Pulsars: Properties, Radiation, and Discovery - Lecture 8

Explore the fascinating world of pulsars in this comprehensive lecture by Professor G Srinivasan, part of a summer course on gravity, astrophysics, and cosmology. Delve into the remarkable story of the Crab Nebula, understanding its expansion, emission properties, and the puzzling acceleration of its wisps. Discover the groundbreaking predictions and conjectures that led to the discovery of pulsars, including Pacini's extraordinary hypothesis and Jocelyn Bell's serendipitous detection. Examine the unique characteristics of neutron stars as pulsars, their electrodynamics, and magnetosphere. Investigate the complex mechanisms behind pulsar radiation, from synchrotron radiation to pair creation. Gain insights into the polar cap model, coherence of radio radiation, and the concept of brightness temperature. Conclude with a Q&A session to further explore this captivating topic in astrophysics.

Time: AM
A Journey through the Universe
Pulsars Lecture - 08
The remarkable story of the Crab Nebula
Crab Nebula is expanding with a velocity ~ 1500 km per second
LINE emission & Continuous emission
Continuous emission is strongly polarized
Expanding wisps near the centre of the nebula
Acceleration of the nebula!
Radio emission from the Crab!
A great prediction by Shklovskii
Radio emission from the Crab Nebula is very strongly linearly polarized.
X-Ray emission from the nebula!
The great puzzle!
The great central engine
An extraordinary conjecture by Pacini!
Properties of neutron stars
Oscillating charge will radiate
A Rotating Magnet will radiate
An extraordinary conjecture by Pacini!
Meanwhile in Cambridge!
Scintillation, or twinkling' of compact radio sources
Jocelyn Bell
An unknown scintillating source
6 Auguest 1967
Periodic pulsations discovered from the same source on 28 November 1967.
The great discovery announced!
Twinkle, twinkle little star
A video made with a TV camera showed that Baade's star pulsed with a period of 33 ms!
The great prediction by Franco Pacini
Neutron Stars as Pulsars
Average pulse profiles are unique to each pulsar. They are like their 'finger print'.
Micro structure of individual pulses
"Nulling" of pulsars
Neutron stars are powerful dynamos!
Pulsar electrodynamics
Magnetosphere of the neutron star
Light Cylinder
Radiation from an accelerated charge
Radiation from a relativistic charge
Synchrotron Radiation
Radio radiation from pulsars
The Polar Cap Model for pulsars
A hollow cone of radiation
Pulsed emission from the CRAB Pulsar.
Radiation from a relativistic charge
Pair creation
Coherence of the radio radiation
Brightness temperature limit
Q&A