Identification of the new INTEGRAL hard X-ray source IGR J03249+4041 with interacting Seyfert 2 galaxies

ATel #2759; A. Lutovinov, R. Burenin, S. Sazonov, M. Revnivtsev (IKI RAS), A. Moiseev, S. Dodonov (SAO RAS)
on 27 Jul 2010; 11:52 UT
Credential Certification: A.Lutovinov (aal@hea.iki.rssi.ru)

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The hard X-ray source IGR J03249+4041, with the coordinates RA=03h24m54.0s, Dec=40deg41m53s (J2000, uncertainty of ~4', 95% probability), was detected during the INTEGRAL all-sky survey with a flux of 0.89+-0.17 mCrab in the 17-60 keV energy band (Krivonos et al., 2010). This sky region had been previously observed with the XRT telescope aboard the Swift observatory, on 21 Nov 2007 and 21 Jan 2008. During both XRT observations a relatively faint extended X-ray source was clearly detected inside the error circle of IGR J03249+4041. Analysis of these observations showed that the extended X-ray source probably consists of two closely located point-like sources with coordinates of RA=03h25m13.2s, Dec=40deg41m51s (source A) and RA=03h25m12.4s, Dec=40deg42m01s (source B), with source B having a significantly harder X-ray spectrum and approximately twice higher flux in the 0.6-10 keV energy band.

These two Swift/XRT sources can be identified with the bright cores of two interacting galaxies LEDA 97012 (at z=0.0477 according to NED) and 2MASX J03251221+4042021, located at RA=03h25m12.96s, Dec=40deg41m53.2s and RA=03h25m12.23s, Dec=40deg42m02.3s (J2000, coordinates are given relative to DSS red plate astrometric solution), respectively.

We performed follow-up spectroscopic observations of the bright cores of these interacting galaxies with the SCORPIO spectrograph at the 6-m BTA telescope (Special Astrophysical Observatory, Russia) on Jul 15/16, 2010. The BTA spectra of both objects show narrow Balmer, [NII], [OIII] and other emission lines. The observed [NII],6583/H_alpha and [OIII],5007/H_beta intensity ratios imply that both objects are Seyfert 2 active galactic nuclei. From these data we measured the redshifts z=0.04752+/-0.00011 and 0.04759+/-0.00010 for object A and object B, respectively.

We note that in the current Swift/BAT catalogues (Tueller et al., 2010, Cusumano et al. 2010) there are sources SWIFT J0324.9+4044 and PBC J0325.1+4042, respectively. Their localization regions partially overlap with that of IGR J03249+4041, but both Swift sources are reported to be associated with the UGC 2724 galaxy (RA=03h25m25.6s, Dec=40deg46m23s according to NED and SIMBAD), which is located ~5' away from LEDA 97012 but is reported to have practically exact the same redshift z=0.0477 (again according to NED) as LEDA 97012. It appears that the designation UGC 2724 was erroneously linked with the object LEDA 97012=IRAS 03219+4031 in the papers by Brunzendorf & Meusinger (1999) and Meusinger et al. (2000) and this error has subsequently been reproduced in the 10th and later versions of the Catalogue of Quasars and Active Nuclei by Veron-Cetty & Veron as well as in some other data bases.

We further note that the history of IGR J03249+4041 can be traced back to 1998, when the ROSAT soft X-ray source RX J0325.2+4042 was identified as a Seyfert 2 galaxy (Motch et al. 1998).

We conclude that all three hard X-ray sources IGR J03249+4041, SWIFT J0324.9+4044 and PBC J0325.1+4042 as well as the soft X-ray source RX J0325.2+4042 are one and the same object -- the pair of interacting Seyfert 2 galaxies (LEDA 97012, 2MASX J03251221+4042021) at z=0.04752+/-0.00011 and z=0.04759+/-0.00010, respectively, while the galaxy UGC 2724 is an unrelated object.

7-Year INTEGRAL All-Sky Survey