PKS 0208-512 is a blazar[1] located in the southern constellation of Eridanus. It has a redshift of 1.003[2] and was first discovered in 1975 by astronomers conducting the Parkes 2700 MHz survey in Australia as a bright astronomical radio source.[3] This object is also classified highly polarized[4] with the radio spectrum appearing to be flat, thus making it a flat-spectrum radio quasar.[5]
| PKS 0208-512 | |
|---|---|
 The blazar PKS 0208-512 | |
| Observation data (J2000.0 epoch) | |
| Constellation | Eridanus |
| Right ascension | 02h 10m 46.200s |
| Declination | −51° 01′ 01.892″ |
| Redshift | 0.999000 |
| Heliocentric radial velocity | 299,493 km/s |
| Distance | 7.926 Gly |
| Apparent magnitude (V) | 16.93 |
| Apparent magnitude (B) | 17.1 |
| Characteristics | |
| Type | HPQ, BL LAC |
| Other designations | |
| LEDA 2822981, HE 0208-5115, PMN J0210-5101, WMAP 158, 3FGL J0210.7-5101 | |
Description
editPKS 0208-512 is found to be strongly variable on the electromagnetic spectrum. It shows a significant correlation between its intensity and spectral index,[2] and is a source of gamma ray activity.[6][7][8] It is known to have three powerful outbursts when observed at optical to near-infrared wavelengths.[9] Between September 11 and 30 in 2008, the quasar brightened upon showing a flare, with increased magnitudes in both B-band and R-band.[10] In the gamma ray lightcurve, it showed a variable flux reaching a factor of 6 on timescales of weeks.[11]
A major gamma ray flare was detected in PKS 0208-512 between November 2019 and May 2020.[12][13] Fermi-LAT observations proposed that its daily average gamma ray flux at > 100 MeV amplified to 1.1 ± 0.2 x 10−6 ph cm−2 s−1 on November 29, 2019, and subsequently to 2.0 ± 0.3 x 10−6 ph cm−2 s−1 by March 15, 2020. During the activity, the gamma ray lightcurve exhibited multiple peaks indicating the presence of subflares.[13]
PKS 0208-512 has a complex radio structure.[14] It is made up of a compact radio core with a projected spectral flux density of 2.8 Jansky and a jet component located at a position angle of 234° from the core with an angular separation of 1.7 mas. Using 2.3 and 5.0 GHz results, the core has a spectral index of 0.15, as well as having an obtained brightness temperature of 1.9 x 1012 K.[4] There is also a long jet present at a position angle of -129°. This jet is found similar to the milliarcsecond-scale radio jet's position angle, suggesting it is straight from parsec to kiloparsec scales.[15] When seen through the jet's structure, there are four knot regions which increases orderly from the nucleus.[14]
The supermassive black hole in PKS 0208-512 is estimated to be 6 x 107 Mʘ based on an assumption of its isotopic Eddington-limited emission.[2] A luminosity of Ld ≈ 8 x 1045 erg s−1 was estimated for its accretion disk.[9]
References
edit- ^ Chatterjee, Ritaban; Bailyn, C. D.; Bonning, E. W.; Buxton, M.; Coppi, P.; Isler, J.; Urry, C. M.; Fossati, G.; Maraschi, L. (2011-08-01). "Optical-IR Re-Brightening of the Blazar PKS 0208-512". The Astronomer's Telegram. 3591: 1. Bibcode:2011ATel.3591....1C.
- ^ a b c Stacy, J. Gregory; Vestrand, W. Thomas; Sreekumar, P. (2003-11-20). "The Gamma-Ray Blazar PKS 0208−512 from MeV to GeV Energies". The Astrophysical Journal. 598 (1): 216–231. doi:10.1086/377632. ISSN 0004-637X.
- ^ Wall, J. V.; Shimmins, A. J.; Bolton, J. G. (1975-01-01). "The Parkes 2700 MHz Survey (Ninth Part): Supplementary Catalogue for the Declination zone -45o to -65o". Australian Journal of Physics Astrophysical Supplement. 34: 55.
- ^ a b Zhen, Z.Q.; Wan, T.S.; Moran, J.M.; Jauncey, D.L.; Jiang, D.R.; Edwards, P.G.; Costa, M.E. (April 1998). "A 5 GHz Southern Hemisphere VLBI Survey of Compact Radio Sources. II". The Astronomical Journal. doi:10.1086/300284. Retrieved 2024-10-26.
