Why in news?
- Researchers from the Indian Institute of Astrophysics (IIA) conducted the first systematic study on the gamma-ray flux variability nature on different types of blazars.
- Their study could provide clues to the processes happening close to the black hole, not visible through direct imaging.
What are blazars?
- At the centre of most galaxies, there’s a massive black hole that can have mass of millions or even billions of Suns that accrete gas, dust, and stellar debris around it.
- As these material falls towards the black hole, their gravitational energy gets converted to light forming active galactic nuclei (AGN).
- A minority of AGN (~15%) emit collimated charged particles called jets travelling at speeds close to the speed of light.
- Blazars are AGN whose jets are aligned with the observer’s line of sight.
- Some blazars are thought to host binary black holes in them and could be potential targets for future gravitational-wave searches.
- Blazars are the most luminous and energetic objects in the known universe were found to be emitters of gamma-rays in the 1990s.
- It is only with the capability of Fermi Gamma-ray space telescope (launched in 2008) to scan the entire sky once in three hours one is able to probe the flux variability characteristics of blazars on a range of time scales.