OQ 172
{{Short description|Quasar in the constellation Boötes}}
{{Infobox galaxy|name=OQ 172|epoch=J2000.0|constellation name=Boötes|ra={{RA|14|45|16.465}}|dec={{DEC|+09|58|36.073}}|z=3.540681|dist_ly=11.543 Gly|appmag_v=17.78|appmag_b=18.58|type=GPS, FSRQ|names=LEDA 2828124, PKS 1442+101, NVSS J144516+095836, QSO B1442+101, TXS 1442+101, CoNFIG 200, IERS B1442+101|image=File:Image of OQ 172.jpg|caption=The quasar OQ 172.}}
OQ 172 (OHIO Q 172) is a quasar{{Cite journal |last1=Fomenko |first1=A. F. |last2=Levshakov |first2=S. A. |last3=Varshalovich |first3=D. A. |last4=Nebelitskii |first4=V. B. |date=1984-02-01 |title=Spectra of the quasar OQ 172 |url=https://ui.adsabs.harvard.edu/abs/1984PAZh...10...83F/abstract |journal=Pis'ma v Astronomicheskii Zhurnal |volume=10 |pages=83–89 |bibcode=1984PAZh...10...83F |issn=0320-0108}} located in the constellation of Boötes. It has a redshift of (z) 3.544,{{Cite journal |last1=Morton |first1=D. C. |last2=Peterson |first2=B. A. |last3=Chen |first3=J.-S. |last4=Wright |first4=A. E. |last5=Jauncey |first5=D. L. |date=1989-12-01 |title=The spectrum of the QSO 1442 + 101 (OQ172) at intermediate dispersion |journal=Monthly Notices of the Royal Astronomical Society |volume=241 |issue=3 |pages=595–612 |doi=10.1093/mnras/241.3.595 |doi-access=free |issn=0035-8711}} making it one of the most distant quasars at the time of its discovery by astronomers in 1973.{{Cite journal |last1=Gurvits |first1=L.I. |last2=Schilizzi |first2=R.T. |last3=Barthel |first3=P.D. |last4=Kardashev |first4=N.S. |last5=Kellermann |first5=K.L. |last6=Lobanov |first6=A.P. |title=Milliarcsecond structures of extremely distant quasars: 0336-017, 0636+680, 1442+101, and 2048+312 |url=https://articles.adsabs.harvard.edu/full/1994A%26A...291..737G/0000738.000.html |journal=Astronomy & Astrophysics |date=1994 |volume=291 |issue=3 |pages=737–742 |bibcode=1994A&A...291..737G |issn=0004-6361}} 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.{{Cite journal |last=Shaver |first=Peter |date=December 1987 |title=Ever more distant quasars? |url=https://www.nature.com/articles/330426a0.pdf |journal=Nature |volume=330 |issue=6147 |pages=426 |doi=10.1038/330426a0 |bibcode=1987Natur.330..426S |issn=0028-0836}}
Description
The 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){{Cite journal |last1=Liu |first1=Y. |last2=Jiang |first2=D. R. |last3=Gu |first3=M. |last4=Gurvits |first4=L. I. |date=2016-02-01 |title=The compact radio structure of the high-redshift quasar OQ172 |url=https://ui.adsabs.harvard.edu/abs/2016AN....337..101L/abstract |journal=Astronomische Nachrichten |volume=337 |issue=1–2 |pages=101 |doi=10.1002/asna.201512273 |bibcode=2016AN....337..101L |issn=0004-6337}}{{Cite journal |last1=Barthel |first1=Peter D. |last2=Vestergaard |first2=Marianne |last3=Lonsdale |first3=Colin J. |date=2000-02-01 |title=Radio imaging of core-dominated high redshift quasars |url=https://articles.adsabs.harvard.edu/pdf/2000A%26A...354....7B |journal=Astronomy and Astrophysics |volume=354 |pages=7–16 |arxiv=astro-ph/9911474 |bibcode=2000A&A...354....7B |issn=0004-6361}} or a compact steep spectrum source (CSS).{{Cite journal |last1=Mantovani |first1=F. |last2=Rossetti |first2=A. |last3=Junor |first3=W. |last4=Saikia |first4=D. J. |last5=Salter |first5=C. J. |date=2013-06-18 |title=Radio polarimetry of compact steep spectrum sources at sub-arcsecond resolution |url=https://www.aanda.org/articles/aa/pdf/2013/07/aa20769-12.pdf |journal=Astronomy & Astrophysics |volume=555 |pages=A4 |doi=10.1051/0004-6361/201220769 |arxiv=1305.1644 |bibcode=2013A&A...555A...4M |issn=0004-6361}}
