Black Holes
One of the most important findings in astrophysics is that when stars die they can collapse to extremely small objects. When their internal fuel sources are exhausted, stars millions of miles across can collapse to roughly 10 kilometers in diameter, known as neutron stars.
Blazars and Active Galactic Nuclei
Nature has provided us with spectacular particle accelerators called active galactic nuclei, or AGN. These are galaxies that host tremendously large black holes at their centers, some of which are known to be a million times heavier than our sun.
Cosmic Microwave Background
The Cosmic Microwave Background, or CMB, is a faint glow in microwave radiation that is almost perfectly uniform across the sky. This thermal radiation was emitted about 380,000 years after the Big Bang, as the universe became transparent for the first time.
Dark Matter and New Physics
To better understand our universe, it is often necessary to estimate the mass of an astrophysical object. Those objects can be found across a vast range, from the size of the Sun, the solar system, the Milky Way, and even the entire universe.
First Cosmological Objects
The first objects to form in the Universe were stars. Some 200 million years after the big bang, the diffuse gas permeating the early Universe is able to contract under its own gravity setting the collapse to the first stars in motion.
Galaxy Clusters
Galaxy clusters are the largest objects in the universe, spanning distances up to ten million light years, and containing the equivalent mass of a million, billion suns.
Galaxy Formation
Galaxies are collections of stars, gas and dark matter that play host to some of the most extreme processes in nature. Galaxies are also the signposts of the universe, beacons of light scattered throughout a mostly dark universe.
Gamma-Ray Bursts
Gamma-ray bursts (GRBs) are short flashes of photons thought to originate from collapsing stars. These strong pulses have energies in the X-ray to gamma-ray ranges and time scales ranging from a few milliseconds to around 100 seconds. The separation between "short" and "long" bursts is around two seconds.
Gravitational Lensing
We cannot see one of the universe’s primary constituents: dark matter. The reason is simple: it's dark. But we can infer where it is located from observations of distant galaxies because of a key property of light, namely that it does not always travel in straight lines.