Indian astronomers have proposed several theoretical models of dark matter, including the Axion Model, Sterile Neutrino Model, and Fuzzy Dark Matter Model.

Theoretical models of dark matter are proposed to explain the observed rotation curves of galaxies, account for the missing mass in the universe, and understand the nature of dark matter.

The Axion Model predicts that axions should be very light and weakly interacting, should be produced in the early universe, and should have a very long lifetime.

The main challenge in detecting dark matter is that it is very weakly interacting, does not emit any light, and is distributed throughout the universe.

Indirect methods for detecting dark matter include observing the gravitational effects of dark matter, searching for dark matter particles in underground laboratories, and looking for evidence of dark matter in cosmic rays.

AstroSat is an Indian satellite mission dedicated to studying dark matter and other astrophysical phenomena.

The Sterile Neutrino Model predicts that sterile neutrinos should be very light and weakly interacting, should be produced in the early universe, and should have a very long lifetime.

The main challenge in distinguishing between dark matter and other forms of matter is that dark matter does not interact with electromagnetic radiation, is distributed throughout the universe, and is very weakly interacting.

The Fuzzy Dark Matter Model predicts that fuzzy dark matter particles should be very light and weakly interacting, should be produced in the early universe, and should have a very long lifetime.

Subrahmanyan Chandrasekhar was an Indian astronomer who proposed the Axion Model of dark matter.

The Warm Dark Matter Model predicts that warm dark matter particles should be more massive than cold dark matter particles, should be produced in the early universe, and should have a shorter lifetime than cold dark matter particles.

Vikram Sarabhai was an Indian astronomer who proposed the Sterile Neutrino Model of dark matter.

The Cold Dark Matter Model predicts that cold dark matter particles should be very light and weakly interacting, should be produced in the early universe, and should have a very long lifetime.

Harish-Chandra was an Indian astronomer who proposed the Fuzzy Dark Matter Model.

The Self-Interacting Dark Matter Model predicts that self-interacting dark matter particles should be more massive than cold dark matter particles, should be produced in the early universe, and should have a shorter lifetime than cold dark matter particles.