4C 58.17 also known as 0850+581, is a quasar located in the northern constellation of Ursa Major. The redshift of the object is (z) 1.317 estimating a light-travel time distance of 9 billion light years away from Earth[1] and was first discovered as an astronomical radio source by astronomers in 1981.[2] It is a flat-spectrum radio quasar and a superluminal source.[3][4]
Description
4C 58.17 has a compact triple radio structure.[5][4] When imaged with Very Long Baseline Interferometry (VLBI), it is shown to have a core-jet morphology that is typical of powerful observed quasars, being mainly dominated by strong nuclear radio emission with a bright radio core and a secondary component present at a position angle of 170° with its distance being 4.5 milliarcseconds away.[6] New VLBI and Very Large Array (VLA) observations showed there is a northern component on mas-scale, several secondary components and a weak resolved feature present in the quasar. This northern component is estimated to hold 85% of the flux density.[7]
A study published in 1986 found 4C 58.17 has superluminal motion in its core. Based on studies, the core of the source is found to be expanding at a speed of 5.3 ± 0.8 per hour with its components separation increasing while the position angle of the components decreases per year.[4] A new component has emerged close to the core position, described as elongated along the position angle of 174 ± 4°.[7] The core itself is variable at slight frequencies with a fairly steep spectrum of between 15 and 5 GHz.[4] It is suggested the core might also be shifting by one milliarcsecond between 2 and 8GHz.[8]
The jet travelling from the core region towards a southeast hotspot on arcsecond scales in 4C 58.17 is described as both curved and knotty, and also displaying a cork-screw behavior.[4][9] When imaged by the Very Long Baseline Array (VLBA), it takes the form of a two-sided jet moving at relativistic speeds with a counter-jet feature displaying diffused radio emission. There is a noted switch in its orientation, indicating it might be interacting with the surround interstellar medium. The Faraday rotationpolarization located downstream from the core by 2 milliarcseconds shows a negative unit of -1612 ± 102 rad/m2, before rising to 270 ± 70 rad/m2 upon reaching 3.5 milliarcseconds.[10] A supermassive black hole mass of 8.49 M☉ has been estimated for this quasar.[11]
↑Kovalev, Y. Y.; Lobanov, A. P.; Pushkarev, A. B. (2008-10-13). "Physics of the central region in the quasar 0850+581". Memorie della Societa Astronomica Italiana. 79: 1153. arXiv:0810.2240. Bibcode:2008MmSAI..79.1153K.
↑Liu, Yi; Jiang, Dong Rong; Gu, Min Feng (2005-10-08). "The Jet Power, Radio Loudness, and Black Hole Mass in Radio-loud Active Galactic Nuclei". The Astrophysical Journal. 637 (2): 669–681. arXiv:astro-ph/0510241. doi:10.1086/498639.
