Blazars distance indications from Fermi and TeV data

Prandini, E. and Bonnoli, G. and Maraschi, L. and Mariotti, M. and Tavecchio, F. (2011) Blazars distance indications from Fermi and TeV data. Il nuovo cimento C, 34 (3). pp. 241-245. ISSN 1826-9885

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A new method to constrain the distance of blazars with unknown redshift using combined observations in the GeV and TeV regimes will be presented. The underlying assumption is that the Very High Energy (VHE) spectrum corrected for the absorption of TeV photons by the Extragalactic Background Light (EBL) via photon-photon interaction should still be softer than the extrapolation of the gamma-ray spectrum observed by Fermi-LAT. Starting from the observed spectral data at VHE, the EBL-corrected spectra are derived as a function of the redshift z and fitted with power laws. Comparing the redshift-dependent VHE slopes with the power-law fits to the LAT data an upper limit to the source redshift can be derived. The method is applied to all TeV blazars detected by LAT with known distance and an empirical law describing the relation between the upper limits and the true redshifts is derived. This law can be used to estimate the distance of unknown redshift blazars: as an example, the distance of PKS 1424+240 is inferred.

Item Type: Article
Uncontrolled Keywords: X- and γ-ray telescopes and instrumentation ; Active and peculiar galaxies and related systems (including BL Lacertae objects, blazars, Seyfert galaxies, Markarian galaxies, and active galactic nuclei) ; Background radiations
Subjects: 500 Scienze naturali e Matematica > 530 Fisica
Depositing User: Marina Spanti
Date Deposited: 06 Apr 2020 18:45
Last Modified: 06 Apr 2020 18:45

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