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arXiv 1211.3452astro-ph.CO
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早型星系21厘米宽的弱吸收:谱线发现和未来巡天的参数化

Broad, weak 21 cm absorption in an early type galaxy: spectral-line finding and parametrization for future surveys

J. R. Allison, S. J. Curran, E. M. Sadler, S. N. Reeves

摘要:

我们报告确凿的验证检测相关HI 21厘米吸收的早期型宿主星系的紧凑的射电源PMNJ 2054 -4242。我们估计有效的谱线速度宽度为418 +/- 20 km s^{-1},观测到的峰值光学深度为2.5 +/-0.2%,这是迄今为止探测到的最宽和最弱的21 cm吸收线之一。对于T_{spin} /f > 100 K,原子中性氢柱密度为N_{HI} > 2 x 10^{21} cm^{-2}。相对于光学光谱测量,观测到的谱线轮廓红移了187 +/- 46 km s^{-1},这可能表明HI气体正在向中央活动星系核下落。我们最初的试探性探测可能会被目视检查驳回,因此它的验证是我们的谱线探测技术的一个很好的测试,目前正在开发中,预计未来的下一代21厘米吸收线调查。

英文摘要:

We report conclusive verification of the detection of associated HI 21 cm absorption in the early-type host galaxy of the compact radio source PMNJ2054-4242. We estimate an effective spectral line velocity width of 418 +/- 20 km s^{-1} and observed peak optical depth of 2.5 +/- 0.2 per cent, making this one of the broadest and weakest 21 cm absorption lines yet detected. For T_{spin}/f > 100 K the atomic neutral hydrogen column density is N_{HI} > 2 x 10^{21} cm^{-2}. The observed spectral line profile is redshifted by 187 +/- 46 km s^{-1}, with respect to the optical spectroscopic measurement, perhaps indicating that the HI gas is infalling towards the central active galactic nucleus. Our initial tentative detection would likely have been dismissed by visual inspection, and hence its verification here is an excellent test of our spectral line detection technique, currently under development in anticipation of future next-generation 21 cm absorption-line surveys.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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