- ^ Szostek, A. (2011-05-01). "Fermi LAT detection of gamma ray activity from blazar PKS 0208-512". The Astronomer's Telegram. 3338: 1. Bibcode:2011ATel.3338....1S.
- ^ Lucarelli, F.; Tavani, M.; Pittori, C.; Verrecchia, F.; Bulgarelli, A.; Parmiggiani, N.; Fioretti, V.; Cardillo, M.; Casentini, C.; Piano, G.; Ursi, A.; Donnarumma, I.; Vercellone, S.; Gianotti, F.; Trifoglio, M. (2019-12-01). "AGILE detection of enhanced gamma-ray activity from the FSRQ PKS 0208-512". The Astronomer's Telegram. 13352: 1. Bibcode:2019ATel13352....1L.
- ^ Nesci, R.; Kadler, M.; Ojha, R.; Pursimo, T.; Tosti, G.; Blanchard, J.; Lovell, J. (2011-06-01). "NIR follow-up of PKS 0208-512". The Astronomer's Telegram. 3421: 1. Bibcode:2011ATel.3421....1N.
- ^ Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasselwander, H. A. (1993-03-01). "Detection of gamma-ray emission from the quasar PKS 0208-512". Astrophysical Journal, Part 2 - Letters. 405 (1): L21. doi:10.1086/186756. ISSN 0004-637X.
- ^ a b Chatterjee, Ritaban; Nalewajko, Krzysztof; Myers, Adam D. (2013-06-21). "Implications of the Anomalous Outburst in the Blazar PKS 0208–512". The Astrophysical Journal. 771 (2): L25. arXiv:1306.1531. doi:10.1088/2041-8205/771/2/l25. ISSN 2041-8205.
- ^ Buxton, M.; Bailyn, C.; Coppi, P.; Kaptur, A.; Isler, J.; Urry, M.; Maraschi, L.; Fossati, G. (2008-10-01). "Increase in optical brightness of blazar PKS 0208-512". The Astronomer's Telegram. 1751: 1. Bibcode:2008ATel.1751....1B.
- ^ Zhang, S.; Collmar, W.; Torres, D. F.; Wang, J.-M.; Lang, M.; Zhang, S.-N. (May 2010). "INTEGRAL and Swift/XRT observations of the source PKS 0208-512" (PDF). Astronomy and Astrophysics. 514: A69. doi:10.1051/0004-6361/200913655. ISSN 0004-6361.
- ^ Ammenadka, Krishna Mohana; Bhattacharya, Debbijoy; Bhattacharyya, Subir; Bhatt, Nilay; Stalin, Chelliah Subramonian (2022-10-01). "Long-Term Monitoring of Blazar PKS 0208-512: A Change of γ-Ray Baseline Activity from EGRET to Fermi Era". Universe. 8 (10): 534. Bibcode:2022Univ....8..534A. doi:10.3390/universe8100534.
- ^ a b Khatoon, Rukaiya; Prince, Raj; Shah, Zahir; Sahayanathan, Sunder; Gogoi, Rupjyoti (2022-04-25). "Temporal and spectral study of PKS 0208−512 during the 2019–2020 flare". Monthly Notices of the Royal Astronomical Society. 513 (1): 611–623. arXiv:2104.12130. doi:10.1093/mnras/stac892. ISSN 0035-8711.
- ^ a b Perlman, Eric S.; Georganopoulos, Markos; Marshall, Herman L.; Schwartz, Daniel A.; Padgett, C. A.; Gelbord, Jonathan; Lovell, J. E. J.; Worrall, Diana M.; Birkinshaw, Mark; Murphy, David W.; Jauncey, David L. (2011-09-07). "Deep Multiwaveband Observations of the Jets of 0208-512 and 1202-262". The Astrophysical Journal. 739 (2): 65. arXiv:1107.2058. doi:10.1088/0004-637x/739/2/65. ISSN 0004-637X.
- ^ Marshall, H. L.; Schwartz, D. A.; Lovell, J. E. J.; Murphy, D. W.; Worrall, D. M.; Birkinshaw, M.; Gelbord, J. M.; Perlman, E. S.; Jauncey, D. L. (January 2005). "A Chandra Survey of Quasar Jets: First Results". The Astrophysical Journal Supplement Series. 156 (1): 13–33. doi:10.1086/425578. ISSN 0067-0049.