AbstractWithinthecompactcentralregionof~3%ofgalaxies,thereisevidenceforluminouslightemission at22GHzoriginatinginMicrowavesAmplifiedbyStimulatedEmissionofRadiation(masers)fromwatermolecules.Morethan60%ofthesedetectionsrevealintensitiesthataremillionsoftimesgreaterthanthatoftheveryfirstmasersdiscoveredinthestar-formingspiralarmsofourownMilkyWaygalaxy,andarethereforecalledmegamasers.Afractionofthesemegamasersarefoundinadisk-likeconfiguration,offeringthusunprecedentedtoolsforaccurate measurementsof:(1)directdistancestotheirhostgalaxies,independentofassumptionsaboutthegeometryoftheuniverse, aswellas(2)themassesofthecentralblackholemassesthatlurkinthecentersofthesesystems, whichareusuallymillions tobillionsoftimesheavierthanourownSun.Unfortunately,thereareonlyahandfulofthesemegamaserdisksthatwehavebeenabletoinvestigateingreatdetail.Inanattempttosignificantlyincreasethedetectionrateoftheseholygrailsofastronomy,weareconductingastudyofthephysicalpropertiesoftheirhostgalaxies,withthehopeofidentifyinggalaxytraitsconnectedtothemegamaserdiskphenomenon.Inthiswork,wepresentourtechniquesforpublicdatacollectionofthetotalfluxemittedacrosstheelectromagneticspectrum(i.e.,buildingspectralenergydistributions;SEDs)ofthehostgalaxiesofallknownmegamaserdisks,withthegoalofquantifyingthedegreetowhichvariousenergeticcomponents(e.g.,blackholeaccretion,starformation,dustobscurationandreprocessing)contributetothetotalgalaxylight. ThroughSEDcomparisonsofhostgalaxiesthatdonothostmaseremission,alongwithSEDfitsoftemplatemodelsfromvariousmainemissionmechanisms,ourSEDplotswillbeusedtobestdiagnosetherelationsbetweenthe22GHzemissionandthatfromnuclearaccretion,stellarlight,orthereprocessingbysurroundingdust.Thismethodwillallowmoreefficientidentificationofthetypesofgalaxiesthataremostlikelytohostmegamaserdisksinordertoincreasetheirdetectionrate.

SpectralEnergyDistributionsofH2OMegamaserDisks

SWIFT

MCPprovidesthelargestcatalogofgalaxiessurveyedforwatermaseremissionin22GHzwiththeprimarygoalofmeasuringtheHubbleconstant(H0)bydetermininggeometricdistancestoH2OmegamaserdiskswellwithintheHubbleflow, greaterthan50Mpc(Braatz,J.,2009)

Ø 47megamaserdiskscandidatestodate;15confirmed(withVeryLargeBaselineInterferometry(VLBI)measurementsofrotationalvelocityasafunctionofimpactparameterthatfitaKepleriandisk)

Ø Mostupdatedlistofmegamaserdisks,alongwithinvestigationoftheiropticalandmid-IRproperties,extractedfromKuo,Constantin,et.al(2018)

Ø NEDisamultiwavelengthdatabaseofforextragalacticobjectsØ CombinesdatafromlargeskysurveysandresearchpublicationsØ Extractedthefrequency (Hz),flux (Jy),uncertaintyforthefluxmeasurement,andthe

aperturesizesusedforeachobservation

SpectralEnergyDistributions(SED)

= ground-based

= space-based

Atadistanceof7Mpc,NGC4258isthefirstmegamaserdiskdetected.ThisisaSeyfert2galaxy(i.e.,onlydetectsnarrowlineemission)andshowsacollectionoffluxesrangingfromradiotoX-ray.Themassoftheblackhole,whichisthoughttobethesesystems’sourceofenergy(i.e.,gravitationalenergyfromaccretiondiskandtheblackhole’sspin),is3.9x107 M☉(Herrnstein,1999).

SloaneMcNeill&AncaConstantin,DepartmentofPhysics&Astronomy,JamesMadisonUniversity

FutureWork

(Braatz,J.,etal.2018inprep.;MCP)

CGCG074-064isthemostrecentlydiscoveredwatermegamaserdisktoincludeVLBIresults.Atadistanceof83Mpc,thisgalaxyhasablackholeatit’scenterwithamassof2.28x107 M☉ (Pesce 2018)

NGC2273isaSeyfert2galaxyatadistanceof26Mpcwithawarpedmaserdiskataninclinationof84◦.Thecentralblackholehasamassof7.5x106 M☉ (Kuo,etal.2010).

Atadistanceof50Mpc,UGC3789isaSeyfert2galaxy.Theedge-onmaserdiskismostlikelywarpedalongthelineofsight.Theblackholehasamassof1.04x107 M☉ (Kuo,etal.2010).

NGC1194isaSeyfert1.9galaxy(i.e.,showsmostfeaturesofaSeyfert2,however,withaweakbroad-lineemissioncomponent)withthelargestmegamaserdiskandblackholemasspresentedinthiscollection.Atadistanceof52Mpc,thismaserdiskhasan

inclinationof85◦ andablackholemassof6.5x107 M☉ (Kuo,etal.2010).

NGC6323isaSeyfert2galaxywithawarped,thindiskataninclinationof89◦anddistanceof105Mpc.Theblackholemassis9.4x106 M☉ (Kuo,etal.2010).

