By week:
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Here is the plan as I see it now, it is, of course, subject to
revision as the start date of the course approaches.
The first evidence for neutron stars, black holes and gamma-ray bursts
was uncovered during the sixties. The stability and frequency of radio
pulsars alone was sufficient to make a convincing argument that they
were neutron stars. The energetics alone of gamma-ray bursts took nearly
three decades to determine, and the nature of a fraction of them is still
completely unconstrained.
I encourage you to follow check out this interesting take on the discovery
of pulsars: A Science Odyssey: On The Edge: Little Green Men.
The first neutron stars to be positively identified are the rotation-powered
neutron stars, specifically the radio pulsars. The most famous of the radio
pulsars is the source at the center of the Crab supernova remnant, the Crab
pulsar. The emission from these neutron stars is powered by the rotation
of the neutron star coupled to electromagnetic radiation through the magnetic
dipole moment of the star.
Check out this
Java Applet that simulates the electric field from a moving
charge.
ATNF Pulsar Catalog
and the sounds of pulsars at Princeton Pulsar Group.
Neutron stars are truly relativistic objects. You cannot understand
their structure without general relativity and nuclear physics. The
key observational quantities that probe this physics are the mass and
radius of neutron stars. You can explore some more and less realistic
equations of state using the Mass-Radius
Relation Applet and the Neutron-Star
Structure Applet.
Neutron stars are born in the fiery explosion of a supernova. Although
they are cold in the sense that the Fermi temperature is much greater than
the thermodynamic temperature except in the outermost layers, neutron stars
radiate like any hot bodies. In fact their interiors and crusts radiate
neutrinos and their surfaces radiate soft x-rays. These soft x-rays are some
of the few direct data that we get from neutron stars.
Many neutron stars are paired with other stars and accrete from their
companions. How a neutron star accretes is an interplay between the magnetic
field of the neutron star, the evolution of the orbit and the properties
of the companion star.
This week we will discuss your project ideas and I will discuss a topic
of your choice. This term it is X-ray Instrumentation.
Millisecond pulsars are among the most extreme denizens of the neutron star
zoo.
They spin up to 600 times per second (faster that a kitchen blender). How
do they form? What can they tell us?
This week we will cover just enough General Relativity to understand some
aspects of the Schwarzschild and Kerr blackholes. We will try to remember
the caveat that a little knowledge is a dangerous thing.
Accretion is ubiquitous in the universe and accounts for much
if not most of the radiation produced. Shakura and Sunyaev
in 1973 presented "the standard model" for accretion disks. Their results
have been applied to understand quasars and protostars and much
in between.
Supermassive black holes fuel the brightest persistent sources in the
universe, quasars. We will explore the rich phenomenology of quasars
and their cousins, the connection between black holes and the galaxies
in which they reside and what quasars can well us about galaxy formation.
Gamma-ray bursts still are mysterious but they were even more so a few
years ago. We will discuss what were the chief paradigms for understanding
gamma-ray bursts. We will frame our discussion within the Paczynski-Lamb
debate which look place in 1995. Although the discovery of afterglows
associated with "long" gamma-ray bursts has advanced our knowledge
substantially, the nature of "short" bursts remains elusive.
The central engines of gamma-ray bursts are completely hidden by the
gamma-ray emission from the bursts themselves, but gamma-ray emission
and other observations give clues to the nature of power behind
GRBs, specifically the collapse of the core of a massive star and the
subsequent hyperaccretion onto the central black hole.
In this final week, we will learn about the afterglows of gamma-ray bursts
that are in a way the relativistic analogoues of supernova remnants.
This afterglows provide a rich set of information about gamma-ray bursts,
their environment and the line of sight between us and them.
Last modified: Tuesday, 06 April 2004 07:28:10
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