The emerging phase of YSCs: constraints for LyC photon leakage from - - PowerPoint PPT Presentation

The emerging phase of YSCs: constraints for LyC photon leakage from HII regions in NGC7793

Lorenza Della Bruna

• A. Adamo, G. Östlin, A. Bik
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Stellar feedback

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Chandra HST Spitzer

http://chandra.harvard.edu

30 Dor 180 pc

Stellar feedback

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Chandra HST Spitzer

M 82 8 kpc

http://chandra.harvard.edu

NGC 7793

• NGC 7793:
• d = 3.4 Mpc
• SFR(UV) = 0.52 Msun/yr
• Z = 0.8 Zsun

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HST ALMA MUSE AO
 science verification (PI A. Adamo)

• MUSE observation:
• λ = 4600 - 9350 Å
• AO, seeing ~ 0.7’’ (10 pc)

Blue: 4875-4950 Å Green: 6520-6528 Å Red: 6750-6810 Å

Blue: [ΟΙΙΙ] Green: [SII] Red: Hα

Halpha line- and velocity map

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HII regions selection

• ASTRODENDRO —> tree representing the hierarchy of

structures in the data

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http:// dendrograms.org

leaves

branch

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HII regions sample

96 regions

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HII regions sample

Median mass ~ (1000 +/- 500) Msun

• Levesque et al. 2010:
• Z = 0.004 - 0.02, q = (1 x 107 - 4 x 108) cm/s
• ne = 100 cm-3 (~HII regions), instantaneous

burst of 0 Myr

• Kewley+Dopita 2001: upper limit for

SF galaxies

• Allen et al. 2008:
• b = (0.001 - 100) μG, vshock = 100 - 1000 km/s
• ne = 10 cm-3 (~ DIG), solar metallicity

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Ionised gas properties

Z q vshock b

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Ionised gas properties

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Ionised gas properties

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Ionised gas properties

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Ionised gas properties

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Ionised gas properties

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Ionised gas properties

Leaking HII regions

• fDIG = F(Hα)DIG / F(Hα)HII = 0.23
• Is the leaking from HII region sufficient to explain the DIG fraction observed?
• Model expected ionising flux Q(H0)expected
• stars: spectral type of stars inside HII regions
• YSC: stellar population synthesis code



 
 
 
 
 —> fesc for each HII region.

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Q(H0)expected Q(H0)observed L(Hα)

∝

Kennicutt 1998

Summary

• We observe diffuse ionised gas permeating the entire

FOV, fDIG ~ 0.23

• YSC in HII regions are observed to be on average

younger than field clusters (3 vs 6 Myr) —> HII regions too faint or already dissolved?

• Ionised gas properties: little overlap of DIG with shock

models in BPT diagram

• Photons streaming out of HII regions?

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• Low-resolution mode (HMM) will allow us to image typical HII

region sizes at d ~ 50 - 80 Mpc

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α

• α
• α
• α luminosity selected to compare ‘inner’

and ‘outer’ regions

• α

Σ –

• usters in

M

• the
• tigate

the

• tribution of

a

– – Ӧ – –

α

• α
• α
• α luminosity selected to compare ‘inner’

and ‘outer’ regions

• α

Σ –

• –

– Ӧ – –

—> K. Hollyhead’s poster

NGC 34 (d = 84 Mpc)

Future science with ELT/MOSAIC

Future science with ELT/MOSAIC

• What’s new/interesting?
• at ~ 80 Mpc we sample the full


spectrum of galaxy types
 (morphology, SF intensity)

• also NIR information:



 shock tracers: e.g [Fe II]
 SF tracers: e.g Pa-β, Br series

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Antenna galaxy
 (20 Mpc)

Future science with ELT/MOSAIC

• High resolution mode (HDM) will allow for similar spatial resolution to

MUSE in local galaxies but at much higher distance ( ~ 20 - 50 Mpc)

• What’s new/interesting? Higher depth + NIR allows e.g to study

extreme SF regimes like UV bright extended disks

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M 83
 (5 Mpc) Bresolin+ 09 Hernandez+ 19

Tiank you!

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