Dr. Sonkamble Satish (Chair)

X-ray Astronomy is a field of astronomy that deals with the study of celestial objects that emit X-rays. It is a relatively new field that has revolutionized our understanding of the universe by revealing many previously unknown phenomena. X-rays are a form of electromagnetic radiation that has a much shorter wavelength than visible light. They are produced by high-energy events, such as the collision of subatomic particles or the emission of radiation by very hot gases. In space, X-rays are emitted by a wide range of objects, including stars, galaxies, and black holes.

One of the most fascinating objects that emit X-rays are galaxy clusters. Galaxy clusters are large collections of galaxies held together by gravity. They are the largest structures in the universe, with masses ranging from a few hundred to a few thousand times that of the Milky Way. The gravitational pull of these clusters is so strong that it bends the path of light passing through them, a phenomenon known as gravitational lensing. The effect of gravitational lensing is to magnify and distort the images of background galaxies, making it easier for astronomers to study them.

Galaxy clusters emit X-rays because of the hot gas that fills the space between galaxies. This gas can be heated to millions of degrees by shock waves generated by the motion of galaxies within the cluster. The hot gas emits X-rays through a process known as thermal bremsstrahlung, in which the electrons in the gas are accelerated by the electric fields of ions, causing them to emit X-rays. By studying the X-ray emission from galaxy clusters, astronomers can learn about the properties of the hot gas, including its temperature, density, and chemical composition.

One of the most interesting features of galaxy clusters is the presence of dark matter. Dark matter is a form of matter that does not emit or absorb light, and is thus invisible to telescopes. However, its presence can be inferred from its gravitational effects on visible matter, such as stars and gas. The gravitational pull of dark matter is responsible for holding galaxy clusters together, and its distribution can be mapped by studying the motion of galaxies within the cluster. X-ray observations of galaxy clusters can also provide information about the distribution of dark matter, by measuring its effect on the hot gas. The gas is subject to the gravitational pull of both visible matter and dark matter, and its distribution is distorted by the presence of dark matter. By comparing X-ray observations with computer simulations, astronomers can estimate the amount and distribution of dark matter in galaxy clusters.

X-ray Astronomy has opened up a new window on the universe, allowing astronomers to study phenomena that are invisible to optical telescopes. By studying the X-ray emission from galaxy clusters, astronomers have gained valuable insights into the properties of hot gas, dark matter, and the large-scale structure of the universe. The study of galaxy clusters is an active area of research, with many new discoveries being made all the time.

In conclusion, X-ray Astronomy is an exciting field of study that has expanded our understanding of the universe. Galaxy clusters are fascinating objects that emit X-rays because of the hot gas that fills the space between galaxies. By studying the X-ray emission from galaxy clusters, astronomers can learn about the properties of the hot gas, the distribution of dark matter, and the large-scale structure of the universe. The study of galaxy clusters is a testament to the power of X-ray Astronomy to reveal previously unknown phenomena in the universe.

Objects of Interest : Galaxy Clusters,  Galaxy Groups,  AGNs,  X-ray point sources, XRBs

Current X-ray Observatories : Chandra   XMM-Newton  Suzaku   NuSTAR   ASTROSAT   eROSITA

Future X-ray Observatories :  XRISM LYNX Arcus ATHENA+

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