Dark matter plays an important role in our Universe: without it, galaxies and stars could not have formed.
Through gravitational instabilities, the initially smooth distribution of dark matter in the early Universe started to form clumps, in which gas could cool down and form stars.
Galaxy formation theories give us an idea of how this process has taken place, and predict the existence and properties of dark matter haloes in which galaxies nowadays should still reside.
But how do we know that these dark haloes are really there?
In this lecture I take you through the observational evidence for dark matter, and discuss the techniques that astronomers use to find and map dark matter in galaxies and galaxy clusters.
We also briefly look at alternatives to dark matter and finally we find out how one day, when our Sun has turned into a white dwarf, dark matter can save our lives…
Dark matter plays an important role in our Universe: without it, galaxies and stars could not have formed.
Through gravitational instabilities, the initially smooth distribution of dark matter in the early Universe started to form clumps, in which gas could cool down and form stars.
Galaxy formation theories give us an idea of how this process has taken place, and predict the existence and properties of dark matter haloes in which galaxies nowadays should still reside.
But how do we know that these dark haloes are really there?
In this lecture I take you through the observational evidence for dark matter, and discuss the techniques that astronomers use to find and map dark matter in galaxies and galaxy clusters.
We also briefly look at alternatives to dark matter and finally we find out how one day, when our Sun has turned into a white dwarf, dark matter can save our lives…
New developments in astronomical instrumentation open entirely new discovery spaces in astronomy. In fact, new instrumentation has often been the driver of very important discoveries.
This lecture discusses the physical processes that directly affect our ability to detect and characterize astrophysical objects.
This lecture contains a brief overview of the types of instrumentation commonly used in astronomy, such as imagers and spectrographs. Finally, Suresh Sivanandam discusses future ambitious instrumentation projects that will shape the scientific landscape over the next 10 years.
Nearly 400,000 years after the Big Bang, electrons and protons formed the first hydrogen atoms, and the Universe became transparent.
The photons that were released at that time form the cosmic microwave background that we observe today.
The cosmic microwave background reveals three surprising features of our Universe:
1. In its infancy, the Universe was remarkably homogeneous, but there were tiny fluctuations already in place.
2. The spatial geometry of the Universe is flat, even though this is an unstable state and there is not enough matter in the Universe to make it flat.
3. Most of the matter in the Universe is composed of unknown particles.
These observations lay the foundation for the current standard model of cosmology, in which the Universe initially underwent a growth spurt called inflation and is now filled with dark matter and dark energy.
I present a brief history of the Universe, focusing on the evidence for inflation, dark matter, and dark energy in the cosmic microwave…
Meet the family: neutron stars, pulsars, magnetars …
Neutron stars are among the most extreme objects populating our Universe and represent one of the ultimate evolutionary stages of massive stars that explode in supernovae.
These stellar remnants are small — 10 km in radius — but have densities comparable to atomic nuclei, and yet can spin at staggering rates of several hundred rotations per second. Most neutron stars are observed as radio pulsars when a narrow beam of radio emission created along its magnetic axis sweeps across our line of sight, similar to the beacon of a lighthouse.
However, the neutron star population is much more diverse and includes magnetars, which are powered by their very large magnetic fields, RRATs, which display transient radio pulsar behaviours, and young isolated neutron stars, which cool down by emitting X-ray thermal radiation.
In this lecture, I guide you through the zoo of neutron stars and explain their main observational properties.
I also describe…
This lecture gives a short, undergraduate level survey of the high energy astrophysics, focusing on the basic concepts, properties of compact objects (mostly neutron stars and black holes) and their associated physics and phenomena.
The second part of the lecture briefly discusses the active research in gamma-ray bursts, one of the most bizarre high energy astrophysical sources.
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