PKS 0454-234 | |
---|---|
Observation data (J2000.0 epoch) | |
Constellation | Lepus |
Right ascension | 04h 57m 03.179s |
Declination | −23° 24′ 52.020″ |
Redshift | 1.003000 |
Heliocentric radial velocity | 300,692 km/s |
Distance | 7.531 Gly |
Apparent magnitude (V) | 18.5 |
Apparent magnitude (B) | 18.85 |
Characteristics | |
Type | HPQ, Blazar, BL Lac |
Other designations | |
OHIO F -292, 4FGL J0457.0-2324, WMAP 128, QSO B0454-234, PKS J0457-2324, NVSS J045703-232452 |
PKS 0454-234 is a blazar [1] located in the constellation of Lepus. It is classified as a highly polarized quasar [2] [3] with a redshift of (z) 1.003. [4] This object was first discovered in 1970 during a 1415 MHz continuum survey conducted by Ohio State University where it was given the designation, OF -292. [5] The radio spectrum of this source is flat, making it a flat-spectrum radio quasar. [4] [6] [7]
PKS 0454-234 is found variable on the electromagnetic spectrum. It is known to show powerful outbursts with a spectrum showing as inverted right up to 20 GHz, but becomes steeper upon reaching its quiescence state after 8 GHz. [2] In additional, PKS 0454-234 exhibits extreme gamma ray activity observed by Large Area Telescope in January 2009 [8] and by the AGILE satellite, where the activity reached above 100 MeV in August 2019. [9] Flares were detected in near-infrared wavelengths in 2011 and 2013. [10] [11] An observation conducted by Japanese scientists in 2013, also found PKS 0454-234 has a soft spectrum with an estimated integral flux of 2.82 x 10-7 ± 1.10 x 10-9 in the ranges of 0.1-300 GeV. [12]
Very Long Baseline Interferometry radio imaging taken at 5 GHz showed PKS 0454-234 having an asymmetric morphology, consisting of a strong radio core and compact jetlike component that is located in a northwest direction with a position angle of -62°. This core has a brightness temperature of around 6 x 1011 Kelvin. [13] When imaged at 2.3 and 8.5 GHz, it shows the object mainly having a core-dominated structure and a weak jet extending out by 5 mas along the position angle of -130°. [14] There is also a presence of a secondary structure located at a distance of 1 mas southeast with its secondary components having 90° position angle differences according to multiepoch monitoring done by United States Naval Observatory (USNO). [15]
In 2022, PKS 0454-234 was found to show two quasi-periodic oscillation signals with duration periods of 3.51 ± 0.33 and 6.10 ± 0.82 years. This might be explained by a binary black hole model with estimated mass of 4.69 x 108 Mʘ and a gravitational wave emission having a decay time period of 9.56 x 104 years. [16]
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PKS 1622-297 is a blazar located in the constellation of Scorpius. It is one of the brightest objects of its type in the gamma ray region. It has a redshift of (z) 0.815. This blazar was first discovered as a compact astronomical radio source in 1970 by astronomers who were conducting interferometer observations and identified with an optical counterpart in 1984. In addition, the radio spectrum of the source appears flat, making it a flat-spectrum radio quasar (FRSQ).
PKS 0458-020 also known as PKS 0458-02, is a quasar located in the constellation of Orion. It has a redshift of (z) 2.286 and was first identified as an astronomical radio source during the radio survey conducted by Parkes Observatory in 1966. Subsequently the source was shown to display optical behavior before being classfied as a blazar via an optical polarimetry study in 1985. This source also shows radio spectrum appearing to be flat, hence making it a flat-spectrum radio quasar (FRSQ).
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