Italian Science Case for ALMA Band 2+3

TL;DR

This paper discusses the development of a combined ALMA Band 2+3 receiver covering 67-116 GHz, aiming to enhance observational capabilities and scientific output for the ALMA observatory.

Contribution

It introduces the concept of a single, wide-band receiver for ALMA Band 2+3 and evaluates the scientific benefits of increased bandwidth and integrated frequency coverage.

Findings

Feasibility of a single receiver covering 67-116 GHz.

Advantages of increased bandwidth to 16 GHz.

Potential scientific gains from the combined system.

Abstract

The Premiale Project "Science and Technology in Italy for the upgraded ALMA Observatory - iALMA" has the goal of strengthening the scientific, technological and industrial Italian contribution to the Atacama Large Millimeter/submillimeter Array (ALMA), the largest ground based international infrastructure for the study of the Universe in the microwave. One of the main objectives of the Science Working Group (SWG) inside iALMA, the Work Package 1, is to develop the Italian contribution to the Science Case for the ALMA Band 2 or Band 2+3 receiver. ALMA Band 2 receiver spans from ~67 GHz (bounded by an opaque line complex of ozone lines) up to 90 GHz which overlaps with the lower frequency end of ALMA Band 3. Receiver technology has advanced since the original definition of the ALMA frequency bands. It is now feasible to produce a single receiver which could cover the whole frequency range from 67 GHz to 116 GHz, encompassing Band 2 and Band 3 in a single receiver cartridge, a so called Band 2+3 system. In addition, upgrades of the ALMA system are now foreseen that should double the bandwidth to 16 GHz. The science drivers discussed below therefore also discuss the advantages of these two enhancements over the originally foreseen Band 2 system.