OQ 172 contains a core-jet structure with the radio core itself located in the northern region of the radio emission.{{Cite journal |last1=Mantovani |first1=F. |last2=Junor |first2=W. |last3=Bondi |first3=M. |last4=Cotton |first4=W. |last5=Fanti |first5=R. |last6=Padrielli |first6=L. |date=1998 |title=Large bent jets in the inner region of CSSs |url=https://articles.adsabs.harvard.edu/pdf/1998A%26A...332...10M |journal=Astronomy & Astrophysics |volume=332 |pages=10–18}} 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.{{Cite journal |last1=Punsly |first1=Brian |last2=Marziani |first2=Paola |last3=Kharb |first3=Preeti |last4=O’Dea |first4=Christopher P. |last5=Vestergaard |first5=Marianne |date=2015-10-09 |title=The Extreme Ultraviolet Deficit: Jet Connection In the Quasar 1442+101 |url=http://dx.doi.org/10.1088/0004-637x/812/1/79 |journal=The Astrophysical Journal |volume=812 |issue=1 |pages=79 |doi=10.1088/0004-637x/812/1/79 |arxiv=1509.02619 |bibcode=2015ApJ...812...79P |issn=1538-4357}}
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.{{Cite journal |last1=Udomprasert |first1=P. S. |last2=Taylor |first2=G. B. |last3=Pearson |first3=T. J. |last4=Roberts |first4=D. H. |date=1997-07-01 |title=Evidence for Ordered Magnetic Fields in the Quasar Environment |url=https://iopscience.iop.org/article/10.1086/310725/fulltext/ |journal=The Astrophysical Journal |volume=483 |issue=1 |pages=L9–L12 |doi=10.1086/310725 |issn=0004-637X|arxiv=astro-ph/9704112 |bibcode=1997ApJ...483L...9U }} 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.{{Cite journal |last1=Zhang |first1=Yingkang |last2=An |first2=Tao |last3=Frey |first3=Sándor |last4=Gabányi |first4=Krisztina Éva |last5=Sotnikova |first5=Yulia |date=September 2022 |title=Radio Jet Proper-motion Analysis of Nine Distant Quasars above Redshift 3.5 |journal=The Astrophysical Journal |language=en |volume=937 |issue=1 |pages=19 |doi=10.3847/1538-4357/ac87f8 |doi-access=free |issn=0004-637X|arxiv=2209.10760 |bibcode=2022ApJ...937...19Z }}
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. 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.{{Cite journal |last1=Liu |first1=Yi |last2=Jiang |first2=D. R. |last3=Gu |first3=Minfeng |last4=Gurvits |first4=L. I. |date=2017-03-15 |title=Multifrequency VLBA polarimetry of the high-redshift GPS quasar OQ172 |journal=Monthly Notices of the Royal Astronomical Society |volume=468 |issue=3 |pages=2699–2712 |doi=10.1093/mnras/stx617 |doi-access=free |issn=0035-8711|arxiv=1703.04066 }} When at 10 mas from the core, the jet's absolute value of RM decreases to <100 rad m−2. 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.
References
External links
- [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=QSO%20B1445%2B101 OQ 172 on SIMBAD]
- [http://ned.ipac.caltech.edu/cgi-bin/objsearch?search_type=Obj_id&objid=63686&objname=2&img_stamp=YES&hconst=73.0&omegam=0.27&omegav=0.73&corr_z=1 OQ 172 on NASA/IPAC Database]
{{Boötes}}