On the Present and Future of Pulsar Astronomy

arXiv:astro-ph/0702254v19Feb2007HighlightsofAstronomy,Volume14XXVIthIAUGeneralAssembly,August2006K.A.vanderHucht,ed.c2007InternationalAstronomicalUnionDOI:00.0000/X000000000000000XOnthepresentandfutureofpulsarastronomyW.Becker1andJ.Gil,2andB.Rudak31Max-PlanckInstitutf¨urextraterr.Physik,Giessenbachstr.1,85741Garching,Germany,email:[e-mail]my,UniversityofZielonaGora,Poland,email:[e-mail]3CAMK,Rabianska8,87-100Torun,Polandemail:[e-mail]manydifferentways,forexample,aspulsars,anomalousX-raypulsars(AXPs)andsoftgamma-rayrepeaters(SGRs)andtheso-called’radio-quietneutronstars’.Theseobjectsaremadevisiblebyhigh-energyprocessesoccurringontheirsurfaceorinthesurroundingregion.Inmostoftheseobjects,ultra-strongmagneticfieldsareacrucialelementintheradio,optical,X-rayandgamma-rayemissionprocesseswhichdominatetheobservedspectrum.Thephysicsofpulsarsspansawiderangeofdisciplines,fromnuclearandcondensedmatterphysicsofverydensematterinneutronstarinteriors,toplasmaphysicsandelec-trodynamicsofthemagnetospheres,torelativisticmagnetohydrodynamicsofelectron-positronpulsarwindsinteractingwiththesurroundingambientmedium.Nottoforgetthetestbedtheyprovideforgeneralrelativitytheoriesaswellasbeingsourcesofgrav-itationalwaves.Observationally,pulsarresearchisadvancingrapidly.Agreatarrayofspaceinstru-ments(theHubbleSpaceTelescope,ROSAT,ASCA,BeppoSAX,RXTEandtheComp-tonGamma-RayObservatory),launchedinthelastdecadeofthepreviouscentury,haveopenednewwindowsinpulsarresearchwithhighqualitydatainenergybandsfromop-ticaltothegamma-rays.WiththemorerecentlylaunchedsatelliteX-rayobservatoriesCHANDRAandXMM-Newton,upgradedradioobservatoriesandgroundbasedopticaltelescopeslikeKeck,GEMINI,SubaruandtheVLTlotsofthequestionsremainedunan-sweredfromthepreviousgenerationofobservatoriescouldbeaddressedandresultedinnewandexcitingresultswhichchangedthepreviouspictureofneutronstarevolutionsubstantially(e.g.makingCrab-likepulsarstheexceptionnottherulefortheappear-anceofayoungneutronstar).TheX-rayObservatorySUZAKU(formerlyASTRO-E2)launchedin2005,andthegamma-rayObservatoriesAGILEandGLAST,whicharesup-posedtobelaunchedendof2007/beginningof2008,willcomplementthepulsarstudiesandwillenlargetheclassofpulsarsdetectedattheirenergybands.However,eveninviewofthesegreatobservationalcapabilities,thephysicalprocessesresponsibleforthepulsars’broad-bandemission,observedfromtheinfraredtothegamma-raybandarestillpoorlyknown.Althoughnouniquelyacceptedtheoryexistssofar,anotableprogresswasmadeveryrecentlyinthisrespect.Newdevelopmentsincludecausticslotgapsaswellasmodifiedoutergaps.Lastbutnotleast:polarization-dependenttreatmentofhigh-energyradiativeprocessesisunderway,sinceX-rayand12Becker,Gil&Rudak2007gamma-raypolarimetry-anewpowerfultooltodiscriminatebetweencompetingmodels-isaroundthecorner.Tofacerecentobservationalresultsobtainedinmulti-wavelengthstudiesfromneu-tronstarsandpulsarswiththevarioustheoreticalmodelsandtodiscussonfutureper-spectivesonneutronstarastronomyweorganizedaJoinedDiscussion(JD02)duringtheXXVIIAUGeneralAssemblywhichtookplacein2006AugustinPrague.Morethan150scientiststookactivelypartinthisJointDiscussion.Fourteeninvitedreviewtalkswerepresentedtoviewthepresentandfutureofpulsarastronomy.Fiftythreepostercontributionsdisplayednewandexcitingresults.PDF-filesofallreviewtalksandmostofthepostersdisplayedduringthemeetingareavailableonthemeetingwebsite:Currently,1765pulsarsareknown.170ofthemaremillisecondpulsars.131pulsarsareinbinarysystems.129pulsarsaredetectedin24globularclusters.Recentobservationalresultsontheradioemissionpropertiesofpulsarswerereviewed.2.2.NewresultsonrotatingradiotransientsM.A.McLaughlin:Anewpopulationofradio-burstingneutronstarsdiscoveredinalargescalesearchfortransientradiosourceswasdiscussed.Unlikenormalradiopulsars,theseobjects,whicharecalledRotatingRAdioTransient(orRRATs),cannotbedetectedthroughtheirtime-averagedemissionandareradiosourcesfortypicallylessthan1secondperday.Thespinperiodsoftheseobjectsrangefrom0.4to7seconds,withperiodderivativesindicatingthatatleastoneRRAThasamagnetar-strengthmagneticfield.Recentdevelopmentsweredetailed,includingX-rayobservationsandobservationswithmoresensitiveradiotelescopes,anditwasdiscussedhowtheseobjectsarerelatedtootherneutronstarpopulations.Also,theimplicationsofthisnewsourceclassforneutronstarpopulationestimateswasdescribed.2.3.IsolatedneutronstarsinopticalandX-rays:roomfordiscoveryP.A.Caraveo:Themulti-wavelengthbehaviorofisolatedneutronstarsevolvesastheyage.Inparticular,theX-rayandopticalemissionsallowustofollowtheshiftfromthenon-thermalregime,typicalofyoungobjects,toamostlythermalone,typica