Star Formation across cosmic time Florent Renaud & Oscar Agertz - - PowerPoint PPT Presentation

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Star Formation across cosmic time Florent Renaud & Oscar Agertz - - PowerPoint PPT Presentation

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Star Formation across cosmic time Florent Renaud & Oscar Agertz Lund Observatory Polaris (Andr et al. 2010) Universality ... Filamentary structure Diameter (~0.1 pc) Knots = pre-stellar cores Taurus (Palmeirim et al. 2013)

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SLIDE 1

Florent Renaud & Oscar Agertz

Lund Observatory

Star Formation across cosmic time

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SLIDE 2

Universality ...

Taurus (Palmeirim et al. 2013) Polaris (André et al. 2010) IC 5146 (Arzoumanian et al. 2012)

  • Diameter (~0.1 pc)
  • Extinction threshold (Av > 7)
  • Cluster formation at

intersections

  • Universal IMF
  • Filamentary structure
  • Knots = pre-stellar cores

Where it can be resolved = solar neighborhood = one single environment

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... and diversity

isolated disk: M83 (HST) merger: Antennae (HST) clumpy galaxy (z~2): UDF 6462 (ACS)

  • Disk sub-structures

(e.g. spirals, bars)

  • Galaxy interactions / mergers
  • Galaxy formation
  • Different star cluster

formation

(open, massive, globular, nuclear ...)

  • IMF variations

§ from galaxy to galaxy § within galaxies

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SLIDE 4

Cosmic star formation history

Evolution of the cosmic SFR density

Madau & Dickinson (2014)

  • with gas content
  • turbulence
  • disk formation
  • merger rate

(~ expansion of the Universe)

  • quenching

(starvation, stripping, feedback etc.)

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SLIDE 5

Beware of quenching

  • Satellites get quenched faster than centrals

à different processes

van den Bosch et al. (2008), Bahe & McCarthy (2015) Tinker et al. (2013)

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Evolution of MW-like galaxies

  • Proto-galaxy
  • Growth by major mergers
  • Formation of the disk
  • Possible clumpy phase
  • Formation of the disks
  • Formation of the bar

Low-mass (= fragile) Interaction-driven Rotation-support Highly turbulent Episodic mergers Quiet, steady phase

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SLIDE 7

PDFs and KS laws

  • Make turbulence compressive

à increase SFE

and move to the starburst regime

Renaud et al. (2014)

  • Increased turbulence

à increase SFR

and remain on Kennicutt's law

Observations from Kennicutt et al. (1998, 2007) Bigiel et al. (2008) Tacconi et al. (2010) Daddi et al. (2010) Analytical model from Renaud et al. (2012) Numerical confirmation in Kraljic et al. (2014) See also Padoan & Nordlund (2011) Hennebelle & Chabrier (2011)

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SLIDE 8

Starbursts

  • Due to gas inflows

(negative torques inside co-rotation)

Keel (1985) Barnes & Hernquist (1991)

  • Most of SF in central regions

(in advanced mergers)

Sanders & Mirabel (1996)

  • But also a non-negligible
  • ff-nuclear activity

Wang et al. (2004) Hancock et al. (2009) Chien & Barnes (2010) Smith et al. (2014) Moreno et al. (2015) Elmegreen et al. (2016,2017) ... NGC 7252 NGC 2207

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SLIDE 9

Off-nuclear starbursts

  • Trigger starburst

Renaud et al. (2014)

  • Tidal and turbulent compression

where/when potentials overlap

Renaud et al. (2008, 2014) Jog (2015)

  • Increase turbulence

and change its nature

Irwin (1994) Elmegreen et al. (1995) NGC 4093/39

  • Form denser structures

Hennebelle & Falgaronne (2012) Federrath et al. (2014)

isolated galaxies interacting galaxies Solenoidal-dominated (energy equipartition) Compression-dominated (comp. tidal forcing)

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SLIDE 10

In interactions

Antennae-like galaxies

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SLIDE 11

In interactions

Cartwheel-like galaxy

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SLIDE 12

Same SFR, different physics

  • A starburst and a disk: same SFR but different ISM

à different star (cluster) formation

Renaud et al. (in prep.) Bournaud et al. (2015)

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SLIDE 13

Star formation at very high redshift

Renaud, Agertz et al. (in prep.)

  • Density of the Universe

increases with redshift

20 kpc z = 5 red = compressive tides

∝ (1 + z)3

  • More interactions
  • More tidal + turbulent

compression

  • Formation of massive

clusters (globulars?)

  • In galactic outskirts

Fornax dwarf galaxy, Larsen et al.

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SLIDE 14

At very high redshift

Cosmological simulation

Renaud et al. (in prep)

20 kpc

But short... (z > 8)

500 pc

z = 9.3 Resolve formation sites

(~1 pc)

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SLIDE 15

Formation of the first clusters

200 pc

Illustris Eagle

4x106 M ~ 5 pc Young massive clusters Formation triggered by galactic interaction 2x107 M z = 9.3

Renaud et al. (in prep)

In galaxy outskirts Same physics than at low z? Survival?

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Summary

  • Several stages in galaxy formation

= several stages in star formation

  • Possibly important for formation of globular

clusters at high redshift

  • Different sources of turbulence

(injection at kpc scale)

  • Including mergers (but not only)
  • Compression (tides + turbulence) induces

starbursts and the formation of young massive clusters

  • How/where/when galaxies get their stellar populations