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Hunting for faint INTEGRAL AGN in the direction of the Galactic poles: IGR J02341+0228

ATel #4102; C. Ricci, E. Bozzo, R. Walter, S. Paltani (ISDC/University of Geneva, Switzerland), L. Stella (INAF-OAR, Italy)
on 8 May 2012; 11:27 UT
Credential Certification: Claudio Ricci (claudio.ricci@unige.ch)

Subjects: X-ray, Gamma Ray, AGN, Black Hole, Quasar

Referred to by ATel #: 4345

We recently started an observational program aimed at searching for soft X-ray counterparts of faint unidentified sources detected in the direction of the Galactic poles with the hard X-ray imager IBIS/ISGRI on-board INTEGRAL. The first object identified in our program is IGR J02341+0228. This source is detected in the 17-80 keV IBIS/ISGRI mosaic at a significance level of 6.5 (on source exposure time ~610 ks). The corresponding estimated flux is 0.8+/-0.1 mCrab (i.e. 1.2+/-0.2E-11 erg/cm^2/s). The ISGRI spectrum is well described (chi^2_red/dof=0.8/3) by a power-law model with photon index 1.5+/-0.9. The best determined INTEGRAL position of IGR J02341+0228 is at RA=38.5249 DEC=2.4646 (J2000), with an associated 90% c.l. uncertainty of 5.0 arcmin. Observations performed with the narrow field instrument on-board Swift, XRT (total exposure time 3.6 ks), identified within the ISGRI error circle a single X-ray counterpart. The best determined XRT position is at RA=38.45464 DEC=2.49043 (J2000), with an associated 90% c.l. uncertainty of 2 arcsec. The XRT position is consistent with that of the quasar QSO B0231+022. The XRT spectrum is well described (chi^2_red/dof=1.2/24) by using a power-law model. We estimated an absorption column density of N_H<0.5E+20 cm^(-2) and a photon index of 2.1+/-0.3, compatible with that estimated in the ISGRI energy band and with values usually observed in a type-1 AGN. The observed 0.5-10 keV X-ray flux is 5.5E-12 erg/cm^2/s.