correspondence To the Editor — This issue of Nature just the past few years have more than but their timeline and ultimate sensitivity Astronomy highlights the importance of doubled their sensitivities. NANOGrav’s remain unclear. Moreover, access to these radio-astronomical pulsar measurements gravitational-wave investigations rely on telescopes for US-based scientists will be, at for the detection and characterization of continued observations with the GBT and best, limited to many fewer hours than in very long wavelength (nanohertz frequency) Arecibo, with the combined timing and current observing programs, offering scant 1,2 gravitational waves , a regime not probed pulsar searching observations using opportunity for US leadership. by any other method. Such measurements roughly 20% of the available time on In summary, there are no plans to build are critical to realizing one of the National each telescope. suitable replacements for the GBT or Science Foundation’s (NSF) '10 Big Ideas': Sadly, continuity of science operations Arecibo — let alone anything that improves multi-messenger astrophysics. This has at both of these telescopes is in serious upon their performance — in the US, and been recognized through the award of jeopardy. Over the past three years, NSF their closure would effectively sound the a NSF Physics Frontiers Center to the support for GBT operations has decreased death knell for US pulsar astrophysics, low- North American Nanohertz Observatory from 95% of the operating budget to 65%, frequency gravitational wave astrophysics, for Gravitational Waves (NANOGrav) with further reductions to 30% expected. and the many other areas where these collaboration. Pulsar timing experiments NSF recently announced a funding profile instruments provide unique capabilities for are just beginning to probe astrophysically for Arecibo that will gradually decrease US astronomers. These two telescopes must plausible gravitational wave strengths and support from its current level of remain operational. are likely to make a detection within the US$8 million per year to US$2 million per year A version of this letter has been next five years . by 2022. The situation is, in fact, dire: signed by 91 members of the NANOGrav Accurate timing of radio pulses from complete closure of both facilities is a very collaboration and 96 other scientists. A pulsars contributes uniquely to other areas real possibility if additional funding cannot full list of the authors and signatories of of physics as well, including the study of be found to make up the shortfall. this letter is available at http://go.nature. matter in its densest state, tests of general Our community understands that NSF com/2AbypCz. ❐ relativity in the strong-field limit and support for facilities may cease when they the evolution of massive stellar systems have fulfilled their mission or have been Maura McLaughlin (see references in ref. ). A glance at the replaced by more capable instruments. But Department of Physics and Astronomy, West Virginia astrophysics preprint server will affirm that is not the case here. Arecibo and the University, Morgantown, WV, USA. that radio studies of pulsars and related GBT remain world-class, oversubscribed, e-mail: Maura.Mclaughlin@mail.wvu.edu phenomena are a vital, growing part of and without peer . The only other US Published online: 1 December 2017 astrophysics, with a strong US presence. telescope operating in a similar frequency https://doi.org/10.1038/s41550-017-0333-8 Between them, the 300-m Arecibo radio range, the Jansky Very Large Array, has telescope and the 100-m Robert C. Byrd neither the sensitivity nor the available time References Green Bank Telescope (GBT) account for to replace either facility . Collaboration with 1. Lommen, A. N. Nat. Astron. https://doi.org/10.1038/s41550-017- nearly all observational pulsar research by astronomers using less sensitive European 0324-9 (2017). 2. Mingarelli, C. M. F. et al. Nat. Astron. https://doi.org/10.1038/ American scientists, and they also provide and Australian telescopes augments work s41550-017-0299-6 (2017). the greatest sensitivity to the International done at Arecibo and the GBT, but it is 3. Taylor, S. et al. Astrophys. J. 819, 6 (2016). Pulsar Timing Array effort. They both no substitute for maintaining a strong 4. Lockman, F. J. et al. Preprint at https://arxiv.org/abs/1610.02329 (2016). offer large collecting areas at frequencies American radio astronomy program. 5. Bally, J. et al. Preprint at https://arxiv.org/abs/1610.09014 (2016). < 2 GHz, sensitive receivers, and state-of-the- Large radio telescopes in China and South 6. Ransom, S. M. et al. Consequences of Replacing the GBT and/or art digital data analysis systems necessary Africa — FAST and MeerKAT — will begin Arecibo with the Jansky VLA for NANOGrav (2016); for precise pulsar timing. Upgrades over pulsar timing experiments in a few years, https://library.nrao.edu/public/memos/gbt/GBT_294.pdf Nature astroNomy | VOL 1 | DECEMBER 2017 | 808 | www.nature.com/natureastronomy © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved. © 2017 Macmillan Publishers Limited, part of Springer Nature. All rights reserved.
Nature Astronomy – Springer Journals
Published: Dec 1, 2017
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