NewIdeasAboutDarkMa2erMITCTP50

w/JakubSholtz,JamesUnwinw/Ma2Reece,JijiFan,AndreyKatz,Eric

Kramer,PrateekAgrawal,AlexandraShelestFrancisCyr-Racine

AFewDecades….•  50yearsCTP

–  16.5yearsagoforme•  Whathaschanged?

–  Higgsfound•  StronginteracUons,Supersymmetry,ExtraDimnotYET

–  DarkMa2er•  Increasinglystrongevidence•  But

–  MuchmoresensiUveWIMPsearches—nothing–  Muchbe2erastronomicalstudies–  Growingawarenessofotherpossiblemodels

–  GravityWaves,BlackHoles•  HybridInflaUonandBlackHoles•  NuclearColloquium

FOCUSTODAYONDARKMATTER—PERCHEDONDISCOVERY?

MAKEUPOFUNIVERSE

DarkMa2er

•  Currentlyoutstandingcosmologicalmodel•  But…leavescriUcalquesUonsunanswered– Natureofmostofthema2erandenergyintheUniverse

•  Actuallynottoosurprising– Wehaveonlylimitedmeasuringtools–  IfsomethinginteractsonlygravitaUonallyweliterallycan’tseeit

Howdowe“see”(sofar)

•  GalacUcrotaUoncurves•  GalaxyclustersvirialvelociUes•  GravitaUonallensing•  Bulletclusterandothers•  Supernovae•  Cosmicmicrowavebackgroundstructure•  ExistenceofgalaxiesinlifeUmeofUniverse•  ExistenceofgalaxiesonscaleofMilkyWay

•  Thereisalotofevidence•  Andit’sallconsistent•  Basicallyhowanynewphenomenonorthingestablished

WhatIsDarkMa=er?

•  Someformofma2er– ButisitaparUcle?– Whatisitsmass?– WhatareinteracUons/charges–  IsitjustonetypeofparUcle

•  WeknowonlyofgravitaUonalinteracUons– NootherdiscernibleinteracUons(yet)

•  Existencenotnecessarilysomysterious•  Butmakeupofthema2ersUllis

NatureDarkMa=er?•  Wedon’tyetknow•  WeknowgravitaUonalinteracUons

–  ButnootherdiscernibleinteracUons(yet)•  Existenceofdarkma2ernotnecessarilysomysterious•  Buthowtofindwhatitis?

–  Lookunderthelamppost–  FindtheoreUcal,experimentalclues

•  Whataretherightlampposts•  WeneedtoconsiderallpossibiliUes

–  Doesdarkma2erinteractas?–  Doesitinteractdifferently?

•  Nopromises•  Opportunitytoconsidernewideas•  Won’targuethatanysingleideahastobecorrect

–  Infactweshouldneverhavedonethat•  ButwillintroducepossibiliUes•  AndconsiderpotenUalimplicaUons

•  Buthowtofindwhatitis?– Lookunderthelamppost– FindtheoreUcal,experimentalclues

•  WeneedtoconsiderallpossibiliUes

WIMPs

•  UnUlrecentlymost“popular”candidate•  WeaklyInteracUngMassiveParUcle•  Merits– OccursinextensionsoftheStandardModel– TestablebecausenotonlygravitaUonalconnecUon

WIMPS•  Demerits– Notseen–  BSMnotseen– Overhyped—otherpossibiliUes

•  SearchestodatealwaysbasedonopUmisUcassumpUons– Darkma2erdoesinteractwithourma2eratsomelevel

– WIMP“standard”paradigm•  ButSoFar– NodirectdetecUon– NoindirectdetecUon–  LHChasn’tshownanysignofnewweakscalephysics

Today

•  Natureofdarkma2erremainsamystery– NosignofWIMPs– Sparsesignofnewweak-scalephysics

•  PerhapssignsofdeviaUonsinsmall-scalestructure

•  Somenewmodel-buildingideas•  IfnotWIMPs,besttestsprobablyinvolvedetailedstructure

•  CriUcaltofindimplicaUonsofmodels•  Moregenerallyunderstandmodels,andhowtointegrateintoabiggerpicture

OtherinteresUngpossibiliUes?

