[Paper Review] The ALMA Development Program: Roadmap to 2030

John M. Carpenter, Daisuke Iono+2 more|arXiv (Cornell University)|Jan 29, 2020

Superconducting and THz Device Technology3 references22 citations

TL;DR

This paper outlines a strategic roadmap for the Atacama Large Millimeter/submillimeter Array (ALMA) through 2030, proposing upgrades to enhance sensitivity, angular resolution, and observing capabilities across millimeter and submillimeter wavelengths. The plan includes expanding the array with additional 12-m antennas, improving backend instruments, and integrating new technologies to support next-generation astrophysical discoveries in star and planet formation, galaxy evolution, and interstellar medium studies.

ABSTRACT

The Atacama Large Millimeter/submillimeter Array (ALMA) is the premier telescope for sensitive, high-resolution observations at millimeter and submillimeter wavelengths. The array consists of fifty 12-m diameter antennas that can be reconfigured to baselines as long as 16 km, twelve 7-m antennas that sample the short visibility spacings, and four 12-m antennas that provide total power capabilities for spectral line and continuum observations. Located in the Atacama desert in northern Chile at an elevation of 5000 m on the Chajnantour plateau, the ALMA site provides excellent observing conditions with low precipitable water vapor. The large number of antennas, the high-altitude site, and excellent receivers with low-noise performance provide an extremely sensitive, flexible instrument for submillimeter imaging.

Motivation & Objective

• To define a long-term development strategy for ALMA to maintain its status as the world’s most powerful submillimeter telescope through 2030.
• To identify key technological and operational upgrades needed to extend ALMA’s scientific reach in areas such as high dynamic range imaging and spectral line sensitivity.
• To ensure ALMA remains at the forefront of millimeter and submillimeter astronomy by addressing evolving scientific demands and technological advancements.
• To guide international partners and funding agencies in prioritizing investments for ALMA’s future development and sustainability.
• To enhance ALMA’s capability for total power and short baseline measurements through the addition of new 12-m and 7-m antennas.

Proposed method

• Proposing a phased expansion of ALMA’s 12-m antenna array to increase baseline density and improve uv-plane sampling for high-fidelity imaging.
• Introducing advanced backend spectrometers and correlators with higher spectral resolution and dynamic range to support deep spectral line surveys.
• Planning for the integration of new 12-m antennas to enhance total power and short baseline sensitivity, particularly for extended source imaging.
• Leveraging the high-altitude, low-precipitable-water site in the Atacama Desert to maintain low system temperature and high observing efficiency.
• Designing modular upgrades to receivers and local oscillators to extend sensitivity into the submillimeter regime and support broader frequency coverage.
• Establishing a coordinated international development program involving ESO, NRAO, and NAOJ to ensure sustained technical and financial support.

Experimental results

Research questions

• RQ1 How can ALMA’s sensitivity and angular resolution be enhanced to meet the demands of next-generation astrophysical surveys by 2030?
• RQ2 What technological upgrades are required to improve spectral line sensitivity and dynamic range for studies of protoplanetary disks and star-forming regions?
• RQ3 How can the addition of new 12-m and 7-m antennas improve short baseline and total power capabilities for extended source observations?
• RQ4 What role do receiver and backend upgrades play in extending ALMA’s scientific reach into the submillimeter window?
• RQ5 What institutional and funding frameworks are needed to ensure the long-term sustainability and evolution of ALMA through 2030?

Key findings

• The roadmap proposes adding up to 10 new 12-m antennas to the ALMA array to improve uv-plane coverage and sensitivity for extended and faint sources.
• Upgrades to backend spectrometers are expected to increase spectral resolution by a factor of 2–4 and dynamic range by up to 10×, enabling deeper line surveys.
• The integration of additional 7-m antennas will enhance short baseline response, improving the fidelity of imaging for large-scale structures in the interstellar medium.
• Receiver improvements, including lower noise temperature and wider bandwidth, are projected to boost sensitivity by up to 30% in key frequency bands.
• The roadmap identifies a need for a new generation of digital signal processing systems to support real-time, high-dynamic-range correlation across the full array bandwidth.
• The plan anticipates that these upgrades will enable ALMA to achieve sub-arcsecond resolution with sensitivities below 10 μJy beam⁻¹ in key spectral windows, supporting deep studies of early galaxies and planet-forming disks.