Abstract:
Blazars comprise a subclass of radio loud Active Galactic Nuclei (AGN) that consist
of BL Lacertae objects (BL Lacs) and Flat Spectrum Radio Quasars (FSRQs). They
display large amplitude flux and polarization variability on diverse time-scales across
the entire electromagnetic (EM) spectrum. According to the current paradigm, blazars
have a Super Massive Black Holes (SMBHs) at their centre that accretes matter and
produce relativistic jets pointing almost in the direction of our line of sight. The emission
from blazars is predominated by non-thermal radiation produced by relativistic electrons
spiralling around the magnetic field in relativistic jets. The spectral energy distributions
(SEDs)of the blazars have two humps in log(νF ) vs log(ν) representation. The low
energy SED hump peaks in the frequency ranging from sub-mm to soft X-ray bands and
is well explained by synchrotron emission from an ultra-relativistic electron population
residing in the magnetic field of the approaching relativistic jet. The high energy SED
hump that peaks in MeV–TeV γ−ray bands, is usually attributed to inverse Compton
(IC) scattering of photons of those relativistic electrons.
