Sökning: "square kilometre array"

Hittade 5 avhandlingar innehållade orden square kilometre array.

  1. 1. Ultra-wideband feed design and characterization for next generation radio telescopes

    Författare :Jonas Flygare; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; reflector feed; geodesy; radio astronomy; quad-ridge flared horn; square kilometre array; dielectric loading; spline-defined; decade bandwidth; Ultra-wideband antennas;

    Sammanfattning : Radio telescopes are used as tools for observations in both radio astronomy and geodesy. To observe the weak sources in space, highly sensitive receivers headed by optimized reflector feeds are needed. Wideband and ultra-wideband (UWB) receiver systems enable large continuous frequency bandwidth and reduce the number of receivers that are needed. LÄS MER

  3. 2. Dielectrically Loaded Quad-ridge Flared Horns for Ultra Wideband Reflector Feed Applications in Radio Astronomy

    Författare :Jonas Flygare; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; dielectric loaded antennas; dielectric materials; reflector antenna feeds; radio astronomy; ultra wideband antennas; quad-ridge flared horn qrfh ; radio receivers; horn antennas; broadband antennas; aperture antennas.;

    Sammanfattning : Reflector-based radio telescopes are used as tools for observations in both radio astronomy and space geodesy. To observe the weak sources in space, highly sensitive receivers, fronted by optimized reflector feeds, are therefore needed. LÄS MER

  4. 3. Understanding the large-scale structure of the the21-cm signal originating from the Epoch of Reionisation

    Författare :Ivelin Georgiev; Garrelt Mellema; Jens Jasche; Aurel Schneider; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; reionisation; cosmology; 21-cm; large-scale structure; Astronomy; astronomi;

    Sammanfattning : The first billion years from the beginning of the Universe is the focus of multiple astronomical facilities in the upcoming decade. This unique era is marked by the formation of the first stars and galaxies, which release ionising radiation into the intergalactic medium(IGM). LÄS MER

  5. 4. Tomographic study of the 21-cm signal

    Författare :Sambit Kumar Giri; Garrelt Mellema; Matthew Hayes; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; dark ages; reionization; first stars – early universe – methods: statistical – radio lines: galaxies – techniques: interferometric – techniques: image processing; Astronomy; astronomi;

    Sammanfattning : The next generation radio telescopes such as the Square Kilometre Array (SKA) will be able to produce images of the redshifted Hi (neutral hydrogen) 21-cm signal from the Epoch of reionization (EoR). In this thesis, we use the simulated tomographic images of the signal and investigate methods to extract and interpret information from those images. LÄS MER

  7. 5. Tomographic studies of the 21-cm signal during reionization : Going beyond the power spectrum

    Författare :Sambit K. Giri; Garrelt Mellema; Benoît Semelin; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; reionization; non-gaussianity; first stars; image processing; Astronomy; astronomi;

    Sammanfattning : The formation of the first luminous sources in the Universe, such as the first generation of stars and accreting black holes, led to the ionization of hydrogen gas present in the intergalactic medium (IGM). This period in which the Universe transitioned from a cold and neutral state to a predominantly hot and ionized state is known as the Epoch of Reionization (EoR). LÄS MER