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Swift-XRT follow-up of 2 unidentified INTEGRAL sources

ATel #3290; A. Malizia, R. Landi, L. Bassani (INAF IASF-Bologna), A. Bazzano (INAF IASF-Roma) A. J. Bird (University of Southampton), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU)
on 18 Apr 2011; 11:55 UT
Credential Certification: Raffaella Landi (landi@iasfbo.inaf.it)

Subjects: X-ray, Gamma Ray, AGN, Binary

In this telegram we report the X-ray follow-up observations performed with Swift-XRT of 2 unidentified INTEGRAL sources listed in Bird et al. 2010 (ApJS, 186, 1).

IGR J11014-6103

Within the IBIS error circle, XRT detects an X-ray source with coordinates R.A.(J2000) = 11h 01m 46.4s and Dec.(J2000) = -61d 01m 21s and 6 arcsec positional uncertainty. XRT detection is at 7.7 sigma in the 0.3-10 keV band and 4.6 sigma above 3 keV. This X-ray source is consistent with a ROSAT (1RXH J110146.1-610121) source and also with an XMM-Serendipitous (2XMM J110147.1-61012) object reported to have a flux of 1.39 x 10-12 erg cm-2 s-1 over the entire EPIC (0.2-12 keV) band. This X-ray source coincides with the USNO-A2.0 object (USNO-A2.0 0225_10221381) with magnitudes R ∼ 14.7 and B ∼ 16.2 and the 2MASS source (2MASS J11014625-6101189) having J ∼ 13.9, H ∼ 13.6 and K ∼ 13.5. The Swift-XRT data are well fitted with a black body component with a temperature of 85 [+4, -3] eV plus a power law of photon index of 2.6 ±0.91. The observed 2-10 keV flux is 6.1 x 10-13 erg cm-2 s-1.

IGR J14488-4008

In the IBIS error circle of IGR J14488-4008, XRT detected two X-ray sources :

  • source #1: This is the brightest of the two; it is detected in the 0.3-10 keV band at 14 sigma, and 11.5 sigma above 3 keV. The XRT position is R.A.(J2000) = 14h 48m 50.98s and Dec.(J2000) = -40d 08m 47.12s with a positional uncertainty of 3.83 arcsec. This is consistent with the radio source CRATES J1448-4008 (NED03) having a 6cm flux of 126 mJy and NVSS J144851-400846 with a 20 cm flux of 48 ±1.9 mJy. In the optical band this source coincides with the a USNO-A2.0 object (USNO-A2.0 0450_18513818) having R ∼ 14.0 and B ∼ 14.7 while in infrared is associated to a 2MASS source (2MASS J14485097-4008456) displaying J ∼ 16.7 H ∼ 12.7 and K ∼ 11.6. The XRT data are well fitted using a double power law model with indices tied together and with a value of 2.38 ±0.34; in addition to the Galactic absorption, we find an intrinsic column density of 7 [+2.2, -0.95] x 1022 cm-2. The 2-10 keV flux is 2.4 x 1012 erg cm-2 s-1.
  • source #2: This second source is detected in the 0.3-10 keV band at 5.7 sigma but it is not detected above 3 keV. The XRT position is R.A.(J2000) = 14h 48m 50.68s and Dec.(J2000) = -40d 10m 56.52s with 4.6 arcsec uncertainty. Within this positional error we find a USNO-A2.0 object (USNO-A2.0 0450_18513735) having R ∼ 15.2 and B ∼ 16.3 which is also a 2MASS source (2MASS J14485085-4010558) with J ∼ 13.4, H ∼ 12.8 and K ∼ 12.6. The XRT spectrum extracted from this second source is well fitted with a simple power law having Gamma = 2.4 [+0.45, -0.44] and a 2-10 keV flux is of 3.4 x 10-13 erg cm-2 s-1.

Given the above characteristics, we propose source #1 as the X-ray counterpart of the IBIS unidentified source.