(ORDO NEWS) — A research team led by Dr. Zhao Gongbo of the National Astronomical Observatory of the Chinese Academy of Sciences (NAOC), in collaboration with scientists from the UK and Germany, studied the distribution of the large-scale structure of radio galaxies observed by the Low Frequency Array Telescope (LOFAR) and determined the displacement of galaxies, which can help to better understand clustering property of these galaxies.
In the standard model of cosmology, the density of matter in the Universe is dominated by cold dark matter. The formation and evolution of galaxies take place within these dark matter halos, and the mass and evolution of the halo host correlate with the evolution and type of galaxy within.
Using the displacement of galaxies, astronomers describe the relationship between the spatial distribution of galaxies and the underlying dark matter density field. Measuring the displacement of radio galaxies can help us understand the history of their formation and evolution.
LOFAR (LoTSS) is a continuous, high-resolution survey of the northern hemisphere of the sky. This survey is 10 times more sensitive than the current best high-resolution sky survey and will detect more than 10 million radio sources, mostly star-forming galaxies but with a high proportion of active galactic nuclei (AGNs).
Since the strongest radio sources are often optically weak or invisible, AGN radio loudspeakers have been found to be in more massive halos than optical AGNs.
Radio surveys select galaxies with a large offset compared to optical observations and thus complement existing and discover new visible galaxies. LoTSS opens up a new perspective for studying the large-scale structure of the universe.
The research team systematically studied and processed the LoTSS DR1 catalog, used the appropriate flux reduction and sky filter to ensure sampling completeness, and finally selected over 100,000 sources for cluster analysis.
Unlike previous studies, the LoTSS DR1 catalog contains a significant number of multicomponent sources, and the researchers took this effect into account when interpreting the measured angular power spectrum.
Using the standard model of cosmology and applying the Markov chain Monte Carlo method, the research team obtained limits on the displacement of radio galaxies.
The results show that the LOFAR survey is suitable for cosmological studies. Upcoming LOFAR data releases are expected to be deeper and broader, allowing for improved cosmological measurements.
“This work helps to understand the displacement of the LoTSS galaxy population and lays the groundwork for the future analysis of LoTSS DR2,” said Dr. Prabhakar Tiwari, first author of the study.
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