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mm Spectral Line Survey of the Starburst Galaxy M82

mm Spectral Line Survey of the Starburst Galaxy M82. Rebeca Aladro Instituto de Radio Astronomía Milimétrica (IRAM, Spain) Sergio Martín (ESO - Chile) Jesús Martín-Pintado (CAB - CSIC, Spain) Rainer Mauersberger (ALMA, Chile). Outline. Introduction

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mm Spectral Line Survey of the Starburst Galaxy M82

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  1. mm Spectral Line Survey of the Starburst Galaxy M82 Rebeca Aladro Instituto de Radio Astronomía Milimétrica (IRAM, Spain) Sergio Martín (ESO - Chile) Jesús Martín-Pintado (CAB - CSIC, Spain) Rainer Mauersberger (ALMA, Chile)

  2. Outline Introduction • Why an extragalactic frequency survey? Spectral Surveys in Starburst Galaxies (Chemistry) • M82: PDR-dominated galaxy • NGC253: shock-dominated galaxy Comparison of the M82 and NGC253 surveys • Detected molecules • Non-detected molecules Key molecules & Conclusions Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  3. Why Extragalactic Surveys? • There are only few frequency extragalactic surveys in the mm range. • Non biased data: many molecules can be studied. • Information about the physical properties of the molecular clouds (densities, temperatures …). • Very important for modelling at high redshift. • Surprises! Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  4. M82 • I0, M ~ 1010Mʘ • D ~ 3 Mpc • Recent interaction with M81 possibly triggered the starburst • LIR=3x1010 Lʘ • SFR=9 Mʘ year-1 • Galactic superwinds • Mainly PDR-dominated starbust Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  5. Chemical complexity in M82 Aladro et al. in prep. M82 2mm M82 1mm IRAM 30-m: 130.3 – 174.4 GHz @ ~8 km/s 241.4 – 273.4 GHz @ ~5 km/s rms ~ 2 mK • 44 detected lines • 18 different molecular species

  6. NGC253 • D ~ 3 Mpc • LIR=2.1x1010Lʘ • SFRIR = 3.6 Mʘyr-1 • SNR= 0.05-0.3 yr-1 • Galacticsuperwinds • No interaction • Prototype of starburst • Mainly shock-dominated starburst Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  7. Chemical complexity in NGC253 • 111 lines • 8 molecules detected for the first time in an extragalactic source • 25 different molecular species Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  8. Comparison of the NGC253 and M82 surveys Dv ~ 28 km s-1 Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  9. Comparison of the M82 and NGC253 fractional abundances Log (Nmol / NC18O) Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  10. Upper Limits Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  11. Key molecules • Shock tracers. HNCO, CH3OH, HC3N, SiO. Easily dissociated. Much less abundant in PDR-dominated regions. • PDR tracers: c-C3H2, CO+, HOC+, HCO. Their formation is favoured by the UV fields. • Molecules that are not (much) affected by the type of physical processes: C18O, C34S, C2H, H2S, H2CO…  some are good dense gas tracers, that can be used for comparison. • Surprises! OCS, NS, HOCO+ Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  12. Conclusions Frequency surveys are very powerful tools to disentangle the dominant processes in the starburst galaxies nuclei. The differences in the abundances between PDR-tracers and shock-tracers are clearly seen in both galaxies. HOCO+ and NS could also be good molecules to differenciate the starburst evolution. These frequency surveys can also also used to differenciate between other kinds of activities, like AGNs, ULIRGS, normal spirals… (Aladro et al. in prep). Extragalactic Star Formation, 21th UCL Colloquium, Cumberland Lodge, 5-8th July 2010. R. Aladro

  13. THANK YOU!!!

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