PKS 1127−145
PKS 1127−145 is a radio-loud quasar located in the constellation of Crater. This is a Gigahertz Peaked Spectrum object with a redshift of 1.187, first discovered by astronomers in 1966. Its radio spectrum appears to be flat making it a flat-spectrum radio quasar, or an FSRQ in short.
Description
PKS 1127−145 displays blazar-like behavior. It is known to undergo a period of gamma ray activity, especially in December 2020 where its daily gamma ray flux reached a peak of of x 10−6 photons cm−2 s−1. Two flares were detected by Fermi-LAT in May and October 2022.The radio structure of PKS 1127−145 is found to be complex. A radio image made by the Very Long Baseline Interferometry shows the object has two components, mainly a bright component and a much weaker component with same brightness temperatures of 1.3 x 1011 Kelvin. No extension is found in northwest direction. There is a presence of a compact core displaying strong increase of flux density with the outermost component being separated into several smaller regions enveloped completely by emission. A stationary feature is also seen located 4 mas from the core via a 22 GHz image taken by VLBI. Circular polarization has also been found in the quasar as well.
X-ray jet
An X-ray jet has been discovered in PKS 1127−145 by Chandra [X-ray Observatory]. With an estimated length of 300 kiloparsecs, this makes the longest one detected so far in any of the high redshift quasars. Advanced CCD Imaging Spectrometer also revealed a complex structure in the X-ray jet from the core with bright knots of different morphologies. Two of the knots showed changes in their profiles while the other knot is found fainter with presence of X-ray emission scattered over a large area.A more in-depth analysis of the X-ray jet in PKS 1127−145 showed the inner jet of PKS 1127−145 located from the core is found to be extremely polarized and a parallel magnetic field towards the jet's axis. Upon reaching 18 arcseconds from the core, the jet suddenly bends slightly causing the re-brightening of radio emission. In additional, there is a 90° rotation of the magnetic field suggesting it might be compressed to the plane that is found perpendicular to the axis.