H.E.S.S. discovery of very high energy $\gamma$-ray emission from PKS 0625−354
Language
en
Article de revue
This item was published in
Monthly Notices of the Royal Astronomical Society. 2018, vol. 476, n° 3, p. 4187-4198
Oxford University Press (OUP): Policy P - Oxford Open Option A
English Abstract
PKS 0625−354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1σ. ...Read more >
PKS 0625−354 (z = 0.055) was observed with the four High Energy Stereoscopic System (H.E.S.S.) telescopes in 2012 during 5.5 h. The source was detected above an energy threshold of 200 GeV at a significance level of 6.1σ. No significant variability is found in these observations. The source is well described with a power-law spectrum with photon index Γ = 2.84 ± 0.50_stat ± 0.10_syst and normalization (at E_0 = 1.0 TeV) N_0(E_0) = (0.58 ± 0.22_stat ± 0.12_syst) × 10^−12 TeV^−1 cm^−2 s^−1. Multiwavelength data collected with Fermi-LAT, Swift-XRT, Swift-UVOT, ATOM and WISE are also analysed. Significant variability is observed only in the Fermi-LAT γ-ray and Swift-XRT X-ray energy bands. Having a good multiwavelength coverage from radio to very high energy, we performed a broad-band modelling from two types of emission scenarios. The results from a one zone lepto-hadronic and a multizone leptonic models are compared and discussed. On the grounds of energetics, our analysis favours a leptonic multizone model. Models associated to the X-ray variability constraint support previous results, suggesting a BL Lac nature of PKS 0625−354 with, however, a large-scale jet structure typical of a radio galaxy.Read less <
English Keywords
radiation mechanisms: non-thermal
galaxies: active
galaxies: individual: PKS 0625−354
galaxies: jets
gamma-rays: galaxies
model: leptonic
gamma ray: emission
energy: threshold
gamma ray: VHE
galaxy: radio wave
GLAST
X-ray
HESS
structure
photon
power spectrum
Origin
Hal imported