Microquasar
A stellar black hole system with relativistic jets and X-ray emission.
A microquasar is essentially a scaled-down version of a quasar, centered on a stellar-mass black hole that is several times heavier than its companion star. These systems are close enough—within our own galaxy or a nearby one—to be studied in detail. The black hole pulls matter from its companion, creating an accretion disk. Friction within this disk can heat it to extreme temperatures, causing it to emit X-rays. Additionally, the disk shoots out narrow streams, or jets, of subatomic particles moving at nearly the speed of light, which produce strong radio emissions.
The first microquasar, SS 433, was discovered in 1979 in the Milky Way when its relativistic jets were observed by Margon and colleagues. It was considered an exotic oddity until similar objects, like GRS 1915+105, were confirmed in 1994. In some cases, bright blobs of plasma within the jets appear to move faster than light—an illusion called superluminal motion, caused by particles traveling just below light speed at a small angle toward the observer. In 1996, the American Astronomical Society awarded the Bruno Rossi Prize to Felix Mirabel and Luis Rodríguez for discovering this superluminal motion in GRS 1915+105 and for finding double-sided radio jets from the galactic sources 1E1740.7-2942 and GRS 1758-258.
Because microquasars are much smaller than quasars, their effects scale differently. A quasar’s accretion disk averages a few thousand degrees, while a microquasar’s disk averages several million degrees. The typical quasar accretion disk spans about 1 billion square kilometers, compared to just 1,000 square kilometers for a microquasar. Quasar jets can stretch millions of light-years, but microquasar jets only reach a few light-years. However, the knots within microquasar jets can appear to move across the sky about a thousand times faster than those in quasar jets, simply because observed microquasars are located within the Milky Way—at distances of kiloparsecs—rather than hundreds of megaparsecs or more.
- first_discovered
- 1979
- first_example
- SS 433
- discoverers
- Margon et al.
- key_feature
- relativistic jets
- accretion_disk_temperature
- several million degrees
- accretion_disk_size
- average 1000 km²
- jet_length
- a few light-years
Lore & Background
In 1979, SS 433, in our own galaxy, became the first microquasar to be discovered, when Margon et al. observed its relativistic jets. It was thought to be the most exotic case until similar objects such as GRS 1915+105 were confirmed in 1994. In some cases, blobs or 'knots' of brighter plasma within the jets appear to be traveling faster than the speed of light, an optical illusion called superluminal motion caused by sub-light-speed particles projected at a small angle relative to the direction to the observer.
Reader's Guide
Microquasars provide a scaled-down laboratory for studying relativistic jet phenomena that also occur in much larger quasars. Their proximity within the Milky Way allows detailed observation of accretion disk dynamics, jet formation, and superluminal motion—an optical illusion that does not violate relativity. The discovery of SS 433 in 1979 opened the field, and subsequent confirmation of objects like GRS 1915+105 expanded understanding. The 1996 Bruno Rossi Prize recognized key contributions to observing superluminal motion and double-sided jets. Because microquasars have accretion disks millions of degrees hotter and thousands of times smaller than quasar disks, they offer unique insights into extreme physics near stellar-mass black holes. Their jets, though only a few light-years long, exhibit rapid angular motion across the sky due to their relative closeness, enabling studies of particle acceleration and plasma behavior not possible with distant quasars. This makes microquasars essential for testing models of black hole accretion and jet production.
Did You Know?
- The first microquasar discovered was SS 433 in 1979, observed by Margon et al.
- Superluminal motion in microquasar jets is an optical illusion caused by sub-light-speed particles projected at a small angle toward the observer.
- The average accretion disk temperature in a microquasar is several million degrees, compared to several thousand degrees in a quasar.
- The 1996 Bruno Rossi Prize was awarded for discovering superluminal motion in GRS 1915+105 and double-sided radio jets from 1E1740.7-2942 and GRS 1758-258.
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