We present the first HI 21 cm spectroscopy detection of J030417.78+002827.4, which is an active galactic nucleus (AGN) with an intermediate-mass black hole (IMBH) in the center. The observations were carried out with the Five-hundred-meter Aperture Spherical Radio Telescope (FAST) last year. We relied on the ON-OFF observing approach with the 19-beam receiver covering 1.05 – 1.45 GHz. Within a total integration time of about 20 min, the root mean square (RMS) of our data reaches 1.2 mJy beam⁻¹, at a velocity resolution of 1.6 kms. Radio frequency interference (RFI) is checked and excluded during the data analysis. The detected HI spectroscopy shows a dual-horned profile with a line width of 223.5 kms, indicating gas rotation around this AGN. The redshift of this galaxy derived from our HI observation is 0.0447. We calculate the atomic gas mass by the integrated flux of the HI emission line. The total gas mass in this galaxy is estimated to be 1.8 10¹⁰ M _⊙. We find the fraction of gas-to-stellar mass ratio in J030417.78+002827.4 is more than 50%. This ratio is much higher than the typical value found in other AGNs with supermassive black holes (SMBHs), and is comparable to some star-forming galaxies recently observed by FAST.

我们首次展示了 J030417.78+002827.4 的 HI 21 cm 光谱检测，它是一个活动星系核 (AGN)，中心有一个中等质量黑洞 (IMBH)。去年，这些观测是使用 500 米口径球面射电望远镜 (FAST) 进行的。我们依靠覆盖 1.05 – 1.45 GHz 的 19 波束接收器的 ON-OFF 观测方法。在大约 20 分钟的总积分时间内，我们数据的均方根 (RMS) 达到 1.2 mJy 光束^-1，速度分辨率为 1.6 公里。在数据分析期间检查并排除射频干扰 (RFI)。检测到的 HI 光谱显示线宽为 223.5 公里的双角剖面，表明气体围绕该活动星系核旋转。从我们的 HI 观测中得出的这个星系的红移是 0.0447。我们通过 HI 发射线的积分通量计算原子气体质量。这个星系的总气体质量估计为 1.8 ₁₀ ¹⁰ M⊙ 。我们发现J030417.78+002827.4中的气体与恒星质量比的分数超过了50%。这个比率远高于在其他具有超大质量黑洞 (SMBH) 的活动星系核中发现的典型值，并且与 FAST 最近观测到的一些恒星形成星系相当。