Testing Density Wave Theory with Stellar Populations around Spiral - - PowerPoint PPT Presentation

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Testing Density Wave Theory with Stellar Populations around Spiral - - PowerPoint PPT Presentation

Mar 12, 2024 222 likes •464 views

Testing Density Wave Theory with Stellar Populations around Spiral Arms in M81 Yumi Choi 1 Julianne J. Dalcanton 1 , Benjamin F. Williams 1 , and Daniel Weisz 2 1 University of Washington, 2 UC Santa Cruz Relationship between Spiral Arms and SF

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Testing Density Wave Theory with Stellar Populations around Spiral Arms in M81

Yumi Choi1

Julianne J. Dalcanton1, Benjamin F. Williams1, and Daniel Weisz2

1University of Washington, 2UC Santa Cruz

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SLIDE 2

Relationship between Spiral Arms and SF

Q: What is the role of spiral pattern in SF?

NGC 6946

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SLIDE 3

Density Wave Theory

CO emission traces cold, dense molecular gas

Pearson education, Inc.

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Density Wave Theory

CO emission traces cold, dense molecular gas 24μm emission traces

  • bscured SF

Pearson education, Inc.

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SLIDE 5

Density Wave Theory

CO emission traces cold, dense molecular gas 24μm emission traces

  • bscured SF

Hα, UV traces young stars

Pearson education, Inc.

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SLIDE 6

Density Wave Theory

CO emission traces cold, dense molecular gas 24μm emission traces

  • bscured SF

Hα, UV traces young stars Evolved stars

Pearson education, Inc.

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How to Detect/Quantify this?

— Angular offsets among SF tracers tracing different

stages of SF

(e.g.) Tamburro et al. (2008), Egusa et al. (2009), Foyle et al. (2011)

— Color gradient

(e.g.) Martínez-García et al. (2013)

— Age distribution of star clusters

(e.g.) Santiago-Cortés et al. (2010), Grosbøl et al. (2012)

— Resolved stellar populations

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Recover SFH using CMD fitting

Color

Magnitude

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Recover SFH using CMD fitting

1 2 3 F435W-F606W 26 24 22 20 F435W 1 2 3 F435W-F606W 26 24 22 20 F435W 1 2 3 F435W-F606W 26 24 22 20 F435W 1 2 3 F435W-F606W 26 24 22 20 F435W 1 2 3 F435W-F606W 26 24 22 20 F435W

Observation Model

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Grand-design Spiral M81

PA = 330° & Inclination = 59° (de Blok et al. 2008) Ωp ~ 17 km/s/kpc & RCO ~ 12-13 kpc (Kendall et al. 2008)

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M81 Group

M81 NGC 3077 M82

Jordi Gallego

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M82 M81 N 3077

Tidal Interactions in M81 group

Yun et al. (1994, 1999)

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Optical & HI DATA

— 29 ACS fields

  • F435W(B) & F606W(V)

— HI map from THINGS

(Walter et al. 2008)

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Identify Spiral Arms

Rad 1 Rad 2 Rad 3 Rad 4

~2.8 kpc

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Recovered SFHs

Inner Outer Trailing Leading

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Recovered SFHs

Inner Outer Trailing Leading

Tidally induced SF?

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SF Propagation

9 13

Rad 1

Red box = expected propagation of SF

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SF Propagation

Rad 2

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SF Propagation

Rad 3

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SF Propagation

Rad 4

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Conclusions

— No predicted trends detected in M81

  • resolved stellar populations inconsistent with other results?
  • no systematic spatial ordering between SF tracers

(Foyle et al. 2011)

— Complexities

  • not a single pattern speed
  • scattering by stellar feedback
  • highly embedded stars, etc.,…
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Thanks!

Yumi Choi