English

Discovery of a suspected giant radio galaxy with the KAT-7 array

Astrophysics of Galaxies 2015-12-23 v1 Cosmology and Nongalactic Astrophysics

Abstract

We detect a new suspected giant radio galaxy (GRG) discovered by KAT-7. The GRG core is identified with the WISE source J013313.50-130330.5, an extragalactic source based on its infrared colors and consistent with a misaligned AGN-type spectrum at z0.3z\approx 0.3. The multi-ν\nu spectral energy distribution (SED) of the object associated to the GRG core shows a synchrotron peak at ν1014\nu \approx 10^{14} Hz consistent with the SED of a radio galaxy blazar-like core. The angular size of the lobes are 4\sim 4 ^{\prime} for the NW lobe and 1.2\sim 1.2 ^{\prime} for the SE lobe, corresponding to projected linear distances of 1078\sim 1078 kpc and 324\sim 324 kpc, respectively. The best-fit parameters for the SED of the GRG core and the value of jet boosting parameter δ=2\delta =2, indicate that the GRG jet has maximum inclination θ30\theta \approx 30 deg with respect to the line of sight, a value obtained for δ=Γ\delta=\Gamma, while the minimum value of θ\theta is not constrained due to the degeneracy existing with the value of Lorentz factor Γ\Gamma. Given the photometric redshift z0.3z \approx 0.3, this GRG shows a core luminosity of P1.4GHz5.52×1024P_{1.4 GHz} \approx 5.52 \times 10^{24} W Hz1^{-1}, and a luminosity P1.4GHz1.29×1025P_{1.4 GHz} \approx 1.29 \times 10^{25} W Hz1^{-1} for the NW lobe and P1.4GHz0.46×1025P_{1.4 GHz} \approx 0.46 \times 10^{25} W Hz1^{-1} for the SE lobe, consistent with the typical GRG luminosities. The radio lobes show a fractional linear polarization 9%\approx 9 \% consistent with typical values found in other GRG lobes.

Keywords

Cite

@article{arxiv.1511.08330,
  title  = {Discovery of a suspected giant radio galaxy with the KAT-7 array},
  author = {S. Colafrancesco and N. Mhlahlo and T. Jarrett and N. Oozeer and P. Marchegiani},
  journal= {arXiv preprint arXiv:1511.08330},
  year   = {2015}
}

Comments

7 pages, 6 figures, 2 tables, accepted for publication in MNRAS