NSF ATI for realfast
** to do: systematic references to co-observing resources and commensal VLASS **
We propose a set of enhancements to the Jansky Very Large Array (VLA) to enable 24/7 surveys for fast radio transients. Large, single-dish radio telescopes have dedicated thousands of hours to surveys for millisecond-scale transients with the aim of capturing rare classes of cosmological transient, understanding the lifecycle of neutron stars, and measuring otherwise inaccessible properties of interstellar and intergalactic material. This field has been revitalized in the past decade with the discovery of new classes of transient. As the most sensitive radio interferometer on earth, the VLA will revolutionize this field with its ability to form sensitive images with unmatched spatial resolution.
The core of the proposed system is a 32-node, GPU-accelerated compute cluster that will search images generated on timescales from 1 ms to 1 minute. Real-time processing will allow triggered recording of the parallel data stream for later analysis and the rapid announcement of candidates for follow-up observing. By integrating with a high-speed, duplicate data stream of the VLA, this system will turn each observation into a fast transient survey, ultimately encompassing thousands of hours per year.
Interferometric imaging will do pioneering science with a mysterious new class of radio transients known as “fast radio bursts”. These millisecond transients have inferred distances that imply a cosmological origin and extreme luminosities. Such an event would open a new window on the intergalactic medium and cosmology. Only an interferometer can uniquely identify counterparts (e.g., a host galaxy or gamma-ray burst) well enough to constrain their nature and enable their use as cosmic probes. The proposed system will provide the first arcsecond localization of a burst and will detect more than 12 bursts over the course of the program. Similarly, the interferometric discovery and localization of other classes of millisecond transient will address topics ranging from the missing baryon problem to (sub)stellar magnetism to the search for exotic binary pulsar systems.
Time-domain astronomy has been identified as a discovery frontier in the recent Decadal Review of Astronomy and Astrophysics. Real-time, commensal analysis creates discovery potential by searching an otherwise inaccessible data stream. Developing this system at the VLA will produce multiplicative improvement to scientific productivity for this already powerful telescope.
The completed system will autonomously detect radio transients and drive follow-up observing across the electromagnetic spectrum. Co-observing with other observatories, such as the Long Wavelength Array and Skynet, opens novel science and public outreach opportunities. Additional computing power and flexible software at the VLA site will open new observing models. The data analysis software is open source, which allows any astronomer to reproduce VLA detections or integrate the software into other interferometric fast transient surveys.
Consider the excitement of seeing a shooting star: a dynamic flash in what seems a static sky. We aim for our transient detection system to inspire similar recognition of the evolving and dynamic sky at timescales faster than the blink of an eye. Alerts will be announced for all new discoveries and will be visualized with movies, images, and spectra to engage the public at NRAO sites and via the web. Opportunities for student training will be available on topics such as transient astrophysics, interferometric algorithms, heterogeneous/high-performance computing, and front-end web development. These topics, and the data-intensive nature of this project, have increasing relevance for academic, commercial, and national security applications.