Detection of a double-peaked H$α$ component from the accretion disc of NGC 4958

T. V. Ricci, J. E. Steiner

Published 2019-04-05Version 1

Active Galactic Nuclei are objects associated with the presence of an accretion disc around supermassive black holes found in the very central region of galaxies with a well-defined bulge. In the optical range of the spectrum, a possible signature of the accretion disc is the presence of a broad double-peaked component that is mostly seen in H$\alpha$. In this paper, we report the detection of a double-peaked feature in the H$\alpha$ line in the nucleus of the galaxy NGC 4958. The narrow line region of this object has an emission that is typical of a LINER galaxy, which is the usual classification for double-peaked emitters. A central broad component, related to the broad line region (BLR) of this object, is seen in H$\alpha$ and also in H$\beta$. We concluded that the double-peaked emission is emitted by a circular relativistic Keplerian disc with an inner radius $\xi_{\rm i}$ = 570$\pm$ 83, an outer radius $\xi_{\rm o}$ = 860$\pm$170 (both in units of $GM_{\rm SMBH}/c^2$), an inclination to the line of sight $i$ = 27.2$^o \pm$0.7$^o$ and a local broadening parameter $\sigma$ = 1310$\pm$70 km s$^{-1}$.