PKS 1127−145
Quasar in the constellation Crater
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PKS 1127−145 is a radio-loud quasar[1] located in the constellation of Crater. This is a Gigahertz Peaked Spectrum object[2][3] with a redshift of (z) 1.187,[4] first discovered by astronomers in 1966.[5] Its radio spectrum appears to be flat making it a flat-spectrum radio quasar, or an FSRQ in short.[6][7]
| PKS 1127−145 | |
|---|---|
The quasar, PKS 1127−145. | |
| Observation data (J2000.0 epoch) | |
| Constellation | Crater |
| Right ascension | 11h 30m 07.0526s |
| Declination | −14° 49′ 27.388″ |
| Redshift | 1.180000 |
| Heliocentric radial velocity | 353,755 km/s |
| Distance | 8.170 Gly |
| Apparent magnitude (V) | 17.17 |
| Apparent magnitude (B) | 16.90 |
| Characteristics | |
| Type | Blazar, LPQ, FSRQ |
| Notable features | Longest X-ray jet detected in a high redshift quasar |
| Other designations | |
| INTREF 453, 2E 2471, LEDA 2826758, 4FGL J1129.8−1447, WMAP 157, QSO B1127−1432, PKS 1127−14, OHIO M -146, PMN J1130−1449 | |
Description
PKS 1127−145 displays blazar-like behavior. It is known to undergo a period of gamma ray activity,[8] especially in December 2020 where its daily gamma ray flux reached a peak of (E > 100 MeV) of (1.6 ± 0.3) × 10−6 photons cm−2 s−1.[9] Two flares were detected by Fermi-LAT in May and October 2022.[10][11]
The radio structure of PKS 1127−145 is found to be complex. A radio image made by the Very Long Baseline Interferometry (VLBI) shows the object has two components, mainly a bright component and a much weaker component with same brightness temperatures of 1.3 × 1011 Kelvin. No extension is found in northwest direction.[12] There is a presence of a compact core displaying strong increase of flux density[13] with the outermost component being separated into several smaller regions enveloped completely by emission.[9] A stationary feature is also seen located 4 mas from the core via a 22 GHz image taken by VLBI.[14] Circular polarization has also been found in the quasar as well.[15]
X-ray jet
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An X-ray jet has been discovered in PKS 1127−145 by Chandra X-ray Observatory.[16] With an estimated length of 300 kiloparsecs, this makes it the longest detected so far in any high redshift quasar.[17] 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 fainter with presence of X-ray emission scattered over a large area.[18]
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.[9]