Skip to main content

How Black Holes Accelerate Particles to Incredible Energies

Black holes, depending on their size, can accelerate particles like electrons to incredible speeds. There are four main types of black holes based on their mass:

  1. Stellar-Mass Black Holes (small)
  2. Intermediate-Mass Black Holes (medium-sized)
  3. Supermassive Black Holes (large)
  4. Ultra-Massive Black Holes (extremely large, like the one in Abell 1201)

Electrons near a black hole get trapped in its magnetic field, which spins along with the black hole. This magnetic field accelerates the electrons, but several factors limit their speed:

  • Inverse Compton Scattering: Electrons lose energy when they collide with light particles.
  • Curvature Radiation: Electrons lose energy as they follow the curved magnetic field lines.
  • Breaking Free: Electrons may eventually escape the magnetic field.

The maximum speed an electron can reach depends on the black hole’s size and where the electron starts its journey. For example:

  • Stellar-mass black holes can accelerate electrons up to speeds with Lorentz factors of 2×1062 \times 10^6 to 2×1082 \times 10^8.
  • Supermassive black holes can accelerate electrons to speeds as high as 2×10152 \times 10^{15}.

The position of the electron near the black hole also matters—closer to the black hole, the more energy it loses, while farther away allows for more efficient acceleration.

Black holes are fascinating objects in space that can pull in everything around them due to their immense gravity. But did you know they can also speed up tiny particles, like electrons, to incredibly high energies? Scientists Nikuradze and Osmanov have studied how black holes do this using their rotating magnetic fields. 

Different Types of Black Holes

Black holes come in different sizes, and their ability to accelerate particles depends on their mass:

  1. Stellar-Mass Black Holes (Stellar-MBHs): Small black holes with masses less than 100 times the Sun’s mass.
  2. Intermediate-Mass Black Holes (IMBHs): Medium-sized black holes with masses between 100 and 100,000 times the Sun’s mass.
  3. Supermassive Black Holes (SMBHs): Huge black holes with masses over 100,000 times the Sun’s mass.
  4. Ultra-Massive Black Holes (UMBHs): Exceptionally large black holes, like the one in the galaxy cluster Abell 1201, which is 32.7 billion times the Sun’s mass.

Stellar-MBHs and SMBHs are well-known, but IMBHs are still mysterious, and scientists are trying to confirm if they exist.

How Black Holes Accelerate Particles

Black holes have strong magnetic fields that spin along with them. Electrons near the black hole get trapped in these fields and move along magnetic lines like beads on a wire. As the black hole spins, it flings the electrons outward, speeding them up like a slingshot.

Electron trajectory (Blue curve), Black disk in the middle is the BH and outer black circle is the LC © authors

However, the acceleration doesn’t go on forever. Several factors limit how fast these electrons can go:

  1. Inverse Compton Scattering: Electrons lose energy when they hit light particles (photons).
  2. Curvature Radiation: Electrons lose energy as they travel along the curved magnetic field lines.
  3. Breaking Free: Sometimes, electrons can’t stay on the magnetic lines and lose their acceleration.

The balance between speeding up and losing energy determines how fast an electron can go.

How Electron Energies Vary by Black Hole Size

1. Stellar-Mass Black Holes (Stellar-MBHs)

  • Electrons reach speeds described by Lorentz factors of 2×1062 \times 10^6 to 2×1082 \times 10^8.
  • These black holes are small, so the only limit to electron speed is how fast the magnetic field spins with the black hole.

2. Intermediate-Mass Black Holes (IMBHs)

  • Electrons can reach Lorentz factors of 2×1082 \times 10^8 to 2×10112 \times 10^{11}.
  • The limits depend on the black hole’s size and where the electron starts. For larger IMBHs:
    • Closer to the black hole, inverse Compton scattering reduces acceleration.
    • Farther away, electrons can speed up more efficiently.

3. Supermassive Black Holes (SMBHs)

  • Electrons can reach Lorentz factors of 2.45×10102.45 \times 10^{10} to 2×10152 \times 10^{15}.
  • Bigger SMBHs have stronger limits because of intense inverse Compton scattering. To speed up effectively, electrons must start near a region called the "light cylinder," where the magnetic field lines spin fastest.

4. Ultra-Massive Black Holes (UMBHs)

  • Electrons near the UMBH in Abell 1201 can reach Lorentz factors of 1.1×10131.1 \times 10^{13} to 6.6×10166.6 \times 10^{16}.
  • These black holes have so much energy that both curvature radiation and co-rotation effects limit electron acceleration.

Why Starting Position Matters

Where an electron begins its acceleration around a black hole affects how fast it can go:

  • Closer to the Black Hole: Energy loss is higher because of strong forces like curvature radiation and inverse Compton scattering.
  • Farther from the Black Hole: Acceleration is more efficient, allowing electrons to reach higher energies.

This means that even in the same black hole, electrons starting in different places can end up with different maximum speeds.

Why This Matters

Studying how black holes accelerate particles helps us understand some of the most energetic events in the universe, like:

  1. Cosmic Rays: High-energy particles that hit Earth, possibly coming from black holes.
  2. Gamma-Ray Blazars: Extremely bright objects powered by supermassive black holes.
  3. Intermediate-Mass Black Holes: These mysterious black holes might be easier to detect if we can link them to specific particle accelerations.

