Confirming the gamma-ray blazar nature of the low energy counterpart QSO GB6 J1604+5714 of 2FGL J1604.6+5710 with WISE

ATel #4190; F. Massaro (Stanford University), R. D'Abrusco (SAO), A. Paggi (SAO)
on 20 Jun 2012; 07:15 UT
Credential Certification: Francesco Massaro (francesco_mss@yahoo.it)

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Following the rapid optical variability detected in the QSO GB6 J1604+5714 (=BZQJ1604+5714) (ATEL #4184), associated to the gamma-ray source 2FGL J1604.6+5710 (=1FGL J1604.3+5710) in Nolan et al. (2012 ApJS, 199, 31), we searched in the Wide-field Infrared Survey Explorer (WISE; Wright et al. 2010 AJ, 140, 1868) catalog at the VLBI position of the QSO GB6 J1604+5714 (R.A.(J2000): 16h04m37.3546s, Dec.(J2000): +57d14m36.660s) reported in Beasley et al. (2002, ApJS, 141, 13).

We found a candidate infrared counterpart: WISE J160437.36+571436.6, with IR colors typical of gamma-ray blazars. Its coordinates are:
R.A.(J2000) = 16h04m37.36s (241.1556741 deg)
Dec. (J2000) = +57d14m36.68s (+57.2435234 deg).

As reported in the WISE All-sky catalog (available at http://wise2.ipac.caltech.edu/docs/release/allsky/ ), WISE J160437.36+571436.6 is detected in all four energy bands with the following magnitudes:
m(3.4 micron) = 13.354 +/- 0.021
m(4.6 micron) = 12.243 +/- 0.023
m(12 micron) = 9.297 +/- 0.020
m(22 micron) = 6.791 +/- 0.040

The WISE gamma-ray blazar candidate (WISE J160437.36+571436.6) is positionally consistent (0.062 arcsec offset) with the VLBI position reported in Beasley et al. (2002, ApJS, 141, 13).

Then, we searched in the WISE all-sky catalog at the position of the Fermi source 2FGL J1604.6+5710 (R.A.(J2000): 241.15445 deg, Dec.(J2000): +7.178528) with a searching radius of 0.0859 deg (corresponding to the 95% level of confidence), for a gamma-ray blazar candidate. We used the association procedure outlined in Massaro, F. et al. (2011 ApJ, 740L, 48) and in Massaro, F. et al. (2012 ApJ, 752, 61), based on infrared color analyses using WISE data. We found that according to our method WISE J160437.36+571436.6 is the unique gamma-ray blazar candidate within the searching region defined previously, in agreement with the GB6 J1604+5714 association reported in Nolan et al. (2012 ApJS, 199, 31) and in Ackermann et al. (2011 ApJ, 743, 171).

This analysis makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.

Additional details concerning the association procedure can be found in D'Abrusco, R. et al. 2012 ApJ, 748, 68; Massaro, F. et al. 2012 ApJ, 750, 138; Massaro, F., et al. 2012 ApJ, 750L, 35.