Star Formation Taste TestsAlyssa A. Goodman

Harvard-Smithsonian Center for Astrophysics&

Initiative for Innovative Computing at Harvard

Taste Tests?“Taste Tests”? We frame this project by analogy. How does a great chef, making a complicated dish, know if she has created what she originally intended when she is done cooking? She “tastes.” She informs her cooking with her extensive knowledge of food chemistry (analytic theory), uses all the cooking equipment (simulations) she has in the kitchen to try to make something edible and tasty (starforming, and realistic), and then she uses her senses (observations) to see if what she made tastes as intended. “Tasting” in cooking actually encompasses the joint action of many senses: we propose here a combination of statistical techniques that we call “taste tests.” The tests will allow us to discerningly decide if what we sense (observe) and what we can cook (simulate) might actually be tasty (form stars), and how (analytic theory) that happens.

from: Goodman & Rosolowsky, NSF Proposal Fall 2006

Getting to “Observational Space”

Includes

–Radiative Transfer

–Projection to 2D sky plane, or “3D” of spectral-line data cubes

–Adding appropriate noise

– Imposing observing characteristics of a telesope

Example: The Spectral Correlation Function

(Padoan, Goodman & Juvela 2003)

COMPLETE Collaborators, Spring 2007:

Alyssa A. Goodman (CfA/IIC)

João Alves (Calar Alto, Spain)

Héctor Arce (AMNH)

Michelle Borkin (CfA/IIC)

Paola Caselli (Arcetri, Italy/CfA)

James DiFrancesco (HIA, Canada)

Jonathan Foster (CfA, PhD Student)

Sebastian Guillot (U. Victoria, Canada)

Mark Heyer (UMASS/FCRAO)

Doug Johnstone (HIA, Canada)

Jens Kauffmann (CfA/IIC)

Helen Kirk (HIA, Canada)

Di Li (JPL)

Jason Li (Harvard College)

Jaime Pineda (CfA, PhD Student)

Erik Rosolowsky (CfA)

Scott Schnee (Caltech)

Mario Tafalla (OAN, Spain)

COordinated Molecular Probe Line Extinction Thermal Emission Survey of Star-Forming Regions=

+

TasteTests

COMPLETE Collaborators, Spring 2007:

Alyssa A. Goodman (CfA/IIC)

João Alves (Calar Alto, Spain)

Héctor Arce (AMNH)

Michelle Borkin (CfA/IIC)

Paola Caselli (Arcetri, Italy/CfA)

James DiFrancesco (HIA, Canada)

Jonathan Foster (CfA, PhD Student)

Sebastian Guillot (U. Victoria, Canada)

Mark Heyer (UMASS/FCRAO)

Doug Johnstone (HIA, Canada)

Jens Kauffmann (CfA/IIC)

Helen Kirk (HIA, Canada)

Di Li (JPL)

Jason Li (Harvard College)

Jaime Pineda (CfA, PhD Student)

Erik Rosolowsky (CfA)

Scott Schnee (Caltech)

Mario Tafalla (OAN, Spain)

Meaningful structure in position-position-velocity space

Modeling l.o.s. temperature fluctuations

What stars form from what gas, when?

COordinated Molecular Probe Line Extinction Thermal Emission Survey of Star-Forming Regions=

Is the gas density distribution lognormal or not?

And scattering! (Cloudshine models)

Errors introduced by the assumption of isothermal dust along each line of sight

Variable fraction of emission from transiently heated very small dust grains

Variable dust properties (e.g. emissivity or emissivity spectral index)

1.2

1.0

0.8

0.6

0.4

0.2

0.0

log

(NIR

AS [m

ag A

V])

1.21.00.80.60.40.20.0

log (N2MASS [mag AV])

1.2

1.0

0.8

0.6

0.4

0.2

0.0

greyscale shows log (N

13CO [m

ag AV ])

2MASS/NICER

IRIS

Schnee, Bethell & Goodman 2006

Modeling line-of-sight temperature fluctuations

MHD Simulation+Radiative Xfer Code (No NOISE)

100/240 micron

Schnee, Bethell & Goodman 2006

60/100 micron

True AV

A V F

rom

Em

issi

on

A V F

rom

Em

issi

on

0.1

0.10.1

0.11.0 1.0 10.010.0

1.0

10.0

1.0

10.0

…and the correlationgets tighter still

at longer λ’s

True AV

Modeling line-of-sight temperature fluctuations

Tasting the Simulations

AV from NIR AV from NIR

60/100

True AV

Schnee, Bethell & Goodman 2006

A V F

rom

Em

issi

onModeling line-of-sight temperature fluctuations

I’ll show you later why that’s “True Av”

2006

“Cloudshine”=Scattered Ambient StarlightExtinction and scattering! (Cloudshine)

Almost Tasting a Very Simple Recipe

Foster & Goodman

2006

Extinction and scattering! (Cloudshine)

Theorists doing the Tasting!Extinction and scattering! (Cloudshine)

Padoan et al. 2006

Tastes “right”, with 20% scatter, at 1<AV<10, for NIR.

