The NANOGrav 15-year Data Set: Search for Anisotropy in the Gravitational-Wave Background

Gabriella Agazie; Akash Anumarlapudi; Anne M Archibald; Zaven Arzoumanian; Paul T Baker; Bence Bécsy; Laura Blecha; Adam Brazier; Paul R Brook; Sarah Burke-Spolaor; J. Andrew Casey-Clyde; Maria Charisi; Shami Chatterjee; Tyler Cohen; James M Cordes; Neil J Cornish; Fronefield Crawford; H. Thankful Cromartie; Kathryn Crowter; Megan E DeCesar; Paul B Demorest; Timothy Dolch; Brendan Drachler; Elizabeth C Ferrara; William Fiore; Emmanuel Fonseca; Gabriel E Freedman; Emiko Gardiner; Nate Garver-Daniels; Peter A Gentile; Joseph Glaser; Deborah C Good; Kayhan Gültekin; Jeffrey S Hazboun; Ross J Jennings; Aaron D Johnson; Megan L Jones; Andrew R Kaiser; David L Kaplan; Luke Zoltan Kelley; Matthew Kerr; Joey S Key; Nima Laal; Michael T Lam; William G Lamb; T. Joseph W Lazio; Natalia Lewandowska; Tingting Liu; Duncan R Lorimer; Jing Luo; Ryan S Lynch; Chung-Pei Ma; Dustin R Madison; Alexander McEwen; James W McKee; Maura A McLaughlin; Natasha McMann; Bradley W Meyers; Chiara M. F Mingarelli; Andrea Mitridate; Cherry Ng; David J Nice; Stella Koch Ocker; Ken D Olum; Timothy T Pennucci; Benetge B. P Perera; Nihan S Pol; Henri A Radovan; Scott M Ransom; Paul S Ray; Joseph D Romano; Shashwat C Sardesai; Ann Schmiedekamp; Carl Schmiedekamp; Kai Schmitz; Levi Schult; Brent J Shapiro-Albert; Xavier Siemens; Joseph Simon; Magdalena S Siwek; Ingrid H Stairs; Daniel R Stinebring; Kevin Stovall; Abhimanyu Susobhanan; Joseph K Swiggum; Stephen R Taylor; Jacob E Turner; Caner Unal; Michele Vallisneri; Sarah J Vigeland; Haley M Wahl; Caitlin A Witt; Olivia Young

doi:10.48550/arxiv.2306.16221

Preprint

The NANOGrav 15-year Data Set: Search for Anisotropy in the Gravitational-Wave Background

Gabriella Agazie, Akash Anumarlapudi, Anne M Archibald, Zaven Arzoumanian, Paul T Baker, Bence Bécsy, Laura Blecha, Adam Brazier, Paul R Brook, Sarah Burke-Spolaor, …

28/06/2023

DOI: https://doi.org/10.48550/arxiv.2306.16221

Abstract

The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) has reported evidence for the presence of an isotropic nanohertz gravitational wave background (GWB) in its 15 yr dataset. However, if the GWB is produced by a population of inspiraling supermassive black hole binary (SMBHB) systems, then the background is predicted to be anisotropic, depending on the distribution of these systems in the local Universe and the statistical properties of the SMBHB population. In this work, we search for anisotropy in the GWB using multiple methods and bases to describe the distribution of the GWB power on the sky. We do not find significant evidence of anisotropy, and place a Bayesian $95\%$ upper limit on the level of broadband anisotropy such that $(C_{l>0} / C_{l=0}) < 20\%$. We also derive conservative estimates on the anisotropy expected from a random distribution of SMBHB systems using astrophysical simulations conditioned on the isotropic GWB inferred in the 15-yr dataset, and show that this dataset has sufficient sensitivity to probe a large fraction of the predicted level of anisotropy. We end by highlighting the opportunities and challenges in searching for anisotropy in pulsar timing array data.

