Simulated [CII] 158 µm observations for SPICA

/ SAFARI

F. LevrierF. LevrierP. Hennebelle, E. Falgarone, M. Gerin P. Hennebelle, E. Falgarone, M. Gerin

(LERMA - ENS)(LERMA - ENS)

F. Le PetitF. Le Petit(LUTH - Observatoire de Paris)(LUTH - Observatoire de Paris)

J. R. GoicoecheaJ. R. Goicoechea(CAB)(CAB)

SPICA Workshop, University of Oxford, 6-8 July 2009SPICA Workshop, University of Oxford, 6-8 July 2009

Why the [CII] 158 µm line ?

Fine structure of the ground state of C+Fine structure of the ground state of C+UV to IR energy transfer via photoelectric effectUV to IR energy transfer via photoelectric effect

UVUV

electronselectrons

dustIR ContinuumIR Continuum

gasgas

Cooling linesCooling lines

• Carbon ionization potential : 11.3 eV• One of the dominant cooling lines of interstellar gas• Early stages of star formation • 0.3% of the bolometric FIR emission of the Galaxy (Wright et al. 91)• Seen “everywhere”

Observations of the [CII] 158 µm line

Nakagawa et al. 98 (BICE) Makiuti et al. 2002 (FILM /

IRTS)

Bennett et al. 94 (COBE / FIRAS)

Proposed objective and method Estimate the ability of SAFARI to map the [CII] emission over large

areas

MHD turbulence simulation ISM structures

PDR code on selected LOS

UV radiative transfer and

chemical network

HI content CII emissionHI content

CII emission

Mapping speed

Compressible MHD turbulence simulationsHennebelle et al. 2008

50 pc

• RAMSES code (Teysier 2002, Fromang et al. 2006)• Adaptive Mesh Refinement with up to 14 levels• Converging flows of warm (10,000 K) atomic gas• Periodic boundary conditions on remaining 4 sides• Includes magnetic field, atomic cooling and self-gravity consistently• Covers scales 0.05 pc - 50 pc• Heavy computation : ~30,000 CPU hours ; 10 to 100 GB

X-Y column density X-Y density cut X-Y temperature cut

cold clumpscold clumps

warm turbulent warm turbulent interclump mediuminterclump medium

Line of sight

Total gas column density

Density structures along the LOS

Total gas column density

Savage et al. 77

Total column density

Mol

ecul

ar

fract

ion

Total gas and HI column densities

HI gas column density

The Meudon PDR code

UVUV UVUV

Molecular regionMolecular region

C+C+ CC COCO C+C+CCCOCO

Stationary 1D model, including : Outputs :• • UV radiative transfer: UV radiative transfer: Absorption in molecular linesAbsorption in molecular linesAbsorption in the continuum (dust)Absorption in the continuum (dust)10000’s of lines 10000’s of lines • • Chemistry : Chemistry : Several hundred chemical speciesSeveral hundred chemical speciesNetwork of sevral thousand chemical reactionsNetwork of sevral thousand chemical reactionsPhotoionizationPhotoionization• • Statistical equilibrium of level populationsStatistical equilibrium of level populationsRadiative and collisional excitations and de-excitationsRadiative and collisional excitations and de-excitationsPhotodissociationPhotodissociation• • Thermal balance:Thermal balance:Photoelectric effectPhotoelectric effectChemistryChemistryCosmic raysCosmic raysAtomic and molecular coolingAtomic and molecular cooling

• • Local quantities :Local quantities :Abundance and excitation of speciesAbundance and excitation of speciesTemperature of gas and dutsTemperature of gas and dutsDetailed heating and cooling ratesDetailed heating and cooling ratesEnergy densityEnergy densityGas and grain temperaturesGas and grain temperaturesChemical reaction ratesChemical reaction rates• • Integrated quantities on the line of sight : Integrated quantities on the line of sight : Species column densitiesSpecies column densitiesLine intensitiesLine intensitiesAbsorption of the radiation fieldAbsorption of the radiation fieldSpectraSpectra

http://pdr.obspm.fr/

J. Le BourlotF. Le PetitE. Roueff

M. Gonzalez-Garcia

J. R. GoicoecheaP. Hily-BlantS. Guilloteau

C. JoblinG. Pineau des

Forêts[...]

1-2

34

1-4

Local emissivity of the [CII] line

Integrated emissivity of the [CII] line

1-2 3 4

1-4

HI column density

Simulation results

(See Bennett et al. 94)

Num

ber o

f lin

es o

f sig

htSAFARI mapping speed

• Say the cloud is 1.75 kpc away, 1.6º across• Pixel size is 5.75” (ie that of the SAFARI FPA pixels)• FPA is 20x20 (FOV=2’x2’)• 2600 pointings needing between 1 and 24 seconds• Total mapping time : 4.5 hours

2’

5-sigma, 1-hour sensitivity :

Conclusions

• Heavy computations : a few hours per “clump”• Convergence issues in low density regions• Geometry issue : requires 2D/3D PDR code

SAFARI will be able to map the [CII] emission over large areas in a short time

STAR FORMAT (Astronet)• • Simulation results databases :Simulation results databases :MHD simulationsMHD simulationsDense coresDense coresPDR calculationsPDR calculations• • Code interplay and publication : Code interplay and publication : MHD codes (RAMSES, FLASH)MHD codes (RAMSES, FLASH)Meudon PDR codeMeudon PDR codeRadiative transfer code (PHOENIX) Radiative transfer code (PHOENIX) • • Observational diagnostics :Observational diagnostics :Statistical analysis toolsStatistical analysis toolsInstrumental simulations (ALMA)Instrumental simulations (ALMA)

HennebelleKlessenBanerjeeDullemondFalgaroneGloverHauschildtLe BourlotLe PetitLesaffreLevrier

First approach towards integrating MHD and PDR codes

Grid computation Code developmentInteraction with observers