Low Frequency Two Meter Sky Survey Radial Artifacts Identified as BL
  Quasars
  Through the use of a High Band Antenna system, the Low Frequency Array
Two-Meter Sky Survey (LoTSS) is an attempt to complete a high-resolution survey
of the northern celestial sky. To date, thousands of radio sources have been
classified by LOFAR with most of them consisting of active galactic nuclei
(AGN). The strong AGN emissions detected by LoTSS, it is thought, are powered
by supermassive black holes (SMBHs) at the center of galaxies. During an
analysis of 1500 images of these AGNs, we identified 10 radio sources with
radial spokes emitted from an unknown source. According to LOFAR, the radial
spokes are artifacts due to calibration errors with no origin, and therefore
they cannot be associated with an optical source. Our preliminary hypothesis
for the artifacts was that they were produced by ionized jets emitted from
quasi-stellar objects (QSOs). Specifically, that strong emissions from Type 1
broadline (BL) quasars were directed in the line of sight of the observer
(i.e., LOFAR) and as a result produced the image artifacts. To test our
hypotheses, we cross-referenced the ra and dec coordinates of the artifacts
with the galactic coordinates indexed in the Sloan Digital Sky Survey (SDSS)
and confirmed that the artifacts were associated with BL QSOs. Further analysis
of the QSOs, moreover, demonstrated they exhibited prominent broad emission
lines such as CIII and MgII, which are characteristic of Type 1 BL quasars. It
is our interpretation, therefore, that the radial spokes characterized as
artifacts by LOFAR were produced by the emission of Type 1 BL quasars in the
line of sight of the radio telescope.
