TeV photons from blazars at relatively large distances, interacting with the optical-infrared cosmic background, are efficiently converted into electron-positron pairs. The produced pairs are extremely relativistic (Lorentz factors of the order of 106- 107) and promptly lose their energy through inverse Compton scatterings with the photons of the microwave cosmic background, producing emission in the GeV band. The spectrum and the flux level of this reprocessed emission are critically dependent on the intensity of the intergalactic magnetic field, B, that can deflect the pairs diluting the intrinsic emission over a large solid angle. We derive a simple relation for the reprocessed spectrum expected from a steady source. We apply this treatment to the blazar ÍES 0229+200, whose intrinsic, very hard TeV spectrum is expected to be approximately steady. Comparing the predicted reprocessed emission with the upper limits measured by the Fermi/Large Area Telescope, we constrain the value of the intergalactic magnetic field to be larger than B ≃ 5 × 10-15 G, depending on the model of extragalactic background light. © 2010 The Authors. Journal compilation © 2010 RAS.

Tavecchio, F., Ghisellini, G., Foschini, L., Bonnoli, G., Ghirlanda, G., Coppi, P. (2010). The intergalactic magnetic field constrained by Fermi/Large Area Telescope observations of the TeV blazar 1ES 0229+200. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. LETTERS, 406(1), L70-L74 [10.1111/j.1745-3933.2010.00884.x].

The intergalactic magnetic field constrained by Fermi/Large Area Telescope observations of the TeV blazar 1ES 0229+200

Bonnoli, G.;
2010-01-01

Abstract

TeV photons from blazars at relatively large distances, interacting with the optical-infrared cosmic background, are efficiently converted into electron-positron pairs. The produced pairs are extremely relativistic (Lorentz factors of the order of 106- 107) and promptly lose their energy through inverse Compton scatterings with the photons of the microwave cosmic background, producing emission in the GeV band. The spectrum and the flux level of this reprocessed emission are critically dependent on the intensity of the intergalactic magnetic field, B, that can deflect the pairs diluting the intrinsic emission over a large solid angle. We derive a simple relation for the reprocessed spectrum expected from a steady source. We apply this treatment to the blazar ÍES 0229+200, whose intrinsic, very hard TeV spectrum is expected to be approximately steady. Comparing the predicted reprocessed emission with the upper limits measured by the Fermi/Large Area Telescope, we constrain the value of the intergalactic magnetic field to be larger than B ≃ 5 × 10-15 G, depending on the model of extragalactic background light. © 2010 The Authors. Journal compilation © 2010 RAS.
2010
Tavecchio, F., Ghisellini, G., Foschini, L., Bonnoli, G., Ghirlanda, G., Coppi, P. (2010). The intergalactic magnetic field constrained by Fermi/Large Area Telescope observations of the TeV blazar 1ES 0229+200. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. LETTERS, 406(1), L70-L74 [10.1111/j.1745-3933.2010.00884.x].
File in questo prodotto:
File Dimensione Formato  
j.1745-3933.2010.00884.x.pdf

non disponibili

Descrizione: Articolo su rivista
Tipologia: PDF editoriale
Licenza: NON PUBBLICO - Accesso privato/ristretto
Dimensione 1.02 MB
Formato Adobe PDF
1.02 MB Adobe PDF   Visualizza/Apri   Richiedi una copia

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/1002278
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo