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Massive black holes of a few million to billion solar masses lurk at the centers of the most present-day massive galaxies but their origin is still unknown. The low mass galaxies (M* ~ 3x109 Mʘ) hosting black holes with masses ranging from 103 to 105 Mʘ are ideal laboratories to test the models of black hole formation and they may help in understanding the co-evolution of central black holes with their host galaxies. In this thesis, we have developed a detailed theoretical model/framework to estimate the radio emission from low-mass active galactic nuclei (AGN). We also compute the contribution of radio emission from HII regions and supernova remnants in the host galaxy. Our estimated radio fluxes for AGN of 105 -107 Mʘ range from 0.6-2000 nJy at redshift 10 assuming the Eddington limited accretion. The most recent observations by the James Webb Space Telescope (JWST) have unveiled the presence of low-mass AGN at high redshift. We predict that these newly observed sources can be detected in radio with upcoming radio telescopes such as the next-generation Very Large Array (ngVLA) and the Square Kilometer Array (SKA) for integration times of 1-100 hours. These observations will unambiguously confirm the existence of AGN.

Massive black holes of a few million to billion solar masses lurk at the centers of the most present-day massive galaxies but their origin is still unknown. The low mass galaxies (M* ~ 3x109 Mʘ ) hosting black holes with masses ranging from 103 to 105 Mʘ are ideal laboratories to test the models of black hole formation and they may help in understanding the co-evolution of central black holes with their host galaxies. In this thesis, we have developed a detailed theoretical model/framework to estimate the radio emission from low-mass active galactic nuclei (AGN). We also compute the contribution of radio emission from HII regions and supernova remnants in the host galaxy. Our estimated radio fluxes for AGN of 105 -107 Mʘ range from 0.6-2000 nJy at redshift 10 assuming the Eddington limited accretion. The most recent observations by the James Webb Space Telescope (JWST) have unveiled the presence of low-mass AGN at high redshift. We predict that these newly observed sources can be detected in radio with upcoming radio telescopes such as the next-generation Very Large Array (ngVLA) and the Square Kilometer Array (SKA) for integration times of 1-100 hours. These observations will unambiguously confirm the existence of AGN.

The battlespace environment extends far above the surface of the Earth. Of special importance are the outer layers of the Earth's atmosphere, from altitudes 100 to 1000 km, where there is sufficient mass to impede the motion of Earth-orbiting spacecraft, and where layers of charged particles control the propagation of radio waves. Changes in atmospheric "drag" alter the orbits of the thousands of space objects in low Earth orbit (LEO) that are tracked by the U.S. Space Command. The ionosphere transmits, reflects, retards, and refracts kHz to MHz radio wave frequencies. As a result, fluctuations in the neutral and ionized environment can negatively impact Naval operations by disrupting communications and navigation and by degrading radar accuracy, targeting precision, and orbit prediction. The Sun is the primary source of variations in the neutral and ionized upper atmosphere. A suite of new solar and atmospheric data bases that extend over the Sun's 11-year activity cycle are now refining our understanding of the intricately interconnected Sun-Earth system, thereby improving the ability to predict this region's impact on DoD systems. The new data bases include solar imagery from NRL instruments aboard the Solar Heliospheric Observatory (SOHO), daily thermospheric mass density derived from spacecraft drag via a new NRL algorithm, and total electron content obtained from analyses of GPS timing by the Center for Orbit Determination in Europe (CODE)., Published in NRL Review, p133-135, 2007. Sponsored in part by NASA.