Contact Name: Marcello Giroletti
Abstract:
ALMA Early Science results began transforming astronomy in 2011. Construction has recently ended as scheduled and on budget.
Seven receiver bands achieve wavelength coverage sweeping from 3mm to 0.3mm across a decade of nearly complete frequency access, broken only by the atmospheric limitations of its spectacular site. With access to nearly any line redshifted within that range, ALMA’s sensitivity allows it to address the questions of how the first stars and galaxies in the Universe were born, to measure the abundances of the first metals and to chronicle the development of isotopic diversity among the elements. As this is written, the longest baselines are being commissioned for ALMA, enabling resolutions down to 0.01". Very long baseline capability, also currently under initial testing, can tie other antennas' collecting area in with ALMA's to create a global telescope capable of delineating detail as fine as ten microarcseconds, allowing imaging of the black hole at the center of our galaxy. Already ALMA has changed paradigms for objects both distant and near. Oxygen and carbon, the most abundant metals produced by the first stars, nitrogen, and CO all have lines detectable by ALMA in its wavelength range. The 157 micron [C II] line has already been detected out to z~7 in ALMA Early Science observations. ALMA's sensitivity and resolution have revolutionized the study of circumstellar planet-forming disks. Molecular imaging has revealed CO 'snow lines' in those disks, delineating where in a disk mid plane where ice grains may form as the temperature drops. ALMA has also imaged highly asymmetric distribution of gas and particularly of dust in evolved disks, revealing 'dust traps' where new planets may form from agglomerated material