A redshifted Fe K$\alpha$ line from the unusual gamma-ray source PMN J1603-4904

Abstract

Multiwavelength observations have revealed the highly unusual properties of the gamma-ray source PMN J1603-4904, which are difficult to reconcile with any other well established gamma-ray source class. The object is either a very atypical blazar or compact jet source seen at a larger angle to the line of sight. In order to determine the physical origin of the high-energy emission processes in PMN J1603-4904, we study the X-ray spectrum in detail. We performed quasi-simultaneous X-ray observations with XMM-Newton and Suzaku in 2013 September, resulting in the first high signal-to-noise X-ray spectrum of this source. The 2-10 keV X-ray spectrum can be well described by an absorbed power law with an emission line at 5.44$\pm$0.05 keV (observed frame). Interpreting this feature as a Kα line from neutral iron, we determine the redshift of PMN J1603-4904 to be z=0.18$\pm$0.01, corresponding to a luminosity distance of 872$\pm$54 Mpc. The detection of a redshifted X-ray emission line further challenges the original BL Lac classification of PMN J1603-4904. This result suggests that the source is observed at a larger angle to the line of sight than expected for blazars, and thus the source would add to the elusive class of gamma-ray loud misaligned-jet objects, possibly a γ-ray bright young radio galaxy.

5 pages, 1 figure, A&A accepted

References in corpus (10)

• The X-ray nuclei of intermediate-redshift radio sources
• The multiwavelength variability of 3C 273
• On the Evolution of and High-Energy Emission from GHz-Peaked-Spectrum Sources
• On the origin of the Fe K-alpha line cores in Active Galactic Nuclei
• The broad band spectral variability of MCG-6-30-15 observed by NuSTAR and XMM-Newton
• X-ray Properties of the GigaHertz-Peaked and Compact Steep Spectrum Sources
• The Suzaku Observation of the Nucleus of the Radio-Loud Active Galaxy Centaurus A: Constraints on Abundances of the Accreting Material
• The narrow Fe K$\alpha$ line and the molecular torus in active galactic nuclei - an IR/X-ray view
• Suzaku Observations of gamma-Ray Bright Radio Galaxies: Origin of the X-ray Emission and Broad-Band Modelin
• X-ray emission from GPS and CSS sources

Cited by in corpus (6)

• Gamma-ray emission in radio galaxies under the VLBI scope -- I. Parsec-scale kinematics and high-energy properties of $\gamma$-ray detected TANAMI radio galaxies
• The MHz-peaked radio spectrum of the unusual gamma-ray source PMN J1603-4904
• X-ray Emission of the $\gamma$-ray Loud Young Radio Galaxy NGC 3894
• Highly Variable $\gamma$-Ray Emission of CTD 135 and Implications for its Compact Symmetric Structure
• X-ray and GeV-gamma-ray emission property of TeV Compact Symmetric Object PKS 1413+135 and Implication for Episodic Jet Activity
• Multiwavelength and parsec-scale properties of extragalactic jets