Abstract
We present the results of a cluster search in the Fermi-LAT Pass 8 \(\gamma\)-ray sky by means of the Minimum Spanning Tree algorithm, at energies higher than 10 GeV and at Galactic latitudes higher than \(25^{\circ}\). The selected clusters have a minimum number of photons higher than or equal to 5, a high degree of concentration, and are without a clear corresponding counterpart in blazar catalogues. A sample of 30 possible \(\gamma\)-ray sources was obtained. These objects were verified by applying the standard Maximum Likelihood analysis on the Fermi-LAT data. A search for possible radio counterparts in a circle having a radius of \(6'\) was performed, finding several interesting objects, the majority of them without optical spectroscopical data. These can be considered as new blazar candidates. Some of them were already noticed as possible blazars or Active Galactic Nuclei in previous surveys, but never associated with high energy emission. These possible counterparts are reported and their properties are discussed.
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Abdo, A.A., et al.: Astrophys. J. 721, 1425–1447 (2010)
Ackermann, M., Ajello, M., Allafort, A., Asano, K., Atwood, W.B., Baldini, L., Ballet, J., Barbiellini, G., et al.: Astrophys. J. 765, 54 (2013)
Ackermann, M., Ajello, M., Asano, K., Atwood, W.B., Axelsson, M., Baldini, L., Ballet, J., Barbiellini, G., et al.: Science 343, 42 (2014)
Alam, S., Albareti, F.D., Allende Prieto, C., Anders, F., Anderson, S.F., Anderton, T., Andrews, B.H., Armengaud, E., Aubourg, É., Bailey, S., et al.: Astrophys. J. Suppl. Ser. 219, 12 (2015)
Appenzeller, I., Thiering, I., Zickgraf, F.-J., Krautter, J., Voges, W., Chavarria, C., Kneer, R., Mujica, R., Pakull, M., Rosso, C., Ruzicka, F., Serrano, A., Ziegler, B.: Astrophys. J. Suppl. Ser. 117, 319 (1998)
Arsioli, B., Fraga, B., Giommi, P., Padovani, P., Marrese, P.M.: Astron. Astrophys. 579, 34 (2015)
Brescia, M., Cavuoti, S., Longo, G.: Mon. Not. R. Astron. Soc. 450, 3893 (2015)
Brinkmann, W., Siebert, J., Feigelson, E.D., Kollgaard, R.I., Laurent-Muehleisen, S.A., Reich, W., Fuerst, E., Reich, P., Voges, W., Truemper, J., McMahon, R.: Astron. Astrophys. 323, 739 (1997)
Campana, R., Massaro, E., Gasparrini, D., Cutini, S., Tramacere, A.: Mon. Not. R. Astron. Soc. 383, 1166 (2008)
Campana, R., Bernieri, E., Massaro, E., Tinebra, F., Tosti, G.: Astrophys. Space Sci. 347, 169 (2013)
Campana, R., Massaro, E., Bernieri, E., D’Amato, Q.: Astrophys. Space Sci. 360, 19 (2015)
Campana, R., Massaro, E., Bernieri, E.: Astrophys. Space Sci. 361, 185 (2016a)
Campana, R., Massaro, E., Bernieri, E.: Astrophys. Space Sci. 361, 183 (2016b)
Condon, J.J., Cotton, W.D., Greisen, E.W., Yin, Q.F., Perley, R.A., Taylor, G.B., Broderick, J.J.: Astron. J. 115, 1693 (1998)
Cutri, R.M., Wright, E.L., Conrow, T., Fowler, J.W., Eisenhardt, P.R.M., Grillmair, C., Kirkpatrick, J.D., Masci, F., et al.: Explanatory supplement to the AllWISE data release products. Technical report (November 2013)
D’Abrusco, R., Longo, G., Walton, N.A.: Mon. Not. R. Astron. Soc. 396, 223 (2009)
D’Abrusco, R., Massaro, F., Ajello, M., Grindlay, J.E., Smith, H.A., Tosti, G.: Astrophys. J. 748, 68 (2012)
D’Abrusco, R., Massaro, F., Paggi, A., Smith, H.A., Masetti, N., Landoni, M., Tosti, G.: Astrophys. J. Suppl. Ser. 215, 14 (2014)
Evans, P.A., Osborne, J.P., Beardmore, A.P., Page, K.L., Willingale, R., Mountford, C.J., Pagani, C., Burrows, D.N., Kennea, J.A., Perri, M., Tagliaferri, G., Gehrels, N.: Astrophys. J. Suppl. Ser. 210, 8 (2014)
Flesch, E.: Proc. Astron. Soc. Aust. 27, 283 (2010)
Gregory, P.C., Vavasour, J.D., Scott, W.K., Condon, J.J.: Astrophys. J. Suppl. Ser. 90, 173 (1994)
Hartman, R.C., Bertsch, D.L., Bloom, S.D., Chen, A.W., Deines-Jones, P., Esposito, J.A., Fichtel, C.E., Friedlander, D.P., Hunter, S.D., McDonald, L.M., Sreekumar, P., Thompson, D.J., Jones, B.B., Lin, Y.C., Michelson, P.F., Nolan, P.L., Tompkins, W.F., Kanbach, G., Mayer-Hasselwander, H.A., Mücke, A., Pohl, M., Reimer, O., Kniffen, D.A., Schneid, E.J., von Montigny, C., Mukherjee, R., Dingus, B.L.: Astrophys. J. Suppl. Ser. 123, 79 (1999)
