Cygnus A

* Cyg A
* Black Hole

## Kurzgesagt

### **First appearance**

The Largest Black Hole in the Universe - Size Comparison

### **Latest appearance**

The Largest Black Hole in the Universe - Size Comparison

## Kurzgesagt

### **First appearance**

The Largest Black Hole in the Universe - Size Comparison

### **Latest appearance**

The Largest Black Hole in the Universe - Size Comparison

## General Information

Cygnus A is a radio galaxy and one of the strongest radio sources in the sky. It is 760 million light years from Earth. With Cassiopeia A and Puppis A, they were the first radio stars discovered by directly looking at them.

Cygnus A has a large central supermassive black hole, with the width of half the Solar System, creating magnetic funnels that make radio lobes extending from the center of the galaxy, invisible in visible light. This black hole is the engine of an active galactic nucleus at the center of Cygnus A galaxy.

### History

In 1939, Grote Reber discovered a radio source in the constellation of Cygnus. Later in 1946, James S. Hey and James Phillips, identified that this radio source repeatedly emitted flashes of light. This implied that the source could be a compact object.

By 1950, more detailed observations in England and Australia showed that Cygnus A radiation was quite steady. The variability was due to the bending of radio waves by Earth's ionosphere, which is the same thing that causes stars to twinkle. In 1953, radio astronomers Roger Jennison and M. K. Das Gupta identified that the radio source is a double source, meaning there's two of them.

In 2015, another radio source was discovered, by Perley et al. and Karl Jansky at the Very Large Array telescope, 1,500 light-years away from the center of Cygnus A and was named Cygnus A-2. Between 1989 and 2015, the object, which also happens to be in the same place as an infrared source we already knew about, increased in brightness in terms of radio frequencies 6 times.

### Properties

When scientists and radio astronomers took a picture of this galaxy in radio wavelengths, they saw two giant radio lobes towering over the galaxy in opposite directions. In visible light, these jets are invisible, so you can't see them.

The jets extend many times the size of the visible part of the galaxy. The length of each jet is estimated to be 250,000 light-years. Both jets combined is 2.5 Milky Ways wide.

The galaxy has an apparent magnitude of 16.22, which is very dim from Earth and requires a strong telescope to be seen.

Like all other radio galaxies, Cygnus A has an active galactic nucleus. This galactic nucleus is powered by the central supermassive black hole, Cygnus A-1.

The supermassive black hole has a mass 2.5 billion times that of our Sun, giving it a diameter of 17.4 billion kilometers.

In 2015, scientists at the Very Large Array telescope discovered another radio source 1,500 light-years away from the center of Cygnus A. For several years, the object, which also happens to be in the same place as a infrared source we already knew about, increased in brightness in terms of radio frequencies 6 times, comparable to the brightest known supernova. Due to lack of measurements, the brightening rate of this object is unknown.

The collected data is consistent with a second supermassive black hole, orbiting the primary. It has been suggested that the radio frequency increase is the result of an outflow caused by the second black hole disturbing the primary.