OQ 172 (OHIO Q 172) is a quasar[1] located in the constellation of Boötes. It has a redshift of (z) 3.544,[2] making it one of the most distant quasars at the time of its discovery by astronomers in 1973.[3] This object was the record holder for almost a decade, before being surpassed by PKS 2000-330 in 1982 located at the redshift of (z) 3.78.[4]
| OQ 172 | |
|---|---|
 The quasar OQ 172. | |
| Observation data (J2000.0 epoch) | |
| Constellation | Boötes |
| Right ascension | 14h 45m 16.465s |
| Declination | +09° 58′ 36.073″ |
| Redshift | 3.540681 |
| Distance | 11.543 Gly |
| Apparent magnitude (V) | 17.78 |
| Apparent magnitude (B) | 18.58 |
| Characteristics | |
| Type | GPS, FSRQ |
| Other designations | |
| LEDA 2828124, PKS 1442+101, NVSS J144516+095836, QSO B1442+101, TXS 1442+101, CoNFIG 200, IERS B1442+101 | |
Description
editThe source of OQ 172 has a radio spectrum characterized by its spectral peak in the gigahertz domain, making it a gigahertz-peaked spectrum quasar (GPS)[5][6] or a compact steep spectrum source (CSS).[7]
OQ 172 contains a core-jet structure with the radio core itself located in the northern region of the radio emission.[8] This core is found to show a flat spectrum up to > 30 GHz in the rest frame with a steep spectrum above 30 GHz which continues steepening until 1000 GHz, thus confirming there is no buried flat spectrum core within the emission source.[9]
The jet of OQ 172 is found to turn almost at an 180° angle with jet emission in the west-southwest direction extending right from the core, eventually bending almost southwards. When reaching 20 mas south of the core, the jet immediately bends once again, this time at 90° and extends towards the east.[10] A further study also shows the jet has three components, one of which is the fastest at a proper motion of 0.13 ± 0.01 mas yr-1. With a mean TB of 15.5 ± 6.4 x 1010 K, this suggests OQ 172 has a highly beamed jet.[11]
Very long baseline interferometry radio observations revealed OQ 172 has magnetic fields on parsec scales which rotate the polarization plane of the radio emission originating from both its core and inner jet.[10] Based on the derived rest-frame rotational measurement of RM 40,000 rad m-2, it is found OQ 172 has the highest value amongst other known RM sources.[12] When at 10 mas from the core, the jet's absolute value of RM decreases to <100 rad m-2.[10] Additionally, linear polarized emission has been detected in both components in all five frequencies. The core has low fractional polarization, while the jet components have a higher polarization. A rotational measurement was obtained at 4.8 and 8.3 GHz respectively, showing a high value of 2000 rad m-2 in the innermost region of OQ 172. Towards the outer jet regions, this value drops to 700 rad m-2, quickly decreasing to lower values.[12][8]
References
edit- ^ Fomenko, A. F.; Levshakov, S. A.; Varshalovich, D. A.; Nebelitskii, V. B. (1984-02-01). "Spectra of the quasar OQ 172". Pisma V Astronomicheskii Zhurnal. 10: 83–89. Bibcode:1984PAZh...10...83F. ISSN 0320-0108.
- ^ Morton, D. C.; Peterson, B. A.; Chen, J.-S.; Wright, A. E.; Jauncey, D. L. (1989-12-01). "The spectrum of the QSO 1442 + 101 (OQ172) at intermediate dispersion". Monthly Notices of the Royal Astronomical Society. 241 (3): 595–612. doi:10.1093/mnras/241.3.595. ISSN 0035-8711.
- ^ Gurvits, L.I.; Schilizzi, R.T.; Barthel, P.D.; Kardashev, N.S.; Kellermann, K.L.; Lobanov, A.P. (1994). "Milliarcsecond structures of extremely distant quasars: 0336-017, 0636+680, 1442+101, and 2048+312". Astronomy & Astrophysics. 291 (3): 737–742. Bibcode:1994A&A...291..737G. ISSN 0004-6361.
- ^ Shaver, Peter (December 1987). "Ever more distant quasars?" (PDF). Nature. 330 (6147): 426. doi:10.1038/330426a0. ISSN 0028-0836.
- ^ Liu, Y.; Jiang, D. R.; Gu, M.; Gurvits, L. I. (2016-02-01). "The compact radio structure of the high-redshift quasar OQ172". Astronomische Nachrichten. 337 (1–2): 101. Bibcode:2016AN....337..101L. doi:10.1002/asna.201512273. ISSN 0004-6337.
- ^ Barthel, Peter D.; Vestergaard, Marianne; Lonsdale, Colin J. (2000-02-01). "Radio imaging of core-dominated high redshift quasars". Astronomy and Astrophysics. 354: 7–16. arXiv:astro-ph/9911474. ISSN 0004-6361.
- ^ Mantovani, F.; Rossetti, A.; Junor, W.; Saikia, D. J.; Salter, C. J. (2013-06-18). "Radio polarimetry of compact steep spectrum sources at sub-arcsecond resolution" (PDF). Astronomy & Astrophysics. 555: A4. doi:10.1051/0004-6361/201220769. ISSN 0004-6361.
- ^ a b Mantovani, F.; Junor, W.; Bondi, M.; Cotton, W.; Fanti, R.; Padrielli, L. (1998). "Large bent jets in the inner region of CSSs". Astronomy & Astrophysics. 332: 10–18.
- ^ Punsly, Brian; Marziani, Paola; Kharb, Preeti; O’Dea, Christopher P.; Vestergaard, Marianne (2015-10-09). "The Extreme Ultraviolet Deficit: Jet Connection In the Quasar 1442+101". The Astrophysical Journal. 812 (1): 79. arXiv:1509.02619. doi:10.1088/0004-637x/812/1/79. ISSN 1538-4357.
- ^ a b c Udomprasert, P. S.; Taylor, G. B.; Pearson, T. J.; Roberts, D. H. (1997-07-01). "Evidence for Ordered Magnetic Fields in the Quasar Environment". The Astrophysical Journal. 483 (1): L9–L12. arXiv:astro-ph/9704112. doi:10.1086/310725. ISSN 0004-637X.
- ^ Zhang, Yingkang; An, Tao; Frey, Sándor; Gabányi, Krisztina Éva; Sotnikova, Yulia (September 2022). "Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5". The Astrophysical Journal. 937 (1): 19. arXiv:2209.10760. doi:10.3847/1538-4357/ac87f8. ISSN 0004-637X.
- ^ a b Liu, Yi; Jiang, D. R.; Gu, Minfeng; Gurvits, L. I. (2017-03-15). "Multifrequency VLBA polarimetry of the high-redshift GPS quasar OQ172". Monthly Notices of the Royal Astronomical Society. 468 (3): 2699–2712. arXiv:1703.04066. doi:10.1093/mnras/stx617. ISSN 0035-8711.