论文标题
HST WFC3/候选超高红色射线银河系的GRISM观测值J0917-0012
HST WFC3/Grism Observations of the Candidate Ultra-High-Redshift Radio Galaxy GLEAM J0917-0012
论文作者
论文摘要
我们提出了Hubble空间望远镜宽场摄像头3候选超高红外（Z> 7）射电射线星系的光度和GRISM观测值，GLEAM J0917-0012。由于其70-230 MHz的曲率，低频Murchison广场阵列频谱及其在K波段中的微弱性，因此选择了该无线电源。对于其红移，使用VLA和ALMA对此来源的随访光谱观察尚无定论。我们的F105W和F0986M成像观测值检测到GLEAM J0917-0012的宿主和一个伴侣银河系，〜一个Arcsec。 G102 GRISM观察结果揭示了宿主和同伴的每个光谱中的单个弱线。为了帮助识别这些线路，我们利用了几种光度红移技术，包括将模板拟合到Grism光谱中，将UV-To-Radio光度法与星系模板以及同步器模型拟合，将UV-Near-Near-In-Frared光度计拟合到EAZY中，并与无线电数据拟合。对于GLEAM J0917-0012的宿主，我们在1.12微米处找到一条线，紫外线到Radio光谱分布拟合拟合溶液在Z〜2或Z〜8时有利于溶液。虽然这种拟合表现出对较低红移溶液的偏爱，但来自较高红移溶液的模型与光谱线的强度更加一致。 Z> 6.5的RISERED的红移约束也支持以下解释：这条线可以是z = 8.21的lyman-alpha;但是，Eazy有利于Z〜2解决方案。我们讨论两种解决方案的含义。对于同伴银河系，我们在0.98微米处找到一条线，光谱分布拟合在z <3处有利于溶液，这意味着该线可以是z = 1.63时的[OII] 3727 DoubleT（尽管Eazy溶液为z〜2.6 +/- 0.5）。仍然需要进一步的观察，以明确确定这个有趣的候选人超高红移射电射线银河系（删节）的红移。
We present Hubble Space Telescope Wide Field Camera 3 photometric and grism observations of the candidate ultra-high-redshift (z>7) radio galaxy, GLEAM J0917-0012. This radio source was selected due to the curvature in its 70-230 MHz, low-frequency Murchison Widefield Array radio spectrum and its faintness in K-band. Follow-up spectroscopic observations of this source with the VLA and ALMA were inconclusive as to its redshift. Our F105W and F0986M imaging observations detect the host of GLEAM J0917-0012 and a companion galaxy, ~one arcsec away. The G102 grism observations reveal a single weak line in each of the spectra of the host and the companion. To help identify these lines we utilised several photometric redshift techniques including template fitting to the grism spectra, fitting the UV-to-radio photometry with galaxy templates plus a synchrotron model, fitting of the UV-to-near-infrared photometry with EAZY, and fitting the radio data alone with RAiSERed. For the host of GLEAM J0917-0012 we find a line at 1.12 micron and the UV-to-radio spectral energy distribution fitting favours solutions at z~2 or z~8. While this fitting shows a weak preference for the lower redshift solution, the models from the higher redshift solution are more consistent with the strength of the spectral line. The redshift constraint by RAiSERed of z>6.5 also supports the interpretation that this line could be Lyman-alpha at z=8.21; however EAZY favours the z~2 solution. We discuss the implications of both solutions. For the companion galaxy we find a line at 0.98 micron and the spectral energy distribution fitting favours solutions at z<3 implying that the line could be the [OII]3727 doublet at z=1.63 (although the EAZY solution is z~2.6+/-0.5). Further observations are still required to unambiguously determine the redshift of this intriguing candidate ultra-high-redshift radio galaxy (abridged).
