The Incredible 6.7 GHz Methanol Masers: A key to understanding high-mass star formation. Jimi Green (for Gary Fuller) CSIRO Astronomy & Space Science, ATNF (Jodrell Bank Centre for Astrophysics, University of Manchester) Great Barriers in Massive Star Formation 13 th September 2010, Townsville THE METHANOL MULTIBEAM SURVEY: SURVEYING THE MASSIVE STAR FORMATION IN OUR GALAXY

Galactic plane survey (±2° latitude) for 6.7-GHz methanol masers. Parkes: ~140 days, -174 o < l < 60 o 3 sigma sensitivity of ~0.7 Jy. Completeness of 100% at 1 Jy kms -1 spectral resolution. Australia Telescope Compact Array: comparable spectral resolution to Parkes mJy per channel. positional accuracy of ~0.4 arcsec. Velocity coverage is full range of CO The Methanol Multibeam (MMB) Survey The MMB collaboration: J. L. Caswell, G. A. Fuller, A. Avison, S. Breen, K. Brooks, M. G. Burton, A. Chrysostomou, J. Cox, P. J. Diamond, S. Ellingsen, M. D. Gray, M. G. Hoare, M. R. W. Masheder, N. McClure-Griffiths, M. Pestalozzi, C. Phillips, L. Quinn, M. Thompson, M. Voronkov, A. Walsh, D. Ward-Thompson, D. Wong-McSweeney, J. A. Yates and R. J. Cohen.

Class II 6.7-GHz methanol masers Models and observations (Pestalozzi et al. 2002, Minier et al. 2003, Xu et al. 2008) show these masers are confined to regions of high-mass star formation. Methanol forms on ice mantles and evaporates. Masers originate in gas surrounding the forming star, pumped by mid IR emission from heated dust. Require high density and methanol abundance (>10 -8 ) and dust temperatures ~ K. Associated with hot-core like sources. Cragg et al. 2002

Catalogue Papers & Maser Distribution I. +345°<l<+6° Caswell, Fuller, Green et al. 2010, MNRAS 183 masers (86 new) II. +6°<l<+20° Green, Caswell, Fuller et al. 2010, MNRAS 119 masers (42 new) |l|<1° 28 sources (11 in Sgr B2) and only 4 (15%) new (cf. Caswell 1996) CO covers velocities from -206 km/s to +280 km/s, but masers only occur with velocities -60 km/s to +77 km/s, implying no high-mass star formation at these high velocities. |l| 1° but l <-6°: b distribution wider + masers, ▲ Sgr B2, ● 3kpc arm

Location of masers R<3 kpc, 1.8 masers/kpc2 (excl. GCZ) GCZ 55 masers/kpc2 Spiral arms ~ 20 masers/kpc2 GCZ has higher star formation rate but comparable to spiral arms 3.5 to 13 kpc R<3 kpc 3kpc arm Sun

Longitude-velocity domain structure studies

Structure & Nature of sources (A. Avison PhD Thesis). A. Avison (PhD Thesis) Velocity gradient across source Two clumps shifted in velocity Colour-Luminosity MIPSGAL (24um) – Hi-GAL PACS (70um) Use Robitaille models to fit SED from 3.6um to 500um Class II masers in Hi-GAL l=30 o SDP (Molinari et al. 2010) (Not (yet) MMB sources). Only 7 masers in field. + non-maser maser

Circumstellar Gas (Fuller et al. follow-up) Mopra 45 GHz and Parkes NH 3 surveys of 240 MMB sources Observed complete sample in 3 longitude ranges. SpeciesFractionTracing CS95%Dense gas, vel SiO33%Shocks/outflows HNCO15%Hot cores CH 3 OH62% (1,1) CH 3 OH SiO (1,1) (2,2) (3,3) NH 3

Summary Southern Galactic plane survey complete: -174°< l < 60° Detected 954 masers, of which 598 previously known, 356 new. Methanol Multibeam Publications: Magellanic Cloud Survey (Green et al. 2008) Techniques (Green et al. 2009) High-mass star formation in 3-kpc arms (Green et al. 2009) Catalogue I: Galactic Centre region (Caswell et al. 2010) Catalogue II: +6°< l < +20° (Green et al. 2010) Catalogue III: 330° < l < 345° (coming soon!) Extensive follow-up programme underway GLIMPSE IR association (Poster 20) 12 GHz masers (Shari Breen talk on Wednesday) Ground-state OH & magnetic fields (MAGMO talk on Thursday)

Jimi Green/Gary Fuller Thank you