3C 346

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3C 346
SDSS image of 3C 346.jpg
SDSS image of 3C 346.
Observation data (J2000.0 epoch)
Constellation Hercules
Right ascension 16h 43m 48.59s [1]
Declination +17° 15′ 49.46″ [1]
Redshift 0.163025 [1]
Heliocentric radial velocity 48,874 km/s [1]
Distance 2.484 Gly (761.59 Mpc)
Apparent magnitude  (B)17.2
Characteristics
Type E;NLRG, Sy2 [1]
Size~452,900  ly (138.85  kpc) (estimated) [1]
Notable features Radio galaxy
Other designations
4C 17.70, PKS J1643+1715, PGC 58857, DA 422, OS 170, NVSS J164348+171548

3C 346 is an elliptical galaxy located in the constellation Hercules. It is located nearly 2.5 billion light years away from Earth and classified a Seyfert galaxy and a compact steep-spectrum source (CSS), [1] although later studies confirm it as a Fanaroff-Riley class II source. [2]

Contents

Characteristics

Hubble image, showing the jet 3C 346 HST.png
Hubble image, showing the jet

3C 346 is classified a narrow-line radio galaxy. [3] It has a projected 0.5-3 keV luminosity of 1.4 x 1044 ergs s−1. The galaxy has a lack of X-ray emission given most of it originates from a cluster environment with a temperature of 1.9+1.3-0.7. [4] It is part of a double galaxy system where the object is found merging with a nearby companion galaxy. [5] 3C 346 also contains a jetted double radio source when observed in X-rays [6] and a bright hotspot region showing strong emission in ultraviolet, mainly caused by synchrotron radiation. [7]

The point-like emission of 3C 346 is found to be unabsorbed, measuring NH ≤ 2 x 1021 cm−2 with a spectral slope of αx = 0.69+0.16-0.14 and flux of 7.4 x 10−13erg cm−2 s−1 when observed by ROSAT PSPC observations. However, when observed by the Advanced Satellite for Cosmology and Astrophysics (ASCA) two years later, the emission presents a different spectral slope of αx = 0.73+0.17-0.23 with a lower flux level of 7.4 x 10−13 erg cm−2 s−1. [8]

The nucleus of 3C 346 is found to be luminous. [5] It contains a core component in which a one-sided radio jet is seen emerging with a projected extension of around ~ 2 arcsecs, hinting the jet's inclination to the line of sight has a tiny angle. [9] Reaching at high radio frequencies, the jet of 3C 346 contains individual bright knots located at different positions with increased distances from the core region. [4]

According to the jet being detected using Hubble Space Telescope optical polarimetry, Very Large Array polarimetry at 14.9 and 22.5 GHz and data from Chandra X-ray observatory, it shows similarities between optical and radio morphology. However the X-ray emission is found offset by 0.80 ± 0.17 kiloparsecs from both optical and radio peak positions. Based on polarization modeling, the jet of 3C 346 has a relativistic upstream flow of βu = 0.91+0.05-0.07 with an inclined shock front plane angle of η = 51° ± 11° and upstream flow angle of θ = 14+8−7 degrees. The deflection angle of the jet on the other hand, is 22°. [10]

There is also the presence of an extended structure with an extent of ~ 12" around the jet and its opposite side. When observed at 1.7 GHz, the region has two other components with an estimated separation of ~ 2".2. One of the components is found to be stronger and compacted, while the other component is merely a glowing knot inside the jet and mainly surrounded by extended emission. [11]

