Astronomy and Astrophysics, volume 522, A53-53 (2010/11-1)
XMM-Newton observations of the hot spot galaxy NGC 2903.
PEREZ-RAMIREZ D., CABALLERO-GARCIA M.D., EBRERO J. and LEON S.
Abstract (from CDS):
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 NGC 2903 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 0.3-10.0keV located within the galaxy D25 optical disk. Three of these sources are detected for the first time, and one of them, XMM-NGC2903 X2 with a luminosity of higher than 1039erg/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. The spectrum is dominated by a strong OVIII Lyα emission line along with NeX Lyα and several FeXVII features. The OVII complex is also significantly detected, although only the forbidden and resonance lines could be resolved. Both Ovii 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±0.01keV and an emission measure EM=nHne V=6.4–0.4+0.5x1061cm-3. We also estimated abundances that are consistent with solar values.
galaxies: individual: NGC 2903 - galaxies: ISM - galaxies: starburst - X-rays: galaxies - X-rays: binaries