Level 1 - Absolute Beginner
Space is very big. In the middle of many galaxies, there is a black hole. A black hole pulls things in with strong gravity.
Scientists looked at a galaxy called Mrk 501. They watched it with radio telescopes for 23 years.
They think there may be two black holes there. The two black holes go around each other. One trip takes about 121 days.
The scientists are not sure yet. But the idea may explain strange things in the galaxy.
- galaxy
- A huge group of stars.
- black hole
- A place in space that pulls everything in.
- gravity
- A force that pulls things together.
- telescope
- A tool to see far away things.
- scientist
- A person who studies the world.
- radio
- A kind of wave used by some telescopes.
- strange
- Not normal.
- orbit
- To go around something.
Level 2 - Elementary
Astronomers say a galaxy called Markarian 501, or Mrk 501, may hide two giant black holes that circle each other. The idea comes from a team led by Silke Britzen at the Max Planck Institute for Radio Astronomy in Germany.
The team studied about 23 years of radio data. They found a second, fainter jet of particles near the center of the galaxy. A second jet suggests a second black hole.
In their model the two black holes orbit each other once every 121 days. They are very close together, only a few hundred times the distance from Earth to the Sun. Depending on their size, they could merge within about a hundred years.
The result is not final. The two black holes cannot be seen separately, even by the best telescopes, so other scientists will want to test the idea.
- astronomer
- A scientist who studies space.
- jet
- A fast beam of particles shot out from near a black hole.
- merge
- To join together into one.
- model
- An idea that explains how something works.
- data
- Facts and numbers collected in a study.
- faint
- Not bright.
- separately
- One by one, not together.
- test
- To check if something is true.
Level 3 - Intermediate
A team led by Silke Britzen of the Max Planck Institute for Radio Astronomy reports evidence that the active galaxy Markarian 501, roughly 460 million light years away, hosts a close pair of supermassive black holes. The study, published in Monthly Notices of the Royal Astronomical Society, rests on about 23 years of radio observations.
The key finding is a second, fainter jet looping around the radio core. Until now, only one jet, the one pointing toward Earth, had been tracked. A second jet implies a second central engine, and the wobble in the system's orientation fits two black holes whose orbital plane sways.
In the proposed model the pair circles every 121 days, separated by roughly 250 to 540 times the distance between Earth and the Sun. Depending on their masses, they could collide within about a century, an instant by cosmic standards.
The authors stress that the detection is not conclusive. The two objects are far too close to be imaged separately, even by the Event Horizon Telescope, so confirmation will have to come indirectly. If it holds, Mrk 501 could also become a candidate source for the gravitational wave background that pulsar timing arrays have detected.
- supermassive
- Having a mass millions or billions of times that of the Sun.
- hosts
- Contains or has present.
- implies
- Suggests something without stating it directly.
- orbital plane
- The flat surface in which an orbit lies.
- conclusive
- Settling a question beyond doubt.
- indirectly
- Not through direct observation.
- pulsar timing array
- A network of radio observations of pulsars used to detect gravitational waves.
- by cosmic standards
- Compared with the huge scale of the universe.
Level 4 - Advanced
Astronomers led by Silke Britzen of the Max Planck Institute for Radio Astronomy have assembled what they regard as the most compelling explanation yet for the erratic behaviour of Markarian 501: a binary of supermassive black holes spiralling toward each other roughly 460 million light years from Earth. Their analysis, drawing on about 23 years of radio data, appears in Monthly Notices of the Royal Astronomical Society.
The linchpin is a second, fainter jet of relativistic particles, discovered looping around the galaxy's radio core. Only the jet pointing toward us had been followed before. A second outflow implies a second engine, and the slow precession of the system's orientation is naturally explained if the orbital plane of two bodies sways over time.
The model assigns the pair an orbital period of about 121 days and a separation of a few hundred astronomical units. Depending on the masses involved, coalescence could occur within roughly a hundred years, a blink in cosmological terms, though the shrinking of the orbit itself cannot be observed directly.
The authors are careful to call the detection suggestive rather than conclusive. Even the Event Horizon Telescope lacks the resolution to split such a tight pair, so verification will have to rest on indirect signatures. A confirmed binary would make Mrk 501 a prime suspect for contributing to the gravitational wave background that pulsar timing arrays have registered, linking one galaxy to a cosmic hum.
- erratic
- Not even or regular; unpredictable.
- binary
- A pair of objects orbiting each other.
- linchpin
- A key element that holds a whole argument together.
- relativistic
- Moving at a speed close to that of light.
- precession
- A slow change in the direction of a spinning or orbiting object.
- coalescence
- The process of merging into one body.
- suggestive
- Hinting at something without proving it.
- signatures
- Characteristic signs by which something can be identified.
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