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The astrophysics of nanohertz gravitational waves

Burke-Spolaor, Sarah and Taylor, Stephen R. and Charisi, Maria and Dolch, Timothy and Hazboun, Jeffrey S. and Holgado, A. Miguel and Kelley, Luke Zoltan and Lazio, T. Joseph W. and Madison, Dustin R. and McMann, Natasha and Mingarelli, Chiara M. F. and Rasskazov, Alexander and Siemens, Xavier and Simon, Joseph J. and Smith, Tristan L. (2019) The astrophysics of nanohertz gravitational waves. Astronomy and Astrophysics Review, 27 . Art. No. 5. ISSN 0935-4956.

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Pulsar timing array (PTA) collaborations in North America, Australia, and Europe, have been exploiting the exquisite timing precision of millisecond pulsars over decades of observations to search for correlated timing deviations induced by gravitational waves (GWs). PTAs are sensitive to the frequency band ranging just below 1 nanohertz to a few tens of microhertz. The discovery space of this band is potentially rich with populations of inspiraling supermassive black hole binaries, decaying cosmic string networks, relic post-inflation GWs, and even non-GW imprints of axionic dark matter. This article aims to provide an understanding of the exciting open science questions in cosmology, galaxy evolution, and fundamental physics that will be addressed by the detection and study of GWs through PTAs. The focus of the article is on providing an understanding of the mechanisms by which PTAs can address specific questions in these fields, and to outline some of the subtleties and difficulties in each case. The material included is weighted most heavily toward the questions which we expect will be answered in the near-term with PTAs; however, we have made efforts to include most currently anticipated applications of nanohertz GWs.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Burke-Spolaor, Sarah0000-0003-4052-7838
Taylor, Stephen R.0000-0003-0264-1453
Charisi, Maria0000-0003-3579-2522
Hazboun, Jeffrey S.0000-0003-2742-3321
Kelley, Luke Zoltan0000-0002-6625-6450
Lazio, T. Joseph W.0000-0002-3873-5497
Mingarelli, Chiara M. F.0000-0002-4307-1322
Additional Information:© 2019 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Received: 8 November 2018. First Online: 18 June 2019. We thank Andrew Kaiser and Sean Williams for providing Fig. 16; for questions regarding this Figure please contact NANOGrav is supported by NSF Physics Frontier Center award #1430284. SBS is supported by NSF award #1458952 and by the CIFAR Azrieli Global Scholars program. Portions of this research were carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. DRM was, until recently, a Jansky Fellow of the National Radio Astronomy Observatory, a facility of the NSF operated under cooperative agreement by Associated Universities, Inc. The Flatiron Institute is supported by the Simons Foundation. AR received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Programme for Research and Innovation ERC-2014-STG under grant agreement No. 638435 (GalNUC).
Funding AgencyGrant Number
Canadian Institute for Advanced Research (CIFAR)UNSPECIFIED
National Radio Astronomy ObservatoryUNSPECIFIED
Associated Universities, Inc.UNSPECIFIED
Simons FoundationUNSPECIFIED
European Research Council (ERC)638435
Record Number:CaltechAUTHORS:20190618-134243554
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Official Citation:Burke-Spolaor, S., Taylor, S.R., Charisi, M. et al. Astron Astrophys Rev (2019) 27: 5.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:96503
Deposited By: Tony Diaz
Deposited On:18 Jun 2019 21:44
Last Modified:09 Mar 2020 13:19

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