Healey, S.E., Romani, R.W., Cotter, G., Michelson, P.F., Schlafly, E.F., Readhead, A.C.S., Giommi, P., Chaty, S., Grenier, I.A., Weintraub, L.C.: Astrophys. J. Suppl. Ser. 175, 97 (2008)
Jones, D.H., Saunders, W., Colless, M., Read, M.A., Parker, Q.A., Watson, F.G., Campbell, L.A., Burkey, D., et al.: Mon. Not. R. Astron. Soc. 355, 747 (2004)
Jones, D.H., Read, M.A., Saunders, W., Colless, M., Jarrett, T., Parker, Q.A., Fairall, A.P., Mauch, T., et al.: Mon. Not. R. Astron. Soc. 399, 683 (2009)
Mahony, E.K., Croom, S.M., Boyle, B.J., Edge, A.C., Mauch, T., Sadler, E.M.: Mon. Not. R. Astron. Soc. 401, 1151 (2010)
Maselli, A., Melandri, A., Nava, L., Mundell, C.G., Kawai, N., Campana, S., Covino, S., Cummings, J.R., et al.: Science 343, 48 (2014)
Massaro, F., D’Abrusco, R.: Astrophys. J. 827, 67 (2016). doi:10.3847/0004-637X/827/1/67
Massaro, F., D’Abrusco, R., Ajello, M., Grindlay, J.E., Smith, H.A.: Astrophys. J. Lett. 740, 48 (2011)
Massaro, E., Nesci, R., Piranomonte, S.: Mon. Not. R. Astron. Soc. 422, 2322 (2012)
Massaro, F., Paggi, A., Errando, M., D’Abrusco, R., Masetti, N., Tosti, G., Funk, S.: Astrophys. J. Suppl. Ser. 207, 16 (2013)
Massaro, E., Maselli, A., Leto, C., et al.: Multifrequency Catalogue of Blazars, 5th edn. Aracne Editrice, Rome (2014)
Massaro, F., Thompson, D.J., Ferrara, E.C.: Astron. Astrophys. Rev. 24, 2 (2016)
Mauch, T., Murphy, T., Buttery, H.J., Curran, J., Hunstead, R.W., Piestrzynski, B., Robertson, J.G., Sadler, E.M.: Mon. Not. R. Astron. Soc. 342, 1117 (2003)
Mickaelian, A.M., Hovhannisyan, L.R., Engels, D., Hagen, H.-J., Voges, W.: Astron. Astrophys. 449, 425 (2006)
Padovani, P., Giommi, P.: Mon. Not. R. Astron. Soc. 277, 1477 (1995)
Schwope, A., Hasinger, G., Lehmann, I., Schwarz, R., Brunner, H., Neizvestny, S., Ugryumov, A., Balega, Y., Trümper, J., Voges, W.: Astron. Nachr. 321, 1 (2000)
Smart, R.L., Nicastro, L.: VizieR Online Data Catalog 1324 (2013)
Sowards-Emmerd, D., Romani, R.W., Michelson, P.F., Ulvestad, J.S.: Astrophys. J. 609, 564 (2004)
The Fermi-LAT Collaboration: ArXiv e-prints, 1508.04449 (2015)
Titov, O., Stanford, L.M., Johnston, H.M., Pursimo, T., Hunstead, R.W., Jauncey, D.L., Maslennikov, K., Boldycheva, A.: Astron. J. 146, 10 (2013). doi:10.1088/0004-6256/146/1/10
Tornikoski, M., Lähteenmäki, A., Lainela, M., Valtaoja, E.: Astrophys. J. 579, 136 (2002)
Voges, W., Aschenbach, B., Boller, T., Bräuninger, H., Briel, U., Burkert, W., Dennerl, K., Englhauser, J., Gruber, R., Haberl, F., Hartner, G., Hasinger, G., Kürster, M., Pfeffermann, E., Pietsch, W., Predehl, P., Rosso, C., Schmitt, J.H.M.M., Trümper, J., Zimmermann, H.U.: Astron. Astrophys. 349, 389 (1999)
White, R.L., Becker, R.H., Helfand, D.J., Gregg, M.D.: Astrophys. J. 475, 479 (1997)
Wright, E.L., Eisenhardt, P.R.M., Mainzer, A.K., Ressler, M.E., Cutri, R.M., Jarrett, T., Kirkpatrick, J.D., Padgett, D., et al.: Astron. J. 140, 1868 (2010)
Acknowledgements
We acknowledge use of archival Fermi data. We made large use of the online version of the Roma-BZCAT and of the scientific tools developed at the ASI Science Data Center (ASDC), of the final release of 6dFGS archive, of the Sloan Digital Sky Survey (SDSS) archive, of the NED database and other astronomical catalogues distributed in digital form (Vizier and Simbad) at Centre de Dates astronomiques de Strasbourg (CDS) at the Louis Pasteur University.
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Campana, R., Massaro, E. & Bernieri, E. Application of the MST clustering to the high energy \(\gamma \)-ray sky. IV—Blazar candidates found as possible counterparts of photon clusters. Astrophys Space Sci 361, 367 (2016). https://doi.org/10.1007/s10509-016-2947-1
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DOI: https://doi.org/10.1007/s10509-016-2947-1