Massive star-forming clumps at low and high redshift How can we - - PowerPoint PPT Presentation

Massive star-forming clumps at low and high redshift

How can we study them with ELT?

Matteo Messa, Angela Adamo, Göran Östlin

Overview

Star formation is a hierarchical process

• Star clusters and star-forming clumps
• Ubiquitous (in star-forming galaxies)
• Tracers of the star-formation process

4 kpc Spiral arm of M51 ~1 kpc SF region in LMC 10 pc YMC in the MW

Star formation at high redshift

• Galaxies dominated by bright clumps
• Mass: 108-109 M☉
• Size: 1 kpc

e.g. Elmegreen+2007, Elmegreen+2009, Guo+2012, Tacconi+2013

• Clumps are larger and more massive

than in local universe

• Different Galaxy-scale properties
• Gas-rich
• Highly turbulent
• Rotational supported

e.g. Förster Schreiber+2009, Wisnioski+2015, Girard+2018

Elmegreen+2005

Chain Clump cluster Double clump Tadpole Spiral Elliptical

High-redshift clumps

Star formation at high redshift

• Galaxies dominated by bright clumps
• Mass: 108-109 M☉
• Size: 1 kpc

e.g. Elmegreen+2007, Elmegreen+2009, Guo+2012, Tacconi+2013

• Clumps are larger and more massive

than in local universe

• Different Galaxy-scale properties
• Gas-rich
• Highly turbulent
• Rotational supported

e.g. Förster Schreiber+2009, Wisnioski+2015, Girard+2018

• Survival and migration of clumps

shape galaxies:

• Formation of bulge

Bournaud+2007

High-redshift clumps

Cava+2018

High-redshift clumps

Star formation at high redshift

• Lensed systems: resolving below kpc sizes
• “Cosmic Snake” galaxy (Cava+2018), z=1
• Same clumps at different resolutions: 10 times difference in mass
• High-definition allows study at sub-galactic scales: testing evolution of clumps

Star formation at high redshift

• Lensed systems: resolving below kpc sizes
• “Cosmic Snake” galaxy (Cava+2018), z=1
• Same clumps at different resolutions: 10 times difference in mass
• High-definition allows study at sub-galactic scales: testing evolution of clumps
• Sensitivity
• To study less massive clumps
• Until now: imaging (clumps are too faint for spectroscopy)

High-redshift clumps

Elmegreen+2009

Star formation at low redshift: LARS galaxies

• Analogs of high-z Lyman-break galaxies, study their Ly-α emission
• Redshift = 0.028 – 0.18
• Multi-band observations with HST

Low-redshift clumps

Sizes down to ~10 pc scale Mass down to ~105 M☉

Star formation at low redshift: LARS galaxies

• Testing the effect of different resolutions
• Nearby galaxy ESO 338-IG04: resolved down to cluster scales

Low-redshift clumps

< 10 pc 10-100 pc 100-400 pc Larger sizes Brighter luminosities Lower SFR densities Resolved single clusters Resolved clumps Kpc-size clumps dominating the galaxy

Messa+submitted

Low-redshift clumps

Star formation at low redshift: LARS galaxies

• SFR – size relation
• Comparison to sample at various redshifts
• Denser than clumps at z=0 (SINGS)
• ΣSFR,cl similar to clumps in z=1-3 galaxies (Livermore+2012,2015)
• Less dense than z=3-6 compact star-forming regions (Bouwens+2017,Vanzella+2017)

Messa+submitted

Low-redshift clumps

Star formation at low redshift: LARS galaxies

• Clumpiness:
• Fraction of UV light in clumps
• Higher at lower resolution

Messa+submitted LARS01

Low-redshift clumps

Star formation at low redshift: LARS galaxies

• Clumpiness:
• Fraction of UV light in clumps
• Higher at lower resolution
• In function of galactic-scale properties
• Vshear/σ0: rotational over dispersion velocities
• ΣSFR

Dispersion dominated Rotation dominated

Messa+submitted

Consistent with instability theories

Studying clumps with ELT

What do we need to study clumps across redshifts?

• High spatial resolution
• High sensitivity
• Large field of view (multiplex capability)

ELT-MOSAIC can address this! High–redshift galaxies:

• NIR spectroscopy à rest frame optical (Hα, Hβ, optical lines)
• Gas kinematics
• Ionization state
• Metallicity
• TALK by Lorenza Della Bruna tomorrow

Studying clumps with ELT

High redshift galaxies:

• Current facilities:
• KMOS z~1 galaxies: mK<24, M*>109 M☉
• ELT-MOSAIC:
• lower luminosities (M* ~ 108 M☉)
• More irregular and clumpy galaxies
• Sub-kpc scale

2’’

0’’.075 kpc scale

HDM

Stott+2016 HUDF

Studying clumps with ELT

High redshift galaxies

• Lensed systems: sub-kpc scale

30-pc-scale clumps Cava+2018

FIBERS, HMM: 0’’.6: Interesting high-z compact sources e.g. Bouwens z~6 low-lum galaxies

Studying clumps with ELT

High redshift galaxies

• Lensed systems: sub-kpc scale

Studying clumps with ELT

Low redshift galaxies

• Sub-kpc scale
• Combination HDM+HMM
• Gas dynamics at the same scales as small clumps
• NIR lines
• See POSTER by Katie Hollyhead

Conclusions

• Clumpy star formation at high-z
• Reflecting the galaxy properties
• Important for galaxy evolution across redshifts
• Studying clumps in local galaxies
• To test the galactic-scale properties
• ELT-MOSAIC
• Spectroscopy of clumpy high-redshift galaxies at sub-kpc scale
• Spectroscopy of lensed galaxies at ~10 pc scale