Magne&cfieldsandturbulenceinmolecularclouds:

observa&onsfrom30‐parsectomilliparsecscales

EdithFalgaroneENS&ParisObservatory,France

and

PierreHily‐BlantGrenobleObservatory,France

``CosmicMagne&sm’’,7‐11june2010,Kiama

Kainulainenetal2009

Av<3–5mag:turbulent+BdominatedAv>3‐5mag:gravity+B+?

Bimodaldistribu&onofgascolumndensi&esinmolecularclouds

Outline

•  Sta&s&csofBPOSorienta&onatthe30‐pcscale•  BPOSandintensevelocity‐shearsatthepcscale•  BPOSandshear‐layersatthempc‐scale•  B//intensityfromdiffusemediumtodensecores

Tools:‐Starlightpolariza&on‐ Spectro‐imageryathighspectralandspa&alresolu&onintheCOrota&onallines‐ Zeemaneffectobserva&onsintheHI,OHandCN(1‐0)lines

1–Turbulentandmagne&cenergyatthe30pc‐scale

•  Comparisonofvirialized(TaurusComplex)andnon‐virialized(PolarisFlare)fields

•  Chandrasekhar‐Fermimethod:

B=6.6nH1/2(Δv/δφ)μG

Emag/Eturb=(38o/δφ)2

Validforδφ<25o(MHDsimula&onsOstrikeretal.01)

Two30‐pcscalefields:

PolarisFlareFIRmapMiville‐Deschênesetal.

Δv=4.8km/s

Taurus‐AurigacomplexN(H2)mapGoldsmithetal.08

Δv=3.8km/sComparablevirialmasses@30pc:MV=4.4x104Msun

TaurusComplex:Mgas≈MVPolarisFlare:Mgas=5x103Msun=MV/6

Polarisa&onmeasurementsHeiles2000

12CO(1‐0)(top)13CO(1‐0)(borom)

δφ=(24±5)o

Emag/Eturb=2.5

Tauruscomplex

δφ=19o

NonGaussianPDF:3morecommonPA

Emag/Eturb≈4.0

Hily‐Blantetal.inprepara&on At30pc‐scale,Emag>Eturb≥Egrav

PolarisFlare

2–BPOSandvelocity‐shearsattheparsec‐scale

•  Sta&s&csonvelocityfieldbasedonCOline‐centroid‐velocity(CV)intranslucentfields

•  DeparturefromGaussiansta&s&cs

•  Comparisonofplane‐of‐skyprojec&onofmagne&cfieldsBPOSandlocusofextremeCVincrements(E‐CVI):extremaofΩPOSHily‐Blant&Falgarone09

Parsec‐scalefieldinthePolarisFlare

Hily‐Blant&Falgarone2009

PDFofcentroidvelocityincrementswithvariablelags

•  Non‐Gaussiantailsincreaseatsmallerlags:moreandmorerareevents

•  Locusoftheseevents:E‐CVIs∼extremaofΩPOS

(Lisetal1996)

•  Intermirencyofturbulence

Hily‐Blant,Falgarone,Pety2008

Spa&aldistribu&onofextremeCVIs(1)

Ward‐Thomsonetal.(2010)Herschel/SPIRE

Spa&aldistribu&onofE‐CVIs(2)

TaurusedgeTaurusedge:BPOS//ΩPOS:oneclosemeasurement

PolarisFlare:Specificorienta&onsofBPOSSharpPAchangesNoclosemeasurementΩPOS//BPOSatparsec‐scale

3–BPOSandshear‐layersatmilliparsecscales

Dusttemperature

IRAM‐PdBICO(1‐0)line.Mosaicof13fields,180hoursintegra&onPixelsize:3mpc(4arcsec)Fieldsize:0.09pcx0.045pcTranslucentfieldwithnostructurevisibleat0.01pcresolu&on

Structureatthemilliparsecscale

‐8straightstructuresdetected,thickness3to11mpc‐SpecificPA‐Specificveloci&es(emptychannels)

Falgarone,Pety,Hily‐Blant2009

Notfilaments:sharpedgesofthinextendedsheetsofCOemission

COemissionin2velocityranges:seenbytheIRAM‐PdBinterferometer(lex)andmergedwithshortspacingsfromIRAM‐30m(right)

4edgesformpairsofparallelstructuresofhighvelocityshear:milliparsecscaleshear‐layers

➜

➜ComparisonwithBPOSorienta&onsatthe30‐pcscale

Thelessonsofthemilliparsecscales

•  Layersofmostintensevelocity‐shearsatmpc‐scalesandBlieinparallelplanes:quasi‐parallelprojec&onsontheplane‐of‐sky→BPOS//ΩPOS

•  Coherenceoforienta&onsacrossscales•  Velocityincrementsinshear‐layersatmpc‐scalesofsameorderasrmsvelocityoflargescaleturbulence(2to4kms‐1)→widescalesepara&on

•  Largestobservedvelocity‐shear:3.5kms‐1over7mpcor500kms‐1pc‐1orequivalent&mescale≈2000yr

→short&mescales

4‐HI,OH,CNZeemanmeasurements(1)

Line:M/Φ=(M/Φ)cri&cal

Noevidenceforsubcri&caldensecores

Crutcheretalinprep.

HI,OH,CNZeemanmeasurements(2)

Bayesiananalysis:n<300cm‐3

Bmax=10μGBnotcompressedbyturbulencen>300cm‐3

Uniformdistribu&onofBTOTbetween≈0andBmax∝n2/3

WeakBindensecores

Crutcheretalinprep.

SummaryandOpenings(1)

•  At30pcscales,magne&c>turbulentenergy•  Coherentstructuresofvor&city/shearsparalleltoBPOSfromparsectomilliparsecscales

•  Widescalesepara&on

•  Diffusemedium:Bnotcompressedbyturbulence

•  Noevidenceforsubcri&caldensecores

SummaryandOpenings(2)

•  Turbulence(anditspropertyofintermirency)possiblyattheoriginofthelossofmagne&cfluxofmarer

•  Ion‐neutralambipolardrixinthediffusemediumrequiredtoexplainitsrichchemistry:Herschel/HIFIresultsFalgaroneetal.2010

•  ModelsofwarmchemistryincoldgasGodardetal2009