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QuickTi me™ e t un décomp resse ur son t req uis pour vi sion ner cette im age. QuickTime™ et un décompresseur sont requis pour visionner cette image. The MALT90 survey of massive star forming regions Ana Duarte Cabral MW2011 Rome 19.09.2011 Sylvain Bontemps James Jackson Jill Rathborne Jonathan Foster and the MALT90 consortium Outline - Context and purpose of MALT90 - Current status and pilot results - The first year of MALT90 - Searching for outflows in massive cores: SiO Context On the light of the large continuum submm surveys Need of a large molecular line legacy towards sites of high-mass star formation capable of: - Estimate dynamical distances and understand the Galactic distribution of high-mass star forming clouds - Calculate statistical properties and search for chemical and physical evolutionary changes Survey Millimetre Astronomy Legacy Team 90 GHz (MALT90) Survey, using the 22m Mopra telescope in Australia. PI: James Jackson, Boston University Jill Rathborne, Jonathan Foster • Mapping simultaneously 16 molecular transitions at 90GHz, providing a range of high-density tracers. • Targeting sites of massive star formation, designed to cover several evolutionary stages, from quiescent to PDRs. Key specifications Nb of dense cores targeted: - Pre-stellar (mid-IR dark) - Protostellar (24 m emission) - HII Region (bright 8, 24 m emission) Angular Resolution: Size of each map: Spectral Resolution: Sensitivity 3,000 1,000 1,000 1,000 38’’ 3’ x 3’ 0.11 km/s 0.2 K Survey Region +20° > l > +3° and -3° > l > 60° Dates of data collection Austral winter 2010-2014 Line Frequency (GHz) N2H+ 93.17 13CS 92.49 H41α 92.03 CH3CN 91.98 HC3CN 91.19 13C34S 90.92 HNC 90.66 HC13CCN 90.59 HCO+ 89.18 HCN 88.63 HNCO 41,3 88.24 HNCO 40,4 87.93 C2H 87.32 SiO 86.85 13 + H CO 86.75 H13CN 86.34 Tracer Density, chemically robust Column density Ionized gas Hot core Hot core Column density Density, cold chemistry Hot core Density Density Hot core Hot core Photo-dissociation Shock/outflow Column density Column density Current Status • Pilot Survey, July09 - (182 targets) - complete - Survey strategy - Target source list Foster et al. 2011 • Year 1, June-Sept10 - (499 targets) - complete - ~ 830 hours - Observations from Narrabri, Sydney - Data released Rathborne et al. in prep Jackson et al. in prep • Year 2, May-Sept11 - (~600 targets) - ongoing - ~ 900 hours - Observations from Narrabri, Sydney, Bordeaux, Moscow, Florida, Boston - Mapped ~450 cores so far • Logs, observing schedules, source lists available via team wiki • Automated data reduction pipeline Pilot Survey Outcome Foster et al. 2011 - Source selection using ATLASGAL (870µm) Schuller et al. 2009 - Importance of mapping V.S. pointed observations - Importance of spectral resolution (0.1km/s) First Year • Data available to everyone via the Australia Telescope Online Archive (ATOA: http://atoa.atnf.csiro.au/MALT90) • For each source in each line: – – – – Raw data Processed cubes Moment maps (zeroth, first, second) Signal-to-noise maps • Database of line emission characteristics – Peak spectra • Temp, VLSR, DV – 2-d Integrated emission • morphology of emission, location of peak – Line ratios, extended or compact, broad line-widths, shocked gas, complex chemistry products - kinematical distances With the VLSR we can derive a kinematical distance: – Galaxy rotation models – Reid et al. 2009 – Clemens 1985 Extinction maps HI absorption CO clouds Galactic CO emission (Dame et al. 2001) Galaxy model from Reid et al. 2009 Needed for: - Core masses - Protostellar luminosities - Physical relation of adjacent filamentary features - Galactic structure products - Chemical evolution Chemical variations capable of indicating special phases in the core’s chemical evolution Initial collapse (CO freeze out) Dense gas freeze-out High N2H+ abundance Protostar HII region Low N2H+ abundance N2H+ HNC N2H+ HNC HCO+ HCN HCO+ HCN Lee et al. 2004 products - Chemical evolution Hot vs Cold cores Looking for outflows Duarte-Cabral, Bontemps, et al. in prep The expectations Statistical study of outflow properties and SiO line profiles Find evolutionary changes on the outflow properties IR bright vlsr (km/s) IR quiet vlsr (km/s) Lopez-Sepulcre et al. 2011 Motte et~al.0.009K) 2007 (1.5 km/s, rms (0.14 km/s, rms ~ 0.03K) Lopez-Sepulcre et al. 2011 Looking for outflows The reality… The source sample: 235/499 young sources 129 protostars, 106 quiescent, 156 HII regions, 56 PDRs 30 % SiO detections: 49 % of protostars 20 % of quiescent Velocity binned to 1.3 km/s (rms ~ 0.04K). Looking for outflows Some “not-too-bad” cases Looking for outflows • Some statistics - evolutionary trends? Future • Better distances and SED fittings • Understand the real nature of sources and perform (more) meaningful statistics • Extension to the full 2000 sources (from quiescent to protostars) • Source list worth of follow up with ALMA http://malt90.bu.edu (ATOA: http://atoa.atnf.csiro.au/MALT90)