Agazie G

Anumarlapudi A

Archibald AM

Arzoumanian Z

Baker PT

Becsy B

Blecha L

Brazier A

Brook PR

Burke-Spolaor S

Burnette R

Case R

Charisi M

Chatterjee S

Chatziioannou K

Cheeseboro BD

Chen S

Cohen T

Cordes JM

Cornish NJ

Crawford F

Cromartie HT

Crowter K

Cutler CJ

DeCesar ME

DeGan D

Demorest PB

Deng H

Dolch T

Drachler B

Ellis JA

Ferrara EC

Fiore W

Fonseca E

Freedman GE

Garver-Daniels N

Gentile PA

Gersbach KA

Glaser J

Good DC

Gultekin K

Hazboun JS

Hourihane S

Islo K

Jennings RJ

Johnson AD

Jones ML

Kaiser AR

Kaplan DL

Kelley LZ

Kerr M

Key JS

Klein TC

Laal N

Lam MT

Lamb WG

Lazio TJW

Lewandowska N

Littenberg TB

Liu T

Lommen A

Lorimer DR

Luo J

Lynch RS

Ma C-P

Madison DR

Mattson MA

McEwen A

McKee JW

McLaughlin MA

McMann N

Meyers BW

Meyers PM

Mingarelli CMF

Mitridate A

Natarajan P

Ng C

Nice DJ

Ocker SK

Olum KD

Pennucci TT

Perera BBP

Petrov P

Pol NS

Radovan HA

Ransom SM

Ray PS

Romano JD

Sardesai SC

Schmiedekamp A

Schmiedekamp C

Schmitz K

Schult L

Shapiro-Albert BJ

Siemens X

Simon J

Siwek MS

Stairs IH

Stinebring DR

Stovall K

\ua9 2023. The Author(s). Published by the American Astronomical Society.We report multiple lines of evidence for a stochastic signal that is correlated among 67 pulsars from the 15 yr 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 1014, 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 the latter Bayes factors using a method that removes interpulsar correlations from our data set, finding p = 10−3 (≈3σ) for the observed Bayes factors in the null no-correlation scenario. A frequentist test statistic built directly as a weighted sum of interpulsar correlations yields p = 5 
7 10−5 to 1.9 
7 10−4 (≈3.5σ-4σ). 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 − 0.6 + 0.7 
7 10 − 15 (median + 90% credible interval) at a reference frequency of 1 yr−1. 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

Newcastle University E-Prints

English

The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background

The NANOGrav 15 yr Data Set: Evidence for a Gravitational-wave Background

Abstract

Similar works

Full text

Available Versions

Newcastle University E-Prints