Tidally induced bars in gas-rich dwarf galaxies orbiting the Milky - - PowerPoint PPT Presentation

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tidally induced bars in gas rich dwarf galaxies orbiting

Tidally induced bars in gas-rich dwarf galaxies orbiting the Milky - - PowerPoint PPT Presentation

Jul 10, 2023 188 likes •464 views

Introduction The simulations Tidally induced bars in gas-rich dwarf galaxies orbiting the Milky Way Grzegorz Gajda PhD student (last year) at N. Copernicus Astronomical Center (Warsaw, Poland) and Laboratoire dAstrophysique de Marseille

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Introduction The simulations

Tidally induced bars in gas-rich dwarf galaxies

rbiting the Milky Way

Grzegorz Gajda

PhD student (last year) at

N. Copernicus Astronomical Center (Warsaw, Poland)

and Laboratoire d’Astrophysique de Marseille (France) in collaboration with Ewa L. Lokas (Warsaw) and Lia Athanassoula (Marseille)

5th October 2017

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 1 / 12

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Introduction The simulations

Dwarf galaxies in the Local Group

A. Z. Colvin, wikipedia.org

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Introduction The simulations

Dwarf galaxies in the Local Group

Two type of of dwarf galaxies

Dwarf irregulars disky gas-rich rotating (usually) far away from big spirals WLM dIrr

ESO/VST/Omegacam Local Group Survey

Dwarf spheroidals ellipsoidal gas-poor random motions of stars (usually) close to big spirals Fornax dSph

ESO/Digitized Sky Survey 2 Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 2 / 12

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Introduction The simulations

Dwarf galaxies in the Local Group

HI mass-to-light ratio

McConnachie (2012) Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 2 / 12

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Introduction The simulations

Motivation

Sagittarius is one of the largest dwarf galaxies, currently very close to the MW Top: distribution of M giants Bottom: stellar surface density from simulation Is it a bar?

Lokas et al. (2010)

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 3 / 12

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Introduction The simulations

Motivation

In the Local Group Hercules:

Coleman et al. (2007)

Ursa Major II:

Mu˜ noz et al. (2010) Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 3 / 12

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Introduction The simulations

Motivation

Beyond the Local Group

SDSS Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 3 / 12

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Introduction The simulations

Simulation setup

Dwarf galaxy: 109 M⊙ dark matter halo 2 × 107 M⊙ barionic disc

70% gas fraction

Milky Way-like host: 1012 M⊙ dark matter halo Three simulations N-body Hydrodynamical without SF Hydrodynamical with SF following the evolution for 10 Gyr using Gadget3.

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 4 / 12

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Introduction The simulations

Simulation overview

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 5 / 12

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Introduction The simulations

Simulation overview

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Introduction The simulations

Simulation overview

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Introduction The simulations

Simulation overview

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Introduction The simulations

Surface density after the first pericenter

stars ⇒ gas ⇒ Gaseous component and star formation weaken the bar compared to the N-body case

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 6 / 12

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Introduction The simulations

Bar strength after the first pericenter

Bars in gas-rich galaxies are less elongated in the centers Gas remains axisymmetric

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 7 / 12

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Introduction The simulations

Evolution of bar strength

Bars form at the first pericenter Weaker for gas-rich dwarfs Disappear over time for gas-rich dwarfs

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 8 / 12

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Introduction The simulations

Pattern speed

Initially, all have almost the same Ωp Later, gas-rich bars are slowed down

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 9 / 12

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Introduction The simulations

Final apocenter

stars ⇒ gas ⇒ N-body model remained barred, while the gas-rich regained axisymmetry

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 10 / 12

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Introduction The simulations

Star formation

Star formation rate is slightly enhanced at the pericenters Overall, SFR drops due to tidal stripping of gas

Star formation and SN feedback modelled as in Springel & Hernquist (2003)

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 11 / 12

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Introduction The simulations

Summary

Interaction may drive bar formation in the gas-rich disk galaxies Bars in gas-rich galaxies are

weaker more easily destroyed

than in N-body case Caveat: we did not include hot gas halo of the Milky Way, thus there was no ram pressure stripping Thank you for your attention!

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WLM

Leaman et al. (2012)

M∗ = 1.1 × 107 M⊙, Mgas = 6.3 × 107 M⊙

Grzegorz Gajda (Warsaw|Marseille) Tidally induced bars in gas-rich dwarf galaxies 1 / 1