MPI for Gravitational Physics

Over the weekend, there were three new possible gravitational-wave signals / signal candidates. If confirmed as real, all of them came from merging black hole binaries.

1️⃣ S250927ck on Saturday afternoon: approx. 12 billion light-years away, sky position constrained to an area of 67 square degrees, chirp mass between 22 and 88 solar masses (https://gracedb.ligo.org/superevents/S250927ck/view/)

2️⃣ S250927cy on Saturday evening: approx. 13 billion light-years away, sky position constrained to an area of 944 square degrees, chirp mass between 11 and 88 solar masses. (https://gracedb.ligo.org/superevents/S250927cy/view/)

3️⃣ S250929c last night: approx. 14 billion light years away, sky position constrained to an area of approx. 2200 square degrees, chirp mass between 11 and 44 solar masses. (https://gracedb.ligo.org/superevents/S250929c/view/)

#GravitationalWaves #O4c #O4IsHere #BlackHoles

Sep 29, 2025 at 4:55amWeb
Show threadMPI for Gravitational PhysicsSep 29, 2025

The “chirp mass” mentioned above is a practical quantity if one wants to describe the signals of coalescing black holes: https://en.wikipedia.org/wiki/Chirp_mass.

It depends on the masses of the individual black holes. If these are equal, the following applies

M = 2^(-1/5) * m ≈ 0.87 * m

or

m = 2^(1/5) * M ≈ 1.15 * M

Here, M is the chirp mass and m is the mass of on of the black holes.

#GravitationalWaves #ChirpMass #Astronomy

Chirp mass - Wikipedia