TheMegamaserDiskSample: SEDData:NASAExtragalacticDatabase(NED)

𝜈

VLA

HSTGBT

WISE

GALEX

ChandraSDSS

Radio Optical X-rayUVIR

SEDplotsshowtheenergy(𝜈F𝜈)emittedasafunctionoffrequency(𝜈)ØFittingmulti-frequencyobservations,i.e.SEDs,attempttoidentitythedegreetowhichvariousenergeticcomponentscontributetothetotalfluxofagivengalaxy

FourpanelsexemplifyingthedependenceoftheIRtoX-raySEDshapeonthevaryingnuclearobscurationandluminosityoftheAGN,aswellasthehost

galaxystellarlightcontribution(fromHickox&Alexander2018).

ComponentsandtheiremissionØ AccretiondiskproducesX-rayemissionØ Gasheatedbyhotphotonsfromtheaccretiondisk(powerlaw+

emissionlines)Ø Stellaremissionfromhostgalaxiespeaksinnear-IR+contributions

fromX-raybinariesinsoftX-rayØ Hotdustwithinthetorusemitsinthemid-IRrangeØ Dustheatedinstarformationregionsofhostgalaxyemitsinfar-IRØ Synchrotronemission,relatedtotheaccretiondiskand/orradiojets,

emitsinradio

ImportanceofSEDsWhiletheconnectionbetweenwatermegamasersandAGNsisnotyetwellunderstood,SEDsprovidethetoolstobetterunderstandtherelativedominanceofthelightproducedinthehostgalaxiesofmaserdisks.Inparticular,byquantifyingthelightdistributionoveralargewavelengthrange,weshouldbeabletoaddressthefollowingquestions:

Ø Aremegamaserdisksalwaysassociatedwithblackholeaccretion?Ø Whatmechanismsofthenucleusinfluencethismaseractivity?Ø Doesmaseractivityrequirethetorus?Ø Whatisanaccuratemegamaserdiskdetectionrate?

Ø Collectandincludemid-IRphotometryfromWide-fieldInfraredSurveyExplorer(Wrightetal.2010)totheSEDplotsinordertoinvestigatethelinkbetweenmaseractivityandthereprocessingofthenuclearAGNradiationbythesurroundingdust(e.g.,Sternetal.2012)

Ø ProceedwithSEDfittingtoquantifythecontributionofAGNcomparedtostellarlightandotherenergeticphenomenainthesegalaxies

Results:SEDsforbeststudiedmegamaserdisks

Populationinversionofwatermolecules

𝜈=22GHz𝜆=1.4cm

432x1140as MASER –MicrowaveAmplificationbyStimulatedEmissionofRadiation

r=

GBTspectrumat22GHzrevealsthreecomponents(redshifted +systemic+blueshifted)suggestingdisk-likeconfiguration (Herrnsteinetal.1999).

Modelofcomponentsinnucleusofgalaxywithactivelyaccretingsupermassiveblackhole(ActiveGalacticNucleus,AGN)(Zierr &Biermann2018)

VLBIdataiscleanlyfitbyaKepleriandisk,v(r)∝r-

1/2,allowingusto:

1.MeasuredirectdistancesØ IndependentconstrainttotheHubbleConstant(ageoftheuniverse)

Ø ConstrainthegeometryoftheuniverseØ Betterunderstanddarkenergy2.Measuremassofsupermassiveblackholes(MSMBH=~107M☉).

PhysicsofMasers

?

Megamasers – 106 timesgreaterthantypicalgalacticmasers

OpticalimageofNGC4258

d=7.28±0.3Mpc

LOS(km/s)

SMBH

maser

maser

DustparticlesEmissionlines

Accretiondisk

mid-IR

2018

Acknowledgements.ThisworkhasbeensupportedbyJMU’sPhysicsandAstronomyDepartment,the4-VACollaborativeatJamesMadisonUniversity,andtheNationalScienceFoundationawardNSF:AST#1814594.ThisresearchhasmadeuseoftheNASA/IPACExtragalacticDatabase(NED),whichisoperatedbytheJetPropulsionLaboratory,CaliforniaInstituteofTechnology,undercontractwiththeNationalAeronauticsandSpaceAdministration.

References.Braatz,J.,etal.,2009,ApJ,695,287;Braatz,etal.,2018,https://safe.nrao.edu/wiki/bin/view/Main/MegamaserCosmologyProject;Dattoli,G.,Doria,A.,etal.,2017,IOP,4,1;Herrnstein,etal.,1999,A&A,20,165;Hickox,R.&Alexander,D.,2018,ARA&A,56,1;Kuo,C.,etal.,2010,ApJ,727,20;Kuo,C.,Constantin,A.,etal.,2018,ApJ,860,169;Pesce, 2018,PhDThesis,UVA;Stern,D.,etal.,2012,ApJ,753,30;WrightE., etal.,2010,AJ,140,1868;Zierr,C.&Biermann,P.,2018,A&A,69,1

(Reid,M.,Braatz,J.,etal.2013)

(Kuo,C.,Braatz,J.,etal.2015)

(Braatz,J.,etal.2018inprep.;MCP)

(Braatz,J.,etal.2018inprep.;MCP)

Moredataisneededtoquantifythecontributionofthedustytorus.ThelackofdataintheX-rayrangecouldindicateobscurationorweakaccretionactivityforthisradioquietsystem.

Thelowfluxeswithintheradiorangesuggestsaradioquietsystem.Bluebumpisalsoprominent.

ProminentbluebumpwithintheopticalregionsuggestsastrongAGNcomponent

TheMegamaserCosmologyProject(MCP)