Systematically Measuring Ultradiffuse Galaxies in H i: Results from the Pilot Survey
Systematically Measuring Ultradiffuse Galaxies in H i: Results from the Pilot Survey
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DOI：
10.3847/1538-4357/abb464
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发表时间：
2020-05
期刊：
影响因子：
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通讯作者：
A. Karunakaran;K. Spekkens;D. Zaritsky;R. Donnerstein;J. Kadowaki;A. Dey
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文献类型：
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作者：
A. Karunakaran;K. Spekkens;D. Zaritsky;R. Donnerstein;J. Kadowaki;A. Dey
我们利用罗伯特·C·伯德·格林班克望远镜(GBT)对系统测量超扩散星系调查(SMUGES)中彗发区70个光学探测到的UDG候选者进行了中性氢(HI)观测。我们在18个目标中探测到了H I，确认了9个是富含气体的UDG，其余的是前景矮星。我们的HI检测到的UDG没有一个是COMA星系团成员，除了一个之外，所有的UDG都在低密度环境中。被HI探测到的UDG比未被HI探测到的更红、更光滑的候选UDG更蓝、更不规则，光学颜色和形态的组合比单独使用任何一个参数都能更好地预测气体丰度。在污点成像中，富含气体的UDG和前景矮星之间的视觉差异很小，需要距离来区分它们。我们发现，我们的Hi确认的UDG和其他样品的气体丰度与它们在两个恒星质量箱中的有效半径成比例，可能为它们的形成提供了线索。我们试图使用光学椭圆性和湍流校正的HI线宽将我们的UDG放置在重子Tully-Fisher关系(BTFR)上来估计自转速度，但将平滑的Sérsic轮廓拟合到块状、低倾角的低表面亮度的圆盘上所关联的势系统学阻碍了对潜在BTFR偏移量的有意义的分析。这些观测是GBT目前正在进行的一项大型活动的试点，该活动旨在利用富含气体的UDG的HI属性来定量限制这些星系的形成和演化。
We present neutral hydrogen (H i) observations using the Robert C. Byrd Green Bank Telescope (GBT) of 70 optically detected UDG candidates in the Coma region from the Systematically Measuring Ultra-Diffuse Galaxies survey (SMUDGes). We detect H i in 18 targets, confirming nine to be gas-rich UDGs and the remainder to be foreground dwarfs. None of our H i-detected UDGs are Coma Cluster members and all but one are in low-density environments. The H i-detected UDGs are bluer and have more irregular morphologies than the redder, smoother candidates not detected in H i, with the combination of optical color and morphology being a better predictor of gas richness than either parameter alone. There is little visual difference between the gas-rich UDGs and the foreground dwarfs in the SMUDGes imaging, and distances are needed to distinguish between them. We find that the gas richnesses of our H i-confirmed UDGs and those from other samples scale with their effective radii in two stellar mass bins, possibly providing clues to their formation. We attempt to place our UDGs on the baryonic Tully–Fisher relation (BTFR) using optical ellipticities and turbulence-corrected H i line widths to estimate rotation velocities, but the potential systematics associated with fitting smooth Sérsic profiles to clumpy, low-inclination disks of low surface brightness precludes a meaningful analysis of potential BTFR offsets. These observations are a pilot for a large campaign now under way at the GBT to use the H i properties of gas-rich UDGs to quantitatively constrain how these galaxies form and evolve.