Search for Oxygen Emission from Warm-Hot Intergalactic Medium around A2218 with Suzaku

[摘要] WesearchedforredshiftedOemissionlinesfromapossiblewarm-hotintergalacticmedium(WHIM)surroundingtheclusterofgalaxiesA2218at$$z=0.1756$$usingtheX-rayImagingSpectrometer(XIS)instrumentonSuzaku.Thisclusteristhoughttohaveanelongatedstructurealongthelineofsightbasedonpreviousstudies.WestudiedsystematicuncertaintiesinthespectrumoftheGalacticemissionandinthesoftX-rayresponseofthedetectorsduetothecontaminationbuildingupontheXISfilters.WedetectednosignificantredshiftedOlines,andsetatightconstraintontheintensitywithupperlimitsforthesurfacebrightnessofOVIIandOVIIIlinesof$$1.1imes10^{-7}$$and$$3.0imes10^{-7};mathrm{photons};mathrm{cm}^{-2},mathrm{s}^{-1},mathrm{arcmin}^{-2}$$,respectively.TheseupperlimitsaresignificantlylowerthanthepreviouslyreportedfluxesfromtheWHIMaroundotherclustersofgalaxies.WealsodiscusstheprospectfordetectingtheWHIMlineswiththeSuzakuXISinthefuture.

[学科分类] 天文学(综合)

[关键词] "large-scale structure of universe";"galaxies: clusters: individual (A2218)";"intergalactic medium";"X-rays: diffuse background"