LBA observations for project V591 semester 2020APRS

Blazars are radio-loud active galactic nuclei (rAGN) whose jets are believed to point very close to the line of sight. Their abundance can be used to estimate the population of sources whose jets are seen at larger viewing angles in a given redshift bin. Volonteri et al. (2011) found that the number of radio-loud quasars above redshift 4 calculated from the luminosity function is much smaller than the number derived from the known high-redshift blazars. Our EVN observations however revealed z>4 sources previously categorized as blazar candidates to be reminiscent of small radio galaxies instead of being beamed sources.\r\nBelladitta et al. (2019) reported the discovery of an extremely X-ray weak blazar, DESJ014132.4-542749.9 at z=5. It hosts a relatively smaller black hole compared to other rAGN detected at high redshifts. Blazars are usually characterized by strong X-ray emission, and recently it was even found that blazars at z>4 have higher X-ray-to-radio luminosity ratios than those at lower redshifts (Ighina et al., 2019). In that context, DESJ014132.4-542749.9 seems to be even more atypical. \r\nTo understand how many misaligned radio sources are “missing” at high redshifts, it is essential to obtain the number of confirmed high-z blazars. For DESJ014132.4?542749.9, a reliable blazar classification is crucial due to its unusually low X-ray luminosity. Only high-resolution LBA observations can provide unambiguous evidence for or against the blazar hypothesis.