Recovered map

Simulation

“Cloudshine” Scattering

ModelH-band flux only

Meaningful structure in position-position-velocity space (3D)

Modeling l.o.s. temperature fluctuations

Is the gas density distribution lognormal or not? (2D)

And scattering! (Cloudshine models)

Spectral-Line Data: The 2D (bland)& the “3D” (Spicy) Views

Where am I?

What stars form from what gas, when?

position-postion-velocity is NOT the same asposition-position-position-velocity-velocity-velocitycf. Ostriker, Stone & Gammie 2001

mm peak (Enoch et al. 2006)

sub-mm peak (Hatchellet al. 2005, Kirk et al. 2006)

13CO (Ridge et al. 2006)

mid-IR IRAC composite from c2d data (Foster, Laakso, Ridge, et al. in prep.)

Optical image (Barnard 1927)

3D rendering courtesy AstroMed team at IIC (Borkin, Halle, Kauffmann, Alan, Goodman)

33

32

31

30

Dec

linat

ion

[J20

00, D

egre

es]

58 56 54 52 50

Right Ascension [J2000, Degrees]

0.40

0.35

0.30

0.25

0.20

Equivalent A

V [mag]

1-σ uncertainty (NICER)

33

32

31

30

Dec

linat

ion

[J20

00, D

egre

es]

58 56 54 52 50

Right Ascension [J2000, Degrees]

shellHD 278942 20

19

18

17

16

60 to 100µ C

olor Temperature [K

]

Dust Color Temperature (IRAS)

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30

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linat

ion

[J20

00, D

egre

es]

58 56 54 52 50

Right Ascension [J2000, Degrees]

2.0

1.5

1.0

0.5

0.0

τ ( 13CO

)

Opacity (13CO)

33

32

31

30

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linat

ion

[J20

00, D

egre

es]

58 56 54 52 50

Right Ascension [J2000, Degrees]

~5 pc 12

10

8

6

4

2

Equivalent A

V [mag]

Extinction (NICER/2MASS)

33

32

31

30

Dec

linat

ion

[J20

00, D

egre

es]

58 56 54 52 50

Right Ascension [J2000, Degrees]

12

10

8

6

4

2

Equivalent A

V [mag]

Dust Emission (IRAS)

33

32

31

30

Dec

linat

ion

[J20

00, D

egre

es]

58 56 54 52 50

Right Ascension [J2000, Degrees]

12

10

8

6

4

2

Equivalent A

V [mag]

Line Emission (13CO)

Is the gas density distribution lognormal or not? (2D)

The (secret) uncertainties inherent in

column density mapping.

Goodman et al. 2007

Extin

ctio

nD

ust

Emis

sion

13C

O E

mis

sion

400

300

200

100

0

Num

ber

log (Equivalent AV [mag])

13COlognormal fit

to 13CO W(13CO )

400

300

200

100

0

Num

ber

2MASS/NICER

lognormal fit to2MASS column density

(all panels)

400

300

200

100

0

Num

ber

1.00.50.0

IRAS

lognormal fit toIRAS column density

Implied Column Density Distributions and lognormal Fits(Perseus COMPLETE data)

★Extinction & thermal emission are log-normal-ish & more so when non-13CO detected points are included.

★13CO is not a very faithful tracer of column density .

Is the gas density distribution lognormal or not? (2D)

Dendrograms (Hierarchical) vs. CLUMPFIND (Non-hierarchical)Meaningful structure in position-position-velocity space (3D)

Dendrogram (Rosolowsky et al. 2007;

cf. Houlahan & Scalo 1992)

CLUMPFIND(Williams et al. 1994)

Sky “x” (Right Ascension)

ObservedReality

“Observed”Simulations

(Dendro)Surfaces “CLUMPFIND”

work of Rosolowsky, Pineda, Kauffmann, Borkin,Padoan, Halle & Goodman; figure from Goodman & Rosolowsky NSF “Star Formation Taste Tests” Proposal, Fall 2006

Sky “y” (Declination

)

Velocity

Meaningful structure in position-position-velocity space (3D)

step 0.3 step 0.5threshold 0.3

threshold 0.5

threshold 0.7

Is CLUMPFIND OK as a Statistic? (Like Cayenne Pepper?)

CLUMPFIND output for L1448 with 1.2K step & threshold!(Lower values give too many clumps to show!!)

Rosolowsky, Borkin, Goodman, Kauffmann & Pineda 2007, in prep.

Dendrograms: A Physical Hierarchy?

The “self-gravitating” parts

of L1448:

And, coming soon, to a cookbook (Journal)

near you... (3D PDF)

Which “stars” “form” from what gas, when?Fi

gure

Cre

dit:

Jona

than

Fos

ter

L1448

'Cause if my eyes don't deceive me,There's something going wrong around here

--Joe Jackson

Theorists using

Observers Ingredients

e.g. Schmeja & Klessen 2006

What stars form from what gas, when?

Are you hungry yet?

Who can make this?