TY - JOUR
T1 - The NANOGrav 15 yr Data Set
T2 - Bayesian Limits on Gravitational Waves from Individual Supermassive Black Hole Binaries
AU - The NANOGrav Collaboration
AU - Agazie, Gabriella
AU - Anumarlapudi, Akash
AU - Archibald, Anne M.
AU - Arzoumanian, Zaven
AU - Baker, Paul T.
AU - Bécsy, Bence
AU - Blecha, Laura
AU - Brazier, Adam
AU - Brook, Paul R.
AU - Burke-Spolaor, Sarah
AU - Case, Robin
AU - Casey-Clyde, J. Andrew
AU - Charisi, Maria
AU - Chatterjee, Shami
AU - Cohen, Tyler
AU - Cordes, James M.
AU - Cornish, Neil J.
AU - Crawford, Fronefield
AU - Cromartie, H. Thankful
AU - Crowter, Kathryn
AU - DeCesar, Megan E.
AU - Demorest, Paul B.
AU - Digman, Matthew C.
AU - Dolch, Timothy
AU - Drachler, Brendan
AU - Ferrara, Elizabeth C.
AU - Fiore, William
AU - Fonseca, Emmanuel
AU - Freedman, Gabriel E.
AU - Garver-Daniels, Nate
AU - Gentile, Peter A.
AU - Glaser, Joseph
AU - Good, Deborah C.
AU - Gültekin, Kayhan
AU - Hazboun, Jeffrey S.
AU - Hourihane, Sophie
AU - Jennings, Ross J.
AU - Johnson, Aaron D.
AU - Jones, Megan L.
AU - Kaiser, Andrew R.
AU - Kaplan, David L.
AU - Kelley, Luke Zoltan
AU - Kerr, Matthew
AU - Key, Joey S.
AU - Laal, Nima
AU - Lam, Michael T.
AU - Lamb, William G.
AU - W. Lazio, T. Joseph
AU - Lewandowska, Natalia
AU - Unal, Caner
N1 - Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.
PY - 2023/7/1
Y1 - 2023/7/1
N2 - Evidence for a low-frequency stochastic gravitational-wave background has recently been reported based on analyses of pulsar timing array data. The most likely source of such a background is a population of supermassive black hole binaries, the loudest of which may be individually detected in these data sets. Here we present the search for individual supermassive black hole binaries in the NANOGrav 15 yr data set. We introduce several new techniques, which enhance the efficiency and modeling accuracy of the analysis. The search uncovered weak evidence for two candidate signals, one with a gravitational-wave frequency of ∼4 nHz, and another at ∼170 nHz. The significance of the low-frequency candidate was greatly diminished when Hellings-Downs correlations were included in the background model. The high-frequency candidate was discounted due to the lack of a plausible host galaxy, the unlikely astrophysical prior odds of finding such a source, and since most of its support comes from a single pulsar with a commensurate binary period. Finding no compelling evidence for signals from individual binary systems, we place upper limits on the strain amplitude of gravitational waves emitted by such systems. At our most sensitive frequency of 6 nHz, we place a sky-averaged 95% upper limit of 8 × 10−15 on the strain amplitude. We also calculate an exclusion volume and a corresponding effective radius, within which we can rule out the presence of black hole binaries emitting at a given frequency.
AB - Evidence for a low-frequency stochastic gravitational-wave background has recently been reported based on analyses of pulsar timing array data. The most likely source of such a background is a population of supermassive black hole binaries, the loudest of which may be individually detected in these data sets. Here we present the search for individual supermassive black hole binaries in the NANOGrav 15 yr data set. We introduce several new techniques, which enhance the efficiency and modeling accuracy of the analysis. The search uncovered weak evidence for two candidate signals, one with a gravitational-wave frequency of ∼4 nHz, and another at ∼170 nHz. The significance of the low-frequency candidate was greatly diminished when Hellings-Downs correlations were included in the background model. The high-frequency candidate was discounted due to the lack of a plausible host galaxy, the unlikely astrophysical prior odds of finding such a source, and since most of its support comes from a single pulsar with a commensurate binary period. Finding no compelling evidence for signals from individual binary systems, we place upper limits on the strain amplitude of gravitational waves emitted by such systems. At our most sensitive frequency of 6 nHz, we place a sky-averaged 95% upper limit of 8 × 10−15 on the strain amplitude. We also calculate an exclusion volume and a corresponding effective radius, within which we can rule out the presence of black hole binaries emitting at a given frequency.
UR - http://www.scopus.com/inward/record.url?scp=85165635479&partnerID=8YFLogxK
U2 - 10.3847/2041-8213/ace18a
DO - 10.3847/2041-8213/ace18a
M3 - Article
AN - SCOPUS:85165635479
SN - 2041-8205
VL - 951
JO - Astrophysical Journal Letters
JF - Astrophysical Journal Letters
IS - 2
M1 - L50
ER -