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BL Lac Identification for the Ultraluminous X-ray Source Observed in the Direction of NGC 4698

L. Foschini·L. C. Ho·N. Masetti·M. Cappi·M. Dadina·L. Bassani·G. Malaguti·E. Palazzi·G. Di Cocco·P. Martini·S. Ravindranath·J. B. Stephen·M. Trifoglio·F. Gianotti
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Abstract

We report the identification of the optical and radio counterparts of the ultraluminous X-ray (ULX) source XMMU J124825.9+083020 (NGC4698-ULX1). The optical spectrum taken with the VLT yields a redshift of z=0.43, which implies that the ULX is not associated with the nearby galaxy NGC4698. The spectral energy distribution calculated from the available data indicates that the source is likely to be a BL Lac object. The possible synchrotron peak at X-ray energies suggests that this source may be a gamma-ray emitter.

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L. Foschini, L. C. Ho, N. Masetti, M. Cappi, M. Dadina, L. Bassani, G. Malaguti, E. Palazzi, G. Di Cocco, P. Martini, S. Ravindranath, J. B. Stephen, M. Trifoglio, F. Gianotti. 2002-09-24. BL Lac Identification for the Ultraluminous X-ray Source Observed in the Direction of NGC 4698. https://doi.org/10.1051/0004-6361%3A20021391

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