Research Highlight

Window into early universe

doi:10.1038/nindia.2010.117 Published online 25 August 2010

Researchers have shed new light on blazars, a type of quasar that forms the energetic region surrounding the supermassive black hole at the centre of an active elliptical galaxy. The researchers have provided new insight into the short-lived energetic jets of blazar S5 0716+714.

Energy from blazars can take billions of years to reach the Earth's atmosphere, thus providing astronomers with information about the early stages of the universe.

To investigate possible periodic emission from blazar S5 0716+714, the researchers captured its optical emission using an Andor EMCCD (electron-multiplying charge-coupled device) camera mounted on a telescope operated by the Physical Research Laboratory at Gurushikhar, Mount Abu, India. The researchers discovered that the blazar has a periodicity in emission of around 900 s in the optical range. This provides a unique perspective on the variability studies of blazars at intraday timescales.

The simplest possible explanation for such a short period might be the flux arising from hot spots or some other phenomena related to the orbital motions that are close to the innermost stable circular orbit surrounding a supermassive black hole.

Although this particular blazar exhibited earlier evidence of periodic variations in emission of tens of minutes to several years for wavelengths ranging from radiowaves to X-rays, the researchers say that this new data provides the shortest known quasi-period yet detected in a blazar.

The authors of this work are from: Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, and the Physical Research Laboratory, Ahmedabad, India; Department of Physics, The College of New Jersey, New Jersey and Department of Physics and Astronomy, Georgia State University, Atlanta, USA.


  1. Rani, B. et al. Quasi-periodic oscillations of ~15 minutes in the optical light curve of the BL Lac S5 0716+714. Astrophys. J. Lett. 719, L153-L157 (2010) Article