Dust in Hot Plasma of Nearby Dusty Elliptical Galaxies Observed with the Spitzer Space Telescope

[摘要] Wereportonmid-andfar-IRSpitzerobservationsof7nearbydustyellipticalgalaxiesbyusingtheMultibandImagingPhotometerforSpitzer(MIPS)andInfraredSpectrograph(IRS).Oursamplegalaxiesareknowntocontainexcessiveamountsofinterstellardustagainstsputteringdestructioninhotplasmafillingtheinterstellarspaceofellipticalgalaxies.Inordertostudytheoriginandthepropertiesoftheexcessdustinthehotplasma,weselectedgalaxieswithawiderangeofX-rayluminosities,butsimilaropticalluminositiesforourSpitzerGuestObservers(GO1)program.The7galaxiesweredetectedattheMIPS24$$mu$$m,70$$mu$$m,and160$$mu$$mbands;thefar-tomid-IRfluxratiosofrelativelyX-ray-brightellipticalgalaxiesarelowerthanthoseofX-ray-faintgalaxies.FromtheIRSspectra,polycyclicaromatichydrocarbon(PAH)emissionfeaturesweredetectedsignificantlyfrom5ofthe7galaxies;theemissionintensitiesareweakerastheX-rayluminosityofthegalaxyislarger.Wehavefoundacorrelationbetweenthefar-tomid-IRfluxratioandtheequivalentwidthofthePAHemissionfeature.Wehaveobtainedanapparentspatialcorrespondencebetweenthemid-IRandX-raydistributionsintheouterregionsforthethreeX-ray-brightestgalaxiesinoursample.Possibleinterpretationsforourobservationalresultsarediscussed.

[学科分类] 天文学(综合)

[关键词] "infrared: ISM";"ISM: lines and bands";"dust;extinction";"galaxies: elliptical and lenticular;cD";"galaxies: ISM"