Volume 522, November 2010
|Number of page(s)||5|
|Published online||01 November 2010|
XMM-Newton observations of the hot spot galaxy NGC 2903
Universidad de Jaén, Campus Las Lagunillas s/n, 23007
2 University of Cambridge, Institute of Astronomy, Cambridge CB3 0HA, UK
3 SRON-Netherlands Institute for Space Research, 3584 CA, Utrecht, The Netherlands
4 Joint Alma Observatory/ESO, Las Condes, Santiago, Chile
Received: 24 September 2010
Accepted: 13 October 2010
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 0.3–10.0 keV 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 1039 erg s-1. 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 O viii Lyα emission line along with Ne x Lyα and several Fe xvii features. The O vii complex is also significantly detected, although only the forbidden and resonance lines could be resolved. Both O 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 ± 0.01 keV and an emission measure cm-3. We also estimated abundances that are consistent with solar values.
Key words: galaxies: individual: NGC 2903 / galaxies: ISM / galaxies: starburst / X-rays: galaxies / X-rays: binaries
© ESO, 2010
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