The physics of the star formation process in M51
The physics of the star formation process in M51
The physics of the star formation process in M51
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Infrared Emission, ISM and Star Formation!<br />
Workshop at <strong>the</strong> MPIA, Heidelberg!<br />
February 22 nd - 24 th 2010!<br />
Star <strong>formation</strong> <strong>in</strong> <strong>M51</strong>!<br />
Local IR-radio relation !<br />
& <strong>star</strong> <strong>formation</strong> <strong>process</strong>!<br />
Dumas Gaelle (MPIA)!<br />
Eva Sch<strong>in</strong>nerer (MPIA), Fatemeh Tabatabaei (MPIfR), Ra<strong>in</strong>er Beck (MPIfR), Eric Murphy (Caltech/SSC), Rob Kennicutt (IoA,<br />
Cambridge), Daniela Calzetti (UMass), Andrew Fletcher (Univ <strong>of</strong> Newcastle)!
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
SFR determ<strong>in</strong>ation!<br />
Star <strong>formation</strong> tracers:<br />
• UV, optical: dust ext<strong>in</strong>ction<br />
• IR: contribution <strong>of</strong> old <strong>star</strong>s, resolution<br />
• Radio: radio/IR correlation<br />
Global vs local SFR: environment, spatial scale/time<br />
scale<br />
Is radio cont<strong>in</strong>uum a “good” SF tracer?
Radio/IR relation!<br />
• Global (de Jong et al. 85, Condon 92,<br />
Bell 03….)<br />
• & local (Murphy et al. 06, Tabatabei<br />
et al. 07…)<br />
• L<strong>in</strong>ear relation<br />
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
q = log(FIR/20cm) quantitative<br />
measure <strong>of</strong> <strong>the</strong> radio/IR correlation<br />
From Bell 03<br />
<strong>M51</strong>
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• IR: cold and warm dust<br />
• NT radio SNe <br />
massive <strong>star</strong>s<br />
• <strong>The</strong>rmal radio HII<br />
regions<br />
Radio/IR relation!<br />
20cm/1.4GHz<br />
Non <strong>The</strong>rmal<br />
6cm/4.9GHz<br />
3.6cm/8.4GHz<br />
Dust<br />
<strong>The</strong>rmal
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• Local radio/IR correlation<br />
• Orig<strong>in</strong>?<br />
• Scales on which it breaks down?<br />
• Is NT radio a “good” SF tracer?<br />
Radio/IR relation!
• face-on<br />
• Bright<br />
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• Well def<strong>in</strong>ed spiral arms<br />
• nearby D=8.2Mpc 1” ~ 40pc<br />
• data from UV to radio<br />
• SFR=3.4 M /yr<br />
• Contrast arms/<strong>in</strong>terarm,<br />
<strong>in</strong>teraction, AGN<br />
<strong>M51</strong>!<br />
different physical environments<br />
HST/ACS, APOD 2008 June 14
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• 3.6cm<br />
VLA CD +Effelsberg<br />
2.4”<br />
Radio Maps!<br />
VLA + s<strong>in</strong>gle dish Effelsberg<br />
Resolution ~ 2” (80pc)<br />
• 6cm<br />
VLA BCD+Effelsberg<br />
2”<br />
• 20cm<br />
VLA ABCD<br />
1.5”
20cm (VLA ABCD)<br />
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
Radio Maps!<br />
VLA + s<strong>in</strong>gle dish Effelsberg<br />
Resolution ~ 2” (80pc)<br />
3.6cm (VLA CD+Eff)<br />
6cm (VLA BCD+Eff)
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• MiPS (Calzetti et al. 05)<br />
Resolution = 6”<br />
MIPS<br />
24μm Spitzer Map!<br />
• MIPS + HiRes (Velusamy et al. 08)<br />
Resolution = 2.4”<br />
HIRES
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
Wavelet analysis!<br />
• Frick et al 2001, Tabatabaei et al. 2007,2008, Hugues et al<br />
2006<br />
• Comparison <strong>of</strong> structures at different spatial scales<br />
• Cross-correlation <strong>of</strong> multi-λ data
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
24µm vs 3.6cm<br />
24µm vs 6cm<br />
24µm vs 20cm<br />
12” ~ 500pc<br />
Wavelet cross-correlation!<br />
• 24µm vs 3.6cm ~ TR/IR<br />
high correlation<br />
• 24µm vs 20cm ~ NTR/IR<br />
correlation down to 50% for<br />
scales < 500pc<br />
• Local extrema role <strong>of</strong><br />
<strong>the</strong> structures: spiral<br />
arms…
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• Radio/IR relation on small<br />
scales<br />
• Environment:<br />
• spiral arms<br />
• <strong>in</strong>terarm<br />
• outer disk<br />
• <strong>in</strong>ner disk<br />
• Apertures 6” diameter<br />
Radio/IR relation!
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• NT radio: synchrotron<br />
emission,<br />
• <strong>The</strong>rmal radio<br />
• IR: heated dust<br />
Radio/IR relation!<br />
arms Interarm<br />
Power law fit: 24µm = b (20cm) a
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• NT radio: synchrotron<br />
emission,<br />
• <strong>The</strong>rmal radio<br />
• IR: heated dust<br />
Radio/IR relation!<br />
arms L<strong>in</strong>ear : 24µm α 20cm Interarm Non l<strong>in</strong>ear : 24µm α (20cm) 0.5<br />
• L<strong>in</strong>ear 24µm α 20cm<br />
Spiral arms, whole galaxy<br />
• Non L<strong>in</strong>ear 24µm α 20cm 0.5<br />
Interarm, outer disk
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
Take home messages!<br />
• <strong>The</strong>rmal radio/IR better than NT radio/IR<br />
<strong>The</strong>rmal/non-<strong>the</strong>rmal separation<br />
• NT radio/IR relation l<strong>in</strong>ear <strong>in</strong> spiral arms but not <strong>in</strong> <strong>in</strong>terarm<br />
time-scales?<br />
orig<strong>in</strong> IR emission <strong>in</strong> <strong>in</strong>terarm?<br />
KS law different spiral arms/<strong>in</strong>terarm?<br />
non physical <strong>in</strong> <strong>in</strong>terarm?<br />
• Relation rema<strong>in</strong>s l<strong>in</strong>ear on <strong>the</strong> whole galaxy<br />
particular case or true for all galaxies?<br />
spread <strong>of</strong> <strong>the</strong> <strong>in</strong>tegrated fluxes correlation?
• Schmidt law<br />
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
• Niklas & Beck, 1997<br />
• Beck et al., 1996<br />
Non l<strong>in</strong>earity <strong>in</strong> <strong>in</strong>terarm!
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
Radio/IR relation!<br />
Outer disk Inner region Non l<strong>in</strong>ear : 24µm α (20cm) 1.5<br />
Non l<strong>in</strong>ear : 24µm α (20cm) 0.5<br />
Power law fit: 24µm = b (20cm) a
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
outliers!
Infrared Emission, ISM and Star Formation!<br />
Dumas Gaelle, February 24 th 2010!<br />
GMC<br />
SR and emission!<br />
SF UV<br />
Massive <strong>star</strong>s<br />
SN<br />
B field<br />
SNRs<br />
CR<br />
Synchrotron<br />
Dust heat<strong>in</strong>g<br />
FIR<br />
CORRELATION<br />
NT Radio
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