The NANOGrav 12.5-year Data Set: Search for Non-Einsteinian Polarization Modes in the Gravitational-wave Background

Arzoumanian, Zaven and Baker, Paul T. and Blumer, Harsha and Bécsy, Bence and Brazier, Adam and Brook, Paul R. and Burke-Spolaor, Sarah and Charisi, Maria and Chatterjee, Shami and Chen, Siyuan and Cordes, James M. and Cornish, Neil J. and Crawford, Fronefield and Cromartie, H. Thankful and DeCesar, Megan E. and DeGan, Dallas M. and Demorest, Paul B. and Dolch, Timothy and Drachler, Brendan and Ellis, Justin A. and Ferrara, Elizabeth C. and Fiore, William and Fonseca, Emmanuel and Garver-Daniels, Nathan and Gentile, Peter A. and Good, Deborah C. and Hazboun, Jeffrey S. and Holgado, A. Miguel and Islo, Kristina and Jennings, Ross J. and Jones, Megan L. and Kaiser, Andrew R. and Kaplan, David L. and Kelley, Luke Zoltan and Key, Joey Shapiro and Laal, Nima and Lam, Michael T. and W. Lazio, T. Joseph and Lorimer, Duncan R. and Liu, Tingting and Luo, Jing and Lynch, Ryan S. and Madison, Dustin R. and McEwen, Alexander and McLaughlin, Maura A. and Mingarelli, Chiara M. F. and Ng, Cherry and Nice, David J. and Olum, Ken D. and Pennucci, Timothy T. and Pol, Nihan S. and Ransom, Scott M. and Ray, Paul S. and Romano, Joseph D. and Sardesai, Shashwat C. and Shapiro-Albert, Brent J. and Siemens, Xavier and Simon, Joseph and Siwek, Magdalena S. and Spiewak, Renée and Stairs, Ingrid H. and Stinebring, Daniel R. and Stovall, Kevin and Sun, Jerry P. and Swiggum, Joseph K. and Taylor, Stephen R. and Turner, Jacob E. and Vallisneri, Michele and Vigeland, Sarah J. and Wahl, Haley M. and Witt, Caitlin A. (2021) The NANOGrav 12.5-year Data Set: Search for Non-Einsteinian Polarization Modes in the Gravitational-wave Background. The Astrophysical Journal Letters, 923 (2). L22. ISSN 2041-8205

[thumbnail of Arzoumanian_2021_ApJL_923_L22.pdf] Text
Arzoumanian_2021_ApJL_923_L22.pdf - Published Version
Download (1MB)

Abstract

We search NANOGrav's 12.5 yr data set for evidence of a gravitational-wave background (GWB) with all the spatial correlations allowed by general metric theories of gravity. We find no substantial evidence in favor of the existence of such correlations in our data. We find that scalar-transverse (ST) correlations yield signal-to-noise ratios and Bayes factors that are higher than quadrupolar (tensor-transverse, TT) correlations. Specifically, we find ST correlations with a signal-to-noise ratio of 2.8 that are preferred over TT correlations (Hellings and Downs correlations) with Bayesian odds of about 20:1. However, the significance of ST correlations is reduced dramatically when we include modeling of the solar system ephemeris systematics and/or remove pulsar J0030+0451 entirely from consideration. Even taking the nominal signal-to-noise ratios at face value, analyses of simulated data sets show that such values are not extremely unlikely to be observed in cases where only the usual TT modes are present in the GWB. In the absence of a detection of any polarization mode of gravity, we place upper limits on their amplitudes for a spectral index of γ = 5 and a reference frequency of fyr = 1 yr−1. Among the upper limits for eight general families of metric theories of gravity, we find the values of ${A}_{\mathrm{TT}}^{95 \% }=(9.7\pm 0.4)\times {10}^{-16}$ and ${A}_{\mathrm{ST}}^{95 \% }=(1.4\pm 0.03)\times {10}^{-15}$ for the family of metric spacetime theories that contain both TT and ST modes.

Item Type: Article
Subjects: STM Open Press > Physics and Astronomy
Depositing User: Unnamed user with email support@stmopenpress.com
Date Deposited: 05 May 2023 10:06
Last Modified: 05 Sep 2024 11:07
URI: http://journal.submissionpages.com/id/eprint/1117

Actions (login required)

View Item
View Item