For all your gravitational-wave needs, the new @LIGO– @ego_virgo catalogue in out, covering the first half of the third observing run. Look at all the discoveries! #GWTC2

https://www.gw-openscience.org/eventapi/html/GWTC/

The #GWTC2 papers will be on today's arXiv. While we wait, here are links to our document server:

The Catalogue Paper: https://dcc.ligo.org/LIGO-P2000061/public
Tests of General Relativity Paper: https://dcc.ligo.org/LIGO-P2000091/public
The Binary Population Paper: https://dcc.ligo.org/LIGO-P2000077/public

The @LIGOLA @LIGOWA & @ego_virgo detectors were more sensitive than ever before in #O3, enabling a much higher rate of detection. We've totally eclipsed what came before, with 39 gravitational wave candidates from O3a #GWTC2

We have so far announced #GW190412, #GW190425, #GW190521 and #GW190814 from #GWTC2. This leaves a lot more. Most look like binary black holes (my favourite), but GW190426 (a low significance candidate) could be a neutron star–black hole binary?

#GWTC2 has a false alarm rate threshold for inclusion of 2 per year. This is applied to each of our detection pipelines independently, so we'd expect about 3 false alarms mixed in with the real signals, so we do need to be careful (especially with the low significance ones)

This plot is art. Gravitational-wave astronomy is only 5 years old and already we have more data than we know how to plot.

The masses of the components of the binaries (m1 > m2), the mass ratio q = m2/m1, the effective inspiral spin chi_eff and luminosity distance D_L #GWTC2

With our *50* gravitational-wave candidates, we can start to do some really cool things #GWTC2 With more detections we can perform more exacting tests of @AlbertEinstein's theory of general relativity. So far, so good. Next time

We performed 8 tests of general relativity (one per reindeer):
1 After subtracting best fitting waveforms, our residuals are consistent with noise
2 The low-frequency inspiral and high-frequency merger & ringdown parts of the waveform are consistent

3 We check for parametrized deviations in the waveform
4 We look for deviations in the spin-induced quadrupole moment
5 We look for changes in the way gravitational waves propagate (including looking for a graviton mass term)
6 We measure the final black hole ringdown

7 We look for gravitational wave echoes after the merger
8 We check for evidence of additional gravitational-wave polarizations
In all cases, we find no evidence for deviations from general relativity, unaccounted for physics or evidence of systematics in our analysis #GWTC2

Our observations can tell us about how black holes and neutron stars form. We infer a binary black hole merger rate density of 23.9+14.9−8.6 Gpc−3 yr−1 (which increases with redshift) and a binary neutron star merger rate density of = 320+490−240 Gpc−3 yr−1 #GWTC2

The inferred mass distribution for primary (larger) black holes in binary black holes using different parameterised models. A simple power law doesn't work so well. The mass distribution extends higher than previously. This is what the family of black holes looks like! #GWTC2

For the first time, we can measure that some black holes have spins misaligned with their orbital angular momentum. On the whole more spins are misaligned by less than 90 degrees than more than 90 degrees. This could be a hint on how they form #GWTC2

For dynamically formed binaries we'd expect an isotropic distribution of spins. For binaries from isolated evolution we'd expect spins mostly aligned with the orbital angular momentum. We seem to have a mix of these properties: there's not one way of making binary black holes?

I'm very excited to see what everyone makes of these new observations. Putting together #GWTC2 was a huge effort by many, many people in @LIGO and @ego_virgo. We've never analysed these many signals before! For more gravitational-wave goodness: https://twitter.com/i/lists/232216910

Overwhelmed by *all* the gravitational-wave science? This science summary has you covered #GWTC2 https://twitter.com/EveAChase/status/1321637993673826306