BeppoSAX/PDS serendipitous detections at high galactic latitudes

¹ INAF – Istituto di Astrofisica Spaziale e Fisica Cosmica, Sezione di Bologna, via Gobetti 101, 40129 Bologna, Italy e-mail: landi@bo.iasf.cnr.it
² Dipartimento di Fisica, Università degli Studi di Bologna, Viale C. Berti Pichat 6/2, 40127 Bologna, Italy

Received: 28 July 2004
Accepted: 7 June 2005

Abstract

At a flux limit of ~10^-11 erg cm^-2 s^-1 in the 20–100 keV band, the PDS instrument on-board BeppoSAX offers the opportunity to study the extragalactic sky with an unprecedented sensitivity. In this work we report on the results of a search in the BeppoSAX archive for serendipitous high energy sources at high galactic latitudes (). We have defined a set of twelve regions in which the PDS/MECS cross-calibration constant is higher than the nominal value. We attribute this mismatch to the presence of a serendipitous source in the PDS field of view. In four cases the likely high energy emitter is also present in the MECS field of view. In these cases, we have performed a broad band spectral analysis (1.5–100 keV) to understand the source spectral behaviour and compare it with previous BeppoSAX observations when available. In eight cases the identification of the source likely to provide the PDS spectrum is based on indirect evidence (extrapolation to lower energies and/or comparison with previous observations). This approach led to the discovery of six new hard X-ray emitting objects (PKS 2356–611, 2MASX J14585116–1652223, NGC 1566, NGC 7319, PKS 0101–649 and ESO 025–G002) and to the presentation the PDS spectrum of NGC 3227 for the first time. In the remaining five cases we provide extra BeppoSAX observations that can be compared with measurements already published and/or in the archive.