Galactic Winds in Dwarf Galaxies?

DGs

Dwarf Galaxies as ideal Laboratories to study astrophysical Processes (a madley of research) Gerhard Hensler University of Vienna

Simone Recchi, Sylvia Ploeckinger, Lei Liu, Matthias Kuehtreiber, Patrick Steyrleithner, Bernhard Baumschlager, Thorsten Lisker

10/21/2018 and the SMAKCEDAmity team 6

Dwarf Galaxies as ideal Laboratories to study astrophysical Processes

 Morphological division of DGs  DG gas evacuation by galactic winds; Starbursts?  Transformation channel for dIrrs  dEs?  Starbursts by gas infall  dEs dominate in galaxy clusters: transformation by gas stripping  Self-regulated star formation at low rates  DG formation from merger events? Tidal DGs!

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1 DGs

The Schematic View of DGs Smaller editions of Hubble-type galaxies? 6 10 10 -10 M, m 1-10 kpc, Mv>-18

Transformation paths from one morphological Sandage & Binggeli (1984) type to the other are proposed.

NGC 205 NGC 4214

M32 Antlia NGC 4449

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Correlations of different galaxy types

All “normal“ DGs, dEs and dIrrs follow the same relations even to their faintest end, but differ from UCDs+GCs and from the Hubble- type galaxies.

10/21/2018 Amity 9 Tolstoy et al. (2010) ARAA, 47

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Questions:

 Are Dwarf Galaxies as simple as they look like?

 Can one therefore understand their formation and evolution as simply?

 Did they have the same origin?

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Why are Dwarf Galaxies so interesting? They are extremely sensitive to 1) their formation epoch,

2) their internal evolution, 3) their environmental influence.

 different formation epochs  large variety of evolutionary paths  morphological transformations

DGs10/21/2018 are extremely Amityinteresting AP objects11

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DGs as building blocks in the hierarchical CDM scenario Dark Matter substructures form first and assemble to larger structures

but:

• Downsizing

• No clear DM content

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Arp 188, the Tadpole Galaxy: bright knots as DG precursors?

bright star-formation knots are structured10/21/2018 within the tail. Amity 16

The Large Magellanic Clouds – a dIrr on its passage of the Milky Way: smooth evolution in interaction

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Starbursts + Galactic Wind Possible dIrr → dE transformation

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Possibility of dIrr  dE transition

DGs can show very active modes of star formation, which can be triggered by environmental effects like e.g. gas infall or mergers.

Starburst can drive galactic winds! Can these winds evacuate dIrrs from their gas, i.e. transform them to dEs?

Understanding the cause of enhanced SF and the impact of massive stars on their environment is of fundamental relevance for  understanding the SF process,  galaxy evolution also in the Early Universe. 10/21/2018 Amity 19

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Dwarf Galaxies are strongly affected by Galactic Winds

In NGC 1569 2 Super Star Clusters at the base of the gas stream are the engines of the galactic wind due to their cumulative 10/21/2018 supernovaAmity II explosions. 20

Model: • bipolar outflow; • the S part towards observer is unobscured;  disk inclination known

• metal-enhanced wind: 1-2 Z!

X-ray in colors according to hardness (blue: hard, red: soft) overlaid with HI contours (white) 10/21/2018 Amity Martin et al. (2002) 21

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The mass loss can be determined from the effective yield yeff of the HI ISM. The loss of metals should be visible in the hot gas outflow.

Mass loading of super- bubbles diminishs their energetics (thermal+kinetic).

10/21/2018 Amity Martin et al. (2002)22 ApJ, 574

Metal loss through galactic outflows!

Garnett (2002)

Effective yields yeff of dIrrs < solar! Outflow of SNII gas reduces e.g. O. but: simple outflow models cannot account for gas mixing + turb. heating10/21/2018 Amity 23