A possible line-like emission feature at 8 keV in the Seyfert 1.2 UGC 3973

Abstract

Two short X-ray exposures (< 3600 s each) of the radio-quiet Seyfert 1.2 galaxy UGC 3973 (Mrk 79) were conducted with XMM-Newton as part of an AGN snap-shot survey. In this paper we concentrate on the significance and possible origin of a narrow 8 keV (rest-frame) line-like emission feature detected with the pn instrument during the second observation. Simulations show that the feature is significant at 96.0-98.4% confidence, depending on what a priori assumptions are made. The feature cannot be attributed to background contamination and appears to be variable (or transient) since it was not detected in the first observation of UGC 3973 six months earlier. However, a constant feature cannot be completely dismissed, based on the 90% upper-limit on the flux from the first observation. There is some indication that the feature is variable over the duration of the second observation as well. We discuss various models (e.g. Ni emission, recombination edges, outflows, disc lines) which could potentially produce an emission feature at such energies.

7 pages, 7 figures. Accepted for publication in MNRAS

References in corpus (10)

• Central Masses and Broad-Line Region Sizes of Active Galactic Nuclei. II. A Homogeneous Analysis of a Large Reverberation-Mapping Database
• Aborted jets and the X-ray emission of radio-quiet AGNs
• Narrow Components within the Fe Kalpha Profile of NGC 3516: Evidence for the Importance of General Relativistic Effects?
• Relativistic spectral features from X-ray illuminated spots and the measure of the black hole mass in AGN
• XMM-Newton observation of the Seyfert 1.8 ESO 113-G010: discovery of a highly redshifted iron line at 5.4 keV
• Transient Relativistically-Shifted Lines as a Probe of Black Hole Systems
• Ni abundance in the core of the Perseus Cluster: an answer to the significance of resonant scattering
• A changing inner radius in the accretion disc of Q0056-363?
• A Puzzling X-Ray Source Found in the chandra Deep Field South
• The XMM-Newton view of the relativistic spectral features in AXJ0447-0627

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