ABSTRACT
Massive galaxies in the early Universe have been shown to be forming stars at surprisingly high rates. Prominent examples are dust-obscured galaxies which are luminous when observed at sub-millimetre wavelengths and which may be forming stars at a rate of 1,000 solar masses (M(middle dot in circle)) per year. These intense bursts of star formation are believed to be driven by mergers between gas-rich galaxies. Probing the properties of individual star-forming regions within these galaxies, however, is beyond the spatial resolution and sensitivity of even the largest telescopes at present. Here we report observations of the sub-millimetre galaxy SMMJ2135-0102 at redshift z = 2.3259, which has been gravitationally magnified by a factor of 32 by a massive foreground galaxy cluster lens. This magnification, when combined with high-resolution sub-millimetre imaging, resolves the star-forming regions at a linear scale of only 100 parsecs. We find that the luminosity densities of these star-forming regions are comparable to the dense cores of giant molecular clouds in the local Universe, but they are about a hundred times larger and 10(7) times more luminous. Although vigorously star-forming, the underlying physics of the star-formation processes at z approximately 2 appears to be similar to that seen in local galaxies, although the energetics are unlike anything found in the present-day Universe.
ABSTRACT
A technique to remotely image temperature distributions of heated metallic surfaces is extended to higher temperatures. It uses a Dy(+3):YAG thermographic phosphor (TP) bonded to the surface and excited by radiation at 355 nm. Digital images of the emission from two excited states were recorded and divided by each other to correct by normalization for illumination and coating nonuniformities. Results show that the TP can survive heating and cooling cycles to 1400 K and that emitting states achieve thermodynamic equilibrium before radiating. Temperatures in the range of 300-1300 K were determined by normalization of pairs of emission images with a single calibration constant. Uncertainties of +/-7-13% at a spatial resolution of 20 microm and +/-0.7-4% at a resolution of 500 microm were achieved.
