IMPLICATIONS OF THE ANOMALOUS OUTBURST IN THE BLAZAR PKS 0208-512
- Department of Physics and Astronomy 3905, University of Wyoming, 1000 East University, Laramie, WY 82071 (United States)
- University of Colorado, 440 UCB, Boulder, CO 80309 (United States)
The flat spectrum radio quasar (FSRQ) PKS 0208-512 underwent three outbursts at the optical-near-infrared (OIR) wavelengths during 2008-2011. The second OIR outburst did not have a {gamma}-ray counterpart despite being comparable in brightness and temporal extent to the other two. We model the time variable spectral energy distribution of PKS 0208-512 during those three flaring episodes with leptonic models to investigate the physical mechanism that can produce this anomalous flare. We show that the redder-when-brighter spectral trend in the OIR bands can be explained by the superposition of a fixed thermal component from the accretion disk and a synchrotron component of fixed shape and variable normalization. We estimate the accretion disk luminosity at L{sub d} {approx_equal} 8 Multiplication-Sign 10{sup 45} erg s{sup -1}. Using the observed variability timescale in the OIR band t{sub var,obs} {approx_equal} 2 days and the X-ray luminosity L{sub X} {approx_equal} 3.5 Multiplication-Sign 10{sup 45} erg s{sup -1}, we are able to constrain the location of the emitting region to distance scales that are broadly comparable with the dusty torus. We show that variations in the Compton dominance parameter by a factor of {approx}4-which may result in the anomalous outburst-can be relatively easily accounted for by moderate variations in the magnetic field strength or the location of the emission region. Since such variations appear to be rare among FSRQs, we propose that most {gamma}-ray/OIR flares in these objects are produced in jet regions where the magnetic field and external photon fields vary similarly with distance along the jet, e.g., u{sub B}{sup '}{proportional_to}u{sub ext}{sup '}{proportional_to}r{sup -2}.
- OSTI ID:
- 22118702
- Journal Information:
- Astrophysical Journal Letters, Vol. 771, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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