| NSF Org: |
AST Division Of Astronomical Sciences |
| Recipient: |
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| Initial Amendment Date: | August 15, 2018 |
| Latest Amendment Date: | June 21, 2022 |
| Award Number: | 1835400 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Nigel Sharp
nsharp@nsf.gov (703)292-4905 AST Division Of Astronomical Sciences MPS Directorate for Mathematical and Physical Sciences |
| Start Date: | September 1, 2018 |
| End Date: | August 31, 2023 (Estimated) |
| Total Intended Award Amount: | $620,415.00 |
| Total Awarded Amount to Date: | $720,535.00 |
| Funds Obligated to Date: |
FY 2021 = $59,572.00 FY 2022 = $40,548.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
1 UNIVERSITY OF NEW MEXICO ALBUQUERQUE NM US 87131-0001 (505)277-4186 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
1 University of New Mexico Albuquerque NM US 87131-0001 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
SPECIAL PROGRAMS IN ASTRONOMY, OFFICE OF MULTIDISCIPLINARY AC, MID-SCALE INSTRUMENTATION |
| Primary Program Source: |
01001819DB NSF RESEARCH & RELATED ACTIVIT 01002122DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.049 |
ABSTRACT
This project will support operations of the Long Wavelength Array (LWA) which provides access to the little explored part of the electromagnetic spectrum below 100 MHz. This region includes the recently detected sky-averaged absorption feature at 78 MHz from cosmic dawn when the first stars began to shine and the Universe was only 180 million years old. The LWA, operated by the University of New Mexico, is one of the last remaining University Radio Observatories. Such facilities are essential training grounds for the next generation of instrument builders. Students and post-docs, both at UNM and other US Universities, play an essential role as developers and users.
With this project the highly successful first station of the Long Wavelength Array (LWA1) will be converted to a multi-site observatory by combining LWA1 with the new LWA station at Sevilleta (LWA-SV), and the new low-frequency capability on the Very Large Array (VLA). This expanded LWA (ELWA) will overcome the primary limitation of LWA1 -- angular resolution -- and make the observatory competitive with any other instrument in the world operating in this frequency range. This new capability will be offered to the community in regular calls for proposals. At the same time the existing LWA1 and LWA-SV stations will also be open to the community either separately or together. The LWA stations consist of 256 dual-polarization dipoles, which are digitized and combined into beams, or cross-correlated to form all-sky images. With its high temporal (50 nanoseconds), and high spectral (1 Hz) resolution the LWA is making major contributions to established fields (Jupiter and Solar bursts, pulsars, ionosphere), and opening up new areas of study (radio bursts from fireballs, pulsar environments, and detections or limits on new transients such as gravitational wave sources).
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
With its high altitudes and low population densities New Mexico is a great location for radio telescopes. For over 50 years New Mexico has been the home of the Very Large Array (VLA). This famous instrument has now been joined by the Long Wavelength Array (LWA), with its first station completed in 2011 (LWA1; see aerial view), and the 2nd in 2016 (LWA-SV; see aerial view). This project supported the combination of the first two LWA stations with the VLA to form a radio telescope nearly 100 km in diameter which we call the ELWA.
This project also supported operations and development for the Long Wavelength Array (LWA) telescopes and the restructuring of the LWA archive. Over the lifetime of the project the LWA usercommunity produced over 20 refereed publications reporting on new discoveries in the fields of low frequency instrumentation, pulsars, meteors, transient searches, solar and space weather, ionosphere/atmospheric studies, planets, and 21 cm cosmology. Over 20 graduate and undergraduate students have learned how to build and operate low frequency arrays, and many of these are also engaged in scientific studies. Five graduate students at UNM used the LWA for their PhD thesis completed during this award. Also during this award a 3rd LWA station (LWA-NA; see photo) was completed in 2023.
Below are some specific results from the project including images created using the LWA.
LWA-TV:
A feature of the Long Wavelength Array stations is that they can produce images of the sky above them in real-time. These images are used to look for transient sources such as meteors and gamma-ray bursts, and can be used to monitor the radio frequency interference environment at the station. You can watch LWA-TV either from LWA1 or from LWA-SV station from this web page: http://www.phys.unm.edu/~lwa/lwatv.html.
Lightning:
The LWA is well suited and situated for the observation of lightning which are common during the summer in central New Mexico. Stock et al. (2023) demonstrates some of the capabilities that the array brings to the study of lightning. Once 32 or more LWA antennas are used to image lightning radio sources, virtually every integration period includes at least one identifiable emitter from along the lightning stroke. The use of many antennas also allows multiple simultaneous lightning radio sources to be imaged at sub-microsecond timescales; for the flash examined, 51% of the images contained more than one lightning source. Finally, by using many antennas to image lightning sources, the array is capable of locating sources fainter than the galactic background radio noise level, yielding possibly the most sensitive radio maps of lightning to date. This incredible sensitivity enables, for the first time, the emissions originating from the positive leader tips of natural in-cloud lightning to be detected and located. The tip emission is most likely due to positive breakdown in the atmosphere as the lightning stroke advances (see Figure).
Pulsars:
One of the most interesting results so far from the ELWA was the discovery of a pulsar wind nebula around the bright pulsar B0950+08. This came as a surpise since B0950+08 is an old pulsar with an estimated age of 17 Myr, much older than any previously known pulsar wind nebula. The paper reporting this discovery was written by UNM undergraduate Dilys Ruan (Ruan et al. 2020).
Last Modified: 11/06/2023
Modified by: Gregory B Taylor
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