学海网 文档下载 文档下载导航
设为首页 | 加入收藏
搜索 请输入内容:  
 导航当前位置: 文档下载 > 所有分类 > Distant star forming galaxies, next generation radio telescopes and the radio universe befo

Distant star forming galaxies, next generation radio telescopes and the radio universe befo

I present the various capabilities of upgraded and next generation radio telescopes, in particular their ability to detect and image distant star forming galaxies. I demonstrate that e-MERLIN, EVLA and LOFAR can detect systems similar to Arp 220 out to cos

Distant star forming galaxies, next generation radio telescopes and the radio universe befo

Distant star forming galaxies, next generation radio telescopes and the radio universe befo

Proceedingsofthe6thEuropeanVLBINetworkSymposiumRos,E.,PorcasR.W.,&Zensus,J.A.(eds.)June25th-28th2002,Bonn,Germany

Distantstarforminggalaxies,nextgenerationradiotelescopes

andtheradiouniversebeforere-ionisation

M.A.Garrett1

arXiv:astro-ph/0206270v1 17 Jun 2002

JointInstituteforVLBIinEurope,Postbus2,7990AADwingeloo,theNetherlands

Abstract.Ipresentthevariouscapabilitiesofupgradedandnextgenerationradiotelescopes,inparticulartheirabilitytodetectandimagedistantstarforminggalaxies.Idemonstratethate-MERLIN,EVLAandLOFARcandetectsystemssimilartoArp220outtocosmologicaldistances.TheSKAcandetectsuchsystemsouttoanyreasonableredshiftthattheymightbeexpectedtoexist.Employingverylongintegrationtimesonthemultiple-beamSKAwillrequirethearraytobeextendedbeyondthecurrentspeci cation-simplytoavoidconfusionnoiselimitationsat1.4GHz.OtherarguementsforextendingtheSKAbaselinelengtharealsopresented.Aswellasgoing“deeper”alltheseinstruments(especiallyLOFARandtheSKA)willalsogo“wider”-detectingmanytensofthousandsofgalaxiesinasingleday’sobserving.Ibrie ycommentontheprospectsofdetectingradioemissionatmuchearlierepochs,justbeforetheepochofre-ionisation.

1.Introduction

Thecontinuumsensitivityofradioastronomyinstrumentsissettoimprovebyatleastanorderofmagnitudeoverthenext10years.Developmentsincludethebroad-bandingofexistingfacilities(e.g.e-MERLINandtheEVLA)orthedesignandconstructionofentirelynew,nextgenerationinstruments,suchastheLowFrequencyArray(LOFAR)andtheSquareKmArray(SKA).VLBIarraysarealsoexpectedtotakeadvantageoftheincreasingcapacityofdisk-basedrecordingsystems,andthereal-timeconnec-tionofantennasandcorrelatorsviacommercialoptical brenetworks.Theseupgradedandnextgenerationtele-scopeswillroutinelyreachnoiselevelswhichareattheverylimitofwhatisnowfeasiblewithexistingfacilities.DeepsurveysofthemicroJyradiosky(e.g.Fomalontetal.2002)suggestthattheradioemissionwillbeassociatedwithadominantpopulationofmoderateandhighredshiftgalaxiesthataresubjecttoon-going,massivestarforma-tion.

InthispaperIconsiderandcontrastthecapabilitiesofnextgenerationandupgradedradiotelescopes,inpar-ticulartheirabilitytodetectandimagethesefaintanddistantsystemsouttoredshift6.Ialsobrie ycommentontheprospectsofdetectingradiosourceswiththeSKAbeforetheepochofre-ionisation.

uvcov/eEVN.htm).

Imakeuseoftwospectralenergydistributions(SED)thatIhaveconstructedfrompubliclyavailabledataoftwowellknown,nearbystarforminggalaxies-Arp220andM82.WhiletheradioSEDsofthesetwogalaxiesaresimilar,theydi erindetaile.g.thelow-frequencyradiospectrumofArp220ismuch atterthanM82.Itisnotyetclearwhich(ifeither)ismorerepresentativeofthepopulationofhigh-zstarforminggalaxies.Itiscertainlyworthrememberingthatthemostdistantsystemshavestarformationrates(SFR)oneortwoordersofmagnitudegreaterthanArp220andM82respectively.

Iassumeandextrapolatethe1.4GHzsourcecountsofRichards(2000),imposingasimplefrequencydependenceonthecountsinordertoinvestigateLOFARsourcecountsat200MHz.ThroughoutthispaperIassumethecurrently“preferred”cosmologicalmodel( m=0.3, Λ=0.7,H0=70km/sec/Mpc).

3.Detectionofstarforminggalaxiesatcmwavelengths3.1.ContinuumsensitivityandStarFormationRates

Fig.1showsthe12hour(5σ)sensitivityofe-MERLIN,theEVLA,theeEVNandSKAatcmwavelengthsasafunc-tionofobservingfrequency.SuperimposedontopofthisistheSEDofArp220,projectedtoredshifts1,4and20.Theplotshowsthattheupgradedinstrumentscaninprin-cipledetectArp220(SFR~250M⊙/yr)outtoz~1orbeyondinonly12hours.TheperformanceoftheeEVNisparticularlyencouraging;withthecurrenthighsensitivityarrayaugmentedbythe64-mSardiniaRadioTelescope,theupgradedLovell76-mtelescopeandthe45-mYebes

2.TechnicalandScienti cAssumptions

InthispaperIusethefollowingsourcesofinformationregardingtelescopeparameters:

–VLAExpansionProject(seewww.nrao.edu/evla),–e-MERLINScienceCase&TechnicalSpeci cation(seewww.merlin.ac.uk/e-merlin/),

–LOFARBasicSpeci cations(http://doc.xuehai.net),

第1页

我要评论

相关文档

站点地图 | 文档上传 | 侵权投诉 | 手机版
新浪认证  诚信网站  绿色网站  可信网站   非经营性网站备案
本站所有资源均来自互联网,本站只负责收集和整理,均不承担任何法律责任,如有侵权等其它行为请联系我们.
文档下载 Copyright 2013 doc.xuehai.net All Rights Reserved.  email
返回顶部