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4C 19.44

In this article we are going to explore 4C 19.44 in depth. From its origins to its evolution in today's society, 4C 19.44 has played a fundamental role in various aspects of daily life. Throughout history, 4C 19.44 has been the subject of study and research by experts in the field, who have contributed to expanding our knowledge on this topic. Furthermore, 4C 19.44 has been a topic of debate and controversy in different contexts, which has generated great interest in understanding its impact on society. Through this article, we will try to shed light on the different aspects of 4C 19.44 and its importance today.

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4C 19.44
The quasar 4C 19.44
Observation data (J2000.0 epoch)
ConstellationBoötes
Right ascension13h 57m 04.43s[1]
Declination+19° 19′ 07.37″[1]
Redshift0.719668[1]
Heliocentric radial velocity215751 km/s[1]
Distance6.605 Gly
Apparent magnitude (V)16.03
Characteristics
TypeOpt.var. Sy1.5[1]
Size~241,300 ly (73.98 kpc) (estimated)[1]
Other designations
CoNFIG 181, DA 354, LEDA 2819584, G4Jy 1108, OP +191, PKS 1354+19, SDSS J135704.43+191907.3, VIPS 0717, WMAP 004, VRO 19.13.06[1]

4C 19.44 is a quasar located in the constellation of Boötes. The redshift of the quasar is (z) 0.719[1] and it was first discovered in September 1966 by astronomers J.G. Bolton and T.D. Kinman as a quasi-stellar object.[2] This quasar is best known for its extremely long radio jet.[3]

Description

4C 19.44 is found to be mildly variable based on optical monitoring, which it underwent least one steady brightening event between February 1969 and December 1970.[4][5] However, no variability was noted at 2.2 ɥm.[6]

The radio structure of 4C 19.44 is found to be compact. When observed by Very Long Baseline Interferometry (VLBI), it is found to have a double structure, with its components separated by 0.75 milliarcseconds from each other and orientated along the position angle of -29°. The radio spectrum of the quasar is categorized as of low frequencies and being dominated by a component of steep spectrum. When observed higher than 2 GHz, the radio spectrum becomes flat with a flux density mainly at 1.0 and 2.0 Jansky.[7] Radio imaging made by Very Large Array (VLA), would find it as a triple source instead with its total extend of 44 arcseconds. There is also a north-west component present with a spectral index of 1.04 ± 0.05.[8] A core-jet structure is found located mainly within its nucleus.[9]

The jet of 4C 19.44 is described as one-sided, long and straight with a distance of 18 arcseconds.[10][11] When observed, the jet is found to extend towards the south-east direction before ending in a hotspot position with a knotty appearance containing 11 jet knots in total.[12] Further evidence also pointed out that the jet shows wiggles close to the position of the radio core but remains straight for about nine arcseconds within the core then turns towards east direction. There are also traces of high polarization levels of around 24.7 ± 6.0% with a main position angle of 84 ± 6°.[13] This jet is also observed by Chandra X-ray Observatory where detections of X-ray emission are found.[14]

A study finds there are radio lobes present in the quasar. Based on studies, the lobe on the northern side is located in the direction of its counter-jet, about 16 arcseconds away and has a position angle of -14°. Evidence also found there are features inside the lobe, which is a bright hotspot and a bright knot feature that is separated from the hotspot and located four arcseconds west. Polarization is mainly low in the hotspot, only at 2% suggesting the possibility of its magnetic field rotation direction.[13]

