SIMBAD references

2011ApJ...738..148M - Astrophys. J., 738, 148 (2011/September-2)

Fermi large area telescope observations of the active galaxy 4C +55.17: steady, hard gamma-ray emission and its implications.

McCONVILLE W., OSTORERO L., MODERSKI R., STAWARZ L., CHEUNG C.C., AJELLO M., BOUVIER A., BREGEON J., DONATO D., FINKE J., FURNISS A., McENERY J.E., MONZANI M.E., ORIENTI M., REYES L.C., ROSSETTI A. and WILLIAMS D.A.

Abstract (from CDS):

We report Fermi Large Area Telescope (LAT) observations and broadband spectral modeling of the radio-loud active galaxy 4C +55.17 (z = 0.896), formally classified as a flat-spectrum radio quasar. Using 19 months of all-sky survey Fermi-LAT data, we detect a γ-ray continuum extending up to an observed energy of 145 GeV, and furthermore we find no evidence of γ-ray variability in the source over its observed history. We illustrate the implications of these results in two different domains. First, we investigate the origin of the steady γ-ray emission, where we re-examine the common classification of 4C +55.17 as a quasar-hosted blazar and consider instead its possible nature as a young radio source. We analyze and compare constraints on the source physical parameters in both blazar and young radio source scenarios by means of a detailed multiwavelength analysis and theoretical modeling of its broadband spectrum. Second, we show that the γ-ray spectrum may be formally extrapolated into the very high energy (VHE, ≥ 100 GeV) range at a flux level detectable by the current generation of ground-based Cherenkov telescopes. This enables us to place constraints on models of extragalactic background light within LAT energies and features the source as a promising candidate for VHE studies of the universe at an unprecedented redshift of z = 0.896.

Abstract Copyright:

Journal keyword(s): galaxies: active - galaxies: individual: 4C+55.17 - galaxies: jets - gamma rays: galaxies - radiation mechanisms: non-thermal

Simbad objects: 12

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2019.11.14-08:39:05

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