Using Karl G. Jansky’s Very Large Array (VLA) and upgraded Giant Clock Radio Telescope (uGMRT), astronomers conducted multi-wavelength observations of celestial merged ruins. Ha is called Mrk 212. The results of this observational campaign, presented in an article published October 28 on arXiv.org, shed more light on the properties and nature of this ruin.
Galactic mergers play an essential role in the evolution of galaxies. Large mergers are even capable of changing the shape of parent galaxies and forming an object with a completely new morphology.
Observations show that inflow of gas during galaxy merger can trigger mass accumulation on supermassive black holes (SMBH), turning them into active galactic nuclei (AGN). When both SMBHs are ignited at the same time, it can form AGN pairs. If the distance between two AGNs is less than 326 light years, they are referred to as binary AGNs. In the case of a larger split, the astronomers call them double AGNs.
At a distance of about 322 million light-years away, Mrk 212 is a relic that merges the galaxy with two known radio sources linked to two optical nuclei, designated S1 and S2. The expected distance between the two nuclei is estimated to be about 18,250 light-years, making it a dual AGN candidate.
A team of astronomers led by Khatun Rubinur of the Indian Institute of Astrophysics in Bangalore, India made deep-UV, optical, and radio observations of Mrk 212 using VLA and uGMRT. The main goal of this monitoring campaign is to validate an object’s dual AGN nature and provide more insight into the attributes of this source.
The astronomers wrote in the article: “We have done a multi-wavelength study of a merging galaxy Mrk 212 possessing two optical nuclei S1 and S2 at an expected distance of ∼ 11.8 ” or ∼ 6 kpc “.
Observations of the VLA show a dual radio source linked to S1 and a compact radio structure linked to S2. The VLA image also shows an expanded radio structure at 8.5 GHz, located one arc second from the optical nucleus S2, has a relatively flat spectral index and is thought to be a compact core.
The researchers found that the total range of the S1 is about 2,445 light years and its average spectral index of 1.4-8.5 GHz is approximately −0.81. These properties mean that S1 resembles a compact symmetrical object (CSO).
According to the study, the presence of a compact radio core and the presence of AGN emission lines in the spectrum of S2 indicate the presence of another AGN in S2. Furthermore, optical observations show that S1 and S2 are in the AGN + SF (star formation) region in the BPT diagram (Baldwin, Philips and Terlevich). In general, the astronomers concluded that the results obtained strongly support the dual AGN nature of Mrk 212.
New surviving radio galaxy discovered
Rubinur et al., Multi-wavelength study of dual nuclei at Mrk 212, arXiv: 2010.14914 [astro-ph.GA] arxiv.org/abs/2010.14914
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