FORMATION AND EVOLUTION OF THE MAGELLANIC SYSTEM STEPHEN PARDY - - - PowerPoint PPT Presentation

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FORMATION AND EVOLUTION OF THE MAGELLANIC SYSTEM STEPHEN PARDY - - - PowerPoint PPT Presentation

Oct 30, 2023 150 likes •377 views

STEPHEN PARDY ( STUDENT) ADVISOR: ELENA DONGHIA COLLABORATOR: ANDREW FOX FORMATION AND EVOLUTION OF THE MAGELLANIC SYSTEM STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017 Magellanic Stream is the closest example

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FORMATION AND EVOLUTION OF THE MAGELLANIC SYSTEM

STEPHEN PARDY (∇STUDENT) ADVISOR: ELENA D’ONGHIA COLLABORATOR: ANDREW FOX

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Nidever et. al 2010

LEADING ARM TRAILING STREAM BRIDGE

Magellanic Stream is the closest example of cold gas accretion. More gas in Stream than in Clouds and in all other HVCs combined. Where did it come from? What will happen to it? STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

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Nidever et. al 2010

LEADING ARM TRAILING STREAM BRIDGE

Magellanic Stream is the closest example of cold gas accretion. More gas in Stream than in Clouds and in all other HVCs combined. Where did it come from? What will happen to it? STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

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Besla et al. 2012

Magellanic Stream is the closest example of cold gas accretion. More gas in Stream than in Clouds and in all other HVCs combined. Where did it come from? What will happen to it?

Current formation scenario: Stream is gas stripped from SMC during its interaction with LMC.

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

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STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017 Problems:

  • Current models under-predict HI mass by factor of 5 and do not

include the ionized component. (Models: Besla+2012; HI: Brüns+2005, Nidever+2010;

HII: Fox+2015)

  • Abundance and velocity measurements show LMC origin of some
  • gas. (Nidever+2008,Richter+2013)
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Hammer+2015

LMC$ SMC$ Leading$Arm$ M31$ IC10$ S $

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017 Problems:

  • Current models under-predict HI mass by factor of 5 and do not

include the ionized component. (Models: Besla+2012; HI: Brüns+2005, Nidever+2010;

HII: Fox+2015)

  • Abundance and velocity measurements show LMC origin of some
  • gas. (Nidever+2008,Richter+2013)
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We make two targeted changes: 1) Increase total gas mass of Clouds by 2X 2) increase size of SMC and LMC (place more gas outside tidal radius) STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017 Problems:

  • Current models under-predict HI mass by factor of 5 and do not

include the ionized component. (Models: Besla+2012; HI: Brüns+2005, Nidever+2010;

HII: Fox+2015)

  • Abundance and velocity measurements show LMC origin of some
  • gas. (Nidever+2008,Richter+2013)
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Follow simulation setup of Besla+12. Using Gadget NBody+SPH isolated galaxy models: (1) LMC and SMC interact only with each other for several Gyr (2) LMC—SMC pair falls into Milky Way (1)

Pardy+2017 (submitted)

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

Time (Gyr) Now

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Follow simulation setup of Besla+12. Using Gadget NBody+SPH isolated galaxy models: (1) LMC and SMC interact only with each other for several Gyr (2) LMC—SMC pair falls into Milky Way (2) STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

Pardy+2017 (submitted)

Time (Gyr) Now

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Can we match the mass? We see: STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 1

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Can we match the mass? We see:

  • 4x increase in Stream gas mass ~ 4x108 M☉

✅

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 1

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Can we match the mass? We see:

  • 4x increase in Stream gas mass ~ 4x108 M☉
  • Do not match ionized mass

✅

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

❌

RESULTS PART 1

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Can we match the mass? We see:

  • 4x increase in Stream gas mass ~ 4x108 M☉
  • Do not match ionized mass
  • More mass than observed inside Clouds

✅ ❌

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 1

❌

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Can we match the mass? We see:

  • 4x increase in Stream gas mass ~ 4x108 M☉
  • Do not match ionized mass
  • More mass than observed inside Clouds

✅ ❌

Takeaway:

  • increasing mass of Clouds further will cause a larger mismatch

between observed and predicted HI mass This is a problem of efficiency. Our simulations have ~20% of gas stripped, best estimates for Stream is that ~50% of all of the gas from the Clouds has been removed. (see talk by Brianna Smart) STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 1

❌

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Pardy+2017 (submitted)

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

HI data from Nidever+2010

RESULTS PART 2

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Pardy+2017 (submitted)

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 2

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Pardy+2017 (submitted)

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 2

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Pardy+2017 (submitted)

✅Match Stream location ✅Match density near Clouds ✅Strip material from LMC Predict Arm material from LMC

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 2

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Pardy+2017 (submitted)

❌ Do not match Clouds positions ❌ LMC material not in filament

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017

RESULTS PART 2

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TAKE AWAY

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017 Current dwarf-dwarf formation model has problems reproducing the multiple filaments and the mass in the Magellanic Stream.

  • Increasing the stripping efficiency from the LMC can pull material

into the stream and the leading arm - but not in a long coherent filament as seen in the observations

  • A tidal-only model is not efficient enough to strip enough of the

material from the Clouds

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TAKE AWAY

STEPHEN PARDY - THE ROLE OF GAS IN GALAXY DYNAMICS - VALLETTA, MALTA 2017 Looking Forward - other methods of stripping material:

  • Local outflows (led by collaborators Chad Bustard and

Ellen Zweibel at UW Madison)

  • Ram pressure stripping (ongoing with collaborator

Romeel Davé) Current dwarf-dwarf formation model has problems reproducing the multiple filaments and the mass in the Magellanic Stream.

  • Increasing the stripping efficiency from the LMC can pull material

into the stream and the leading arm - but not in a long coherent filament as seen in the observations

  • A tidal-only model is not efficient enough to strip enough of the

material from the Clouds

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BONUS SLIDES