A search for radio supernovae and supernova remnants in the region of NGC1569's super star

We have used MERLIN, at 1.4 and 5 GHz, to search for radio supernovae (RSNe) and supernova remnants (SNRs) in the unobscured irregular dwarf galaxy NGC1569, and in particular in the region of its super star clusters (SSCs) A and B. Throughout NGC1569 we fi

Astronomy&Astrophysicsmanuscriptno.(willbeinsertedbyhandlater)

Asearchforradiosupernovaeandsupernovaremnants

intheregionofNGC1569’ssuperstarclusters

arXiv:astro-ph/0111221v1 12 Nov 2001

A.Greve1,A.Tarchi2,3,S.H¨uttemeister4,5,R.deGrijs6,J.M.vanderHulst7,S.T.Garrington8,and

N.Neininger2

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InstitutdeRadioAstronomieMillim´etrique,300ruedelaPiscine,38406St.Martind‘H`eres,FranceAstronomischesInstitutderUniversit¨atBonn,AufdemH¨ugel71,D–53121Bonn,GermanyMax-PlanckInstitutf¨urRadioastronomie,AufdemH¨ugel69,D–53121Bonn,GermanyAstronomischesInstitutderRuhr-Universit¨atBochum,Universit¨atsstr.150,D–44780Bochum,GermanyOnsalaSpaceObservatory,S–43920Onsala,Sweden

InstituteofAstronomy,UniversityofCambridge,MadingleyRoad,CambridgeCB30HA,UKKapteynAstronomicalInstituut,Postbus800,9700AVGroningen,TheNetherlands

Nu eldRadioAstronomyLaboratories,JodrellBank,Maccles eldCheshireSK119DL,UK

receiveddate;accepteddate

Abstract.WehaveusedMERLIN,at1.4and5GHz,tosearchforradiosupernovae(RSNe)andsupernovaremnants(SNRs)intheunobscuredirregulardwarfgalaxyNGC1569,andinparticularintheregionofitssuperstarclusters(SSCs)AandB.ThroughoutNGC1569we ndsome5RSNeandSNRsbuttheSSCsandtheirimmediatesurroundingsarelargelydevoidofnon-thermalradiosources.EventhoughmanymassivestarsintheSSCsareexpectedtohaveexplodedalready,whencomparedwithM82anditsmanySSCstheabsenceofRSNeandSNRsinandnearAandBmayseemplausibleonstatisticalarguments.TheabsenceofRSNeandSNRsinandnearAandBmay,however,alsobeduetoaviolentandturbulentout owofstellarwindsandsupernovaejectedmaterial,whichdoesnotprovideaquiescentenvironmentforthedevelopmentofSNRswithinandneartheSSCs.

Keywords.galaxies:individual:NGC1569–galaxies:supernovae–galaxies:ISM

1.Introduction

Forsome150Myr,theMagellanic-typeirregulargalaxyNGC1569experiencedastarburstofrelativelylowav-eragestarformationrate(～0.5M⊙yr 1),untilapproxi-mately10Myragowhenthestarburstgraduallyceased.ThroughoutthebodyofNGC1569thestarbursthaspro-ducedmanyyoungstars(Greggioetal.1998,Aloisietal.2001)andalargenumberofstarclusters(Hunteretal.2000),togethercontainingatotalmassof～108M⊙.However,evidenceforrecentandlocallyverye cientstarformationinNGC1569comesfromtheSuperStarClusters(SSCs)AandB(Ables1971,Arp&Sandage1985,O’Connelletal.1994)whicharesimilarinsizeandmasstothosefoundinNGC1705(Melnicketal.1985),M82(O’Connelletal.1995,deGrijsetal.2001),andotheramorphous,irregular,andinteractinggalaxies.TheSSCsaresiteswhereinarelativelysmallvolumeof

36<～50kpcalargenumberofstars(～10M⊙)havespon-taneouslyformed.Manymassivestarsproducedinthe

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