Amazing stuff! More to come, stay tuned!
Where is the Albert Einstein (or Zweistein) of our time who can explain the workings of the universe in a few, short papers?
"A 15-year collaboration in which Cornell astrophysicists have played leading roles has found the first evidence of gravitational waves slowly undulating through the galaxy, ripples in space-time likely generated by pairs of supermassive black holes in the process of merging. ...
In research ... scientists ... said its 15 years of observations with radio telescopes and a collection of cosmic clocks – rapidly spinning pulsars – now provided compelling evidence of gravitational waves with oscillations lasting years to decades. ...
The detection and ongoing measurements are expected to advance understanding of the universe’s evolution on large and small scales, from insights about how often galaxies collide and what drives black holes to merge, to the fundamental nature of gravity ...
The newly detected gravitational waves differ from the fleeting, high-frequency ones detected in 2015 by the Laser Interferometer Gravitational-wave Observatory (LIGO), which were created by the collision of black holes 30 times as massive as the sun. In contrast, the low-frequency waves are thought to be generated by orbiting pairs of the universe’s most massive black holes – millions or billions of times more massive than the sun, with sizes larger than the distance between Earth and the sun. ...
“We’ve also demonstrated that these massive black holes in the centers of galaxies can get close enough to emit gravitational waves, as they approach and spiral around each other faster and faster. That process also was disputed.” ...
“Even though it’s taken 15-plus years,” ... “this announcement is really just the beginning.” ..."
In research ... scientists ... said its 15 years of observations with radio telescopes and a collection of cosmic clocks – rapidly spinning pulsars – now provided compelling evidence of gravitational waves with oscillations lasting years to decades. ...
The detection and ongoing measurements are expected to advance understanding of the universe’s evolution on large and small scales, from insights about how often galaxies collide and what drives black holes to merge, to the fundamental nature of gravity ...
The newly detected gravitational waves differ from the fleeting, high-frequency ones detected in 2015 by the Laser Interferometer Gravitational-wave Observatory (LIGO), which were created by the collision of black holes 30 times as massive as the sun. In contrast, the low-frequency waves are thought to be generated by orbiting pairs of the universe’s most massive black holes – millions or billions of times more massive than the sun, with sizes larger than the distance between Earth and the sun. ...
“We’ve also demonstrated that these massive black holes in the centers of galaxies can get close enough to emit gravitational waves, as they approach and spiral around each other faster and faster. That process also was disputed.” ...
“Even though it’s taken 15-plus years,” ... “this announcement is really just the beginning.” ..."
From the abstract:
"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 × 10−5 to 1.9 × 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 ${2.4}_{-0.6}^{+0.7}\times {10}^{-15}$ (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."
Figure 1. Summary of the main Bayesian and optimal-statistic analyses presented in this paper, which establish multiple lines of evidence for the presence of Hellings–Downs correlations in the 15 yr NANOGrav data set.
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