North Ecliptic Pole Wide Field Survey of AKARI: Survey Strategy and Data Characteristics

摘要

WepresentthesurveystrategyandthedatacharacteristicsoftheNorthEclipticPole(NEP)WideSurveyofAKARI.Thesurveywascarriedoutforaboutoneyearstartingfrom2006Maywith9passbandsfrom2.5to24a€‰$$mu$$mandthearealcoverageofabout5.8degree$$^2$$centeredonNEP.Thesurveydepthreachesto21.8ABmagnitudenearinfrared(NIR)bands,and$$sim$$18.6ABmagnitudeatthemidinfrared(MIR)bandssuchas15and18a€‰$$mu$$m.Thetotalnumberofsourcesdetectedinthissurveyisabout104000,withmoresourcesinNIRthanintheMIR.WehavecrossmatchedinfraredsourceswithopticallyidentifiedsourcesinCFHTimagingsurveywhichcoveredabout2degree$$^2$$withinNEP-Widesurveyregioninordertocharacterizethenatureofinfraredsources.ThemajorityoftheMIRsourcesat15and18a€‰$$mu$$mbandsarefoundtobestarformingdiskgalaxies,withsmallerfractionofearlytypegalaxiesandAGNs.Wefoundthatalargefraction(60%a€“80%)ofbrightsourcesin9and11a€‰$$mu$$misstarswhilestellarfractiondecreasestowardfaintersources.WepresentthehistogramsofthesourcesatMIRbandsat9,11,15,and18a€‰$$mu$$m.Thenumberofsourcespermagnitudethusvariesas$$m^{0.6}$$forlongerwavelengthsourceswhileshorterwavelengthsourcesshowsteepervariationwith$$m$$,where$$m$$istheABmagnitude.