论文标题
GRB 200716c的候选宿主星系的多尺度VLBI观察
Multi-scale VLBI observations of the candidate host galaxy of GRB 200716C
论文作者
论文摘要
我们介绍了SDSS J130402.36 $+$+$ 293840.6（J1304+2938）的发现和随后的无线电发射的随后随访，这是Gamma-ray Burst Grb 〜200716c的候选候选人Galaxy。在RAC（0.89 GHz），NVSS，APERTIF成像调查以及第一个（1.4 GHz），Vlass（3 GHz）和Public Lofar（130-170 MHz），Wise（3.4-22 $ $ M）和SDSS（Z，Z，I，I，i，r，u，u，g，u，r，u，g，g，i，在公共Lofar（130-170 MHz）中），在RAC（0.89 GHz），NVSS，APERTIF成像调查中检测到了银河系。在1.4 GHz下推断的光度为（5.1 $ \ pm0.2）\ times10^{30} $ erg s $^{ - 1} $ hz $^{ - 1} $。为了表征排放和区分银河系中的不同组件，我们用欧洲VLBI网络 + E-Merlin在1.6和5 GHz进行了专用，高敏性和高分辨率观测值。我们没有从紧凑的核心中检测到任何发射，这表明不太可能存在无线电大风AGN，因此我们将在公共调查中观察到的发射归因于银河系中的星形区域。我们确认并完善红移估计值，$ z = 0.341 \ pm0.004 $，具有专用的TNG光谱观察。最后，我们编制了在无线电中检测到的所有已知的GRB次要宿主的列表，并计算了相应的无线电发光度：如果Grb〜200716c属于J1304+2938，这是GRB的第三大无线电宿主，这是当前最高的星形型（SFRS），$ 31 $ 32 $ 324 $ 324 $ 324 $ 324 m $ _ {\ odot} $ yr $^{ - 1} $。另一方面，通过对及时发射光曲线的分析，最近的作品表明，GRB〜200716c可能是J1304 $+$ 2938以上的短期GRB，并且由Galaxy托管的中间质量黑洞（IMBH）在重力上进行了重力。公共数据和我们的VLBI观察结果都无法确认或排除IMBH的存在，该IMBH充当银河系托管的（毫米）镜头，这种情况仍然与这项工作中介绍的一组无线电观察兼容。
We present the discovery and the subsequent follow up of radio emission from SDSS J130402.36$+$293840.6 (J1304+2938), the candidate host galaxy of the gamma-ray burst GRB~200716C. The galaxy is detected in the RACS (0.89 GHz), the NVSS, the Apertif imaging survey, and the FIRST (1.4 GHz), the VLASS (3 GHz), and in public LOFAR (130-170 MHz), WISE (3.4-22 $μ$m), and SDSS (z, i, r, g, u filters) data. The luminosity inferred at 1.4 GHz is (5.1$\pm0.2)\times10^{30}$ erg s$^{-1}$ Hz$^{-1}$. To characterise the emission and distinguish between different components within the galaxy, we performed dedicated, high-sensitivity and high-resolution observations with the European VLBI Network + e-MERLIN at 1.6 and 5 GHz. We did not detect any emission from a compact core, suggesting that the presence of a radio-loud AGN is unlikely, and therefore we ascribe the emission observed in the public surveys to star-forming regions within the galaxy. We confirm and refine the redshift estimate, $z=0.341\pm0.004$, with a dedicated TNG spectroscopic observation. Finally, we compiled a list of all the known hosts of GRB afterglows detected in radio and computed the corresponding radio luminosity: if GRB~200716C belongs to J1304+2938, this is the third most radio-luminous host of a GRB, implying one of the highest star-formation rates (SFRs) currently known, namely SFR$\sim$324$\pm$61 M$_{\odot}$ yr$^{-1}$. On the other hand, through the analysis of the prompt emission light curve, recent works suggest that GRB~200716C might be a short-duration GRB located beyond J1304$+$2938 and gravitationally lensed by an intermediate-mass black hole (IMBH) hosted by the galaxy. Neither the public data nor our VLBI observations can confirm or rule out the presence of an IMBH acting as a (milli-)lens hosted by the galaxy, a scenario still compatible with the set of radio observations presented in this work.
