Astron. Astrophys. 364, L80-L84 (2000)

Letter to the Editor

On the hypothesis of an advection-dominated flow in the core of NGC 1052: new constraints from a BeppoSAX observation

M. Guainazzi ¹, T. Oosterbroek ², L.A. Antonelli ³ and G. Matt <sup>4

1</sup> XMM-Newton SOC, VILSPA, ESA, Apartado 50727, 28080 Madrid, Spain
² Astrophysics Division, Space Science Department of ESA, ESTEC, Postbus 299, 2200 AG Noordwijk, The Netherlands
³ Osservatorio Astronomico di Roma, Via dell'Osservatorio, 00044 Monteporzio Catone, Italy
⁴ Università degli Studi Roma Tre, Dipartimento di Fisica, Via della Vasca Navale 84, 00046 Roma, Italy

Received 14 September 2000 / Accepted 17 November 2000

Abstract

We report the results of a broadband (0.1-100 keV) X-ray observation of the nearby elliptical galaxy NGC 1052, performed with the BeppoSAX observatory. We confirm the presence of a bright (2-10 keV luminosity  erg s^-1) and strongly absorbed ( cm^-2) X-ray source. The flatness of the X-ray spectrum (photon index, , 1.4), the estimated low accretion rate () and the radio-to-X-ray spectral energy distribution suggest that this observation may represent the first direct measurement above 10 keV of an accretion-dominated flow in an elliptical galaxy.

Key words: accretion, accretion disks galaxies: active galaxies: elliptical and lenticular, cD galaxies: individual: NGC 1052 galaxies: nuclei X-rays: galaxies

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Contents

• 1. Introduction
• 2. Observation and data reduction
• 3. Results
  • 3.1. The PDS spectrum ( keV)
  • 3.2. The broadband BeppoSAX spectrum (0.1-100 keV)
  • 3.3. Comparison with ROSAT and ASCA data
• 4. Discussion
• Acknowledgements
• References

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001
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