The Samikhsya Bureau
NEW DELHI: Astronomers have discovered a new active galaxy identified as the farthest gamma-ray emitting galaxy that has so far been stumbled upon. This active galaxy called the Narrow-Line Seyfert 1 (NLS1) galaxy, which is about 31 billion light-years away, opens up avenues to explore more such gamma-ray emitting galaxies that wait to meet us.
Ever since 1929, when Edwin Hubble discovered that the Universe is expanding, it has been known that most other galaxies are moving away from us. Light from these galaxies is shifted to longer (and this means redder) wavelengths – in other words, it is red-shifted. Scientists have been trying to trace such red-shifted galaxies to understand the early Universe.
Scientists from ARIES, an autonomous institute of the Department of Science & Technology (DST), Government of India, in collaboration with researchers from other institutions, studied around 25,000 luminous Active galactic nuclei (AGN) from the Sloan Digital Sky Survey (SDSS), a major optical imaging and spectroscopic survey of astronomical objects in-operation for the last 20 years and found a unique object that emits high-energy gamma rays located at a high redshift (more than 1). They identified it as a gamma-ray emitting NLS1 galaxy, which is a rare entity in space.
For the research, the scientists used one of the largest ground-based telescopes in the world, the 8.2 m Subaru Telescope located at Hawaii, USA. They helped establish a new method to find high redshift NLS1 galaxies that were not known previously by comparing different emission lines in their spectra. The new gamma-ray emitting NLS1 was formed when the Universe was only about 4.7 billion years old as compared to its current age of about 13.8 billion years.
