Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published March 2019 | Published + Accepted Version
Journal Article Open

Search for AGN counterparts of unidentified Fermi-LAT sources with optical polarimetry: Demonstration of the technique

Abstract

Context. The third Fermi-LAT catalog (3FGL) presented the data of the first four years of observations from the Fermi Gamma-ray Space Telescope mission. There are 3034 sources, 1010 of which still remain unidentified. Identifying and classifying γ-ray emitters is of high significance with regard to studying high-energy astrophysics. Aims. We demonstrate that optical polarimetry can be an advantageous and practical tool in the hunt for counterparts of the unidentified γ-ray sources (UGSs). Methods. Using data from the RoboPol project, we validated that a significant fraction of active galactic nuclei (AGN) associated with 3FGL sources can be identified due to their high optical polarization exceeding that of the field stars. We performed an optical polarimetric survey within 3σ uncertainties of four unidentified 3FGL sources. Results. We discovered a previously unknown extragalactic object within the positional uncertainty of 3FGL J0221.2+2518. We obtained its spectrum and measured a redshift of z = 0.0609 ± 0.0004. Using these measurements and archival data we demonstrate that this source is a candidate counterpart for 3FGL J0221.2+2518 and most probably is a composite object: a star-forming galaxy accompanied by AGN. Conclusions. We conclude that polarimetry can be a powerful asset in the search for AGN candidate counterparts for unidentified Fermi sources. Future extensive polarimetric surveys at high Galactic latitudes (e.g., PASIPHAE) will allow the association of a significant fraction of currently unidentified γ-ray sources.

Additional Information

© ESO 2019. Received 18 October 2018 / Accepted 15 January 2019 We thank Richard Britto and Marcello Giroletti for useful comments that improved this work. We thank the Swift Observatory Team, in particular Brad Cenko, for their rapid approval and scheduling of ToO observations. The RoboPol project is a collaboration between Caltech in the USA, MPIfR in Germany, Toruń Centre for Astronomy in Poland, the University of Crete/FORTH in Greece, and IUCAA in India. D.B. acknowledges support from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program under grant agreement No 771282. G.V.P. acknowledges support by the European Commission Seventh Framework Programme (FP7) through the Marie Curie Career Integration Grant PCIG-GA-2011-293531 "SFOnset". K.K., A.Z., and R.S. acknowledge funding from the European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement n. 617001. This research has made use of the NASA/IPAC Infrared Science Archive, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This publication 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 This research has made use of the SVO Filter Profile Service (http://svo2.cab.inta-csic.es/theory/fps/) supported by the Spanish MINECO through grant AyA2014-55216, The SVO Filter Profile Service (Rodrigo, C., Solano, E., Bayo, A. http://ivoa.net/documents/Notes/SVOFPS/index.html) and The Filter Profile Service Access Protocol (Rodrigo, C., Solano, E. http://ivoa.net/documents/Notes/SVOFPSDAL/index.html).

Attached Files

Published - aa34458-18.pdf

Accepted Version - 1810.06312.pdf

Files

aa34458-18.pdf
Files (1.6 MB)
Name Size Download all
md5:758b9b0966f5d277b9fedfc7c4120ca5
819.9 kB Preview Download
md5:0e9839c4332d2f61f70c5c1f64ef7931
775.0 kB Preview Download

Additional details

Created:
August 19, 2023
Modified:
October 20, 2023