References

  1. ^ a b c d e f g h "NED Search results for 4C 19.44". NASA/IPAC Extragalactic Database. Retrieved 2025-12-13.
  2. ^ Bolton, J. G.; Kinman, T. D. (September 1966). "Radio and Optical Data on Twelve Quasi-Stellar Objects". The Astrophysical Journal. 145: 951. Bibcode:1966ApJ...145..951B. doi:10.1086/148842. ISSN 0004-637X.
  3. ^ "The remarkable jet of the quasar 4C+19.44". Archived from the original on 2022-11-26. Retrieved 2025-12-13.
  4. ^ Tritton, K. P.; Selmes, R. A. (1971-09-01). "Optical Monitoring of Radio Sources--III: Further Observations of Quasars" (PDF). Monthly Notices of the Royal Astronomical Society. 153 (4): 453–469. doi:10.1093/mnras/153.4.453. ISSN 0035-8711.
  5. ^ Lu, Phillip K. (December 1972). "Optical Monitoring of Quasistellar Objects. I". The Astronomical Journal. 77: 829. Bibcode:1972AJ.....77..829L. doi:10.1086/111356. ISSN 0004-6256.
  6. ^ Cutri, R. M.; Wisniewski, W. Z. (September 1983). "Simultaneous Optical and Infrared Photometry of Mildly Variable, Low Polarization QSO's". Bulletin of the American Astronomical Society. 15: 958. Bibcode:1983BAAS...15..958C.
  7. ^ Marscher, A. P.; Broderick, J. J. (June 1983). "VLBI observations of the quasars CTD 20 (0234+285), OJ 248 (0827+243), and 4C 19.44 (1354+195) and the millimeter X-ray connection". The Astronomical Journal. 88: 759–763. Bibcode:1983AJ.....88..759M. doi:10.1086/113364. ISSN 0004-6256.
  8. ^ Saikia, D. J.; Shastri, P.; Sinha, R. P.; Kapahi, V. K.; Swarup, G. (December 1984). "Extragalactic Sources with Asymmetric Radio Structure - Part One - Observations of 17 Sources". Journal of Astrophysics and Astronomy. 5 (4): 429–473. Bibcode:1984JApA....5..429S. doi:10.1007/BF02714470. ISSN 0250-6335.
  9. ^ Saikia, D. J.; Holmes, G. F.; Kulkarni, A. R.; Salter, C. J.; Garrington, S. T. (August 1998). "Polarization observations of the radio cores of AGN - I. A sample of quasars". Monthly Notices of the Royal Astronomical Society. 298 (3): 877–887. Bibcode:1998MNRAS.298..877S. doi:10.1046/j.1365-8711.1998.01699.x. ISSN 0035-8711.
  10. ^ Punsly, Brian (2015-06-05). "Evidence of the Dynamics of Relativistic Jet Launching in Quasars". The Astrophysical Journal. 806 (1): 47. arXiv:1504.00228. Bibcode:2015ApJ...806...47P. doi:10.1088/0004-637x/806/1/47. ISSN 1538-4357.
  11. ^ Schwartz, D. A.; Harris, D. E.; Landt, H.; Siemiginowska, A.; Marshall, H. L.; Gelbord, J. M.; Perlman, E. S.; Georganopoulos, M.; Birkinshaw, M.; Worrall, D. M.; Cheung, C. C.; Stawarz, L.; Jorstad, S. G.; Marscher, A. P.; Uchiyama, Y. (October 2007). "The X-ray jet and lobes of PKS 1354+195 (=4C 19.44)". Astrophysics and Space Science. 311 (1–3): 341–345. Bibcode:2007Ap&SS.311..341S. doi:10.1007/s10509-007-9548-y. ISSN 0004-640X.
  12. ^ Harris, D. E.; Moldón, J.; Oonk, J. R. R.; Massaro, F.; Paggi, A.; Deller, A.; Godfrey, L.; Morganti, R.; Jorstad, S. G. (March 2019). "LOFAR Observations of 4C+19.44: On the Discovery of Low-frequency Spectral Curvature in Relativistic Jet Knots". The Astrophysical Journal. 873 (1): 21. arXiv:1903.06824. Bibcode:2019ApJ...873...21H. doi:10.3847/1538-4357/ab01ff. ISSN 0004-637X.
  13. ^ a b Harris, D. E.; Lee, N. P.; Schwartz, D. A.; Siemiginowska, A.; Massaro, F.; Birkinshaw, M.; Worrall, D. M.; Cheung, C. C.; Gelbord, J. M.; Jorstad, Svetlana G.; Marscher, Alan P.; Landt, H.; Marshall, H.; Perlman, E. S.; Stawarz, L. (2017-09-08). "A Multi-band Study of the Remarkable Jet in Quasar 4C+19.44". The Astrophysical Journal. 846 (2): 119. arXiv:1708.01500. Bibcode:2017ApJ...846..119H. doi:10.3847/1538-4357/aa845c. ISSN 0004-637X.
  14. ^ Sambruna, Rita M.; Maraschi, L.; Tavecchio, F.; Urry, C. Megan; Cheung, C. C.; Chartas, G.; Scarpa, R.; Gambill, Jessica K. (2002-05-20). "A Survey of Extended Radio Jets in Active Galactic Nuclei withChandraand theHubble Space Telescope: First Results". The Astrophysical Journal. 571 (1): 206–217. arXiv:astro-ph/0201412. Bibcode:2002ApJ...571..206S. doi:10.1086/339859. ISSN 0004-637X.
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