最陡光谱晕之一。最后,我们将我们的光晕样本与之前检测到的光晕进行比较,并重新审视已建立的无线电光晕功率的比例关系( $P_{1.4}$ ) 与星团 X 射线光度 ( $L_{\textrm{X}}$ ) 和质量 ( $M_{500}$ )。我们发现新检测到的光晕和候选光晕与 $P_{1.4}$ $L_{\textrm{X}}$ $P_{1.4}$ $M_{500}$ 关系,并看到先前发现的关系的分散性随着样本量的增加而增加,这可能是由不均匀的测定引起的 $P_{1.4}$ 在整个光环样本中。我们表明,MWA 能够检测到银河系内大多数星系团中的光晕和遗迹。普朗克Sunyaev-Zel'dovich 来源的目录取决于确切的光环或遗迹特性。
更新日期:2021-03-18
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