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Title: The NANOGrav 15-year Data Set: Search for Anisotropy in the Gravitational-Wave Background
Creators - without role: Gabriella Agazie - for the NANOGrav Collaboration
Akash Anumarlapudi - for the NANOGrav Collaboration
Anne M Archibald - for the NANOGrav Collaboration
Zaven Arzoumanian - for the NANOGrav Collaboration
Paul T Baker - for the NANOGrav Collaboration
Bence Bécsy - for the NANOGrav Collaboration
Laura Blecha - for the NANOGrav Collaboration
Adam Brazier - for the NANOGrav Collaboration
Paul R Brook - for the NANOGrav Collaboration
Sarah Burke-Spolaor - for the NANOGrav Collaboration
J. Andrew Casey-Clyde - for the NANOGrav Collaboration
Maria Charisi - for the NANOGrav Collaboration
Shami Chatterjee - for the NANOGrav Collaboration
Tyler Cohen - for the NANOGrav Collaboration
James M Cordes - for the NANOGrav Collaboration
Neil J Cornish - for the NANOGrav Collaboration
Fronefield Crawford - for the NANOGrav Collaboration
H. Thankful Cromartie - for the NANOGrav Collaboration
Kathryn Crowter - for the NANOGrav Collaboration
Megan E DeCesar - for the NANOGrav Collaboration
Paul B Demorest - for the NANOGrav Collaboration
Timothy Dolch - for the NANOGrav Collaboration
Brendan Drachler - for the NANOGrav Collaboration
Elizabeth C Ferrara - for the NANOGrav Collaboration
William Fiore - for the NANOGrav Collaboration
Emmanuel Fonseca - for the NANOGrav Collaboration
Gabriel E Freedman - for the NANOGrav Collaboration
Emiko Gardiner - for the NANOGrav Collaboration
Nate Garver-Daniels - for the NANOGrav Collaboration
Peter A Gentile - for the NANOGrav Collaboration
Joseph Glaser - for the NANOGrav Collaboration
Deborah C Good - for the NANOGrav Collaboration
Kayhan Gültekin - for the NANOGrav Collaboration
Jeffrey S Hazboun - for the NANOGrav Collaboration
Ross J Jennings - for the NANOGrav Collaboration
Aaron D Johnson - for the NANOGrav Collaboration
Megan L Jones - for the NANOGrav Collaboration
Andrew R Kaiser - for the NANOGrav Collaboration
David L Kaplan - for the NANOGrav Collaboration
Luke Zoltan Kelley - for the NANOGrav Collaboration
Matthew Kerr - for the NANOGrav Collaboration
Joey S Key - for the NANOGrav Collaboration
Nima Laal - for the NANOGrav Collaboration
Michael T Lam - for the NANOGrav Collaboration
William G Lamb - for the NANOGrav Collaboration
T. Joseph W Lazio - for the NANOGrav Collaboration
Natalia Lewandowska - for the NANOGrav Collaboration
Tingting Liu - for the NANOGrav Collaboration
Duncan R Lorimer - for the NANOGrav Collaboration
Jing Luo - for the NANOGrav Collaboration
Ryan S Lynch - for the NANOGrav Collaboration
Chung-Pei Ma - for the NANOGrav Collaboration
Dustin R Madison - for the NANOGrav Collaboration
Alexander McEwen - for the NANOGrav Collaboration
James W McKee - for the NANOGrav Collaboration
Maura A McLaughlin - for the NANOGrav Collaboration
Natasha McMann - for the NANOGrav Collaboration
Bradley W Meyers - for the NANOGrav Collaboration
Chiara M. F Mingarelli - for the NANOGrav Collaboration
Andrea Mitridate - for the NANOGrav Collaboration
Cherry Ng - for the NANOGrav Collaboration
David J Nice - for the NANOGrav Collaboration
Stella Koch Ocker - for the NANOGrav Collaboration
Ken D Olum - for the NANOGrav Collaboration
Timothy T Pennucci - for the NANOGrav Collaboration
Benetge B. P Perera - for the NANOGrav Collaboration
Nihan S Pol - for the NANOGrav Collaboration
Henri A Radovan - for the NANOGrav Collaboration
Scott M Ransom - for the NANOGrav Collaboration
Paul S Ray - for the NANOGrav Collaboration
Joseph D Romano - for the NANOGrav Collaboration
Shashwat C Sardesai - for the NANOGrav Collaboration
Ann Schmiedekamp - for the NANOGrav Collaboration
Carl Schmiedekamp - for the NANOGrav Collaboration
Kai Schmitz - for the NANOGrav Collaboration
Levi Schult - for the NANOGrav Collaboration
Brent J Shapiro-Albert - for the NANOGrav Collaboration
Xavier Siemens - for the NANOGrav Collaboration
Joseph Simon - for the NANOGrav Collaboration
Magdalena S Siwek - for the NANOGrav Collaboration
Ingrid H Stairs - for the NANOGrav Collaboration
Daniel R Stinebring - for the NANOGrav Collaboration
Kevin Stovall - for the NANOGrav Collaboration
Abhimanyu Susobhanan - for the NANOGrav Collaboration
Joseph K Swiggum - for the NANOGrav Collaboration
Stephen R Taylor - for the NANOGrav Collaboration
Jacob E Turner - for the NANOGrav Collaboration
Caner Unal - for the NANOGrav Collaboration
Michele Vallisneri - for the NANOGrav Collaboration
Sarah J Vigeland - for the NANOGrav Collaboration
Haley M Wahl - for the NANOGrav Collaboration
Caitlin A Witt - for the NANOGrav Collaboration
Olivia Young - for the NANOGrav Collaboration
Identifiers: 991019443988907081
Academic Unit: Physics
Language: English
Resource Type: Preprint