An X-ray bright nucleus in the low-surface-brightness galaxy UGC 6614

Abstract

We report a study of the X-ray emission from the nuclear region of the low-surface-brightness (LSB) galaxy UGC 6614. Very little is known about the central objects in LSB galaxies, especially their X-ray properties and X-ray spectra. In this study we have used XMM–Newton archival data to study the characteristics of the X-ray spectrum and the X-ray flux variability of the active galactic nucleus (AGN) in the LSB galaxy UGC 6614. The nucleus of UGC 6614 is very bright in X-ray emission with an absorption-corrected 0.2–10.0 keV luminosity of ∼1.1 × 1042 erg s−1. The X-ray spectrum is found to be power-law type with a moderate column density. A short time-scale of intensity variation and large X-ray flux are indicative of the presence of a black hole at the centre of this galaxy. Using the method of excess variance, we have determined the black hole mass to be ∼0.12 × 106 M⊙. The X-ray spectral properties are similar to that of the Seyfert I-type AGNs. Our study thus demonstrates that although LSB galaxies are poor in star formation, they may harbour AGNs with X-ray properties comparable to that seen in more luminous spiral galaxies.