Suzaku Observations of Luminous Quasars: Revealing the Nature of High-Energy Blazar Emission in Low-level activity States
We present the results from the Suzaku X-ray observations of five flat-spectrum radio quasars (FSRQs), namely PKS 0208–512, Q 0827+243, PKS 1127–145, PKS 1510–089, and 3C 454.3. Here, all these sources were additionally monitored simultaneously or quasi-simultaneously by the Fermi satellite in gamma rays and the Swift UVOT in the UV and optical bands, respectively. Here, we constructed their broadband spectra covering the frequency range from 1014 Hz up to 1025 Hz, and those reveal the nature of high-energy emission of luminous blazars in their low-activity states. The analyzed X-ray spectra are well fitted by a power-law model with photoelectric absorption. In the case of PKS 0208–512, PKS 1127–145, and 3C 454.3, the X-ray continuum showed indication of hardening at low energies. Moreover, when compared with the previous X-ray observations, we see a significantly increasing contribution of low-energy photons to the total X-ray fluxes when the sources are getting fainter. The same behavior can be noted in the Suzaku data alone. A likely explanation involves a variable, flat-spectrum component produced via inverse-Compton emission, plus an additional, possibly steady soft X-ray component prominent when the source gets fainter. This soft X-ray excess is represented either by a steep power-law (photon indices Γ ~ 3-5) or a blackbody-type emission with temperatures kT ~ 0.1-0.2 keV. We model the broadband spectra of the five observed FSRQs using synchrotron self-Compton and/or external-Compton radiation models. Lastly, our modeling suggests that the difference between the low- and high-activity states in luminous blazars is due to the different total kinetic power of the jet, most likely related to varying bulk Lorentz factor of the outflow within the blazar emission zone.
- Research Organization:
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- Sponsoring Organization:
- USDOE; National Aeronautics and Space Administration (NASA)
- Contributing Organization:
- The Fermi LAT Collaboration
- Grant/Contract Number:
- AC02-76SF00515
- OSTI ID:
- 1357551
- Journal Information:
- The Astrophysical Journal, Vol. 716, Issue 1; ISSN 0004-637X
- Publisher:
- Institute of Physics (IOP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
The long-lasting activity of 3C 454.3: GASP-WEBT and satellite observations in 2008–2010 ⋆⋆⋆
|
journal | October 2011 |
Optical flux behaviour of a sample of Fermi blazars
|
journal | June 2016 |
JET EMISSION IN YOUNG RADIO SOURCES: A FERMI LARGE AREA TELESCOPE GAMMA-RAY VIEW
|
journal | December 2013 |
The long-lasting activity of 3C 454.3. GASP-WEBT and satellite observations in 2008-2010 | text | January 2011 |
Optical flux behaviour of a sample of Fermi blazars | text | January 2016 |
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