Astronomy:PKS 0405−385

From HandWiki
Short description: Quasar in the constellation Eridanus
PKS 0405−385
The blazar PKS 0405−385
Observation data (Epoch J2000.0)
ConstellationEridanus
Right ascension 04h 06m 59.035s[1]
Declination−38° 26′ 28.04″[1]
Redshift1.285[2]
TypeFSRQ[3]
Other designations
4FGL J0407.0−3826[4]
See also: Quasar,List of quasars]]

PKS 0405−385 is a blazar[5] in the constellation of Eridanus. This is a compact radio quasar with a redshift (z) of 1.285, an indicator of its significant distance.[6] The radio spectrum of this source appears flat, making it a flat-spectrum radio quasar (FSRQ).[3]

Description

The visible light spectrum of PKS 0405−385 displays strong, broad emission lines, with an intermediate absorption occurring at a redshift of 0.875.[6] Examination using VLBI shows the radio source spans less than five microarcseconds (μas) in angle.[7] In 1993, this quasar was found to undergo variation in radio flux density during time spans of less than an hour. This variability is intermittent during episodes lasting for weeks or months.[6][8] The radio flux was also found to vary on longer timescales for periods of a month or two.[9]

If the short-term variation were due to the quasar, it would imply an extreme brightness temperature of about 1021 K.[6] Instead, it was proposed that the variation was the result of interstellar scintillation due to ionized clouds in the Milky Way.[9][10] The radio emission from the quasar underwent rotation of linear polarization during these events, lending support to the idea of scintillation.[11] A scattering medium at a distance of 3–30 pc would explain these observations, bringing the modelled peak brightness temperature down to a more plausible 2.0×1013 K.[12][9] The episodic nature of the rapid variations may be explained by changes in the quasar or the interstellar medium.[7] PKS 0405−385 is one of only three known extreme scintillators, the others being PKS 1257−326 and J1819+385.[7]

In 2022, the gamma ray emission from PKS 0405−385 was found to undergo quasi-periodic oscillation with a period of about 2.8 years. This may be explained by helical motion in a jet originating from the supermassive black hole (SMBH), or the core SMBH is itself a binary system.[13][5] Enhanced gamma ray activity was observed from this source in 2019 and 2023.[3][14]

References

  1. ↑ 1.0 1.1 Charlot, P. et al. (2020), "The third realization of the International Celestial Reference Frame by very long baseline interferometry", Astronomy and Astrophysics 644: A159, doi:10.1051/0004-6361/202038368, Bibcode: 2020A&A...644A.159C. 
  2. ↑ Drinkwater, M. J. et al. (January 1997), "The Parkes Half-Jansky Flat-Spectrum Sample", Monthly Notices of the Royal Astronomical Society 284 (1): 85–125, doi:10.1093/mnras/284.1.85, ISSN 0035-8711, Bibcode: 1997MNRAS.284...85D. 
  3. ↑ 3.0 3.1 3.2 Dai, X. et al. (March 2019), "Significant Flux Increase of Blazar PKS 0405-385 Detected by ASAS-SN", The Astronomer's Telegram 12609, Bibcode: 2019ATel12609....1D. 
  4. ↑ "QSO B0405-385". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=QSO+B0405-385. 
  5. ↑ 5.0 5.1 Gong, Yunlu et al. (June 2022), "Quasiperiodic Behavior in the γ-Ray Light Curve of the Blazar PKS 0405-385", The Astrophysical Journal 931 (2): id. 168, doi:10.3847/1538-4357/ac6c8c, Bibcode: 2022ApJ...931..168G. 
  6. ↑ 6.0 6.1 6.2 6.3 Kedziora-Chudczer, L. et al. (November 1997), "PKS 0405-385: The Smallest Radio Quasar?", The Astrophysical Journal 490 (1): L9–L12, doi:10.1086/311001, Bibcode: 1997ApJ...490L...9K. 
  7. ↑ 7.0 7.1 7.2 Kedziora-Chudczer, L. (June 2006), "Long-term monitoring of the intra-day variable quasar PKS 0405-385", Monthly Notices of the Royal Astronomical Society 369 (1): 449–464, doi:10.1111/j.1365-2966.2006.10321.x, Bibcode: 2006MNRAS.369..449K. 
  8. ↑ Cimo, G. et al. (September 2004), Green, D. W. E., ed., "PKS 0405-385", IAU Circular (8403): 1, Bibcode: 2004IAUC.8403....1C. 
  9. ↑ 9.0 9.1 9.2 Protheroe, R. J. (May 2003), "The brightness temperature problem in extreme intra-day variable quasars: a model for PKS 0405-385", Monthly Notices of the Royal Astronomical Society 341 (1): 230–238, doi:10.1046/j.1365-8711.2003.06429.x, Bibcode: 2003MNRAS.341..230P. 
  10. ↑ Kedziora-Chudczer, L. L. et al. (1998), Zensus, J. A.; Taylor, G. B.; Wrobel, J. M., eds., "PKS 0405-385 as Seen by the ISM Telescope", Radio Emission from Galactic and Extragalactic Compact Sources, IAU Colloquium 164, ASP Conference Series 144: p. 267, Bibcode: 1998ASPC..144..267K. 
  11. ↑ Rickett, Barney J. et al. (2002), "Interstellar Scintillation Explains the Intraday Variations in the Linear Polarisation of Quasar PKS 0405-385 at cm-wavelengths", Publications of the Astronomical Society of Australia 19 (1): 106–110, doi:10.1071/AS01119, Bibcode: 2002PASA...19..106R. 
  12. ↑ Rickett, Barney J. et al. (December 2002), "Interstellar Scintillation of the Polarized Flux Density in Quasar PKS 0405-385", The Astrophysical Journal 581 (1): 103–126, doi:10.1086/344167, Bibcode: 2002ApJ...581..103R. 
  13. ↑ Nowakowski, Tomasz (May 16, 2022), Quasi-periodic oscillation detected in blazar PKS 0405-385, https://phys.org/news/2022-05-quasi-periodic-oscillation-blazar-pks-.html, retrieved 2024-10-12. 
  14. ↑ Bernard, Denis (August 2023), "Fermi-LAT detection of enhanced gamma-ray activity from the FSRQ PKS 0405-385", The Astronomer's Telegram 16183, Bibcode: 2023ATel16183....1B. 



Retrieved from "https://handwiki.org/wiki/index.php?title=Astronomy:PKS_0405−385&oldid=3942935"