%0 Generic %1 agazie2023nanograv %A Agazie, Gabriella %A Anumarlapudi, Akash %A Archibald, Anne M. %A Arzoumanian, Zaven %A Baker, Paul T. %A Becsy, Bence %A Blecha, Laura %A Brazier, Adam %A Brook, Paul R. %A Burke-Spolaor, Sarah %A Burnette, Rand %A Case, Robin %A Charisi, Maria %A Chatterjee, Shami %A Chatziioannou, Katerina %A Cheeseboro, Belinda D. %A Chen, Siyuan %A Cohen, Tyler %A Cordes, James M. %A Cornish, Neil J. %A Crawford, Fronefield %A Cromartie, H. Thankful %A Crowter, Kathryn %A Cutler, Curt J. %A DeCesar, Megan E. %A DeGan, Dallas %A Demorest, Paul B. %A Deng, Heling %A Dolch, Timothy %A Drachler, Brendan %A Ellis, Justin A. %A Ferrara, Elizabeth C. %A Fiore, William %A Fonseca, Emmanuel %A Freedman, Gabriel E. %A Garver-Daniels, Nate %A Gentile, Peter A. %A Gersbach, Kyle A. %A Glaser, Joseph %A Good, Deborah C. %A Gultekin, Kayhan %A Hazboun, Jeffrey S. %A Hourihane, Sophie %A Islo, Kristina %A Jennings, Ross J. %A Johnson, Aaron D. %A Jones, Megan L. %A Kaiser, Andrew R. %A Kaplan, David L. %A Kelley, Luke Zoltan %A Kerr, Matthew %A Key, Joey S. %A Klein, Tonia C. %A Laal, Nima %A Lam, Michael T. %A Lamb, William G. %A Lazio, T. Joseph W. %A Lewandowska, Natalia %A Littenberg, Tyson B. %A Liu, Tingting %A Lommen, Andrea %A Lorimer, Duncan R. %A Luo, Jing %A Lynch, Ryan S. %A Ma, Chung-Pei %A Madison, Dustin R. %A Mattson, Margaret A. %A McEwen, Alexander %A McKee, James W. %A McLaughlin, Maura A. %A McMann, Natasha %A Meyers, Bradley W. %A Meyers, Patrick M. %A Mingarelli, Chiara M. F. %A Mitridate, Andrea %A Natarajan, Priyamvada %A Ng, Cherry %A Nice, David J. %A Ocker, Stella Koch %A Olum, Ken D. %A Pennucci, Timothy T. %A Perera, Benetge B. P. %A Petrov, Polina %A Pol, Nihan S. %A Radovan, Henri A. %A Ransom, Scott M. %A Ray, Paul S. %A Romano, Joseph D. %A Sardesai, Shashwat C. %A Schmiedekamp, Ann %A Schmiedekamp, Carl %A Schmitz, Kai %A Schult, Levi %A Shapiro-Albert, Brent J. %A Siemens, Xavier %A Simon, Joseph %A Siwek, Magdalena S. %A Stairs, Ingrid H. %A Stinebring, Daniel R. %A Stovall, Kevin %A Sun, Jerry P. %A Susobhanan, Abhimanyu %A Swiggum, Joseph K. %A Taylor, Jacob %A Taylor, Stephen R. %A Turner, Jacob E. %A Unal, Caner %A Vallisneri, Michele %A van Haasteren, Rutger %A Vigeland, Sarah J. %A Wahl, Haley M. %A Wang, Qiaohong %A Witt, Caitlin A. %A Young, Olivia %D 2023 %K tifr %R 10.3847/2041-8213/acdac6 %T The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background %U http://arxiv.org/abs/2306.16213 %X We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15-year pulsar-timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. The correlations follow the Hellings-Downs pattern expected for a stochastic gravitational-wave background. The presence of such a gravitational-wave background with a power-law-spectrum is favored over a model with only independent pulsar noises with a Bayes factor in excess of $10^14$, and this same model is favored over an uncorrelated common power-law-spectrum model with Bayes factors of 200-1000, depending on spectral modeling choices. We have built a statistical background distribution for these latter Bayes factors using a method that removes inter-pulsar correlations from our data set, finding $p = 10^-3$ (approx. $3\sigma$) for the observed Bayes factors in the null no-correlation scenario. A frequentist test statistic built directly as a weighted sum of inter-pulsar correlations yields $p = 5 10^-5 - 1.9 10^-4$ (approx. $3.5 - 4\sigma$). Assuming a fiducial $f^-2/3$ characteristic-strain spectrum, as appropriate for an ensemble of binary supermassive black-hole inspirals, the strain amplitude is $2.4^+0.7_-0.6 10^-15$ (median + 90% credible interval) at a reference frequency of 1/(1 yr). The inferred gravitational-wave background amplitude and spectrum are consistent with astrophysical expectations for a signal from a population of supermassive black-hole binaries, although more exotic cosmological and astrophysical sources cannot be excluded. The observation of Hellings-Downs correlations points to the gravitational-wave origin of this signal.

