Nobeyama Millimeter Array Observations of GRB 030329: a Decay of Afterglow with Bumps and Molecular Gas in the Host Galaxy

[摘要] NobeyamaMillimeterArraywasusedtoobservemillimeter-waveafterglowofGRB030329at93 GHzand141 GHzfrom2003April6(8.23daysaftertheburst)to2003May30(61.97days).AsensitivesearchforCO$$(J=1hbox{--}0)$$emission/absorptionfromthehostgalaxyofGRB030329wasalsocarriedout.UnresolvedmillimetercontinuumemissionatthepositionofGRB030329wasdetecteduntil2003April21.Wefoundasteepdeclineofcontinuumflux($$proptot^{-2.0}$$)duringthisperiod,inaccordwithapreviousreport.Moreover,ourdataimpliesthatthedecaywasaccompaniedbypossibleplateausphases,orbumps,onatimescaleofseveraldays.Fromanintegratedspectrum,producedbysummingupthedatafrom2003April10to2003May30,wefoundapossibleemissionfeature,whichcouldbearedshiftedCO$$(J=1hbox{--}0)$$line.ItspositionandredshiftcoincidewellwiththoseofGRB030329,thoughfurtherobservationsarerequiredtoconfirmthedetection.Iftheemissionfeatureisreal,theobservedCOfluxis$$1.4pm0.52,mathrm{Jy},mathrm{km},mathrm{s}^{-1}$$,correspondingtoalargemoleculargasmassof$$M(mathrm{H}_2)gt;10^9,{{{M}_{odot}}}$$.Thisimpliesthatthehostgalaxy,whichisopticallyfaint,ishighlyobscuredduetoarichinterstellarmedium.

[学科分类] 天文学(综合)

[关键词] "galaxies: ISM";"gamma-ray burst: general";"gamma rays: individual (GRB 030329)"