Extreme TeV blazars and the intergalactic magnetic field

By F. Tavecchio, G. Ghisellini, G. Bonnoli, Luigi Foschini. 2010

191 citations recorded by the source corpus.

We study the four BL Lac objects (RGBJ0152+017, IES 0229+200, 1ES 0347―121 and PKS 0548-322) detected in the TeV band but not present in the first Fermi-LAT (1FGL) catalogue of the Fermi/Large Area Telescope (LAT). We analyse the 24 months of LAT data deriving γ-ray fluxes or upper limits that we use to assemble their spectral energy distributions (SED). We model the SEDs with a standard one-zone leptonic model, also including the contribution of the reprocessed radiation in the multi-GeV band, emitted by the pairs produced through the conversion of the primary TeV emission by interaction with the cosmic optical-infrared background. For simplicity, in the calculation of this component we adopt an analytical approach including some simplifying assumptions, in particular (i) the blazar high-energy emission is considered on average stable over times of the order of 10 7 yr and (ii) the observer is exactly on-axis. We compare the physical parameters derived by the emission model with those of other high-energy emitting BL Lacs, confirming that TeV BL Lacs with a rather small GeV flux are characterized by extremely low values of the magnetic field and large values of the electron energies. The comparison between the flux in the GeV band and that expected from the reprocessed TeV emission allows us to confirm and strengthen the lower limit of B ≳ 10 ―15 G for the intergalactic magnetic field using a theoretically motivated spectrum for the primary high-energy photons.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/09270958363d5911d69159d1e46b225b75ffd288

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In Nuclear and High Energy Physics

1. Andrii Y. Neronov
2. J. Biteau
3. E. Orlando
4. R. Durrer
5. Anna Franckowiak
6. Kohta Murase
7. A. Reimer
8. C. Dermer

Citations in the corpus

• LOWER LIMIT ON THE STRENGTH AND FILLING FACTOR OF EXTRAGALACTIC MAGNETIC FIELDS (2011, methodology): “In Figure 1, we have used a uniform magnetic field so that our results can be directly compared with the analytical estimates of Tavecchio et al. (2010a).”
• Cosmological Magnetic Fields: Their Generation, Evolution and Observation (2013, background): “Neronov and Vovk (2010); Tavecchio et al (2011) have considered data from the Fermi telescope and deduced a lower bound on the IGMF at the level of B & 10−16 G from the non-observation of the cascade signal in the GeV band.”
• TIME DELAY OF CASCADE RADIATION FOR TeV BLAZARS AND THE MEASUREMENT OF THE INTERGALACTIC MAGNETIC FIELD (2010, methodology): “By comparing blazar TeV fluxes with upper limits on the GeV radiation flux measurements with the Fermi Gamma-ray Space Telescope, several claims (see Table 1) have been made that lower limits on the IGMF have been measured (Neronov & Vovk 2010; Tavecchio et al. 2010a, 2011; Dolag et al. 2011).”
• Planck 2015 results: XIX. Constraints on primordial magnetic fields (2015, unknown): “…is a deflection of the electron-positron pairs owing to the presence of a diffuse magnetic field (see Neronov & Vovk 2010; Taylor et al. 2011; Tavecchio et al. 2011; Vovk et al. 2012; and Neronov et al. 2013b for details on this explanation; and see Broderick et al. 2012 for alternative…”
• THE COSMIC EVOLUTION OF FERMI BL LACERTAE OBJECTS (2013, background): “At the high end, these synchrotron peaks imply that BL Lacs are able to accelerate electrons beyond 100TeV (e.g. Costamante et al. 2001; Tavecchio et al. 2011), making BL Lacs among the most powerful accelerators in the Universe.”
• The Search for Spatial Extension in High-latitude Sources Detected by the Fermi Large Area Telescope (2018, methodology): “…to an excess in the GeV regime of γ-ray spectra, and the non-observation of this feature has been used to derive lower limits on the IGMF strength—or conversely, on the filling factor of the IGMF (Neronov & Vovk 2010; Dolag et al. 2011; Tavecchio et al. 2011; Taylor et al. 2011; Vovk et al. 2012).”
• BLAZARS AS ULTRA-HIGH-ENERGY COSMIC-RAY SOURCES: IMPLICATIONS FOR TeV GAMMA-RAY OBSERVATIONS (2011, background): “Also, in some cases (RGB J0152+017, 1ES 0229+200 and 1ES 0548-322), the optical/UV data show a rather steep spectrum which is thought to be the emission from the host galaxies (Tavecchio et al. 2011).”