@misc{agazie2023nanograv, abstract = {We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15-year pulsar-timing data set collected by the North American Nanohertz Observatory for Gravitational Waves. The correlations follow the Hellings-Downs pattern expected for a stochastic gravitational-wave background. The presence of such a gravitational-wave background with a power-law-spectrum is favored over a model with only independent pulsar noises with a Bayes factor in excess of $10^{14}$, and this same model is favored over an uncorrelated common power-law-spectrum model with Bayes factors of 200-1000, depending on spectral modeling choices. We have built a statistical background distribution for these latter Bayes factors using a method that removes inter-pulsar correlations from our data set, finding $p = 10^{-3}$ (approx. $3\sigma$) for the observed Bayes factors in the null no-correlation scenario. A frequentist test statistic built directly as a weighted sum of inter-pulsar correlations yields $p = 5 \times 10^{-5} - 1.9 \times 10^{-4}$ (approx. $3.5 - 4\sigma$). Assuming a fiducial $f^{-2/3}$ characteristic-strain spectrum, as appropriate for an ensemble of binary supermassive black-hole inspirals, the strain amplitude is $2.4^{+0.7}_{-0.6} \times 10^{-15}$ (median + 90% credible interval) at a reference frequency of 1/(1 yr). The inferred gravitational-wave background amplitude and spectrum are consistent with astrophysical expectations for a signal from a population of supermassive black-hole binaries, although more exotic cosmological and astrophysical sources cannot be excluded. The observation of Hellings-Downs correlations points to the gravitational-wave origin of this signal.}, added-at = {2023-06-29T13:46:07.000+0200}, author = {Agazie, Gabriella and Anumarlapudi, Akash and Archibald, Anne M. and Arzoumanian, Zaven and Baker, Paul T. and Becsy, Bence and Blecha, Laura and Brazier, Adam and Brook, Paul R. and Burke-Spolaor, Sarah and Burnette, Rand and Case, Robin and Charisi, Maria and Chatterjee, Shami and Chatziioannou, Katerina and Cheeseboro, Belinda D. and Chen, Siyuan and Cohen, Tyler and Cordes, James M. and Cornish, Neil J. and Crawford, Fronefield and Cromartie, H. Thankful and Crowter, Kathryn and Cutler, Curt J. and DeCesar, Megan E. and DeGan, Dallas and Demorest, Paul B. and Deng, Heling and Dolch, Timothy and Drachler, Brendan and Ellis, Justin A. and Ferrara, Elizabeth C. and Fiore, William and Fonseca, Emmanuel and Freedman, Gabriel E. and Garver-Daniels, Nate and Gentile, Peter A. and Gersbach, Kyle A. and Glaser, Joseph and Good, Deborah C. and Gultekin, Kayhan and Hazboun, Jeffrey S. and Hourihane, Sophie and Islo, Kristina and Jennings, Ross J. and Johnson, Aaron D. and Jones, Megan L. and Kaiser, Andrew R. and Kaplan, David L. and Kelley, Luke Zoltan and Kerr, Matthew and Key, Joey S. and Klein, Tonia C. and Laal, Nima and Lam, Michael T. and Lamb, William G. and Lazio, T. Joseph W. and Lewandowska, Natalia and Littenberg, Tyson B. and Liu, Tingting and Lommen, Andrea and Lorimer, Duncan R. and Luo, Jing and Lynch, Ryan S. and Ma, Chung-Pei and Madison, Dustin R. and Mattson, Margaret A. and McEwen, Alexander and McKee, James W. and McLaughlin, Maura A. and McMann, Natasha and Meyers, Bradley W. and Meyers, Patrick M. and Mingarelli, Chiara M. F. and Mitridate, Andrea and Natarajan, Priyamvada and Ng, Cherry and Nice, David J. and Ocker, Stella Koch and Olum, Ken D. and Pennucci, Timothy T. and Perera, Benetge B. P. and Petrov, Polina and Pol, Nihan S. and Radovan, Henri A. and Ransom, Scott M. and Ray, Paul S. and Romano, Joseph D. and Sardesai, Shashwat C. and Schmiedekamp, Ann and Schmiedekamp, Carl and Schmitz, Kai and Schult, Levi and Shapiro-Albert, Brent J. and Siemens, Xavier and Simon, Joseph and Siwek, Magdalena S. and Stairs, Ingrid H. and Stinebring, Daniel R. and Stovall, Kevin and Sun, Jerry P. and Susobhanan, Abhimanyu and Swiggum, Joseph K. and Taylor, Jacob and Taylor, Stephen R. and Turner, Jacob E. and Unal, Caner and Vallisneri, Michele and van Haasteren, Rutger and Vigeland, Sarah J. and Wahl, Haley M. and Wang, Qiaohong and Witt, Caitlin A. and Young, Olivia}, biburl = {https://www.bibsonomy.org/bibtex/24f709c243c5e0b188fdcd77d2ca53cd9/citekhatri}, description = {The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background}, doi = {10.3847/2041-8213/acdac6}, interhash = {fa6547e93e5905ac80e4c89730109dd4}, intrahash = {4f709c243c5e0b188fdcd77d2ca53cd9}, keywords = {tifr}, note = {cite arxiv:2306.16213Comment: 30 pages, 18 figures. Published in Astrophysical Journal Letters as part of Focus on NANOGrav's 15-year Data Set and the Gravitational Wave Background. For questions or comments, please email comments@nanograv.org}, timestamp = {2023-06-29T13:46:07.000+0200}, title = {The NANOGrav 15-year Data Set: Evidence for a Gravitational-Wave Background}, url = {http://arxiv.org/abs/2306.16213}, year = 2023 }