XMM-Newtonobservations of the hot spot galaxy NGC 2903

Abstract

We report on the first deeper X-ray broad-band observation of the hot spot galaxy NGC 2903 obtained with XMM-Newton. X-ray imaging and spectra of the spiral barred galaxy were obtained from XMM-Newton archival data to study its X-ray population and the conditions of the hot gas in its central region. We investigate the spectral properties of the discrete point-source population and give estimates of their X-ray spectral parameters. By analysing the RGS spectra, we derive temperature and abundances for the hot gas located in its central region. A total of six X-ray point sources (four of them ULX candidates) were detected in the energy range of 0.3-10.0 keV located within the galaxy D25 optical disk. Three of these sources are detected for the first time, and one of them with a luminosity of higher than 10^39 erg/s. After fitting three different models, we were able to estimate their luminosities, which are compatible with those of binaries with a compact object in the form of black holes (BHs) rather than neutron stars (NSs). We extracted the combined first-order RGS1 and RGS2 spectra of its central region, which display several emission lines. Both O\,{\sc vii} $f$ and $r$ lines seem to be of similar strength, which is consistent with the presence of the collisionally ionized gas that is typical of starburst galaxies. We fitted the spectrum to a model for a plasma in collisional ionization equilibrium (CIE) and the continuum was modelled with a power law, resulting in a plasma temperature of T = 0.31 \pm 0.01 keV and an emission measure EM \equiv n_Hn_eV =6.4_{-0.4}^{+0.5}\times 10^{61}$~cm$^{-3}. We also estimated abundances that are consistent with solar values.