•  Surprisingly,relaUvelyunexploredopUon:•  InteracUngdarkma2er;chargedeven!•  ThoughtUnlikely–  EllipUcityofhalos–  BulletClustertypeconstraints–  Survivalofdwarfgalaxiesinhalos(lackofevaporaUon)

•  Seemedtosignificantlyimpingeonparameterspace•  ButmanyincorrectassumpUons,analyses

Example:EllipUcityasfuncUonofradius

Revisions:Notclearrighttarget

•  RelaUveimportancevelocityanistropyversusthatinpotenUal?– Substructure,darkma2erstreams,asymmetricaccreUon

•  Galaxyconstraintstrongerthangalaxyclusters– ButonlyNGC720measured

•  Mergerhistoryalsoimportant–enoughUmeforellipUcitytobeerased?

OurResult

OtherCurves/Constraints

•  BulletCluster—soweakwedon’tre-evaluate– ButnotepreciseboundisquesUonable– ExisUngboundcomesfromrequiringnomorethan30%ofdarkma2erlostinmerging

– Butwedon’tknowiniUaldarkma2ercontent•  Orbaryontodarkma2erraUo

– Couldbethatconsiderablymoredarkma2ercanbelost

Darkly-ChargedDarkMa2er

•  Clearlyviable!!•  Constraintsonmassconsiderablyweakerthanstated

•  Andperhapsnotreliable– SimulaUonscanhelp

•  ExciUngpossibilitythatdarkma2erhasitsownworldofinteracUons– Andthatconceivablywecandetectthem

NewRegimeofInteracUonsDuality—andnewtests

Anotherpossibility:onlyafracBoninteracts?

ParUallyInteracUngDarkMa2er:PIDM

•  Ratherthanassumealldarkma2er•  Assumeit’sonlyafracUon(maybelikebaryons?)•  FracUonchangesallconstraints•  ConvenUonalconstraintsevenweaker–  IfonlyafracUoninteracUng,wouldn’tmakeenUre

thingisotropicveryefficiently–  ClearlyBulletClusterokayifonlyafracUon–most

darkma2erwouldpassthrough–  Anddwarfgalaxieswouldsurvive

•  LotsofimportantimplicaUonsformeasurements

ParUallyInteracUngDarkMa2er•  Darkma2erwithitsownforce– Ratherthanassumealldarkma2er– Assumeit’sonlyafracUon–likebaryons…

•  NonminimalassumpUon:whywouldwecare?•  ImplicaUonsofasubdominantcomponent– CanberelevantforsignalsifitisdenserØ Canberelevantforstructure–likebaryons!

•  Baryonsma2erbecauseformedinadensedisk–  Perhapssameforcomponentofdarkma2er

•  IntroducesdissipaUvemechanism–  Canleadtodisks,pointlikesources

DissipaUveFracUon

•  Generatesstructure– Easiertodetect

•  Significantconsequences– LeadstorethinkingofimplicaUonsofalmostalldarkma2er,astronomical,cosmologicalmeasurements

•  Sincewedon’tknowwhatdarkma2eris– Shouldkeepanopenmind– Especiallyinlightofabundanceofastronomicaldata

CouldinteracUngdarkma2ercool?IntoaDarkDisk?

•  Togenerateadisk,coolingrequired•  Baryonscoolbecauseelectronsradiateandinteract–  TheytherebylowerkineUcenergyandvelocity–  GetconfinedtosmallverUcalregion

•  Diskbecauseangularmomentumconserved

•  DarkdisktoorequiresameansofdissipaUngenergy•  AssumeinteracUngcomponenthastherequisiteinteracUon

•  SimplestopUondarkly-chargeddarkma2er

SimpleDDDMModel:“DarkLight”•  CouldbeU(1)oranonabeliangroup•  U(1)D,αD•  Twoma2erfields:aheavyfermionXandalightfermionC–  For“coolant”aswewillsee

•  qX=1,qC=-1•  (Inprinciple,XandCcouldalsobescalars)•  (inprinciplenonconfiningnonabeliangroup)•  ThisinaddiUontodarkma2erparUclethatmakesupthehalo

•  WhenXfreezesoutwithweakscalemediators,couldhavehalftempofSMparUcles

•  Inanycase,thermalabundanceofweakscaleparUclenaturallygivesrisetofracUonofdarkma2erabundance

•  Probablyhaveboththermalandnonthermalcomponents

Coolingtempdeterminesdiskheight•  Andthereforedensityofnewcomponent

Summaryofmodel

•  Aheavycomponent– WasiniUallymoUvatedbyFermisignal

•  Fordisktoform,requirelightcomponent– Can’tbethermal(densitywouldbetoolow)– Constraintondensityvsmass

