1. The MALT90 survey of massive star forming regions
Ana Duarte Cabral
Sylvain Bontemps
James Jackson
Jill Rathborne
Jonathan Foster
and the MALT90 consortium
MW2011 Rome

2. Outline Context and purpose of MALT90 Current status and pilot results
The first year of MALT90
Searching for outflows in massive cores: SiO

3. 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

4. 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.

5. Key specifications Nb of dense cores targeted: 3,000
- Pre-stellar (mid-IR dark) 1,000
- Protostellar (24μm emission) 1,000
- HII Region (bright 8, 24μm emission) 1,000
Angular Resolution: 38’’
Size of each map: 3’ x 3’
Spectral Resolution: km/s
Sensitivity K
Survey Region
+20° > l > +3° and -3° > l > -60°
Dates of data collection
Austral winter
Line Frequency (GHz) Tracer
N2H Density, chemically robust
13CS Column density
H41α Ionized gas
CH3CN Hot core
HC3CN Hot core
13C34S Column density
HNC Density, cold chemistry
HC13CCN Hot core
HCO Density
HCN Density
HNCO 41, Hot core
HNCO 40, Hot core
C2H Photo-dissociation
SiO Shock/outflow
H13CO Column density
H13CN Column density
Line Freq (GHz) Tracer
N2H+ J= Density, chemically robust
13CS J= Column density
H41α Ionized gas
CH3CN 5(1)-4(1) Hot core
HC3CN J=10-9 1v6 l=1f Hot core
13C34S J= Column density
HNC J= Density, cold chemistry
HC13CCN J= Hot core
HCO+ J= Density
HCN J=1-0 F= Density
HNCO 4(1,3)-3(1,2) Hot core
HNCO 4(0,4)-3(0,3) Hot core
C2HJ=1-0 3/2-1/2 F= Photo-dissociation
SiO J=2-1 v= Shock/outflow
H13CO+ J= Column density
H13CN J=1-0 F= Column density

6. 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

7. Pilot Survey Outcome Source selection using ATLASGAL (870µm)
Foster et al. 2011
Source selection using ATLASGAL (870µm)
Importance of mapping V.S. pointed observations
Importance of spectral resolution (0.1km/s)
Schuller et al. 2009

8. First Year
Data available to everyone via the Australia Telescope Online Archive (ATOA:
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

9. 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
Needed for:
- Core masses
- Protostellar luminosities
- Physical relation of adjacent filamentary features
- Galactic structure
Galactic CO emission (Dame et al. 2001)
Galaxy model from Reid et al. 2009

10. 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
Protostar
HII region
High N2H+ abundance
Low N2H+ abundance
N2H+
HNC
HCO+
HCN
N2H+
HNC
HCO+
HCN
Lee et al. 2004

11. products - Chemical evolution
Hot vs Cold cores

12. Looking for outflows The expectations
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
Motte et al. 2007
(0.14 km/s, rms ~ 0.03K)
IR bright
IR quiet
Lopez-Sepulcre et al. 2011
(1.5 km/s, rms ~ 0.009K)
vlsr (km/s)
Lopez-Sepulcre et al. 2011

13. Looking for outflows The reality… 235/499 young sources
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).

14. Looking for outflows
Some “not-too-bad” cases

15. Looking for outflows
Some statistics - evolutionary trends?

16. (ATOA: http://atoa.atnf.csiro.au/MALT90)
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
(ATOA: