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Simultaneous Planck, Swift, and Fermi observations of X-ray and gamma-ray selected blazars

文献类型:期刊论文

AuthorGiommi, P.1,3; Polenta, G.1,23; Lahteenmaki, A.2,19; Thompson, D. J.5; Capalbi, M.1; Cutini, S.1; Gasparrini, D.1; Gonzalez-Nuevo, J.44; Leon-Tavares, J.2; Lopez-Caniego, M.33
SourceASTRONOMY & ASTROPHYSICS
Issued Date2012-05-01
Volume541
Keywordrelativistic processes BL Lacertae objects: general quasars: general galaxies: active
English AbstractWe present simultaneous Planck, Swift, Fermi, and ground-based data for 105 blazars belonging to three samples with flux limits in the soft X-ray, hard X-ray, and gamma-ray bands, with additional 5GHz flux-density limits to ensure a good probability of a Planck detection. We compare our results to those of a companion paper presenting simultaneous Planck and multi-frequency observations of 104 radio-loud northern active galactic nuclei selected at radio frequencies. While we confirm several previous results, our unique data set allows us to demonstrate that the selection method strongly influences the results, producing biases that cannot be ignored. Almost all the BL Lac objects have been detected by the Fermi Large Area Telescope (LAT), whereas 30% to 40% of the flat-spectrum radio quasars (FSRQs) in the radio, soft X-ray, and hard X-ray selected samples are still below the gamma-ray detection limit even after integrating 27 months of Fermi-LAT data. The radio to sub-millimetre spectral slope of blazars is quite flat, with similar to 0 up to about 70GHz, above which it steepens to similar to -0.65. The BL Lacs have significantly flatter spectra than FSRQs at higher frequencies. The distribution of the rest-frame synchrotron peak frequency (nu(S)(peak)) in the spectral energy distribution (SED) of FSRQs is the same in all the blazar samples with = 10(13.1+.1) Hz, while the mean inverse Compton peak frequency, , ranges from 10(21) to 10(22) Hz. The distributions of nu(S)(peak) and nu(S)(peak) of BL Lacs are much broader and are shifted to higher energies than those of FSRQs; their shapes strongly depend on the selection method. The Compton dominance of blazars, defined as the ratio of the inverse Compton to synchrotron peak luminosities, ranges from less than 0.2 to nearly 100, with only FSRQs reaching values larger than about 3. Its distribution is broad and depends strongly on the selection method, with gamma-ray selected blazars peaking at similar to 7 or more, and radio-selected blazars at values close to 1, thus implying that the common assumption that the blazar power budget is largely dominated by high-energy emission is a selection effect. A comparison of our multi-frequency data with theoretical predictions shows that simple homogeneous SSC models cannot explain the simultaneous SEDs of most of the gamma-ray detected blazars in all samples. The SED of the blazars that were not detected by Fermi-LAT may instead be consistent with SSC emission. Our data challenge the correlation between bolometric luminosity and nu(S)(peak) predicted by the blazar sequence.
Indexed TypeSCI
Language英语
WOS IDWOS:000304390900160
源URL[http://ir.bao.ac.cn/handle/114a11/6247]  
Collection国家天文台_光学天文研究部
Affiliation1.ESRIN, Agenzia Spaziale Italiana Sci Data Ctr, Frascati, Italy
2.Aalto Univ Metsahovi Radio Observ, Kylmala 02540, Finland
3.Agenzia Spaziale Italiana, Rome, Italy
4.Univ Michigan, Dept Astron, Ann Arbor, MI 48109 USA
5.NASA, Goddard Space Flight Ctr, Astroparticle Phys Lab, Greenbelt, MD 20771 USA
6.Univ Cambridge, Cavendish Lab, Astrophys Grp, Cambridge CB3 0HE, England
7.CSIRO, Australia Telescope Natl Facil, Epping, NSW 1710, Australia
8.CALTECH, Pasadena, CA 91125 USA
9.Univ Oviedo, Dept Fis, E-33007 Oviedo, Spain
10.Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA
Recommended Citation
GB/T 7714
Giommi, P.,Polenta, G.,Lahteenmaki, A.,et al. Simultaneous Planck, Swift, and Fermi observations of X-ray and gamma-ray selected blazars[J]. ASTRONOMY & ASTROPHYSICS,2012,541.
APA Giommi, P..,Polenta, G..,Lahteenmaki, A..,Thompson, D. J..,Capalbi, M..,...&Zhou, X..(2012).Simultaneous Planck, Swift, and Fermi observations of X-ray and gamma-ray selected blazars.ASTRONOMY & ASTROPHYSICS,541.
MLA Giommi, P.,et al."Simultaneous Planck, Swift, and Fermi observations of X-ray and gamma-ray selected blazars".ASTRONOMY & ASTROPHYSICS 541(2012).

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