J/A+A/581/L5ivo://CDS.VizieR/J/A+A/581/L5doi:10.26093/cds/vizier.35819005CDSGarrett M.A.2017-06-21T08:22:15Z2016-01-15T10:55:31ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frradio-galaxiesgalaxiesinfrared-sourcesWright et al. (2014ApJ...792...26W) have embarked on a search for advanced Karadashev Type III civilisations via the compilation of a sample of sources with extreme mid-IR emission and colours. The aim is to furnish a list of candidate galaxies that might harbour an advanced Kardashev Type III civilisation; in this scenario, the mid-IR emission is then primarily associated with waste heat energy by-products. I apply the mid-IR radio correlation to this Glimpsing Heat from Alien Technology (Ghat) sample, a catalogue of 93 candidate galaxies compiled by Griffith et al., 2015ApJS..217...25G. I demonstrate that the mid-IR and radio luminosities are correlated for the sample, determining a k-corrected value of q_22_=1.35+/-0.42 . By comparison, a similar measurement for 124 galaxies drawn from the First Look Survey (FLS) has q_22_=0.87+/-0.27. The statistically significant difference of the mean value of q_22_ for these two samples, taken together with their more comparable far-IR properties, suggests that the Ghat sample shows excessive emission in the mid-IR. The fact that the Ghat sample largely follows the mid-IR radio correlation strongly suggests that the vast majority of these sources are associated with galaxies in which natural astrophysical processes are dominant. This simple application of the mid-IR radio correlation can substantially reduce the number of false positives in the Ghat catalogue since galaxies occupied by advanced Kardashev Type III civilisations would be expected to exhibit very high values of q. I identify nine outliers in the sample with q_22_>2 of which at least three have properties that are relatively well explained via standard astrophysical interpretations e.g. dust emission associated with nascent star formation and/or nuclear activity from a heavily obscured AGN. The other outliers have not been studied in any great detail, and are deserving of further observation. I also note that the comparison of resolved mid-IR and radio images of galaxies on sub-galactic (kpc) scales can also be useful in identifying and recognising artificial mid-IR emission from less advanced intermediate Type II/III civilisations. Nevertheless, from the bulk properties of the Ghat sample, I conclude that Kardashev Type III civilisations are either very rare or do not exist in the local Universe.2015A&A...581L...5Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/581/L5CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)II/328 : AllWISE Data Release (Cutri+ 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/581/L5https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/581/L5http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/581/L5https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/581/L5https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/581/L5http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/581/L5GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/581/L5/table1 (The Ghat sample studied in this paper, including values (or upper limits) of q_22_)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/581/L5/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/581/L5/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/581/L5/table1?GETtext/xml+votable180.050000true54.1627083-20.90188890.0055555555555555566/55 816 1875 2229 2423 2722 3109 3506 3530 3824 4381 6852 8438 8673 8749 9677 9895 10099 10281 11101 11984 12537 13376 13697 13905 14980 15075 15923 15927 16547 17252 17733 18070 18406 18809 18827 19694 20745 20777 21004 21150 21176 21238 21291 21394 21476 21838 22721 23300 23361 23566 24750 24862 24958 25079 25477 26264 26298 26634 26821 27058 27384 27643 28126 28393 28469 28631 31042 31595 31715 32540 35534 35576 35671 36241 36558 36622 38323 40028 40063 42675 43373 43874 44010 44013 44236 44314 47943 48027 48041 482669.276497240453405e-25 9.827027931427413e-21https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/581/L5?format=asciiRadioInfrareddefaultJ/A+A/581/L5/table1The Ghat sample studied in this paper, including values (or upper limits) of q_22_SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainl_S20cm[<] Limit flag on S20cmmeta.code.errorcharS20cmNVSS flux density at 20cm (1.4GHz)mJyphot.flux.density;em.radio.750-1500MHzfloatW4WISE W4 magnitudemagphot.flux.density;em.IR.15-30umfloatl_q22[>] Limit flag on q22meta.code.errorcharq22[0.1/3] q_22_=log[S(22{mu}m)/S(20cm)] (1)phot.flux;arith.ratiofloatz[0/0.15] Redshiftsrc.redshiftdoublegamma[0/1] Fraction of starlight re-emitted in the mid-IR as waste heat products ({gamma})phys.emissivityfloatTypeSIMBAD object typesrc.classcharNameSource Namemeta.id;meta.mainchar