Multi-epoch VLBA observations of radio galaxy 0932+075: is this a compact symmetric object?

A part of the radio structure of the galaxy 0932+075 emerged as a possible compact symmetric object (CSO) after the observation with the Very Long Baseline Array (VLBA) at 5 GHz in 1997. More than a decade later, we carried out observations at 5, 15.4, and 22.2 GHz using the VLBA to test this possibility. We report here that we have found a component whose spectrum is inverted in the whole range from 5 GHz to 22 GHz and we label it a high-frequency peaker (HFP). Using a set of 5 GHz images from two epochs separated by 11.8 years and a set of 15.4 GHz images separated by 8.2 years, we were able to examine the proper motions of the three components of the CSO candidate with respect to the HFP. We found that their displacements cannot be reconciled with the CSO paradigm. This has led to the rejection of the hypothesis that the western part of the arcsecond-scale radio structure of 0932+075 is a CSO anchored at the HFP. Consequently, the HFP cannot be labelled a core and its role in this system is unclear. DOI: https://doi.org/10.1051/0004-6361/201322280 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-98867 Published Version Originally published at: Marecki, Andrzej; Sokołowska, Aleksandra (2014). Multi-epoch VLBA observations of radio galaxy 0932+075: is this a compact symmetric object? Astronomy and Astrophysics, 569:A22. DOI: https://doi.org/10.1051/0004-6361/201322280 A&A 569, A22 (2014) DOI: 10.1051/0004-6361/201322280 c © ESO 2014 Astronomy & Astrophysics Multi-epoch VLBA observations of radio galaxy 0932+075: is this a compact symmetric object? Andrzej Marecki1 and Aleksandra Sokołowska1 ,2 1 Toruń Centre for Astronomy, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University, Toruń, Poland e-mail: [email protected] 2 Institute for Computational Science, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland e-mail: [email protected] Received 15 July 2013 / Accepted 4 July 2014 ABSTRACT A part of the radio structure of the galaxy 0932+075 emerged as a possible compact symmetric object (CSO) after the observation with the Very Long Baseline Array (VLBA) at 5 GHz in 1997. More than a decade later, we carried out observations at 5, 15.4, and 22.2 GHz using the VLBA to test this possibility. We report here that we have found a component whose spectrum is inverted in the whole range from 5 GHz to 22 GHz and we label it a high-frequency peaker (HFP). Using a set of 5 GHz images from two epochs separated by 11.8 years and a set of 15.4 GHz images separated by 8.2 years, we were able to examine the proper motions of the three components of the CSO candidate with respect to the HFP. We found that their displacements cannot be reconciled with the CSO paradigm. This has led to the rejection of the hypothesis that the western part of the arcsecond-scale radio structure of 0932+075 is a CSO anchored at the HFP. Consequently, the HFP cannot be labelled a core and its role in this system is unclear.