Context. The majority of bright extragalactic gamma-ray sources are blazars. Only a few radio galaxies have been detected by Fermi/LAT. Recently, the GHz-peaked spectrum source PKS 1718-649 was confirmed to be gamma-ray bright, providing further evidence for the existence of a population of gamma-ray loud, compact radio galaxies. A spectral turnover in the radio spectrum in the MHz to GHz range is a characteristic feature of these objects, which are thought to be young due to their small linear sizes. The multiwavelength properties of the gamma-ray source PMN J1603-4904 suggest that it is a member of this source class. Aims. The known radio spectrum of PMN J1603-4904 can be described by a power law above 1 GHz. Using observations from the Giant Metrewave Radio Telescope (GMRT) at 150, 325, and 610 MHz, we investigate the behaviour of the spectrum at lower frequencies to search for a low-frequency turnover. Methods. Data from the TIFR GMRT Sky Survey (TGSS ADR) catalogue and archival GMRT observations were used to construct the first MHz to GHz spectrum of PMN J1603-4904. Results. We detect a low-frequency turnover of the spectrum and measure the peak position at about 490 MHz (rest-frame), which, using the known relation of peak frequency and linear size, translates into a maximum linear source size of ~1.4 kpc. Conclusions. The detection of the MHz peak indicates that PMN J1603-4904 is part of this population of radio galaxies with turnover frequencies in the MHz to GHz regime. Therefore it can be considered the second, confirmed object of this kind detected in gamma-rays. Establishing this gamma-ray source class will help to investigate the gamma-ray production sites and to test broadband emission models.
Piggyback search for fast radio bursts using Nanshan 26m and Kunming 40m radio telescopes -- I. Observing and data analysis systems, discovery of a mysterious peryton
Year-timescale changes in AGN radio luminosity as seen by the ASKAP Variables and Slow Transients Survey
The Pennsylvania State University（宾夕法尼亚州立大学）；The University of Sydney（悉尼大学）；University of Wisconsin-Milwaukee（威斯康星大学密尔沃基分校）；University of North Carolina at Chapel Hill（北卡罗来纳大学教堂山分校）；CSIRO（澳大利亚联邦科学与工业研究组织）
Rapid radio variability in the $z\sim7$ blazar VLASS J0410$-$0139: Indication of a hidden population of weak radio jets at Cosmic Dawn
Max-Planck-Institut für Astronomie（马克斯·普朗克天文学研究所）；INAF-Osservatorio di Astrofisica e Scienza dello Spazio（意大利国家天体物理研究所空间科学观测站）；NSF NOIRLab, Gemini Observatory（美国国家光学红外天文研究实验室双子座天文台）；ASTRON, The Netherlands Institute for Radio Astronomy（荷兰射电天文研究所）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；National Radio Astronomy Observatory（国家射电天文台）；Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales（迭戈·波特莱斯大学工程与科学学院天体物理研究所）；Department of Astronomy Astrophysics and Space Engineering, Indian Institute of Technology Indore（印度印多尔理工学院天文、天体物理与空间工程系）
First Detection of Radio Polarization During Jet Formation in the Changing-Look AGN 1ES 1927+654
University of Maryland Baltimore County（马里兰大学巴尔的摩县分校）；NASA Goddard Space Flight Center（美国宇航局戈达德太空飞行中心）；Center for Space Science and Technology, University of Maryland Baltimore County（马里兰大学巴尔的摩县分校空间科学与技术中心）；Center for Research and Exploration in Space Science and Technology, NASA/GSFC（NASA/戈达德太空飞行中心空间科学与探索研究中心）；National Centre for Radio Astrophysics（国家射电天文中心）
