BibTex format
@article{Agazie:2026:2041-8213/ae7086,
author = {Agazie, G and Anumarlapudi, A and Archibald, AM and Arzoumanian, Z and Baier, JG and Baker, PT and Bécsy, B and Bhoonah, A and Blecha, L and Brazier, A and Brook, PR and Burke-Spolaor, S and Burnette, R and Case, R and Casey-Clyde, JA and Charisi, M and Chatterjee, S and Cohen, T and Cordes, JM and Cornish, NJ and Crawford, F and Cromartie, HT and Crowter, K and DeCesar, ME and Demorest, PB and Deng, H and Dey, L and Dolch, T and Ferrara, EC and Fiore, W and Fonseca, E and Freedman, GE and Gardiner, EC and Garver-Daniels, N and Gentile, PA and Gersbach, KA and Glaser, J and Gómez-Cortes, BD and Good, DC and Gültekin, K and Harris, CJ and Hazboun, JS and Jennings, RJ and Johnson, AD and Jones, ML and Kaplan, DL and Kelley, LZ and Kerr, M and Key, JS and Laal, N and Lam, MT and Lamb, WG and Larsen, B and Lazio, TJW and Lewandowska, N and Leys, M and Liu, T and Lorimer, DR and Luo, J and Lynch, RS and Ma, CP and Madison, DR and Matt, C and McEwen, A and McKee, JW and McLaughlin, MA and Mc},
doi = {2041-8213/ae7086},
journal = {Astrophysical Journal Letters},
title = {The NANOGrav 15 yr Data Set: Piecewise Power-law Reconstruction of the Gravitational-wave Background},
url = {http://dx.doi.org/10.3847/2041-8213/ae7086},
volume = {1004},
year = {2026}
}
RIS format (EndNote, RefMan)
TY - JOUR
AB - The NANOGrav 15 yr (NG15) data set provides evidence for a gravitational-wave background (GWB) signal at nHz frequencies, which is expected to originate either from a cosmic population of inspiraling supermassive black hole binaries or new particle physics in the early Universe. A firm identification of the source of the NG15 signal requires an accurate reconstruction of its frequency spectrum. In this Letter, we provide such a spectral characterization of the NG15 signal based on a piecewise power-law (PPL) ansatz that strikes a balance between existing alternatives in the literature. Our PPL reconstruction is more flexible than the standard constant power-law model, which describes the GWB spectrum in terms of only two parameters: an amplitude A and a spectral index γ. Concurrently, it better approximates physically realistic GWB spectra—especially those of cosmological origin—than the free spectral model, since the latter allows for arbitrary variations in the GWB amplitude from one frequency bin to the next. Our PPL reconstruction of the NG15 signal relies on individual PPL models with a fixed number of internal nodes (i.e., constant power law, broken power law, doubly broken power law, etc.), which are ultimately combined in a Bayesian model average. The data products resulting from our analysis provide the basis for fast refits of spectral GWB models.
AU - Agazie,G
AU - Anumarlapudi,A
AU - Archibald,AM
AU - Arzoumanian,Z
AU - Baier,JG
AU - Baker,PT
AU - Bécsy,B
AU - Bhoonah,A
AU - Blecha,L
AU - Brazier,A
AU - Brook,PR
AU - Burke-Spolaor,S
AU - Burnette,R
AU - Case,R
AU - Casey-Clyde,JA
AU - Charisi,M
AU - Chatterjee,S
AU - Cohen,T
AU - Cordes,JM
AU - Cornish,NJ
AU - Crawford,F
AU - Cromartie,HT
AU - Crowter,K
AU - DeCesar,ME
AU - Demorest,PB
AU - Deng,H
AU - Dey,L
AU - Dolch,T
AU - Ferrara,EC
AU - Fiore,W
AU - Fonseca,E
AU - Freedman,GE
AU - Gardiner,EC
AU - Garver-Daniels,N
AU - Gentile,PA
AU - Gersbach,KA
AU - Glaser,J
AU - Gómez-Cortes,BD
AU - Good,DC
AU - Gültekin,K
AU - Harris,CJ
AU - Hazboun,JS
AU - Jennings,RJ
AU - Johnson,AD
AU - Jones,ML
AU - Kaplan,DL
AU - Kelley,LZ
AU - Kerr,M
AU - Key,JS
AU - Laal,N
AU - Lam,MT
AU - Lamb,WG
AU - Larsen,B
AU - Lazio,TJW
AU - Lewandowska,N
AU - Leys,M
AU - Liu,T
AU - Lorimer,DR
AU - Luo,J
AU - Lynch,RS
AU - Ma,CP
AU - Madison,DR
AU - Matt,C
AU - McEwen,A
AU - McKee,JW
AU - McLaughlin,MA
AU - McMann,N
AU - Meyers,BW
AU - Meyers,PM
AU - Mingarelli,CMF
AU - Mitridate,A
AU - Ng,C
AU - Nice,DJ
AU - Ocker,SK
AU - Olum,KD
AU - Pennucci,TT
AU - Perera,BBP
AU - Petrov,P
AU - Pol,NS
AU - Radovan,HA
AU - Ransom,SM
AU - Ray,PS
AU - Romano,JD
AU - Runnoe,JC
AU - Saffer,A
AU - Sardesai,SC
AU - Schmiedekamp,A
AU - Schmiedekamp,C
AU - Schmitz,K
AU - Shapiro-Albert,BJ
AU - Siemens,X
AU - Simon,J
AU - Fiscella,SVS
AU - Stairs,IH
AU - Stinebring,DR
AU - Stovall,K
AU - Susobhanan,A
AU - Swiggum,JK
AU - Taylor,J
AU - Taylor,SR
DO - 2041-8213/ae7086
PY - 2026///
SN - 2041-8205
TI - The NANOGrav 15 yr Data Set: Piecewise Power-law Reconstruction of the Gravitational-wave Background
T2 - Astrophysical Journal Letters
UR - http://dx.doi.org/10.3847/2041-8213/ae7086
VL - 1004
ER -