•  WiththesecondiUons,expectadarkdisk– Evennarrowerthanthegaseousdisk

•  LotsofpotenUallyvisibleconsequences

TradiUonal(WIMPy)Methods

•  SmallerdirectdetecUon,smallvelocity– PossiblyothernoncanonicalpossibiliUes–  Iffound,differentenergydistribuUon,Umedepce

•  IndirectdetecUon– PossibleifmediaUonbetweenvisible,invisiblesectors

–  Iffound,dfferentspaUaldistribuUon

DisUncUveShapetoSignal

AlsonewacousUcpeak

BoundfromStructure•  Recallboundfromshapesnotsobad

–  Butboundfromfromma2eraccounUng–  Anddetailedshapeofgalaxy

•  GravitaUonalpotenUalmeasured–  Bothinandoutofplaneofgalaxy–  StarvelociUes

•  Baryonicma2erindependentlyconstrained•  Dominantcomponentofdarkma2erconstrained

–  Extrapolatehalo•  Totalconstraintonanynewformofma2er•  Constrainsanynew(nonhalo)componentingalacUcplane

w/Kramer

Hipparcos•  FlynnHolberglookedatAandFtypestarsininnerporUonofgalaxy–  BrightstarpopulaUon—enoughnearmidplane

•  FromHipparcos,getvelocitymeasuredatmidplaneanddensityasfuncUonofverUcaldistance

•  UsegalacUcmodelwithseveralisothermalcomponents

•  AskedwhetherequilibriumdistribuUonfitpotenUalgeneratedbyMilkyWaydisk

EricKramer

GeneralLesson

•  RoleforparUclephysicsapproachinastronomy•  “constraint”ondarkdiskcamefromfisngstandardcomponents–  Turnsouterrorsonstandardcomponentsnotproperlyaccountedfor

– Hastobedoneself-consistently•  Heredifferentcomponentsinfluenceeachotherthroughgravity

•  Bigmessydatasets•  TargeUngamodelhelps

FitpotenUal/stardistribuUons

•  Boltzmann/verUcalJeansequaUon•  DistribuUonfallsoffmoreorlessexponenUallyoverascaleheight

•  SolveJeansequaUon•  UsePoisson’sequaUontointroducethedifferentsources/components

ThiswillimprovedramaUcally

•  GaiasurveymeasuringposiUonandvelocityofstarsinsolarneighborhood

•  WillsignificantlyconstrainproperUesofourgalaxy

•  InparUcular,newdiskcomponentwillgivemeasurablesignalifsurfacedensitysufficientlyheight

•  Don’tknowhowmuchgasmeasurementswillimprovebuttheyshouldtoo

ButanothertheoreUcallamppost?•  Similarityofamountofenergyindarkma2erandordinaryma2er

•  Maybema2eranddarkma2erareproducedinsimilarways?

•  Excess“ma2er”over“anUma2er”

SatellitesofAndromedaGalaxy•  Abouthalfthesatellitesareapproximatelyina(bigplane)–  14kpcthick,400kpcwide

•  Hardtoexplain•  ProposedexplanaUon:Udalforceoftwomerginggalaxies

•  Fineexceptofexcessivedarkma2ercontent•  Tidalforcewouldusuallypulloutonlybaryonicma2erfromdisk

•  Nottrueifdarkdisk

w/Scholtz

MeteoroidPeriodicity?

•  Meteoritedatabasegives21cratersbiggerthan20kmincircumferenceinlast250years

•  Evidenceforabout35millionyearperiodicity•  Evidencehowevergoesawaywhenlookelsewhereeffectincorporated

•  Thiswillchangewithamodelandmeasuredpriors•  Weassumeadarkdisktakeintoaccountconstraintsonmeasuredparameters,anddeterminewhetherlikelihoodraUoprefersmodeltoflatdistribuUon

•  AndwhataposterioridistribuUonisfavored

MoUonofSun;DensitySolarSystemEncounters

IV:CouldmaybeevenexplaindinosaurexUncUon…

•  Clearlyabigprogram•  Darkma2erchargedisclearlyapossibility•  ManyimplicaUons•  ButcansomeUmesbemoreelusiveorsubtlethananUcipated–  IniUalcondiUondependence

•  Wearebeginningtogettremendousdata•  Let’sfindoutwhatitmeans