Blazar emission mechanisms
Gamma-ray flux variability of luminous and high energy blazars: clues to blazar emission mechanisms
WHY IN NEWS:
Hot from PIB !
SYLLABUS COVERED: GS 3:Science and Tech
For PRELIMS it is important to understand the concept of Black Hole and AGN ! This can be asked in Prelims 2020.
- 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.
WHAT ARE BLAZARS ?
- Some blazars are thought to host binary black holes in them and could be potential targets for future gravitational-wave searches.
- Their study could provide clues to the processes happening close to the black hole, not visible through direct imaging.
REASEARCH FINDINGS :
- The results of this work will thus fill the gap on the knowledge of the high energy flux variability nature of blazars.
- 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.
CHALLENGES TO ASTROPHYSICS:
- One of the open problems in high energy astrophysics is to localize the site for the production of gamma-rays.
- Gamma-ray band is one of the bands of the electromagnetic spectrum on which there is limited knowledge on the flux variability of blazars.
- With the availability of near-simultaneous data covering the gamma-ray, X-ray, ultra-violet, optical, and infrared bands, the existing notion on high energy emission in blazars is challenged.
- This band needs to be explored as this is the energy range where the high energy emission from blazars peaks.
- Exploring this band of the electromagnetic spectrum will provide key inputs to constrain the high energy production site as well as the high energy emission processes.
- The expertise of handling high energy data from celestial sources gained in this work will build capacity to interpret the gamma-ray data that will emerge from India’s upcoming facility, the Major Atmospheric Cerenkov Experiment Telescope as well as from any X-ray missions by India in the future.
The results obtained from this particular piece of work will provide key inputs to the problem of finding the high energy gamma-ray production site in blazars.
Variability studies in the high energy gamma-ray band can help one to locate the high energy emission site and the high energy emission process.
Now, we are entering an era of multi-messenger astronomy, where light is not the only information we can collect from the heavens.
- Gravitational waves first detected in 2015 allow astronomers to observe collisions of black holes and neutron stars.
- Tracking neutrinos to their source would help astronomers understand the physics behind extreme environments, like the relativistic jets of a blazar, beyond what light alone can tell us.