That was simply astounding and had us asking, How common are black holes of this size, and how often do they merge? The study was an attempt to interpret the gravitational wave detections through the lens of what is known about galaxy formation and to form a framework for understanding future occurrences.
The number of black holes of a given mass per galaxy will depend on the size of the galaxy. The reason is that larger galaxies have many metal-rich stars, and smaller dwarf galaxies are dominated by big stars of low metallicity.
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Knowledge awaits. See Subscription Options Already a subscriber? Create Account See Subscription Options. Such a small size ruled out white dwarfs, pointing towards the hypothesized neutron star as the explanation for these Pulsars , as they came to be known. The reason why we see pulses is because a beam of electromagnetic radiation from one of the star's electromagnetic poles hits us each time the star spins around its' axis. The magnetic and rotational axes of a pulsar are misaligned for a similar reason that "true north" and "magnetic north" are different on Earth.
The high spin rate sometimes thousands of revolutions per second! A special kind of a neutron star is a Magnetar , which is an extremely powerful magnetic star. In fact, they are the most magnetic objects known in the universe.
They do not last long as magnetars, maybe only 30 years, after that the magnetic field fades. However, while a magnetar is active, it can produce magnetic fields with the intensity of 10 15 Tesla. The strongest magnet produced on Earth is only 40 Tesla.
Strange things go on around magnetars.. Astronomers are only aware of 15 or so magnetars' existence. As the name indicates, these objects are black, because they have such strong gravity that the escape velocity from a black hole exceeds the speed of light.
Therefore, nothing, not even light can escape it. Proving their existence was difficult at first, but now astronomers believe they have enough evidence tho be certain that they exist. One way to discover a black hole is if it is located in a close binary star system. Such is the case of Cygnus X-1 , which was the first likely candidate for a black hole that was discovered.
Cygnus X-1 is a migh mass binary starsystem with a blue star, and a black hole containing about 8. These measurements alone rule out a neutron star as the companion. The system holds a separation of 30 million kilometres away from each other, and matter falls from the donor star down to the black hole, in an accretion disc, which is heated up to millions of degrees.
The accretion disc is so warm it radiates x-rays! Strange things happen around black holes. As one gets closer and closer to a black hole's Event Horizon , time appears to slow down to an outside observer. The event horizon is a region, usually spherical if the black hole isn't rotating , which marks the outer boundary of a black hole.
Inside, the gravity is so strong that nothing can escape.
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