From UPSC perspective, the following things are important :
Prelims level : Blazars
Mains level : Black Holes, Blazars
Researchers from the Indian Institute of Astrophysics (IIA), Bangalore have conducted the first systematic study on the gamma-ray flux variability nature on different types of Blazars.
Strange terminologies from space-based studies are very important from prelims point of view. We can expect a statement based question seeking to identify the term which is being referred to in the paragraph.
What are Blazars?
- At the center 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.
- Gamma-ray band is one of the bands of the electromagnetic spectrum on which there is limited knowledge on the flux variability of blazars.
- Major problem while studying them is to localize the site for the production of gamma-rays.
- The study of blazars could provide clues to the processes happening close to the black hole, not visible through direct imaging.
- Exploring blazars will provide key inputs to constrain the high energy production site as well as the high energy emission processes.