Astronomers have discovered a new and unknown object in the Milky Way galaxy, which is heavier than the heaviest known neutron stars but lighter than the lightest known black holes. The team of scientists from several institutions, including the University of Manchester and the Max Planck Institute for Radio Astronomy in Germany, found the object in orbit around a rapidly spinning pulsar with a millisecond period, located 40,000 light-years away in a dense star cluster known as a globular cluster. Millisecond pulsars are a type of pulsar (a neutron star with radiation pulses) that rotate at very high speeds, hundreds of times per second.
Scientists say this mysterious object is a pulsar in a binary system with a compact body, in the mass gap between neutron stars and black holes. According to the scientists, this could be the first discovery of a radio pulsar in a binary black hole system, which may allow for new tests of Einstein's general relativity and open doors for studying black holes. Ben Stappers, an astrophysics professor at the University of Manchester, said, "Any possibility regarding the nature of the companion is exciting. The pulsar-black hole system will serve as an important target for testing gravity theories, and the heavy neutron star will provide new insights into nuclear physics at very high densities."
When a neutron star, the ultra-dense remnant of a dead star, gains too much mass, it collapses. What it becomes afterward is the subject of much speculation, but it is believed that it could turn into a black hole.
