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 (email@example.com)
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).
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.
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.