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4C 25.21

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4C 25.21
The quasar 4C 25.21.
Observation data (J2000.0 epoch)
ConstellationGemini
Right ascension07h 33m 08.7792s[1]
Declination+25° 36′ 24.973″[1]
Redshift2.689711[1]
Heliocentric radial velocity806,355 km/s[1]
Distance10.894 Gly
Apparent magnitude (V)19.26
Apparent magnitude (B)19.60
Characteristics
TypeRLQ[1]
Other designations
B2 0730+25A, [HB89] 0730+257, LEDA 2819888, PKS B0730+257, OI +250, Cul 0730+257, 2CXO J073308.7+253624[1]

4C 25.21 is a radio-loud[2] quasar located in the northern constellation of Gemini. It has a high redshift of (z) 2.689[1] and it was first discovered as an astronomical radio source in August 1967, where it was subsequently identified with a bright object found close to its radio position three years later.[3][4] This object has also been classified as having a Fanaroff-Riley Type II morphology, but is also categorized as a weak-headed quasar (WHQ) with a jet and faint traces of hotspots.[5][6]

Description

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The radio structure of 4C 25.21 is described as a single elongated compact component based on observations using the Cambridge 5-km Telescope, by both J.M. Riley and G.G. Pooley.[7][8] It has a weak radio core, clearly resolved with Very Long Baseline Interferometry observations.[9][10] The core contains a steep radio spectrum based on a 2 centimeter radio mapping. A flux density of 17 Sc was also found for the core, when observed at 5 GHz frequencies.[9]

4C 25.21 contains a powerful jet found to be one-sided, with a flux measuring 126 Sj.[9] This jet has an extension of 8.06 kiloparsecs.[11] An X-ray jet counterpart was also found, based on evidence of an additional structure from the quasar.[12] X-ray emission is present along its direction between its hotspot and inner jet, likely caused by inverse Compton scattering from the cosmic microwave background. Further evidence finds the emission was also found in the upstream direction of a faint radio peak, suggesting the absence of radio emission in these X-ray jets.[13]

Lyman-alpha emission was detected towards northwest of the quasar, mainly dominating the area. Continuum emission extends asymmetrically in both the southeast and south as well, based on optical deep imaging.[14] Radio emission was also detected by the Very Large Array with its 4 GHz peak flux reaching 338.28 mJy in 1999.[15]

References

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  1. ^ a b c d e f g "NED search results for 4C 25.21". NASA/IPAC Extragalactic Database. Retrieved 2025-06-01.
  2. ^ Lehnert, Matthew D.; Heckman, Timothy M.; Chambers, Kenneth C.; Miley, George K. (July 1992). "Multicolor Images of Spatially Resolved Structures around High-Redshift Quasars". The Astrophysical Journal. 393: 68. Bibcode:1992ApJ...393...68L. doi:10.1086/171485. hdl:1887/6624. ISSN 0004-637X.
  3. ^ Olsen, E. T. (August 1967). "Accurate positions of selected 4C sources". The Astronomical Journal. 72: 738–746. Bibcode:1967AJ.....72..738O. doi:10.1086/110302. ISSN 0004-6256.
  4. ^ Hazard, C.; Jauncey, D. L.; Backer, D. C. (November 1970). "The Identification of 4C Sources Using the 4C Right Ascensions and Arecibo Declinations". The Astronomical Journal. 75: 1039. Bibcode:1970AJ.....75.1039H. doi:10.1086/111058. ISSN 0004-6256.
  5. ^ Punsly, Brian (2007-01-01). "Kinetically dominated FR II radio sources". Monthly Notices of the Royal Astronomical Society: Letters. 374 (1): L10 – L14. arXiv:astro-ph/0610042. Bibcode:2007MNRAS.374L..10P. doi:10.1111/j.1745-3933.2006.00254.x. ISSN 1745-3933.
  6. ^ Gopal-Krishna; Wiita, P. J.; Hooda, J. S. (December 1996). "Weak headed quasars". Astronomy and Astrophysics. 316: L13 – L16. Bibcode:1996A&A...316L..13G. ISSN 0004-6361.
  7. ^ Riley, J. M.; Pooley, G. G. (1975). "Observations of 31 extragalactic radio sources with the Cambridge 50-km telescope at 5 GHz". Memoirs of the Royal Astronomical Society. 80: 105. Bibcode:1975MmRAS..80..105R.
  8. ^ Stannard, D.; Neal, D. S. (1977-08-01). "A comparative study of the properties of 3CR and 4C quasars". Monthly Notices of the Royal Astronomical Society. 179 (4): 719–740. Bibcode:1977MNRAS.179..719S. doi:10.1093/mnras/179.4.719. ISSN 0035-8711.
  9. ^ a b c Lonsdale, C. J.; Barthel, P. D. (December 1987). "Radio Sources with Strong Jets and Weak Core". The Astronomical Journal. 94: 1487. Bibcode:1987AJ.....94.1487L. doi:10.1086/114582. ISSN 0004-6256.
  10. ^ Barthel, P. D. (October 1983). "A VLBI search for compact components in extended high redshift quasars". Astronomy and Astrophysics. 126: 16–21. Bibcode:1983A&A...126...16B. ISSN 0004-6361.
  11. ^ McKeough, Kathryn; Siemiginowska, Aneta; Cheung, C. C.; Stawarz, Łukasz; Kashyap, Vinay L.; Stein, Nathan; Stampoulis, Vasileios; Dyk, David A. van; Wardle, J. F. C.; Lee, N. P.; Harris, D. E.; Schwartz, D. A.; Donato, Davide; Maraschi, Laura; Tavecchio, Fabrizio (2016-12-10). "Detecting Relativistic X-Ray Jets in High-Redshift Quasars". The Astrophysical Journal. 833 (1): 123. arXiv:1609.03425. Bibcode:2016ApJ...833..123M. doi:10.3847/1538-4357/833/1/123. ISSN 0004-637X.
  12. ^ Stein, Nathan M.; Dyk, David A. van; Kashyap, Vinay L.; Siemiginowska, Aneta (2015-10-15), "Detecting Unspecified Structure in Low-Count Images", The Astrophysical Journal, 813 (1): 66, arXiv:1510.04662, Bibcode:2015ApJ...813...66S, doi:10.1088/0004-637X/813/1/66, retrieved 2025-06-01
  13. ^ Reddy, Karthik; Georganopoulos, Markos; Meyer, Eileen T. (2021-03-17). "X-Ray-to-radio Offset Inference from Low-count X-Ray Jets". The Astrophysical Journal Supplement Series. 253 (2): 37. arXiv:2101.02024. Bibcode:2021ApJS..253...37R. doi:10.3847/1538-4365/abd8d7. ISSN 0067-0049.
  14. ^ Heckman, Timothy M.; Lehnert, Matthew D.; van Breugel, Wil; Miley, George K. (March 1991). "Spatially Resolved Optical Images of High-Redshift Quasi-stellar Objects". The Astrophysical Journal. 370: 78. Bibcode:1991ApJ...370...78H. doi:10.1086/169794. ISSN 0004-637X.
  15. ^ Wadadekar, Yogesh; Kembhavi, Ajit (1999-06-25), "A Study of Quasar Radio Emission from the VLA FIRST Survey", The Astronomical Journal, 118 (4): 1435–1443, arXiv:astro-ph/9906408, Bibcode:1999AJ....118.1435W, doi:10.1086/301046, arXiv:astro-ph/9906408
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