Radio Science and PILOT Tony Wong ATNF/UNSW PILOT Workshop 26 March 2003

2 New Synergies PILOT: 2m, 1-30  m ( THz). Starlight, thermal dust continuum, recombination lines, excited H 2, PAH features. ATCA: 6 x 22m, GHz. HI, synchrotron, free-free emission, molecular masers, thermal molecular lines, dust continuum. ALMA (2010): 64 x 12m, GHz. Thermal molecular lines, atomic fine-structure lines, dust continuum, recombination lines, CMB. IRQA (2010?): GHz? Synchrotron, free-free absorption, redshifted HI.

3 Radio-IR Astrometry Massive stars tend to form in clusters at great distances, and thus accurate astrometry is needed to make firm IDs. Since mid-IR sources are often invisible in the optical/NIR, astrometry must be performed by comparison with radio synthesis maps. Results can significantly affect interpretation! Methanol masers (diamonds) on 18um OSCIR/Keck contours, de Buizer et al. (2002)

4 Mid-IR as a SFR indicator Relatively few galaxies have been imaged in the mid-IR (e.g. Roussel et al with ISOCAM, 10”). Integrated mid-IR light is a combination of continuum from small grains and aromatic bands due to molecular aggregates (PAHs?). Potentially good tracer of massive star formation if excitation is dominated by HII regions.

5 The mid-IR/radio correlation Gruppioni et al. (2003) have compared faint (~mJy) 15µm sources detected by ISO (ELAIS-S1, S2) with 1.4 GHz ATCA imaging. Strong mid-IR/radio correlation, though not as tight as FIR/radio: uncertain mid-IR K- corrections? Is PILOT sensitive enough to study this population?

6 Summary Radio/submm observations of the ISM can complement PILOT’s capabilities, especially in the mid-IR (4-30 µm). 1. Large FOV facilitates astrometry with radio maps. 2. Mid-IR a useful probe of star formation, both in nearby and distant galaxies. 3. Circumstellar envelopes around AGB stars: mass loss rates from CO line profiles, colours from mid-IR. LMC survey? Competition: Spitzer, SOFIA, Herschel…