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Brook, Paul S. Ray, Paul T. Baker, Peter A. Gentile, Rafael R. Lino dos Santos, Richard von Eckardstein, Ross J. Jennings, Rutger van Haasteren, Ryan S. Lynch, Sarah Burke-Spolaor, Sarah J. Vigeland, Scott M. Ransom, Shami Chatterjee, Shashwat C. Sardesai, Sophia V. Sosa Fiscella, Stella Koch Ocker, Stephen R. Taylor, Timothy Dolch, Timothy T. Pennucci, Tingting Liu, T. Joseph W. Lazio, Tobias Schr\\\"oder, Tyler Cohen, William Fiore, William G. Lamb, Xavier Siemens, Zaven Arzoumanian","submitted_at":"2024-08-19T17:19:30Z","abstract_excerpt":"The NANOGrav 15-year data provides compelling evidence for a stochastic gravitational-wave (GW) background at nanohertz frequencies. The simplest model-independent approach to characterizing the frequency spectrum of this signal consists in a simple power-law fit involving two parameters: an amplitude A and a spectral index \\gamma. 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