Summary of KaVA/EAVN observations of M87 and Sgr A* in 2014-2018 M. Kino (NAOJ/KUTE) & BW Sohn (KASI) on behalf of EAVN AGN Science WG 2019/Sep EAVN Workshop 2019 Sep, at Ibaraki Univ
SummaryofKaVA/EAVNobservationsofM87andSgrA*in2014-2018
M.Kino(NAOJ/KUTE)&BWSohn(KASI)onbehalfofEAVNAGNScienceWG
2019/Sep EAVNWorkshop2019Sep,atIbarakiUniv
Grandchallenge#1:solvingjetformationmechanism
EHTtalksG.Bower(ASIAA)F.Tazaki(NAOJ)
(c)EAVNCollaboration
(c)EHTC
TotestB-drivenjetmodel,wemeasure/constrainbasicquantitiesof
1. velocityfield2. B-field3. flowgeometry
BZprocessatwork?
v-field,B-field,andflowgeometryofM87Park+2019submittedRoetal.inprepCuietal.inprep
EAVNWorkshop2019
Longstandingproblem:“IstheM87jetfastorslowinthecollimationzone?”
Asada+(2014)
fastorslow?
Keytoresolvetheproblemishighcadencemonitoring,
whichcanavoidmisidentificationsofthemultiplejetcomponents!
TheKaVAhigh-cadence(bi-weekly)monitoringin2016revealstheprofileofM87’sjetvelocityfield.
22GHz
Park+submitted
43GHz
1.Velocitystratification!2.Discrepancybtw.observationandGRMHD?!
Park+submitted
ConstrainingB-fieldinM87at22/43GHz(2015-2016data)
H.RowillpresentnewconstraintsonB-fieldpropertiesviaradialprofileofthespectralindex.Staytuned!
Ro+inprep
Flowgeometryatthejetbase
l Unfortunately,EHTcouldnotdetectthejetemissioninEHT2017.
whichdirection?jetopeningangle?
EHTC’sestimateofPositionAngle(PA)ofForwardJet(FJ)viamatchingGRMHDsnapshottothephotonring
EHTC+2019,ApJL
EAVNmeasuretherealjetPAin2017AprilCui+inprep
Southernlimb
Northernlimb
FromtheEAVNdata,wefindthat(1)widejet-openingangle,and(2)EHTCestimatesofPA_FJreasonablyagreewithEAVNjet.
Cui+inprepPo
sition
Ang
le[d
egree]
RelativeRA[mas]
320
230
Northernlimb
Southernlimb
ProbingrealvicinityofSMBHCho+inprep(Zhao+inprep)
EAVNWorkshop2019
Grandchallenge#2:UnveilingaccretionflowontoSMBH
VLAimage(c)Lo
minispiralatGal.Center
(VLA)
1pc
SgrA*(EAVN)
100Rs
Wearealmostthere.However,thereisoneseriousissue.
Longstandingproblem:“ObservedradioimagesofSgrA*isdominatedbyinterstellarscattering.
So,aninferenceofSgrA*imageissensitivetoanassumedscatteringmodel.”
(c)Akiyama
angularbroadening
non-Gaussian&substructure
Johnson+2018
KaVA7mmdata(2014Nov)showsnon-Gaussiananditsignificantlyconstrainsscatteringkernel.
Johnson+2018
Thescatteringparameters(αandr_in)arefinallyconstrainedverytightly!
So,usingtheseparametersinJohnson+2018wecanremovetheeffectofthescatteringandthuswecanderiveintrinsicsizeofSgrA*in2017.
EAVNobservationofSgrA*on2017April3rd@22GHz
Cho+inprep
IntrinsicsizeofSgrA*!
Fromthis,wecanpotentiallyconstrainongeometryofSgrA*andelectrondistributioninit.
Cho+inprep
ThearrayisinatransitionphasefromKaVAtoEAVN.(i)TransversemotionoftheM87jet(ii)OriginofflaresinSgrA*
EAVNworkshop2019
TimeallocatedforinitialphaseofEAVNLPin2019Sep–2020Jan
IljeCHOandGuangyaoZHAO
HyunwookRO
EAVNLPofinvestigatingthetransversemotioninM87
Thetimescaleofapossibleoscillationisoneyearscale.Hence,longtermmonitoringat22GHzisessentialtocharacterizeitsproperties.Wecanstudyoninstabilitiesinthejet.
RA[mas]
Declin
ation[m
as]
Ro+inprep
SignificantIRflareactivityin2019Doetal.(2019)
observedflareflux(mJy)freq
uencydistrib
uXon
TheelevatedIRflareactivityencouragesEAVNLPmonitoringofSgrA*.
Doetal.(2019)saysl “Thedistributionoffluxvariationsobservedthis
yearissignificantlydifferentthanthehistoricaldistribution.”
l “PotentialphysicaloriginsofSgrA*’sunprecedentedbrightnessmaybefromchangesintheaccretion-flowasaresultofthestarS0-2‘sclosestpassagetotheblackholein2018orfromadelayedreactiontotheapproachofthedustyobjectG2in2014.”
SummaryofEAVNAGNScienceWGactivities
l Paperdraftingw/KaVALargeProgramdatain2014-2018ü Park+2019submitted(M87velocityfieldin2016)ü Ro+inprep(M87magneticfieldin204-2016)ü Cui+inprep(M87jetPAin2017-2018)ü Cho+inprep(SgrA*intrinsicsizein2017April)ü Zhao+inprep(SgrA*intrinsicsizein2013-2016)
l ConductinginitialphaseEAVNLPin2019Bü TransverseoscillationoftheM87jetü OriginofsignificantflaresinSgrA*
l Development/upgradeofEAVNü KaVA/EAVNpolarimetry(BWSohn+,K.Hada+,J.Park)ü KaVA/EAVNphase-ref(J.Oh+)ü EATINGVLBI(M.Giroletti+)ü EAVN-high(K.Asada+)