The ALMA Array's Upgrade: Unlocking New Insights into the Universe
For decades, astronomers have peered into the cosmos using radio antennas, revealing the hidden secrets of the universe. From the interstellar medium to planet-forming disks, these antennas have been instrumental in our understanding of the cosmos. Among these powerful tools is the Atacama Large Millimeter/Submillimeter Array (ALMA) in Chile, renowned for its ability to capture millimeter and submillimeter radiation from cold molecular clouds, the birthplaces of stars. Now, with the addition of 145 new low-noise amplifiers (LNAs), ALMA is set to unlock even more groundbreaking discoveries.
These amplifiers, developed by the Fraunhofer Institute for Applied Solid State Physics (IAF) and the Max Planck Institute for Radio Astronomy (MPIfR), expand ALMA's capabilities to the 67-116 GHz range, known as Band 2. This upgrade will enable researchers to delve deeper into the mysteries of the universe, particularly the 'cold interstellar medium'—the dust, gas, radiation, and magnetic fields that give birth to stars. Additionally, scientists will be able to study planet-forming disks with unprecedented detail and explore complex organic molecules (COMs) in nearby galaxies, offering insights into the building blocks of life.
Each LNA incorporates monolithic microwave integrated circuits (MMICs) designed by Fraunhofer IAF using indium gallium arsenide (InGaAs) semiconducting material. These MMICs are based on metamorphic high-electron-mobility transistor (mHEMT) technology, ensuring optimized performance in high-frequency receivers. By amplifying low-noise signals and minimizing background noise, these LNAs significantly enhance the sensitivity of ALMA's receivers, allowing for more precise measurements of millimeter and submillimeter radiation from the depths of the universe.
Dr. Fabian Thome, head of the subproject at Fraunhofer IAF, emphasized the impact of this upgrade: "The performance of receivers depends largely on the performance of the first high-frequency amplifiers installed in them. Our technology is characterized by an average noise temperature of 22 K, which is unmatched worldwide. With the new LNAs, signals can be amplified more than 300-fold in the first step. This enables the ALMA receivers to measure millimeter and submillimeter radiation from the depths of the universe much more precisely and obtain better data. We are incredibly proud that our LNA technology is helping us to better understand the origins of stars and entire galaxies."
The collaboration between Fraunhofer IAF and MPIfR was commissioned by the European Southern Observatory (ESO). Fraunhofer IAF designed, manufactured, and tested the MMICs at room temperature, while MPIfR assembled and qualified the LNA modules, testing them in cryogenic conditions. Prof. Dr. Michael Kramer, executive director at MPIfR, expressed his enthusiasm: "This is a wonderful recognition of our fantastic collaboration with Fraunhofer IAF, which shows that our amplifiers are not only 'made in Germany' but also the best in the world."
This upgrade marks a significant milestone in ALMA's journey, promising to unlock new insights into the universe and deepen our understanding of the cosmos.