Conclusion

Nikuradze and Osmanov’s research shows how black holes act like cosmic particle accelerators, pushing electrons to incredible speeds depending on their size and environment. From small Stellar-MBHs to gigantic UMBHs, these findings help us better understand the extreme forces at work in the universe.

Black holes aren’t just cosmic mysteries—they are powerful engines that shape the high-energy universe in ways we’re only beginning to uncover.

Reference: N. Nikuradze, Z. N. Osmanov, "Maximum possible energies of electrons accelerated in magnetospheres of rotating black holes", Arxiv, 2024. https://arxiv.org/abs/2411.16982


Technical Terms 

1. Black Hole

A black hole is a region in space with gravity so strong that nothing, not even light, can escape from it. They form when massive stars collapse under their own gravity.

2. Lorentz Factor

The Lorentz factor is a way of measuring how fast something is moving compared to the speed of light. Higher Lorentz factors mean the object is moving closer to the speed of light.

3. Magnetic Field Lines

Magnetic field lines are invisible paths that show the direction of a magnetic field. Think of them like lines on a map that show where a compass needle would point.

4. Inverse Compton Scattering

This happens when a fast-moving particle (like an electron) bumps into a light particle (photon). The electron loses some energy, and the photon gains energy, becoming more powerful.

5. Curvature Radiation

When electrons move along a curved path (like around a black hole’s magnetic field), they lose energy in the form of light. This is called curvature radiation.

6. Light Cylinder (LC)

The light cylinder is a special area around a spinning black hole where the magnetic field lines move at the speed of light. Electrons starting near this area can be accelerated faster.

7. Co-Rotation Constraint

This is a limit on how fast electrons can move along magnetic field lines that spin with the black hole. Once they reach this limit, they can’t be accelerated further.

8. Relativistic Factor

The relativistic factor measures how much the energy and motion of an object are affected by its speed. At high speeds (close to the speed of light), relativistic effects become important, and objects gain energy rapidly.

9. Ultra-Massive Black Hole (UMBH)

A UMBH is a type of black hole that is billions of times heavier than the Sun. These are much bigger than the usual supermassive black holes found in the centers of galaxies.

10. Synchrotron Emission

This is the energy released when charged particles, like electrons, spiral around magnetic field lines. It’s how black holes lose some of their energy.

11. Thomson Regime

This term describes how electrons lose energy when they collide with photons. In the Thomson regime, the photon energy after collision remains relatively low, which affects the electron's acceleration.

12. Particle Acceleration

This is the process of speeding up tiny particles, like electrons, to very high speeds. In black holes, magnetic fields act like cosmic slingshots, throwing particles out at incredible speeds.


Popular posts from this blog

How Planetary Movements Might Explain Sunspot Cycles and Solar Phenomena

Sunspots, dark patches on the Sun's surface, follow a cycle of increasing and decreasing activity every 11 years. For years, scientists have relied on the dynamo model to explain this cycle. According to this model, the Sun's magnetic field is generated by the movement of plasma and the Sun's rotation. However, this model does not fully explain why the sunspot cycle is sometimes unpredictable. Lauri Jetsu, a researcher, has proposed a new approach. Jetsu’s analysis, using a method called the Discrete Chi-square Method (DCM), suggests that planetary movements, especially those of Earth, Jupiter, and Mercury, play a key role in driving the sunspot cycle. His theory focuses on Flux Transfer Events (FTEs), where the magnetic fields of these planets interact with the Sun’s magnetic field. These interactions could create the sunspots and explain other solar phenomena like the Sun’s magnetic polarity reversing every 11 years. The Sun, our closest star, has been a subject of scient...
Read more

Could Primordial Black Holes Have Formed from Aborted Phase Transitions?

Ai and colleagues propose a new way that primordial black holes (PBHs) could form in the early universe, using a mechanism that involves an "aborted phase transition." This takes place during the reheating phase after inflation, a period when the universe's temperature rises and then falls. During reheating, the universe is filled with a pressureless fluid called a reheaton. As the temperature rises to a maximum (Tmax), it surpasses the critical temperature needed for a phase transition, but not enough for bubbles to fully form and expand. These bubbles, which briefly nucleate as the temperature reaches Tmax, expand and then shrink as the temperature falls back below the critical level. When the bubbles shrink, they leave behind dense regions. These regions collect surrounding matter and eventually collapse into primordial black holes. The PBHs formed this way continue to grow in mass until the universe transitions into radiation domination. Primordial black holes (PBHs) ...
Read more

How Wedge Holography Reveals the Multiverse?

Have you ever wondered if our universe is just one among many, or if there are parallel universes in a vast cosmic landscape? These are questions that have intrigued scientists and philosophers alike for centuries. In a recent study by Gopal Yadav, the concept of wedge holography sheds light on these mysteries, offering insights into the possibility of communicating universes and multiverses. Unveiling the Concept of Wedge Holography Wedge holography is a fascinating concept that helps us understand the structure of the universe, particularly in the context of de-Sitter space—a space with a positive cosmological constant. In his paper, Yadav constructs wedge holography for the de-Sitter bulk, paving the way for a deeper exploration of the multiverse hypothesis. From AdS to dS: A Journey of Discovery The journey begins with a comparison between wedge holography in anti de-Sitter (AdS) space and de-Sitter (dS) space. While previous research focused on AdS space, Yadav's work delves i...
Read more