References

  1. 1 2 3 4 5 6 7 "NED Search results for 3C 346". NASA/IPAC Extragalactic Database. Retrieved 2025-08-16.
  2. ↑ Dey, Arjun; van Breugel, Wil J. M. (1994-06-01). "Blue Optical Continuum Associated With a Radio Knot in 3C346". The Astronomical Journal. 107: 1977. Bibcode:1994AJ....107.1977D. doi:10.1086/117009. ISSN   0004-6256.
  3. ↑ Trussoni, E.; Capetti, A.; Celotti, A.; Chiaberge, M. (May 2000). "X-ray observations of 3C 66B and 3C 346". Memorie della Società Astronomica Italiana. 72 (1): 111–113. Bibcode:2001MmSAI..72..111T. ISSN   0037-8720.
  4. 1 2 Worrall, D. M.; Birkinshaw, M. (2001-04-10). "The X-Ray Emission of 3C 346 and Its Environment". The Astrophysical Journal. 551 (1): 178–185. arXiv: astro-ph/0012350 . Bibcode:2001ApJ...551..178W. doi:10.1086/320068. ISSN   0004-637X.
  5. 1 2 P. Madrid, Juan; Chiaberge, Marco; Floyd, David; B. Sparks, William; Macchetto, Duccio; K. Miley, George; Axon, David; Capetti, Alessandro; P. O'Dea, Christopher; Baum, Stefi (June 2006). "Hubble Space Telescope Near-Infrared Snapshot Survey of 3CR Radio Source Counterparts at Low Redshift1". The Astrophysical Journal Supplement Series. 164 (2): 307–333. arXiv: astro-ph/0603239 . Bibcode:2006ApJS..164..307M. doi:10.1086/504480.
  6. ↑ Hardcastle, M. J.; Worrall, D. M. (1999-11-11). "ROSAT X-ray observations of 3CRR radio sources". Monthly Notices of the Royal Astronomical Society. 309 (4): 969–990. arXiv: astro-ph/9907034 . Bibcode:1999MNRAS.309..969H. doi: 10.1046/j.1365-8711.1999.02945.x . ISSN   0035-8711.
  7. ↑ de Vries, W. H.; O'Dea, C. P.; Baum, S. A.; Sparks, W. B.; Biretta, J.; de Koff, S.; Golombek, D.; Lehnert, M. D.; Macchetto, F.; McCarthy, P.; Miley, G. K. (June 1997). "Hubble Space Telescope|Imaging of Compact Steep Spectrum Radio Sources". The Astrophysical Journal Supplement Series. 110 (2): 191–211. Bibcode:1997ApJS..110..191D. doi:10.1086/313001. ISSN   0067-0049.
  8. ↑ Trussoni, E.; Capetti, A.; Celotti, A.; Chiaberge, M.; Feretti, L. (March 2003). "A multi-wavelength test of the FR I–BL Lac unifying model" (PDF). Astronomy & Astrophysics. 403 (3): 889–899. arXiv: astro-ph/0304018 . Bibcode:2003A&A...403..889T. doi:10.1051/0004-6361:20030417.
  9. ↑ Gupta, Neeraj; Salter, C. J.; Saikia, D. J.; Ghosh, T.; Jeyakumar, S. (2006-11-13). "Probing radio source environments via H i and OH absorption". Monthly Notices of the Royal Astronomical Society. 373 (3): 972–992. arXiv: astro-ph/0605423 . Bibcode:2006MNRAS.373..972G. doi: 10.1111/j.1365-2966.2006.11064.x . ISSN   0035-8711.
  10. ↑ Dulwich, F.; Worrall, D. M.; Birkinshaw, M.; Padgett, C. A.; Perlman, E. S. (2009-09-21). "The magnetic field and geometry of the oblique shock in the jet of 3C 346". Monthly Notices of the Royal Astronomical Society. 398 (3): 1207–1216. arXiv: 0907.3739 . Bibcode:2009MNRAS.398.1207D. doi: 10.1111/j.1365-2966.2009.15211.x . ISSN   0035-8711.
  11. ↑ Cotton, W.D.; Feretti, L.; Giovannini, G.; Venturi, T.; Lara, L.; Marcaide, J.; Wherle, A.E. (October 1995). "VLBI Observations of a Complete Sample of Radio Galaxies. V. 3C 346 and 4C 31.04: Two Unusual Compact Steep Spectrum Sources". The Astrophysical Journal. 452: 605–612. arXiv: astro-ph/9506038 . Bibcode:1995ApJ...452..605C. doi:10.1086/176333.
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