The Indian Institute of Astrophysics (IIA) in Bangalore has completed a ground-breaking study on the gamma-ray flux variability nature of blazars, which are a type of active galactic nuclei (AGN). The research, the first of its kind, focused on characterising this flux variability on monthly time scales within the high energy gamma-ray band. The findings were recently published in the journal Astronomy and Astrophysics.
The Importance of Blazars
Blazars present a unique area of study for scientists due to their specific alignment with an observer’s line of sight. These types of AGNs may host binary black holes, making them potential targets for future gravitational-wave searches.
The heart of most galaxies is home to a massive black hole. As gas, dust, and stellar debris accumulate around it, the gravitational energy converts these materials into light, forming an AGN. About 15% of these AGNs emit jets of charged particles that travel at nearly the speed of light. These entities are categorised as Quasars, Radio-Galaxies, or Blazars depending on the angle of the jet stream in relation to the observer.
Blazars are the most luminous and energetic objects known in the universe. They were discovered as gamma-ray emitters in the 1990s. Their flux variability characteristics have been studied via the Fermi Gamma-ray space telescope since 2008.
Research From the Indian Institute of Astrophysics
The recent research carried out by the IIA has involved characterising the amplitude and timescale of flux variations in different types of blazars. Near-simultaneous data spanning gamma-ray, X-ray, ultra-violet, optical, and infrared bands challenged existing knowledge about high energy emission in blazars. The data reduction was made possible by the IIA’s High-Performance Computing facility.
Implications of the Study
The study provides insight into previously unseen events near the black hole and augments our understanding of blazars. The exploration of the Gamma-ray band of the electromagnetic spectrum offers valuable input on the production site and emission process of high energy.
Limited knowledge currently exists about flux variability in blazars within the gamma-ray band. This research fills a gap in the field by shedding light on the high energy flux variability nature of blazars.
The Future of Astrophysical Research
Localising the gamma-ray production site remains a significant challenge in high energy astrophysics. The research conducted by IIA builds our capacity to interpret the gamma-ray data that will come from India’s upcoming Major Atmospheric Cerenkov Experiment (MACE) Telescope, as well as future X-ray missions.
The MACE telescope, India’s largest and the world’s highest gamma-ray device, is being established at Hanle, Ladakh. Built by the Electronics Corporation of India Limited (ECIL), Hyderabad for the Bhabha Atomic Research Centre (BARC), this solar-powered device is remotely operated. It will help explore the gamma-ray energy region, bridging the gap between satellites and traditional Atmospheric Cerenkov experiments. The telescope bears the name of the Russian scientist Cerenkov who theorised that high-speed charged particles moving in a medium emit light.