Astron. Astrophys. 360, 447-456 (2000)

X-rays from the barred galaxy NGC 4303

D. Tschöke ¹, G. Hensler ¹ and N. Junkes <sup>2

1</sup> Institut für Theoretische Physik und Astrophysik, Universität Kiel, 24098 Kiel, Germany (tschoeke@astrophysik.uni-kiel.de)
² Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

Received 20 March 2000 / Accepted 21 June 2000

Abstract

The late-type galaxy NGC 4303 (M61) is one of the most intensively studied barred galaxies in the Virgo Cluster. Its prominent enhanced star formation throughout large areas of the disk can be nicely studied due to its low inclination of about 27^o.

We present observations of NGC 4303 with the ROSAT PSPC and HRI in the soft X-ray (0.1-2.4 keV). The bulk of the X-ray emission is located at the nuclear region. It contributes more than 80% to the total observed soft X-ray flux. The extension of the central X-ray source and the / ratio point to a low luminous AGN (LINER) with a circumnuclear star-forming region. Several separate disk sources can be distinguished with the HRI, coinciding spatially with some of the most luminous H  II regions outside the nucleus of NGC 4303. The total star formation rate amounts to 1-2  yr^-1. The X-ray structure follows the distribution of star formation with enhancement at the bar-typical patterns.

The best spectral fit consists of a power-law component (AGN and HMXBs) and a thermal plasma component of hot gas from supernova remnants and superbubbles. The total 0.1-2.4 keV luminosity of NGC 4303 amounts to 510 erg s^-1, consistent with comparable galaxies, like e.g. NGC 4569.

Key words: galaxies: individual: NGC 4303 galaxies: starburst galaxies: active X-rays: galaxies

Send offprint requests to: D. Tschöke

SIMBAD Objects

Contents

• 1. Introduction
• 2. Observations and data reduction
  • 2.1. HRI
  • 2.2. PSPC
• 3. Results
  • 3.1. Spatial analysis
  • 3.2. Properties of the X-ray spectrum
• 4. Discussion
  • 4.1. The nucleus of NGC 4303
  • 4.2. The galactic disk
  • 4.3. Star formation in the disk
• 5. Conclusions
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: August 17, 2000
helpdesk.link@springer.de